@article{pandey_nayak_hatua_bhattacharya_2024, title={A PCB-Incorporated Inductor Based Filter Design Solution for Differential Mode Noise of 3-Phase SiC-MOSFET Based VSI}, volume={12}, ISSN={["2169-3536"]}, url={https://doi.org/10.1109/ACCESS.2024.3368511}, DOI={10.1109/ACCESS.2024.3368511}, abstractNote={Electromagnetic emission is a challenging problem for the Wide Band Gap (WBG) device based power electronic converters. The Differential Mode (DM) noise contains switching frequency components and high-frequency noise peaks. High-frequency DM noise peak depends upon the loop inductance of the converter and output capacitance of the switch. Optimization of switching frequency or variable switching frequency could attenuate switching frequency noise and its harmonics only, but not the switching transient noise. Using a passive filter is common for IGBT based VSI, where the high-frequency DM noise peak occurs in the <inline-formula> <tex-math notation="LaTeX">$1MHz$ </tex-math></inline-formula> to <inline-formula> <tex-math notation="LaTeX">$5MHz$ </tex-math></inline-formula> range. However, the high-frequency DM noise peak appears beyond <inline-formula> <tex-math notation="LaTeX">$10MHz $ </tex-math></inline-formula> for SiC-MOSFET based VSI. It requires a high corner frequency, lower inductance, and capacitance of the DM filter. However, getting an inductor with a high Self-Resonating Frequency (SRF) is challenging. This paper proposes a PCB-incorporated inductor based segmented LCLC filter with high SRF value for high-frequency DM noise of SiC-MOSFET based VSI. The filter design is based on mathematical modeling of the DM noise of SiC-MOSFET based VSI. The proposed filter is implemented and verified on a SiC-MOSFET based VSI, driving a <inline-formula> <tex-math notation="LaTeX">$5 kVA$ </tex-math></inline-formula> induction motor at <inline-formula> <tex-math notation="LaTeX">$40 kHz$ </tex-math></inline-formula> switching frequency.}, journal={IEEE ACCESS}, author={Pandey, Vibhav and Nayak, Sougata and Hatua, Kamalesh and Bhattacharya, Subhashish}, year={2024}, pages={34958–34972} }
 @article{gulur_iyer_bhattacharya_2024, title={A Partially Rated LC Trap Type AC Filter for Grid-Tied Voltage Source Converters}, volume={5}, ISSN={["2644-1314"]}, url={https://doi.org/10.1109/OJPEL.2024.3408272}, DOI={10.1109/OJPEL.2024.3408272}, abstractNote={<bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\boldmath <inline-formula><tex-math notation="LaTeX">$AC$</tex-math></inline-formula> power filters play an important role in limiting the high-frequency current harmonics injected by grid-tied voltage source converters (VSCs). Amongst the various types of filters, \boldmath <inline-formula><tex-math notation="LaTeX">$LCL$</tex-math></inline-formula> filters with integrated \boldmath <inline-formula><tex-math notation="LaTeX">$LC$</tex-math></inline-formula> traps have become popular due to their ability to achieve a size reduction of the grid side inductor while demonstrating a similar current harmonic mitigation performance as a traditional <inline-formula><tex-math notation="LaTeX">$LCL$</tex-math></inline-formula> filter. In this article, a passively damped filter network with a partially rated \boldmath <inline-formula><tex-math notation="LaTeX">$LC$</tex-math></inline-formula> trap (also referred to as the \boldmath <inline-formula><tex-math notation="LaTeX">$L\text{-}PT\text{-}L$</tex-math></inline-formula> filter) is proposed and delineated. The proposed \boldmath <inline-formula><tex-math notation="LaTeX">$L\text{-}PT\text{-}L$</tex-math></inline-formula> filter provides a \boldmath <inline-formula><tex-math notation="LaTeX">$\text{-}60\;dB/dec$</tex-math></inline-formula> roll-off characteristics at frequencies greater than switching frequency. Additionally, it is also demonstrated that this proposed \boldmath <inline-formula><tex-math notation="LaTeX">$L\text{-}PT\text{-}L$</tex-math></inline-formula> filter has smaller voltage ratings for two of its shunt-connected capacitor components due to the specific placement of the damping resistor. A systematic analysis of the proposed \boldmath <inline-formula><tex-math notation="LaTeX">$L\text{-}PT\text{-}L$</tex-math></inline-formula> filter is elucidated to design and select the component parameters. Steady-state and transient experimental results captured from a grid-tied 2-Level, 3\boldmath <inline-formula><tex-math notation="LaTeX">$\phi$</tex-math></inline-formula> VSC prototype are provided to validate the grid current harmonic filtering capability, reduced voltage ratings of the two shunt capacitors and passive damping performance of the proposed \boldmath <inline-formula><tex-math notation="LaTeX">$L\text{-}PT\text{-}L$</tex-math></inline-formula> filter. The proposed approach can achieve 19% and 36% filter shunt branch volume reduction for low voltage (208 V, 60 Hz) and medium voltage (4.16 kV, 60 Hz) grid-tied inverter systems, respectively, compared to state-of-the-art \boldmath <inline-formula><tex-math notation="LaTeX">$LCL$</tex-math></inline-formula> filters with integrated \boldmath <inline-formula><tex-math notation="LaTeX">$LC$</tex-math></inline-formula> traps.</b>}, journal={IEEE OPEN JOURNAL OF POWER ELECTRONICS}, author={Gulur, Srinivas and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish}, year={2024}, pages={852–863} }
 @article{kokkonda_bhattacharya_veliadis_panayiotou_2024, title={A SiC Based Two-Stage Pulsed Power Converter System for Laser Diode Driving and Other Pulsed Current Applications}, volume={5}, ISSN={["2644-1241"]}, url={https://doi.org/10.1109/OJIA.2024.3476428}, DOI={10.1109/OJIA.2024.3476428}, journal={IEEE OPEN JOURNAL OF INDUSTRY APPLICATIONS}, author={Kokkonda, Raj Kumar and Bhattacharya, Subhashish and Veliadis, Victor and Panayiotou, Chrysanthos}, year={2024}, pages={455–468} }
 @article{das_satpathy_bhattacharya_2024, title={An Online Open-Circuit Fault Diagnosis Technique for Three-Level Inverter-Fed Six-Phase PMSM Drives}, volume={39}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2024.3440641}, DOI={10.1109/TPEL.2024.3440641}, number={11}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Das, Partha Pratim and Satpathy, Subhransu and Bhattacharya, Subhashish}, year={2024}, month={Nov}, pages={14974–14987} }
 @article{narasimhan_bhattacharya_zargari_2024, title={Comparison of a 10 kV SiC Current Switch with two 6.5 kV Series Connected Si SGCTs for Medium Voltage Current Source Converter Applications}, url={https://doi.org/10.1109/TIA.2024.3479163}, DOI={10.1109/TIA.2024.3479163}, journal={IEEE Transactions on Industry Applications}, author={Narasimhan, Sneha and Bhattacharya, Subhashish and Zargari, Navid R.}, year={2024} }
 @article{burugula_sharma_dhiman_aljumah_bhattacharya_2024, title={Control of parallel connected Dual Active Bridge converters under unbalanced input voltages in an MV compliant Solid State Transformer}, ISBN={["979-8-3503-1767-1"]}, ISSN={["2473-7631"]}, DOI={10.1109/ITEC60657.2024.10599006}, journal={2024 IEEE TRANSPORTATION ELECTRIFICATION CONFERENCE AND EXPO, ITEC 2024}, author={Burugula, Vasishta and Sharma, Shrivatsal and Dhiman, Shubham and Aljumah, Osamah and Bhattacharya, Subhashish}, year={2024} }
 @article{dhiman_sharma_aljumah_bhattacharya_2024, title={DC Short Circuit Fault Analysis of a Triple Active Bridge Converter for Fault Ride-Through Capability}, ISSN={["1048-2334"]}, DOI={10.1109/APEC48139.2024.10509326}, abstractNote={This paper presents the analysis of a triple active bridge (TAB) converter during a DC short circuit fault (SCF). An understanding of the converter operating during SCF is required to design the converter for fault ride-through capability. The analysis is done by evaluating the inductor currents of a TAB converter during rated conditions and during SCF conditions. The analysis aids the design of magnetic components, thermal requirements, and device selection of a converter. The analytical model based on generalized harmonic approximation (GHA) is developed to derive the fault current magnitudes. The impact of different power transfer inductances and different powersharing operating modes of a TAB converter are analyzed in detail for the SCF study. Extensive simulations are carried out in PLECS to demonstrate the operation of TAB converter during SCF. Experimental results on a laboratory prototype are provided for a wide range of operating conditions to validate the results from the analytical model and switching simulations.}, journal={2024 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Dhiman, Shubham and Sharma, Shrivatsal and Aljumah, Osamah and Bhattacharya, Subhashish}, year={2024}, pages={2112–2118} }
 @article{narasimhan_rastogi_sisson_leslie_bhattacharya_2024, title={Design Considerations, Development, and Experimental Validation of a 3.3 kV SiC-Based Reverse Voltage Blocking Half Bridge Module for Current Source Inverter Application}, volume={60}, ISSN={["1939-9367"]}, url={https://doi.org/10.1109/TIA.2024.3362297}, DOI={10.1109/TIA.2024.3362297}, abstractNote={Wide-band gap (WBG) devices have enabled the re-emergence of current source inverters (CSIs). With increased <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dv/dt$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$di/dt$</tex-math></inline-formula> of WBG devices, the parasitic inductances in the power loop and gate loop are critical in reducing the induced voltage at the devices. This paper presents the design consideration and development of a low inductance 3.3 kV silicon carbide (SiC) based reverse voltage blocking (RVB) half-bridge (HB) module for CSI-based applications. The module comprises a SiC-MOSFET (3.3 kV/50 A die) and a SiC-MPS diode (3.3 kV/50 A die) to form a 3.3 kV SiC-based RVB switch in the HB configuration. The module inductance is estimated using ANSYS Q3D. The impact of the unequal busbar parasitic inductances between the CSI phases on the RVB switch in the HB module is discussed considering the medium voltage (MV) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dv/dt$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$di/dt$</tex-math></inline-formula> limits. The increased substrate thickness helps reduce the module's parasitic capacitance and thus reduces electromagnetic interference (EMI) concerns. The static and dynamic characterization of the RVB switch or current switch (CS) is performed to demonstrate the functionality of the proposed module. The static and dynamic characterization is used to understand a three-phase CSI system's switching frequency limits, heat sink, and cooling requirements. The steady-state hardware result and the dynamic response of the three-phase CSI with the proposed module are presented.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Narasimhan, Sneha and Rastogi, Sagar Kumar and Sisson, Colton and Leslie, Scott and Bhattacharya, Subhashish}, year={2024}, pages={4264–4279} }
 @article{kolli_parashar_kokkonda_bhattacharya_veliadis_2024, title={Design of Asynchronous Microgrid Power Conditioning System with Gen-3 10 kV SiC MOSFETs for MV Grid Interconnection}, ISSN={["1048-2334"]}, DOI={10.1109/APEC48139.2024.10509274}, journal={2024 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Kolli, Nithin and Parashar, Sanket and Kokkonda, Raj Kumar and Bhattacharya, Subhashish and Veliadis, Victor}, year={2024}, pages={514–521} }
 @article{parashar_kolli_kokkonda_kanale_bhattacharya_baliga_2024, title={Dynamic Voltage Balancing Across Series-Connected 10 kV SiC JBS Diodes in Medium Voltage 3L-NPC Power Converter Having Snubberless Series-Connected 10 kV SiC MOSFETs}, volume={5}, ISSN={["2644-1284"]}, url={https://doi.org/10.1109/OJIES.2024.3450509}, DOI={10.1109/OJIES.2024.3450509}, journal={IEEE OPEN JOURNAL OF THE INDUSTRIAL ELECTRONICS SOCIETY}, author={Parashar, Sanket and Kolli, Nithin and Kokkonda, Raj Kumar and Kanale, Ajit and Bhattacharya, Subhashish and Baliga, Bantval Jayant}, year={2024}, pages={1058–1084} }
 @article{satpathy_das_bhattacharya_veliadis_2024, title={Experimental Study Based Switching Sequence for Reduction of Peak Voltage Transients in GaN-based 3L-ANPC Inverter}, ISSN={["1048-2334"]}, DOI={10.1109/APEC48139.2024.10509060}, abstractNote={The high dv/dt and di/dt operation of GaN HEMTs lead to high turn-on and turn-off transient voltage overshoot (TOV). In a 3L-ANPC topology with redundant states of operation, the severity of transients also depends on the switching sequence. Multiple critical power commutation loops in a 3L-ANPC topology make the power loop design optimization a challenging task. Therefore, in cases where further design optimization is not possible, effective use of the different possible switching sequences can achieve lower peak voltage transients. Various possible switching sequences are compared in this work based on the severity of TOV. A modified full-mode formed by an additional high-frequency operation of the clamping switch is presented as an overvoltage mitigation strategy at high voltage and high current. A turn-on and turn-off transient severity analysis is shown for all considered switching modes based on an experimental three-level double pulse test. The test results present a GaN HEMT-equipped three-level ANPC phase leg operating at 700 V DC. Based on the analysis, a current-dependent switching sequence selection is presented to minimize the resulting peak voltage transients for continuous inverter operation.}, journal={2024 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Satpathy, Subhransu and Das, Partha Pratim and Bhattacharya, Subhashish and Veliadis, Victor}, year={2024}, pages={1235–1241} }
 @article{narwal_agarwal_cheng_baliga_bhattacharya_hopkins_2024, title={FET Junction Temperature Monitoring Using Novel On-Chip Solution}, ISSN={["1048-2334"]}, DOI={10.1109/APEC48139.2024.10509157}, abstractNote={A novel junction temperature monitoring sensor is proposed and experimentally demonstrated for application in MOS-gate power devices. The sensor is created using the polycide gate electrode layer of the devices to create a temperature-sensitive resistor without any additional fabrication steps. The resistor is located on the field oxide with one end grounded at the device reference terminal to isolate it from the device current and voltage transients. It allows in-situ monitoring of the device junction temperature during active circuit operation. The technology has been implemented to monitor the junction temperature of Silicon Carbide Junction Barrier Schottky Field Effect Transistors (SiC JBSFETs) with the bi-directional FET (BiDFET).}, journal={2024 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, publisher={IEEE}, author={Narwal, Ramandeep and Agarwal, Aditi and Cheng, Tzu-Hsuan and Baliga, B. Jayant and Bhattacharya, Subhashish and Hopkins, Douglas C.}, year={2024}, pages={2475–2482} }
 @article{parashar_isik_kolli_kokkonda_bhattacharya_2024, title={Overvoltage Protection of Series-Connected 10kV SiC MOSFETs Following Switch Failures in MV 3L-NPC Converter for Safe Fault Isolation and Shutdown}, volume={12}, ISSN={["2169-3536"]}, url={https://doi.org/10.1109/ACCESS.2024.3351184}, DOI={10.1109/ACCESS.2024.3351184}, abstractNote={This paper presents a design methodology for overvoltage protection across 10kV SiC MOSFETs during turn-off after switch failure in a MV SST Power Conditioning System (PCS) enabled by a cascaded Three-Phase (3P) Three-level (3L) Neutral Point Clamped (NPC) Active Front-End Converter (AFEC) and Dual Active Bridge (DAB) using series-connected 10kV SiC MOSFETs and 10kV SiC JBS diodes. The methodology uses an active voltage clamp at the gate terminal and desat detection technique to identify abrupt open and turn-on switch failures across series-connected 10kV SiC MOSFETs. The analytical model estimates over-current time and turn-off voltage transition by considering bus bar inductance, device base plate capacitance and common mode (CM) choke tied between the heat sink and midpoint of the DC link capacitor. The transition model is used to evaluate the turn-off timing for series-connected MOSFETs, snubber resistors, snubber capacitors, and gate resistors to avoid MOSFET overvoltage during converter shutdown, without affecting the voltage balancing and efficiency during normal operation. The MOSFET turn-off transition during the shutdown has been verified in the Saber RD simulation using the validated Saber RD MAST model of 10kV SiC MOSFETs and 10kV SiC JBS diodes at 13.8kV AC/24kV DC level. The fault isolation and MV SST PCS shutdown have been verified in a real-time environment using HIL setup with Xilinx FPGAs and RTDS, at 13.8kV AC/24kV DC link under PCS operating conditions. The normal operation of 3L-NPC pole hardware with modified snubber resistors, snubber capacitors, and gate resistors is verified by experiments conducted at 7kV DC, 10A load current.}, journal={IEEE ACCESS}, author={Parashar, Sanket and Isik, Semih and Kolli, Nithin and Kokkonda, Raj Kumar and Bhattacharya, Subhashish}, year={2024}, pages={10102–10119} }
 @article{anzola_sharma_aizpuru_bhattacharya_artal-sevil_2024, title={Performance Improvement of a Silicon Partial Power Converter Over a Silicon Carbide Full Power Converter}, volume={10}, ISSN={["2332-7782"]}, url={https://doi.org/10.1109/TTE.2023.3292501}, DOI={10.1109/TTE.2023.3292501}, abstractNote={This article studies the new benefits that partial power processing (PPP) brings to silicon (Si) devices compared to wide bandgap (WBG) technologies. To prove this, the proposed case study consists of an onboard charger (OBC) application in which a Si-based partial power converter (PPC) is compared with a silicon carbide (SiC)-based full power converter (FPC). The OBC application considers three different technologies of lithium-ion batteries and the main comparison metrics are: semiconductor switching, temperature rise of semiconductors, volume, and device losses (efficiency). This last one is oriented to energy losses (Wh) and not to power losses (W) as classical design. An analytical model is used to compute switching and conduction losses. Depending on the operating point, switching events are segregated into zero voltage switching (ZVS), incomplete ZVS (iZVS), and hard switching. It is shown that the Si-based PPC may enter non-ZVS in certain operating conditions. However, its efficiency remains above 99%, producing up to five times lower energy losses than the SiC-based FPC. Also, the case temperature of the semiconductors is halved and a reduction in the volume and electrical stress of the devices is achieved. This permits a global multiobjective optimization. The results are experimentally validated using a 3-kW prototype of SiC-based FPC and Si-based PPC.}, number={1}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Anzola, Jon and Sharma, Shrivatsal and Aizpuru, Iosu and Bhattacharya, Subhashish and Artal-Sevil, Jesus Sergio}, year={2024}, month={Mar}, pages={1680–1691} }
 @article{satpathy_das_bhattacharya_2024, title={Power Layout Design of a GaN HEMTs-Based High-Power High-Efficiency Three-Level ANPC Inverter for 800 V DC Bus System}, url={https://doi.org/10.1109/JESTIE.2024.3355881}, DOI={10.1109/JESTIE.2024.3355881}, abstractNote={Multiple commutation paths exist for switching devices in a three-level active neutral point clamped (3L-ANPC) inverter operation based on the selected switching state and current direction. Additionally, the capacitive coupling path of the non-switching device is a key design aspect for enabling high voltage and high current operation of GaN switches in 3L-ANPC topology. A comprehensive study of the switching transient events of inner, outer and clamping devices of 3L-ANPC is presented in this paper. The commutation mechanisms for worst-case transient voltage overshoots (TOVs) are identified. A simplified equivalent circuit model is presented to determine the design criteria for the power layout structure's parasitic inductances. A power layout strategy satisfying the design criteria is then proposed using an insulated metal substrate (IMS) power PCB to enable efficient high-power operation. The proposed design minimizes the commutation and capacitive coupling path inductances to 6nH and 11.5nH, respectively. This enables the fast switching operation of GaN HEMTs at 800 V DC, 36 A with a low TOV of 31% verified through experimental three-level double pulse test results. Experimental evaluation of a three-phase 3L-ANPC hardware prototype based on the proposed power layout shows 99% efficiency at 800 V, 9.5 kVA and 50 kHz switching frequency. The proposed design achieves a low case-to-ambient thermal resistance of 2.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf {^{\circ }C/W}$</tex-math></inline-formula> .}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, author={Satpathy, Subhransu and Das, Partha Pratim and Bhattacharya, Subhashish}, year={2024}, month={Apr} }
 @article{kokkonda_bhattacharya_2024, title={Soft Switching ARCP Inverter Using Series Connected SiC MOSFETs for Medium Voltage Motor Drive Applications}, ISSN={["1048-2334"]}, DOI={10.1109/APEC48139.2024.10509383}, abstractNote={HV SiC MOSFETs can significantly improve the efficiency and power density of medium voltage (MV) motor drives by enabling higher fundamental frequencies. A major constraint, however, is the high dv/dt at motor terminals, leading to the use of external dv/dt filters. Employing auxiliary resonant commutation to realize soft switching allows dv/dt control and potentially eliminates the dv/dt filter. In this work, it has been proposed to use series connected devices in an auxiliary resonant commutated pole (ARCP) inverter with the resonant capacitor split across the series connected devices, providing dynamic voltage balancing. Series connection of devices offers lower specific on-resistance and semiconductor cost compared to an equivalent voltage blocking single device. RC snubbers typically used for dynamic voltage balancing across series connected devices in a conventional hard switching converter decrease the device turn-off loss but result in high turn-on loss due to snubber capacitor discharge. This paper proposes to overcome this limitation by realizing ZVS turn-on through auxiliary resonant commutation and leveraging the split resonant capacitor for dynamic voltage balancing. This results in soft turn-on and turn-off along with controllable output dv/dt eliminating the need for an external dv/dt filter. The operating principle and design criteria for the soft switching converter with series connected devices have been discussed. A 2-level ARCP inverter with 3.6 kV dc bus using two series connected 3.3 kV SiC MOSFETs per switch has been designed and built, and it has been characterized through pulsed tests as a first step under hard and soft switching conditions validating the concept.}, journal={2024 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Kokkonda, Raj Kumar and Bhattacharya, Subhashish}, year={2024}, pages={567–574} }
 @article{satpathy_das_bhattacharya_veliadis_2024, title={Switching Modes for Reduction of Peak Voltage Transients in GaN-Based Three Level ANPC Inverter}, volume={60}, ISSN={["1939-9367"]}, url={https://doi.org/10.1109/TIA.2024.3447608}, DOI={10.1109/TIA.2024.3447608}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Satpathy, Subhransu and Das, Partha Pratim and Bhattacharya, Subhashish and Veliadis, Victor}, year={2024}, month={Nov}, pages={9066–9079} }
 @article{patel_bhawal_harikrishnan_hatua_bhattacharya_2024, title={Three Stage Power Electronic Transformer Based MVAC Collection System and Its Control System Design for Offshore Wind Power Generation Mills}, url={https://doi.org/10.1109/TEC.2024.3381736}, DOI={10.1109/TEC.2024.3381736}, journal={IEEE Transactions on Energy Conversion}, author={Patel, Himanshu and Bhawal, Shekhar and Harikrishnan, P and Hatua, Kamalesh and Bhattacharya, Subhashish}, year={2024}, month={Dec} }
 @article{dhiman_sharma_aljumah_bhattacharya_2024, title={Triple-active Bridge DC-DC Converter Control for PV and ESS Integration in DC Microgrid Applications}, ISBN={["979-8-3503-1767-1"]}, ISSN={["2473-7631"]}, DOI={10.1109/ITEC60657.2024.10598952}, journal={2024 IEEE TRANSPORTATION ELECTRIFICATION CONFERENCE AND EXPO, ITEC 2024}, author={Dhiman, Shubham and Sharma, Shrivatsal and Aljumah, Osamah and Bhattacharya, Subhashish}, year={2024} }
 @article{chakraborty_hatua_bhattacharya_2023, title={A Control Method to Reduce Overshoots in High-Frequency Link Current and Voltages at Load Transients of a Dual-Active-Bridge Series-Resonant Converter}, url={https://doi.org/10.1109/JESTIE.2023.3243844}, DOI={10.1109/JESTIE.2023.3243844}, abstractNote={A dual-active-bridge (DAB) series-resonant converter is well researched in the literature to find out a suitable pulsewidth modulation (PWM) technique that can achieve voltage regulation, zero-voltage switching, and minimum root-mean-square current in the high-frequency (HF) link. Although the advanced PWM techniques achieve desired performance at steady state, the HF link current and voltages suffer from huge overshoots during load transients, which can damage semiconductor devices and can cause the saturation of the high-frequency transformer. Therefore, in this article, a relationship between the pole positions and the percentage overshoot is derived, so that any design with the tradeoff between fast dynamics and overshoot can be done analytically. As the system involves multiple state and input variables, which are also closely coupled, a multivariable state-feedback controller design is proposed to control the dynamics of all the HF link state variables simultaneously. In any DAB-based topology, the peak volt-ampere rating of the passive components can increase by 80% due to these overshoots. The proposed control successfully restricts the overshoots below 25% with a settling time of 5 ms for the output voltage. The experimental verification is carried out in a 2.25-kW hardware prototype.}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, author={Chakraborty, Surja Sekhar and Hatua, Kamalesh and Bhattacharya, Subhashish}, year={2023}, month={Apr} }
 @article{sharma_iyer_bhattacharya_2023, title={A Distributed Control Method With Seamless Hot Swap Capability for Generic DC Microgrids}, volume={9}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2023.3317835}, DOI={10.1109/TIE.2023.3317835}, abstractNote={This article proposes a distributed secondary control method for droop-controlled dc microgrid (MG) systems with ring or mesh configurations. The control method achieves accurate current sharing and improved load voltage regulation than the conventional droop method by using the bus voltage information of any bus of the dc MG system. The secondary controllers are implemented locally at each converter, thus ensuring a distributed control. The proposed method requires communication of only one signal per communication link and it needs less number of communication links than the state-of-the-art distributed secondary control methods. The method also offers a seamless hot swap capability of a converter as there is no interdependence between the secondary controllers of the converters. The effectiveness of the proposed method is validated using switching simulations and hardware-based experiments on different configurations of dc MG systems.}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish}, year={2023}, month={Sep} }
 @article{kokkonda_beddingfield_bhattacharya_carsten_varga_2023, title={A Novel Transformer Leakage Energy Recovery Active Clamp Control Technique for High Power AC/DC Flyback Converters}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131320}, abstractNote={A novel twin-pulse active clamp has been proposed for flyback converters that can efficiently recover the transformer leakage energy and route it to the output with reduced clamp current ratings and clamp capacitance compared to existing active clamp methods. This extends the application power range for ac/dc flyback converters by enabling a cost-effective leakage energy recovery method for high-power applications. In the case of a 2.5 kW flyback converter, the proposed clamp offers a potential reduction of the required clamp capacitance by 500x and the clamp current by more than 2x at the expense of a higher peak switch voltage stress when compared to an equivalent conventional active clamp. The operating principle and the design criteria for the proposed clamp method are discussed. Experimental results for a 2.5 kW ac/dc flyback converter prototype with the proposed clamp have been presented, validating the clamp operation. Its performance and efficiency improvement compared to a dissipative clamp with active discharge has also been evaluated over the entire operating region.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Kokkonda, Raj Kumar and Beddingfield, Richard and Bhattacharya, Subhashish and Carsten, Bruce and Varga, Bo}, year={2023}, pages={1238–1245} }
 @article{das_satpathy_bhattacharya_2024, title={A Six-Phase Space Vector PWM Technique for Wide Bandgap Device-Based Three-Level Inverters}, volume={10}, ISSN={["2332-7782"]}, url={https://doi.org/10.1109/TTE.2023.3319271}, DOI={10.1109/TTE.2023.3319271}, abstractNote={This paper presents a Space Vector Pulse-Width Modulation (SVPWM) technique for Wide-Bandgap (WBG) device-based Three-Level (3L) six-phase inverters. Implementation of the SVPWM techniques for any six-phase inverter is complex for its high number of possible voltage vectors. Different six-phase load configurations are also possible depending on the angle between two consecutive phases and neutral point connections. The implementation techniques change depending on the load configuration. Moreover, a common neutral point for all six phases leads to circulating currents. Capacitor voltage balancing is also needed for 3L inverters. Capacitor voltage balancing and addressing the circulating current problem further increases the implementation complexity. In this paper, a generalized SVPWM technique is proposed for the six-phase 3L inverters that is implementable using two three-phase 3L SVPWM blocks. The SVPWM technique also ensures DC bus capacitor voltage balancing and minimizes circulating current. The SVPWM technique is experimentally verified using a GaN-based 3L six-phase Active Neutral Point Clamped (ANPC) inverter prototype, and the results are presented in the paper.}, number={3}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Das, Partha Pratim and Satpathy, Subhransu and Bhattacharya, Subhashish}, year={2024}, month={Sep}, pages={5819–5830} }
 @article{das_satpathy_bhattacharya_2024, title={A Voltage Injection-Based Current Harmonics Suppression Strategy for Six-Phase PMSM With Nonsinusoidal Back EMF}, url={https://doi.org/10.1109/JESTIE.2023.3337724}, DOI={10.1109/JESTIE.2023.3337724}, abstractNote={This article presents a voltage injection-based current harmonic minimization method for wide bandgap device-based six-phase permanent magnet synchronous machine (PMSM) drives. The presence of low-order harmonics is common in the back EMF of PMSMs with low slot and high pole numbers. The back EMF harmonics generate low-order harmonic currents that increase torque ripples. Furthermore, zero-sequence current (ZSC) is also observed if all six phases are connected to a common neutral point. ZSC does not affect the torque ripple but reduces the system efficiency. A special technique is required to reduce ZSC for variable speed drives as direct ac component to synchronous reference frame (SRF) dc transformation is not possible for ZSC. In this article, a voltage injection-based current harmonics reduction method is proposed. The injected harmonic voltage coefficients are calculated from the harmonic estimations of back EMF and updated using closed-loop harmonic compensators to improve steady-state performance. For ZSC reduction, third harmonics power controller, and for $6n\pm 1$ (n = 1, 2,...) order harmonic current reduction, SRF current controllers are presented in this article. The current harmonics minimization method is experimentally verified using a GaN-based three-level active neutral point clamped inverter-driven six-phase PMSM.}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, author={Das, Partha Pratim and Satpathy, Subhransu and Bhattacharya, Subhashish}, year={2024}, month={Jan} }
 @inproceedings{narwal_rawat_kanale_cheng_agarwal_bhattacharya_baliga_hopkins_2023, title={Analysis and Characterization of Four-quadrant Switches based Commutation Cell}, volume={2023-March}, ISSN={["1048-2334"]}, url={http://dx.doi.org/10.1109/apec43580.2023.10131312}, DOI={10.1109/APEC43580.2023.10131312}, abstractNote={A four-quadrant switch (FQS) blocks either polarity voltage and controls current flow in both directions. Unlike voltage-source converters, in which two-quadrant switches operate over a narrow voltage range, four-quadrant switches are required to operate over a wide range of both voltage and current in applications such as matrix converters and current-source converters. Furthermore, matrix converters require multi-step commutation schemes compared to two-step schemes for current-bidirectional switch based voltage-source converters and voltage-bidirectional switch based current-source converters. This paper provides a generalized overview of commutation schemes used for two and four quadrant switches based two-level commutation cells, identifies comparison indices for FQS commutation schemes, and discusses the need for adaptive commutation-step times for wide voltage and current variation applications. Also, the static and dynamic characteristics of 1.2 kV rated FQS implementations utilizing commercial SiC MOSFETs from four different manufacturers and novel monolithic SiC BiDirectional Field Effect Transistor (BiDFET) have been reported.}, booktitle={2023 IEEE Applied Power Electronics Conference and Exposition (APEC)}, publisher={IEEE}, author={Narwal, Ramandeep and Rawat, Shubham and Kanale, Ajit and Cheng, Tzu-Hsuan and Agarwal, Aditi and Bhattacharya, Subhashish and Baliga, B. Jayant and Hopkins, Douglas C.}, year={2023}, month={Mar}, pages={209–216} }
 @article{agarwal_prabowo_bhattacharya_2023, title={Analysis and Design Considerations of Input Parallel Output Series-Phase Shifted Full Bridge Converter for a High-Voltage Capacitor Charging Power Supply System}, volume={59}, ISSN={["1939-9367"]}, url={https://doi.org/10.1109/TIA.2023.3276353}, DOI={10.1109/TIA.2023.3276353}, abstractNote={Capacitor charging power supply (CCPS) is used for impulse-power applications such as electromagnetic rail guns, flash lamps, medical sterilization, and rock crushing, among many other application fields. This article describes the design and analysis of an Input Parallel Output Series-Phase Shifted Full Bridge converter for CCPS. The proposed system has a low output current ripple to improve the lifetime of the high-voltage pulsed capacitor. Design considerations of topology's electrical parameters such as HF transformer's leakage inductor and output inductor for the CCPS application are presented. The intermediate DC-link capacitance is provided as an energy storage element to minimize the disturbances (power variation) on the source for the CCPS application. Analysis and sizing of the capacitance for two different charging methods are analyzed and compared. A controller design procedure for the Active Front End Converter (AFEC) is also included to ensure near-constant power drawn, rejecting the load disturbances. Finally, a complete design procedure for the whole CCPS system is presented. Design and simulation results are presented for a rated system, followed by experimental results from a scaled-down hardware prototype to validate the design.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Agarwal, Apoorv and Prabowo, Yos and Bhattacharya, Subhashish}, year={2023}, month={Sep}, pages={6037–6050} }
 @article{narwal_bhattacharya_baliga_hopkins_2023, title={Bidirectional Three-phase Current Source Converter based Buck-boost AC/DC System using Bidirectional Switches}, ISSN={["2473-7631"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85168253560&partnerID=MN8TOARS}, DOI={10.1109/ITEC55900.2023.10186945}, abstractNote={The 1.2 kV 4H-SiC BiDirectional Field Effect Transistor (BiDFET) is the first monolithic SiC bidirectional switch, which offers a lower voltage drop and semiconductor devices count alternative to the reverse-voltage-blocking (RB) switch used in the current-source converters (CSC). The bidirectional switch based CSC also allows DC-link current reversal for bidirectional power flow and provides multiple system-level benefits in a buck-boost AC/DC system consisting of buck-type DC/DC converter and CSC. This paper discusses the selection of buck converter duty cycle and CSC modulation index for the system's buck-boost operation with a wide variation in DC voltage. CSC modulation schemes categorized based on the number of hard-turn-on transitions per switching cycle are also analyzed along with the three-step and four-step commutation schemes that are essential for the CSC commutation cells. Finally, the different schemes are evaluated and compared through the experimental results of a 10 kW, 480 $\mathbf{V}_{\mathbf{RMS},\mathbf{LL}}/$ (400 - 800) V AC/DC system.}, journal={2023 IEEE TRANSPORTATION ELECTRIFICATION CONFERENCE & EXPO, ITEC}, author={Narwal, Ramandeep and Bhattacharya, Subhashish and Baliga, B. Jayant and Hopkins, Douglas C.}, year={2023} }
 @article{sharma_prabowo_bhattacharya_2023, title={Control of a Dual-Active-Bridge DC-DC Converter in a MV Grid-Compliant Solid-State Transformer Based DC Fast Charger}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131314}, abstractNote={A solid-state transformer (SST) system comprising cascaded H-bridge (CHB) and dual-active bridge (DAB) converters is a promising solution for a DC fast charger. This paper primarily focuses on the control design of the DAB converters for this system and utilizes a dual-loop based control scheme. The dual-loop consists of central voltage and inner current control loops. The inner current loops are needed to achieve current sharing between the paralleled DABs. In this paper, the inner current loop uses the DC output current of each DAB as the feedback signal. Thus, the control structure implemented in this paper is more cost-effective and computationally less intensive than the traditional approach of using a high-frequency current as the feedback signal. To provide a well-regulated output DC bus voltage, the control design considers the input disturbance due to the double-line frequency component in the DC-link voltage and the output disturbance due to load throw-off scenarios. An analytical model is derived for the complete dual-loop control structure of the DAB converter. The model evaluates the impact of disturbances due to the double-line frequency component and load throw-off scenarios on output DC bus voltage for different bandwidth combinations of the central voltage and inner current loops. Experimental results validating the analytical model are shown and discussed using a prototype of an SST system.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Sharma, Shrivatsal and Prabowo, Yos and Bhattacharya, Subhashish}, year={2023}, pages={3147–3153} }
 @article{narasimhan_sisson_leslie_parmar_rastogi_bhattacharya_2023, title={Design Considerations of a 3.3 kV SiC-based Reverse Voltage Blocking Module for Current Source Inverter Application}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131381}, abstractNote={This paper presents the design and development of a 3.3 kV silicon carbide (SiC) based reverse voltage blocking half-bridge module for the first time. This low inductance module can build a single-phase or a three-phase current source inverter (CSI). The module comprises of a SiC-MOSFET (3.3 kV/50 A die) and a SiC-MPS diode (3.3 kV/50 A die) to form a 3.3 kV SiC-based current switch in the half-bridge configuration. The static characterization of the current switch (CS) is performed, and a double pulse test circuit is used to verify the switching performance of the developed module. Additionally, the inverter efficiency is estimated for a 30 kW three-phase CSI for a motor drive application, using the obtained static and dynamic characterization results. The impact of the module inductances on the switch voltage and currents is discussed, thus illustrating the importance of a module-based design for CSI applications.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Narasimhan, Sneha and Sisson, Colton and Leslie, Scott and Parmar, Keval and Rastogi, Sagar Kumar and Bhattacharya, Subhashish}, year={2023}, pages={350–357} }
 @article{das_satpathy_bhattacharya_veliadis_deshpande_bhargava_2023, title={Determination of Parameters of Symmetrical Six-Phase Permanent Magnet Synchronous Machines}, DOI={10.1109/IEMDC55163.2023.10238906}, abstractNote={This paper presents offline methods to determine different parameters of Symmetrical Six-Phase (SSP) Permanent Magnet Synchronous Machines (PMSMs). Accurate estimations of different parameters are crucial for proper machine modeling, control, and performance estimations. This paper discusses two offline methods to accurately determine different inductances and the stator resistance of SSP-PMSMs using a single-phase AC source. A method to calculate the Permanent Magnet (PM) flux linkage is also discussed. Machine parameters of a high-speed, low-inductance SSP-PMSM are determined using both methods. The determined parameters are compared with Finite Element Analysis (FEA)-based simulation results and the results are presented in this paper.}, journal={2023 IEEE INTERNATIONAL ELECTRIC MACHINES & DRIVES CONFERENCE, IEMDC}, author={Das, Partha Pratim and Satpathy, Subhransu and Bhattacharya, Subhashish and Veliadis, Victor and Deshpande, Uday and Bhargava, Brij}, year={2023} }
 @article{sharma_iyer_bhattacharya_zou_kikuchi_2023, title={Droop-Based Distributed Secondary Control Method With Reduced Communication Complexity for Radial DC Microgrids}, url={https://doi.org/10.1109/JESTIE.2023.3246932}, DOI={10.1109/JESTIE.2023.3246932}, abstractNote={This article proposes a distributed secondary control method for radial dc microgrid systems with reduced communication complexity. The proposed method utilizes the bus voltage information of the dc microgrid, which is communicated to the individual converters. The proposed method is distributed in nature as the secondary controllers are implemented locally at each converter. The proposed method does not require communication channels between individual converters. Thus, it achieves accurate current sharing and good load voltage regulation with reduced complexity compared to state-of-the-art control methods. The proposed method is robust, and its performance gracefully degrades in the event of a failure of a communication channel. Also, the addition or removal of a converter is seamless with the proposed method. The effectiveness of the proposed method is validated using circuit simulations and hardware-based experiments on different configurations of radial dc microgrid systems.}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish and Zou, Ke and Kikuchi, Jun}, year={2023}, month={Jul} }
 @article{parashar_kolli_kokkonda_kanale_bhattacharya_baliga_2024, title={Mitigating Voltage Imbalance Across Series-Connected 10 kV SiC JBS Diodes in a Medium-Voltage High-Power 3L-NPC Converter}, volume={39}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2023.3339809}, DOI={10.1109/TPEL.2023.3339809}, abstractNote={This article presents a design methodology for RC snubbers to address dynamic voltage imbalance in series-connected 10 kV SiC junction barrier Schottky (JBS) diodes, utilized in a 3-level (3L) neutral point clamped (NPC) converter. The proposed method considers the effect of bus bar inductance, unequal diode junction capacitance, baseplate capacitance, and common mode (CM) choke tied between the heat sink and midpoint of the dc link capacitor on snubber losses and turn-off voltage mismatch across series-connected diodes. In addition, the effect of hard-switched turn-on across complementary SiC mosfets has been considered on snubber loss and dynamic voltage balancing across SiC JBS diodes. The following steps have been used to simplify the RC snubber design: modeling the switching transition across series-connected 10 kV SiC JBS diodes and 10 kV SiC mosfets on two-level clamped inductive switching test setup, modification of snubber capacitor and switching transition model for 3L-NPC topology, using the experimental data, and modification of snubber resistor using experimental data from 3L-NPC setup with CM choke. Key design parameters obtained from the proposed model have been compared with the experimentally obtained data, which validates the accuracy of the model. Experimental results at the 7 kV dc bus show that the designed RC snubber constrains the turn-off voltage mismatch, snubber loss, and turn-on transition time within the specified limit.}, number={3}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Parashar, Sanket and Kolli, Nithin and Kokkonda, Raj Kumar and Kanale, Ajit and Bhattacharya, Subhashish and Baliga, Jay}, year={2024}, month={Mar}, pages={2896–2911} }
 @article{rastogi_shah_singh_bhattacharya_2023, title={Mode Analysis, Transformer Saturation, and Fault Diagnosis Technique for an Open-Circuit Fault in a Three-Phase DAB Converter}, volume={38}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2023.3241654}, DOI={10.1109/TPEL.2023.3241654}, abstractNote={The three-phase dual active bridge (DAB3) is a popular dc–dc converter topology for high-power applications, capable of high-efficiency bidirectional power transfer with galvanic isolation. A single point of failure in power converters is the open-circuit fault (OCF) due to failure in a semiconductor device or its gate drive circuit. This study presents detailed waveform analyses for the normal- and the fault-mode operation. A novel logic-based fault diagnosis scheme is proposed based on the unique pattern in the dc bias of phase currents. Unlike previous schemes, the proposed scheme requires low-bandwidth current sensing only one side of the transformer to detect faults on either side, providing a cost and design benefit. Experimental results verify the analyses and the proposed identification scheme, detecting the fault within a few switching cycles. An in-depth study of the transformer under fault mode is presented for the first time, setting a guideline of time available for fault diagnosis and response. Experimental B–H curves and magnetizing currents of the three-phase transformer illustrate the cycle-by-cycle progression toward core saturation under fault mode. The study also reveals a new potential benefit of the three-phase DAB over the single-phase DAB; i.e., even in the presence of a secondary-side OCF, the DAB3 may continue to operate normally at full load.}, number={6}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Rastogi, Sagar Kumar and Shah, Suyash Sushilkumar and Singh, Brij N. and Bhattacharya, Subhashish}, year={2023}, month={Jun}, pages={7644–7660} }
 @article{prabowo_iyer_agarwal_bhattacharya_aeloiza_2023, title={Modular Hybrid Transformers Toward Grid Resilience: Efficiency Analysis and Operation}, volume={12}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2023.3340215}, DOI={10.1109/TIE.2023.3340215}, abstractNote={This article proposes modular hybrid transformer architectures to improve grid resilience. The conventional line-frequency transformer is augmented with a partially rated power electronics converter to realize a hybrid transformer system. The proposed modular approach is envisioned to replace a single large power low-frequency transformer with multiple smaller rated hybrid transformer systems during disasters and emergencies. A hybrid transformer system enables controlled current sharing between the modular system. The efficiency analysis and operational aspects of a modular hybrid transformer architecture are thoroughly discussed in this article. The proposed efficiency analysis combines empirical data and numerical analysis of the overall modular hybrid transformer system. The optimum current sharing ratio to achieve maximum efficiency operation is presented for the proposed architectures. One of the proposed architectures (Configuration B) also offers load voltage regulation in case of grid voltage sag/swell occurrence. The proposed concept and analyses are experimentally validated through a scaled-down hardware prototype. The total ownership cost of the proposed system is also presented to emphasize the potential cost-benefits. Supplementary video files accompany this article to showcase the extensive experimental validation cases.}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Prabowo, Yos and Iyer, Vishnu Mahadeva and Agarwal, Apoorv and Bhattacharya, Subhashish and Aeloiza, Eddy}, year={2023}, month={Dec} }
 @article{sharma_iyer_bhattacharya_zou_2024, title={New Mesh Configurations With Decentralized Droop Control Method for DC Microgrids}, volume={71}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2023.3245220}, DOI={10.1109/TIE.2023.3245220}, abstractNote={This article proposes new, practical, and scalable mesh configurations for dc microgrids. The new mesh configurations are inspired by the concepts in graph theory. A decentralized secondary droop control method without involving communication complexity is also presented in this article. The proposed control method eliminates the limitations of the conventional droop control method in the scenarios where the cable resistances in a dc microgrid system cannot be neglected. The new mesh configurations with the proposed control method achieve accurate current sharing among all the converters. The effectiveness and performance of the proposed control method are validated using circuit simulations and hardware-based experiments on existing and proposed configurations of multi-converter dc microgrid systems.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish and Zou, Ke}, year={2024}, month={Jan}, pages={560–571} }
 @article{nath_isik_burugula_bhattacharya_2023, title={Novel Control for Active Power Compensation using DSCC-MMC based ES-STATCOM}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131288}, abstractNote={In recent years, modular multilevel converters (MMC) have gained popularity for high-power applications such as in flexible AC transmission systems (FACTS) and High Voltage DC (HVDC) applications, due to their scalability and modularity along with high efficiency in handling high-power and high voltage needs of the power grid. In the same domain of applications, one such usage of the MMC-based system is the integration of energy storage with static synchronous compensator (STATCOM) technology (known as ES-STATCOM) for providing active power compensation along with reactive power support to the grid. This paper introduces a novel dynamic model-based control approach to the MMC-based ES-STATCOM for the integration of energy sources with the power grid. The design of various controller elements is based on detailed harmonic evaluations for both dynamic and steady-state operation modes. The design of the circulating current control adds second-harmonic computation of the modulation indexes for the suppression of second-harmonic circulating current. This approach further improves the converter's performance by reducing the fluctuation in the capacitor voltages and eventually the losses. Finally, the operating range of the MMC-based ES-STATCOM system is being discussed, which lays down the operating limit for active power compensation with reactive power compensation given the priority. The functionality of the proposed control architecture is validated through a Real-Time Digital Simulator (RTDS) and Virtex 7-based FPGA controller in a Controller Hardware-in-Loop (C-HIL) environment.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Nath, Harshit and Isik, Semih and Burugula, Vasishta and Bhattacharya, Subhashish}, year={2023}, pages={1102–1108} }
 @article{gulur_iyer_bhattacharya_2023, title={Passive CM Filter Configuration for a Multistage Grid-Tied Solid State Transformer}, url={https://doi.org/10.1109/JESTIE.2023.3268623}, DOI={10.1109/JESTIE.2023.3268623}, abstractNote={This work proposes a common mode (CM) filter configuration for a grid-tied two-stage ac/dc solid state transformer (SST). The proposed CM filter utilizes passive components along with the heat-sinks of the individual power converter stages to mitigate the overall conducted emissions (CE) injected by the SST system into the grid. The working principle of the proposed CM filter is analyzed and elucidated using CM equivalent circuit models. In addition to CE reduction with the proposed CM filter, it is also demonstrated that the heat-sinks of the SST system can be closer to ground-potential while being impedance grounded. The effectiveness of the proposed CM filter is validated by experimentally measuring the CE of the grid-tied SST system using a line impedance stabilization network.}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, author={Gulur, Srinivas and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish}, year={2023}, month={Jul} }
 @article{kokkonda_parashar_bhattacharya_2023, title={Performance Comparison of 10 kV and Series-connected 3.3 kV SiC MOSFETs based VSCs for MV Grid Interfacing Applications}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131385}, abstractNote={The latest HV SiC devices can significantly improve the efficiency and power density of MV grid interfacing converters. A VSC (Voltage Source Converter) with 7.2 kV dc bus can directly interface with a 4160 V grid which can be realized in a 2-level configuration using a 10 kV blocking switch. HV SiC devices such as 6.5 kV and 10 kV SiC MOSFETs are still in their nascency and being used in research applications, whereas 3.3 kV SiC MOSFETs have already been qualified for commercial applications by multiple vendors. In this regard, an equivalent 10 kV switch formed by series connection of three 3.3 kV SiC MOSFETs has been proposed as a potential alternative, and it has been quantitatively compared to a single 10 kV SiC MOSFET. Normalized device parameters have been considered in both cases for a fair comparison. Two types of 10 kV $120\ \mathrm{m}\Omega$ switching cells have been realized through series connected 3.3 kV $40\ \mathrm{m}\Omega$ SiC MOSFETs and parallel connected 10 kV $350\ \mathrm{m}\Omega$ SiC MOSFETs for effective power loss comparison. Experimentally determined device conduction and switching losses have been employed for further efficiency and loss modeling of 3-phase VSCs using both switching cells. The power loss and efficiency trends with load and switching frequency variation have been presented for both cases. The converter power processing capability dependence on the switching frequency has also been compared for both cases.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Kokkonda, Raj Kumar and Parashar, Sanket and Bhattacharya, Subhashish}, year={2023}, pages={995–1002} }
 @article{narasimhan_kanale_bhattacharya_baliga_2023, title={Performance Evaluation of 3.3 kV SiC MOSFET and Schottky Diode Based Reverse Voltage Blocking Switch for Medium Voltage Current Source Inverter Application}, volume={11}, ISSN={["2169-3536"]}, url={https://doi.org/10.1109/ACCESS.2023.3302916}, DOI={10.1109/ACCESS.2023.3302916}, abstractNote={SiC power devices are used for medium-voltage (MV) motor drive and traction applications due to their higher temperature operation, switching frequencies, and higher efficiencies than Si-based devices. This article investigates three 3.3 kV reverse blocking or current switch configurations for their suitability in MV current-source inverter (CSI) applications. The three configurations are 1) Type I - SiC MOSFET and series Schottky diode; 2) Type II - SiC MOSFETs connected in common-source (CS); and 3) Type III - SiC MOSFETs connected in common-drain (CD) configuration. The switch configurations are characterized by comparing their on-state and switching performance at different junction temperatures varying from 25°C to 125°C. The results are used to evaluate three-phase CSI losses with three different switch configurations and choose the preferred switch configuration for MV-based CSI applications based on inverter efficiency while considering a wide range of operating points. The permissible limits of a 3.3 kV Type I switch-based CSI are presented, thus providing a safe operating area (SOA) of the switch configuration for a CSI application. Finally, the CSI is built using Type I switch configuration and is experimentally validated with an R-L load.}, journal={IEEE ACCESS}, author={Narasimhan, Sneha and Kanale, Ajit and Bhattacharya, Subhashish and Baliga, Jayant B.}, year={2023}, pages={89277–89289} }
 @article{bhattacharya_narwal_shah_baliga_agarwal_kanale_han_hopkins_cheng_2023, title={Power Conversion Systems Enabled by SiC BiDFET Device}, volume={10}, ISSN={["2329-9215"]}, url={https://doi.org/10.1109/MPEL.2023.3237060}, DOI={10.1109/MPEL.2023.3237060}, abstractNote={The BiDirectional Field-Effect Transistor (BiDFET) can enable circuit topologies requiring four-quadrant switches, that were earlier designed using discrete combinations of MOSFETs, IGBTs, GaN HEMTs, and PiN diodes. The monolithic nature of the BiDFET allows lower device count, smaller switch volume, lower inductance, and simpler packaging, and hence more reliable and commercially viable implementation in power electronics converters. The matrix converter topologies, now feasible using BiDFETs, can eliminate the bulky and unreliable dc link capacitors or inductors required for conventional voltage-source or current-source converters in ac–ac and ac–dc applications. The 1.2 kV BiDFET has the potential to disrupt all the applications utilizing 1.2 kV switches, including electric vehicle (EV) drivetrain, bidirectional EV chargers, industrial motor drives, solid-state transformers, datacenter power supplies, elevator drives, dc microgrids, energy storage grid integration, solid-state breakers, etc.}, number={1}, journal={IEEE POWER ELECTRONICS MAGAZINE}, author={Bhattacharya, Subhashish and Narwal, Ramandeep and Shah, Suyash Sushilkumar and Baliga, B. Jayant and Agarwal, Aditi and Kanale, Ajit and Han, Kijeong and Hopkins, Douglas C. and Cheng, Tzu-Hsuan}, year={2023}, month={Mar}, pages={39–43} }
 @article{bhawal_patel_hatua_vasudevan_bhattacharya_2023, title={Solid-State Transformer Based on Naturally Cell Balanced Series Resonant Converter With Cascaded H-Bridge Cells Switched at Grid Frequency}, volume={38}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2023.3263754}, DOI={10.1109/TPEL.2023.3263754}, abstractNote={This article proposes a closed-loop control architecture for a three-stage [medium-voltage (MV), isolated dc/dc, low-voltage (LV)] solid-state transformer (SST) system and a modulation technique for the MV stage that shows better performance over existing solutions in terms of control simplicity, semiconductor loss, and cost. A simple and effective closed-loop control architecture is proposed for the entire SST system using the natural cell balancing ability of the series resonant dual-active bridge converters in the dc/dc stage. In order to reduce semiconductor losses and cost, Si insulated-gate bipolar transistor and SiC mosfet devices are introduced properly in the MV stage of the SST power architecture, and the proposed modulation technique switches these devices appropriately according to their merits. The proposed modulation scheme ensures more than 50% semiconductor loss reduction in the MV stage. A circulating logic is proposed to achieve equal power sharing among cells in the MV stage and associated components. Detailed dynamic modeling, closed-loop control architecture, and modulation scheme are discussed in this article. The proposed control technique and modulation scheme are verified experimentally in a 600-/100-V, 5-kW SST system.}, number={7}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Bhawal, Shekhar and Patel, Himanshu and Hatua, Kamalesh and Vasudevan, Krishna and Bhattacharya, Subhashish}, year={2023}, month={Jul}, pages={8208–8222} }
 @article{kolli_parashar_kokkonda_bhattacharya_veliadis_2023, title={Switching Loss Analysis of Three-Phase Three-Level Neutral Point Clamped Converter Pole Enabled by Series-Connected 10 kV SiC MOSFETs}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131392}, abstractNote={The recent advancement in the technology of SiC MOSFETs has spurred interest in designing compact and high switching frequency (10–20 kHz) power converters. However, grid-integration of these power converters at medium voltage (MV) scale would require a conventional transformer. With the development of new high voltage (HV) 10 kV and 15 kV SiC MOSFETs, these converters can directly interface with medium voltage (MV) grids without the need for line-frequency transformers, using simple two-level and three-level topologies. The application of these devices is currently being explored in all MV Applications (8 kV to 30 kV) like Solid State Transformer, MV Drives, Power Conditioning Systems, and MVDC isolators. This paper discusses application of 10 kV SiC MOSFETs and JBS Diodes for enabling Asynchronous Microgrid Power Conditioning System (AMPCS). This medium voltage power converter is enabled by series-connection of devices, in a Three-Level Neutral Point Clamped (3L-NPC) configuration. The voltage balancing of these series-connected devices is achieved by using R C-snubbers. This paper addresses the different conduction modes and switching sequences of a 3L-NPC pole, which is used as building block for the three-phase converter. The switching loss analysis, for various snubber values, is presented for the MOSFETs and the clamping diodes along with experimental results. This research helps in providing an overview of switching losses that are disspated through the device (and heatsink) and through the snubber resistor in a 3L-NPC convertor pole.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Kolli, Nithin and Parashar, Sanket and Kokkonda, Raj Kumar and Bhattacharya, Subhashish and Veliadis, Victor}, year={2023}, pages={2353–2360} }
 @article{baliga_hopkins_bhattacharya_agarwal_cheng_narwal_kanale_shah_han_2023, title={The BiDFET Device and Its Impact on Converters}, volume={10}, ISSN={["2329-9215"]}, url={https://doi.org/10.1109/MPEL.2023.3237059}, DOI={10.1109/MPEL.2023.3237059}, abstractNote={The matrix converter topology for direct ac-to-ac conversion offers elimination of the bulky and unreliable d.c. link capacitors used in the popular voltage-source inverter (VSI) with a front-end rectifier. The resulting more compact and higher efficiency implementation is a desirable solution for a wide variety of applications, such as photovoltaic energy generation, motor drives, and energy storage systems.}, number={1}, journal={IEEE POWER ELECTRONICS MAGAZINE}, author={Baliga, B. Jayant and Hopkins, Douglas and Bhattacharya, Subhashish and Agarwal, Aditi and Cheng, Tzu-Hsuan and Narwal, Ramandeep and Kanale, Ajit and Shah, Suyash Sushilkumar and Han, Kijeong}, year={2023}, month={Mar}, pages={20–27} }
 @article{rastogi_shah_singh_bhattacharya_2023, title={Vector-Based Open-Circuit Fault Diagnosis Technique for a Three-Phase DAB Converter}, volume={9}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2023.3312430}, DOI={10.1109/TIE.2023.3312430}, abstractNote={A three-phase dual active bridge (DAB3) has become a popular topology for high-power dc–dc conversion. An open-circuit fault in DAB3 can produce a dc bias in its phase currents, which can saturate the transformer, resulting in the device overcurrents and catastrophic failure. This letter proposes a robust fault diagnosis technique to detect the fault and identify the faulty transistor within three to four switching cycles with high noise immunity. The technique requires low-bandwidth current sensing only on one side of the transformer, providing a cost and design benefit, especially in the case of a high-gain high-power converter, where the currents can be sensed on the low-current side. Moreover, in dual-active-bridge circuits, where current sensing is a norm for control and protection purposes, the proposed algorithm can be deployed as a software update on the existing hardware and does not require any hardware modifications. Experimental verification results of the proposed technique on a 5-kW DAB3 hardware prototype are also presented.}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Rastogi, Sagar Kumar and Shah, Suyash Sushilkumar and Singh, Brij N. and Bhattacharya, Subhashish}, year={2023}, month={Sep} }
 @article{alharbi_isik_alfaris_alkuhayli_bhattacharya_2022, title={A Fault Clearance and Restoration Approach for MMC-Based MTDC Grid}, volume={11}, ISSN={["2079-9292"]}, DOI={10.3390/electronics11142127}, abstractNote={With the growth in continuous energy demand, high-voltage Multi-Terminal DC (MTDC) systems are technically and economically feasible to transmit bulk power and integrate additional energy sources. However, the high vulnerability of the MTDC systems to DC faults, especially pole-to-pole (P2P) faults, is technically challenging. The development of DC fault ride-through techniques such as DC circuit breakers is still challenging due to their high cost and complex operation. This paper presents the DC fault clearance and isolation method for an MMC-based MTDC grid without adopting the high-cost DC circuit breakers. Besides, a restoration sequence is proposed to re-energize the DC grid upon clearing the fault. An MMC-based four-terminal DC grid is implemented in a Control-Hardware-in-Loop (CHIL) environment based on Xilinx Virtex-7 FPGAs and Real-Time Digital Simulator (RTDS). The RTDS results show that the MTDC system satisfactorily rides through DC faults and can safely recover after DC faults.}, number={14}, journal={ELECTRONICS}, author={Alharbi, Mohammed and Isik, Semih and Alfaris, Faris E. and Alkuhayli, Abdulaziz and Bhattacharya, Subhashish}, year={2022}, month={Jul} }
 @article{dewani_gopakumar_loganathan_bhattacharya_2022, title={A General Multilevel Polygonal Space Vector Generation Scheme With Reduced Switching for the Inverter and Harmonic Suppression Using a Switched-Capacitive Filter for the Full Modulation Range}, volume={37}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2022.3152497}, DOI={10.1109/TPEL.2022.3152497}, abstractNote={In this article, a general multilevel polygonal space vector generation scheme is proposed for open-end induction motor drive schemes, fed with any conventional multilevel inverter with active dc-link supply on one end and a low-voltage capacitor-fed inverter working as a switched-capacitive filter on the other end. The main power delivery primary inverter provides active power for motoring operation, and the capacitor-fed secondary switched-capacitive filter suppresses lower order harmonics by forming polygonal space vector structures of 36, 42, 48, etc., sides. In the proposed general modulation scheme, the primary inverter is visualized as a combination of subhexagons. Two subhexagons of the primary inverter are modulated in the pseudo six-step mode of operation to generate the desired fundamental component to drive the induction motor load. The primary inverter also generates undesirable lower order harmonics due to low switching per cycle in the primary inverter. The secondary inverter is used as a switched-capacitive filter to suppress the lower order harmonics of the 5th, 7th, 11th, 13th, etc., order by forming polygonal switching vectors with sides more than six, i.e., 36, 42, 48, etc. The proposed general scheme is verified for a three-level primary inverter fed with an active dc link of $V_{\text{dc}}$ and a six-level secondary inverter fed with a capacitive supply balanced at nearly one-third of the dc-link voltage ($\text{0.39}V_{\text{dc}}$).}, number={7}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Dewani, Rahul and Gopakumar, K. and Loganathan, Umanand and Bhattacharya, Subhashish}, year={2022}, month={Jul}, pages={8167–8176} }
 @article{satpathy_das_bhattacharya_veliadis_2022, title={A New Switching Strategy for a GaN-based Three-Level Active Neutral Point Clamped Converter}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947699}, abstractNote={This paper investigates a suitable switching strategy for a GaN-based three-level active neutral point clamped (3L-ANPC) converter. The 3L-ANPC operation is considered at 800V DC bus with the use of 650V GaN devices. The different switching modes for obtaining the zero state result in short-loop and long-loop commutations. A parallel operation of zero states termed full-mode is preferable for reducing conduction losses. However, this results in a multi-loop commutation producing high voltage stress across the inner devices. This paper proposes a modified full-mode switching strategy to mitigate this issue by a timed switching sequence involving clamping devices. The proposed switching mode involves active switching of the clamping device in 3L-ANPC for coupling and decoupling the long loop path. The commutation process for the proposed switching mode is explained in detail in this paper. Simulation results are presented using the device Spice model and parasitic inductances of a designed 3L-ANPC phase leg. The voltage stress and loss results determined from simulation results are compared with existing switching modes. A three-level double pulse test circuit is presented, and experimental test results are provided for the proposed switching mode.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Satpathy, Subhransu and Das, Partha Pratim and Bhattacharya, Subhashish and Veliadis, Victor}, year={2022} }
 @article{kokkonda_bhattacharya_veliadis_panayiotou_2022, title={A SiC based Two-Stage Pulsed Power Converter System for Laser Diode Driving Applications}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947820}, abstractNote={This paper discusses the unique driving requirements of a laser diode array and evaluates potential converter configurations to meet those requirements. A two-stage capacitive energy storage based pulsed power converter system consisting of a phase shifted full bridge (PSFB) based capacitor charging power supply (CCPS) and a buck based pulse current source with inductor energy recovery has been adopted. Buck based pulse current source with inductor energy recovery enabled by SiC FETs allows significant reduction in energy loss and required energy storage capacitance when compared to conventionally used linear current regulator. A reconfigured pulse forming circuit has been proposed for the pulse current source which mitigates the effect of the output parasitic inductance on the laser diode without the need for an additional freewheeling diode across the load. A pulsed laser diode driver capable of driving 280 V laser diode arrays at 56 kW peak pulse power has been designed and a full-scale hardware prototype has been built. The complete system has been experimentally validated by generating 50 A current pulses at 250 V output voltage (12.5 kW) which proves the feasibility of the proposed converter configuration for high pulse power laser diode driving applications.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Kokkonda, Raj Kumar and Bhattacharya, Subhashish and Veliadis, Victor and Panayiotou, Chrysanthos}, year={2022} }
 @article{alharbi_isik_bhattacharya_2022, title={An Equivalent Hybrid Model for a Large-Scale Modular Multilevel Converter and Control Simulations}, volume={10}, ISSN={["2169-3536"]}, url={https://doi.org/10.1109/ACCESS.2022.3176006}, DOI={10.1109/ACCESS.2022.3176006}, abstractNote={Modular multilevel converter (MMC) is adopted mainly for high voltage applications with many power blocks per arm. Before commissioning a large-scale MMC application, it is vital to simulate and study internal and system-level dynamics. However, it is challenging to simulate an MMC with many SMs in EMT simulation tools due to simulation time and computation burden. Therefore, several simplified modeling techniques are proposed to reduce the challenges. Even though the existing models reasonably reduce the computation complexity and simulation time, there are still challenges as the internal dynamics of an MMC cannot be fully captured. On the other hand, the detailed equivalent models capture the internal dynamics, but the simulation complexity and the time increase. Therefore, it is still a need for better, faster, and more accurate simulation models to study the system-level and internal dynamics of an MMC. Therefore, this paper proposes a hybrid simulation model for a large-scale MMC application using a scale-up control structure method. The proposed method is verified in the MATLAB/Simulink simulation tool. Besides, the proposed model is tested and verified at the Real-Time Digital Simulator (RTDS) in a Hardware-in-Loop (HIL) environment.}, journal={IEEE ACCESS}, author={Alharbi, Mohammed and Isik, Semih and Bhattacharya, Subhashish}, year={2022}, pages={53504–53512} }
 @article{sharma_iyer_bhattacharya_2023, title={An Optimized Nonlinear Droop Control Method Using Load Profile for DC Microgrids}, url={https://doi.org/10.1109/JESTIE.2022.3208513}, DOI={10.1109/JESTIE.2022.3208513}, abstractNote={Paralleling of power electronic converters to achieve current sharing is a critical aspect of a dc microgrid. Droop control is a popular technique to parallel converters. This article presents a novel perspective of different practically realizable nonlinear droop characteristics. Using the probability distribution function of the load current, a methodology is proposed to optimize the characteristics of nonlinear droop control. In a stand-alone dc microgrid system, the load current information used in the proposed control method is typically known using historical data or can be estimated using load forecasting methods. The advantages of the proposed nonlinear droop control method over several state-of-the art nonlinear droop control methods are discussed and shown. The effectiveness of the proposed nonlinear droop control method is validated using circuit simulations and hardware-based experiments on a multiconverter system for different load profiles.}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish}, year={2023}, month={Jan} }
 @article{beddingfield_leary_noebe_nations_bowman_bhattacharya_2022, title={Calculation of Transformer Leakage Inductance by Simplified Flux Path Geometries}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947606}, abstractNote={Series inductance is a critical energy storage element in isolated power converters. Many have explored methods of estimating the total leakage inductance of transformers as an integrated series inductance without external inductors. However, this poses challenges with medium frequency converters and magnetic ribbon-based cores, e.g., metal amorphous nanocrystalline. The material's relatively high conductivity allows eddy currents to develop when magnetic flux intersects wide surfaces. These eddy currents result in significant additional losses that increase with increasing power flow. This paper presents a simplified and accurate method of estimating leakage flux while identifying separate leakage flux paths that correlate with the magnetic material surfaces. This enables an understanding the proportion of leakage flux that will contribute to extra losses. The methods presented are applicable to both leakage and fringing (around heterogeneous material interfaces) fluxes. This paper includes detailed FEA studies and 3D flux vector measurements matching the presented analytical models.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Beddingfield, Richard B. and Leary, Alex M. and Noebe, Ronald and Nations, Mark and Bowman, Randy and Bhattacharya, Subhashish}, year={2022} }
 @article{nations_beddingifield_bhattacharya_2022, title={Design Considerations and Performance Evaluation of 50kW, 40kHz DAB Converter with Coaxial Winding Transformer}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947822}, abstractNote={Design of power electronic systems is often done with top-down specifications for each subsystem, which leaves system-level tradeoffs between power electronics, magnetics, control strategies invisible to the design process. If all parts of the system are well modeled, it is possible to perform optimal design on the entire system in a single step, taking into account all modeled trade-offs and cross coupling between components. A 50kW dual active bridge converter utilizing a coaxial winding transformer is used to demonstrate this as a whole system co-design. Detailed modeling of coaxial transformer capacitance, winding design, and thermal performance is developed. The NSGA-II genetic algorithm-based optimization implementation is utilized with an extension to the simulated binary crossover (SBX) operator to handle bounded design variables. Co-design is performed, results are discussed, and a design with 40kHz switching frequency is selected. The converter is built utilizing Finemet nanocrystalline magnetic cores and improvements on CWT tubular winding construction are presented. The converter is tested and shown to operate above 98% efficiency over a wide load range. Converter thermal performance is verified with the proposed model.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Nations, Mark and Beddingifield, Richard B. and Bhattacharya, Subhashish}, year={2022} }
 @misc{kanale_cheng_narwal_agarwal_baliga_bhattacharya_hopkins_2022, title={Design Considerations for Developing 1.2 kV 4H-SiC BiDFET-enabled Power Conversion Systems}, ISSN={["2329-3721"]}, url={http://dx.doi.org/10.1109/ECCE50734.2022.9947715}, DOI={10.1109/ECCE50734.2022.9947715}, abstractNote={Bidirectional switches are essential for cycloconverter and matrix converter applications to facilitate single-stage AC-AC conversion without intermediate energy storage elements. The 1.2 kV 4H-SiC BiDFET was developed as the first monolithic bidirectional SiC power transistor. This paper describes the design considerations taken into account while creating the BiDFET device and developing custom packages for housing the switch in discrete form for low power applications and in module form for high-power applications. The realized switches are characterized for their on-state and switching performance. The versatility of the BiDFET device is demonstrated by operating a single BiDFET H-bridge in voltage-source-inverter and current-source-inverter topologies only by varying the gate bias on the individual BiDFETs and reversing the input-output connections.}, journal={2022 IEEE Energy Conversion Congress and Exposition (ECCE)}, publisher={IEEE}, author={Kanale, Ajit and Cheng, Tzu-Hsuan and Narwal, Ramandeep and Agarwal, Aditi and Baliga, B. Jayant and Bhattacharya, Subhashish and Hopkins, Douglas C.}, year={2022}, month={Oct} }
 @article{das_satpathy_bhattacharya_veliadis_2022, title={Design Considerations of Multi-Phase Multilevel Inverters for High-Power Density Traction Drive Applications}, DOI={10.1109/ITEC53557.2022.9813937}, abstractNote={This paper presents the effect of multi-phase machines in Three-Level (3L) Active Neutral-Point Clamped (ANPC) inverter design for high-speed traction drive applications. In this work, GaN-based 3L-ANPC inverters are considered to drive high-speed Permanent Magnet Synchronous Machines (PMSMs) with an 800V DC bus. Two different analytical models are developed to calculate the DC bus capacitor and dv/dt filter requirements of the 3L-ANPC inverters. Using the analytical models, the requirement of the DC bus capacitor and dv/dt filter sizes are compared for driving three-phase, six-phase symmetrical, and asymmetrical PMSMs. Another model is developed from experimental Double Pulse Test (DPT) data to calculate the heat sink size requirements for driving the three types of PMSMs mentioned above. A discussion on the Common Mode Voltage (CMV) is also provided. Finally, a comparison is made in terms of DC bus capacitor, dv/dt filter, heat sink size requirements, and common-mode voltages for the three types of drives. The analytical models are verified in simulation, and the results are presented in this paper.}, journal={2022 IEEE/AIAA TRANSPORTATION ELECTRIFICATION CONFERENCE AND ELECTRIC AIRCRAFT TECHNOLOGIES SYMPOSIUM (ITEC+EATS 2022)}, author={Das, Partha Pratim and Satpathy, Subhransu and Bhattacharya, Subhashish and Veliadis, Victor}, year={2022}, pages={23–30} }
 @article{isik_parashar_bhattacharya_2022, title={Fault-Tolerant Control and Isolation Method for NPC-Based AFEC Using Series-Connected 10kV SiC MOSFETs}, volume={10}, ISSN={["2169-3536"]}, url={https://doi.org/10.1109/ACCESS.2022.3190370}, DOI={10.1109/ACCESS.2022.3190370}, abstractNote={Power Conditioning Systems (PCS) based on three-level converters with series-connected 10kV SiC MOSFETs have gained popularity for medium voltage applications with the increase in distributed energy sources. With the use of Silicon Carbide (SiC), a wide bandgap semiconductor composed of Silicon (Si) and Carbon (C), MOSFET increases in power electronics application due to higher switching frequency operations. A high switching frequency such as 10 kHz or more leads to a reduction in magnetic components’ size and the PCS structure’s size. Therefore, the smaller, modular, and lightweight PCS can be attained for micro-grid integration, EV charging, or high inertia-dominated power grid applications. The three-level NPC (3L-NPC) inverter using series-connected 10kV SiC MOSFET is a suitable topology for coupling the PCS with the medium-voltage utility grid. The converter’s pole sustainability increases with the two series-connected switches, yet the switches are still sensitive and prone to malfunction under various environmental and mechanical causes. Therefore, a meticulous fault isolation and coordination design may be necessary for the front-end converter for possible switch faults in the converter poles. A well-designed fault-tolerant controller may sustain the converter operation under fault conditions while protecting the healthy parts of the converter. Besides, it minimizes the harmful effects of fault on the grid side and increases the system availability. This paper analyzes short and open circuit switch faults that might occur in the PCS. Accordingly, a fault-tolerant method and a fault isolation method are proposed. The proposed methods are verified with Saber™ and the Real-Time Digital Simulator simulation platforms.}, journal={IEEE ACCESS}, author={Isik, Semih and Parashar, Sanket and Bhattacharya, Subhashish}, year={2022}, pages={73893–73906} }
 @article{das_satpathy_bhattacharya_veliadis_2022, title={Generalized Control Technique for Three-Level Inverter Fed Six-Phase Permanent Magnet Synchronous Machines Under Fault Conditions}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947672}, abstractNote={This paper presents a control technique of a GaN-based Three-Level (3L) Active Neutral Point Clamped (ANPC) inverter fed high-speed six-phase Permanent Magnet Synchronous Machine (PMSM) under both Open Circuit Fault (OCF) and Short Circuit Fault (SCF) conditions. The loss of one or more phases due to OCF or SCF in PMSMs can generate a high torque ripple. A high torque ripple can disrupt the operation of electric drives and even bring the drive to a standstill. Smooth operation under any fault conditions is becoming necessary to increase the reliability of the electric drives. This paper discusses an optimization method that calculates the operating points in different fault conditions while maximizing the torque without exceeding the rated line current rating of the inverter/ motor. The optimization method also provides the torque limit in post-fault conditions without compromising the speed for both one and two isolated neutral point configurations. The post-fault operating points are implemented using a control technique that can be achieved seamlessly from the state-of-the-art vector control method. The proposed control technique is verified in simulation, and the results are presented in this paper.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Das, Partha Pratim and Satpathy, Subhransu and Bhattacharya, Subhashish and Veliadis, Victor}, year={2022} }
 @article{isik_burugula_alharbi_azidehak_bhattacharya_2022, title={Implementation of a Modular Distributed Fault-Tolerant Controller for MMC Applications}, volume={15}, ISSN={["1996-1073"]}, DOI={10.3390/en15228427}, abstractNote={Centralized control algorithm limits the hardware flexibility of a modular multilevel converter (MMC). Therefore, distributed control structure has recently started to be seen in the industry application. Even though distributed controller reduces a single point of failure risk compared to the centralized controller, the failure risk of the entire control systems increases due to the number of local controllers. However, the distributed controller can be programmed in such a way as to replace the faulty local controller and sustain the MMC operation. In this paper, the distributed modular fault-tolerant controller is implemented in a laboratory-scale MMC prototype. The controller is built to control four SMs per phase for the proof-of-concept. Therefore, the MMC prototype is also built by two SMs per arm. The controller capability is validated with experimental and the Opal-RT result-time simulator results in a control-hardware-in-loop (CHIL) environment.}, number={22}, journal={ENERGIES}, author={Isik, Semih and Burugula, Vasishta and Alharbi, Mohammed and Azidehak, Ali and Bhattacharya, Subhashish}, year={2022}, month={Nov} }
 @article{kim_lee_bhattacharya_2022, title={Improved EEMF-Based Position Sensorless Control for Non-sinusoidal Back-EMF PMSMs}, volume={1}, ISSN={["2093-7423"]}, DOI={10.1007/s42835-021-00985-1}, journal={JOURNAL OF ELECTRICAL ENGINEERING & TECHNOLOGY}, author={Kim, Heonyoung and Lee, Kibok and Bhattacharya, Subhashish}, year={2022}, month={Jan} }
 @article{kumar_bhattacharya_baliga_2022, title={Influence of the Inverter Dead-time on the Reverse Recovery Characteristics of 3.3-kV SiC MOSFETs and JBSFETs}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947390}, abstractNote={The switching behavior of the high voltage (HV) SiC MOSFETs is superior to that of HV silicon IGBTs. In medium voltage high switching frequency power conversion applications, the reverse recovery effect of the body diode results in large switching losses. In this work, the reverse recovery behavior of the body diode of the recently developed 3.3 kV SiC MOSFETs is investigated at varying junction temperature and current levels. Two solutions are proposed to reduce the reverse recovery losses - by using the optimized dead-time and by integrating Schottky diode in the MOSFETs. The experimental results validate the proposed solutions. A device physics-based numerical model is used to explain the improvement in the body diode reverse recovery characteristics at the smaller dead-time.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Kumar, Ashish and Bhattacharya, Subhashish and Baliga, Jayant}, year={2022} }
 @article{gulur_iyer_bhattacharya_2022, title={Integrated Single-Stage EMI Filters for Grid-Tied Voltage Source Converters: A Design Oriented Approach}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947614}, abstractNote={This work introduces and elucidates a general framework for designing and evaluating the performance of a standard single-stage, multi-order integrated electromagnetic interference (EMI) filter for grid-tied, 3ϕ voltage source converters (VSCs). The proposed methodology is based on designing the EMI filter to meet power quality (PQ) requirements while providing adequate attenuation to both differential mode (DM) and common mode (CM) noise generated by the 3ϕ VSC to comply with conducted emissions (CE) recommendations. The impact of switching frequency of the power converter on the filter size is investigated to understand the performance limits of single-stage EMI filters and to offer guidelines as to when such a single-stage filter is feasible. A size comparison for the magnetic components used in the EMI filter has been performed using an area product approach. Additionally, various single-stage CM and DM filter performances have been analyzed and compared. A hardware prototype with a single-stage EMI filter has been implemented based on the proposed design guidelines. Time-domain and CE experimental results for a 3ϕ VSC prototype interfaced to the utility grid are provided to showcase the validity of the single-stage integrated EMI filter design to meet multiple performance constraints.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Gulur, Srinivas and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish}, year={2022} }
 @article{alalwani_isik_bhattacharya_2022, title={Inter- area Oscillation Damping Controller for DFIG based Wind Power Plants}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947750}, abstractNote={Low-frequency inter-area oscillation is typical for transmission tie-line interconnecting neighboring power systems. Inter-area modes result from generators in one area of the power system oscillating against another group of generators in another area across a weak transmission tie line. Modulating active and reactive power in a wind turbine system equipped with a Doubly Fed Induction Generator (DFIG) may effectively dampen inter-area oscillation. In this paper, modifications of Rotor Side Converter (RSC) control and Grid Side Converter (GSC) control by adding active and reactive Power Oscillation Damping (POD) controllers to improve the dynamic system response are studied. Kundur's well-known two-area system is adopted to demonstrate the impacts of active POD and reactive POD controllers of DFIG on the inter-area oscillation using the PSCAD electromagnetic simulation tool. Besides, system stability is studied based on a frequency sweep using the impedance ratio of the different subsystems inside Kundur's system. The Nyquist Stability Criterion (NSC) is adopted to determine system stability.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Alalwani, Sami and Isik, Semih and Bhattacharya, Subhashish}, year={2022} }
 @article{kanale_agarwal_baliga_bhattacharya_2022, title={Monolithic Reverse Blocking 1.2 kV 4H-SiC Power Transistor: A Novel, Single-Chip, Three-Terminal Device for Current Source Inverter Applications}, volume={37}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2022.3166933}, DOI={10.1109/TPEL.2022.3166933}, abstractNote={Current sourceinverters (CSIs) require power switches with first quadrant current conduction and gate-controlled output characteristics as well as reverse blocking capability. Experimental demonstration of a SiC monolithic reverse blocking transistor (MRBT) suitable for CSI applications is described in this letter. The proposed device is based on the integration of a SiC JBS diode with a SiC power mosfet on the same chip. The cathode of the SiC JBS diode is connected to the drain of the SiC power mosfet by their common N+ substrate. The proposed device structure creates a novel SiC-based unipolar single-chip three-terminal transistor with reverse blocking capability. The measured characteristics of a 1.2 kV 4H-SiC MRBT, fabricated in a commercial six-inch wafer foundry, are reported in this letter. The devices show a diode-like on-state characteristic with a low knee voltage of 1.3 V and an on-state voltage drop of 2.8 V at 5 A. The measured reverse transfer capacitance and output capacitance for the MRBT at a drain bias of 2 and 1000 V are a factor of ∼3x and ∼1.6x smaller than the measured values for the internal mosfet device. Switching measurements show a 12% reduction in the gate-drain charge for the MRBT compared with the internal mosfet which is favorable for reducing switching losses.}, number={9}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Kanale, Ajit and Agarwal, Aditi and Baliga, B. Jayant and Bhattacharya, Subhashish}, year={2022}, month={Sep}, pages={10112–10116} }
 @article{burugula_isik_bhattacharya_2022, title={Performance Comparison of a Modular Multilevel Converter under Centralized and Decentralized Control Structures}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947465}, abstractNote={A Modular Multilevel Converter (MMC) consists of series-connected bi-directional chopper cells with a floating capacitor on each leg. Despite the inherent modularity of the chopper cells, most MMC controllers have been designed based on a Central Controller Unit (CCU) until recently. Using classical linear controllers, the CCU executes the operator-defined setpoints based on measured signals in the outer-level control. Even though a CCU is relatively fast and has fewer communication routes, the CCU retains the scalability and modularity features of an MMC as modification of the controller may be challenging. For this reason, the decentralized control structure has been considered for the recent MMC applications to utilize the scalability and modularity features of an MMC effectively. The decentralized controllers introduce delays, especially for the circulating current, due to the local controllers, so the delays may drastically affect the MMC currents. In this paper, the centralized and the decentralized control structures are implemented and their effects in the arm and the circulating currents are investigated for an MMC operation.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Burugula, Vasishta and Isik, Semih and Bhattacharya, Subhashish}, year={2022} }
 @article{alharbi_isik_alkuhayli_bhattacharya_2022, title={Power Ripple Control Method for Modular Multilevel Converter under Grid Imbalances}, volume={15}, ISSN={["1996-1073"]}, DOI={10.3390/en15103535}, abstractNote={Modular multilevel converters (MMCs) are primarily adopted for high-voltage applications, and are highly desired to be operated even under fault conditions. Researchers focused on improving current controllers to reduce the adverse effects of faults. Vector control in the DQ reference domain is generally adopted to control the MMC applications. Under unstable grid conditions, it is challenging to control double-line frequency oscillations in the DQ reference frame. Therefore, active power fluctuations are observed in the active power due to the uncontrolled AC component’s double line frequency component. This paper proposes removing the active power’s double-line frequency under unbalanced grid conditions during DQ transformation. Feedforward and feedback control methods are proposed to eliminate ripple in active power under fault conditions. An extraction method for AC components is also proposed for the power ripple control to eliminate the phase error occurring with the conventional high-pass filters. The system’s stability with the proposed controller is tested and compared with a traditional MMC controller using the Nyquist stability criterion. A real-time digital simulator (RTDS) and Xilinx Virtex 7-based FPGA were used to verify the proposed control methods under single-line-to-ground (SLG) faults.}, number={10}, journal={ENERGIES}, author={Alharbi, Mohammed and Isik, Semih and Alkuhayli, Abdulaziz and Bhattacharya, Subhashish}, year={2022}, month={May} }
 @article{narasimhan_rastogi_bhattacharya_2022, title={Short-Circuit Fault Diagnosis of a Three-Phase Current-Source Inverter}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947610}, abstractNote={The development of the wide-band gap devices has led to the re-emergence of current-source inverters (CSIs). With the modernization of future power systems, the importance of the reliability of power converters is critical. Fault identification is vital to enhancing the reliability of the system. A prominent failure mode in power converters occurs due to the semiconductor device failure. The normal and fault mode operation of the converter is discussed for the three short-circuit fault conditions observed in current-source inverters. This paper proposes a method to detect and locate the short-circuit fault of a MOSFET switch, a diode switch, and a current switch comprising of both MOSFET and diode simultaneously, in a CSI. A fault detection method that involves checking the ratio of the average value of the ac currents and average value of the reference currents in one fundamental cycle to threshold limits is used to detect and identify the location of the fault. This method does not need additional voltage or current sensors for implementing the proposed algorithm. The effectiveness of the proposed method is shown in simulation and experimental results are provided to validate the same. This proposed method for fault identification improves the system reliability of CSIs.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Narasimhan, Sneha and Rastogi, Sagar Kumar and Bhattacharya, Subhashish}, year={2022} }
 @article{aljumah_isik_alshammari_bhattacharya_2022, title={SiC-based Isolated Three-port DC-DC Converter Implementation for MV Microgrid Applications}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9948147}, abstractNote={Integrating microgrids or distributed energy sources into a utility grid requires a meticulous control design. The energy management between the source and the load should be rapidly and carefully controlled. Solid State Transformer (SST) and Power Conditioning System (PCS) are emerging technologies with the development of medium voltage (MV) Silicon Carbide (SiC) power semiconductor devices, which offer high-frequency isolation between MV grids, distributed energy storage, Electric Vehicle (EV) charging, etc. Besides, power flow and power factor can be easily controlled. This paper presents three-port Triple Active Bridge (TAB) applications for micro-grid integration. The system consists of three power conversion stages: AC to DC, DC to DC, and DC to AC. The front-end converters control the DC voltage, and the power flow is dispatched by controlling the TAB. Verification of the system at 24.5 kV DC is tested with the NovaCor, Real-Time Digital Simulator (RTDS).}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Aljumah, Osamah and Isik, Semih and Alshammari, Sulaiman and Bhattacharya, Subhashish}, year={2022} }
 @article{alharbi_isik_bhattacharya_2022, title={Submodule Fault-Tolerant Strategy for Modular Multilevel Converter with Scalable Control Structure}, volume={14}, ISSN={["2071-1050"]}, DOI={10.3390/su142416445}, abstractNote={Modular Multilevel Converter (MMC) topology is considered a good candidate for high-voltage applications. One of the reasons is that an MMC can quickly generate a higher voltage with an excellent sine wave with the series connection of many power blocks, called Sub-Modules (SMs). In such applications, the control system of an MMC can be challenging, and the possibility of an SM failure increases. As a result, the reliability and availability of the application reduce over time. To reduce the effects of SM failure, an MMC is usually equipped with Redundant SMs (RSMs). The RSMs are added into MMC arms as regular SMs to increase the application’s reliability and reduce downtime. This paper proposes a unique decentralized SM fault-tolerant control model for RSMs to participate in any SM sets. In an MMC arm, a dedicated controller is assigned to RSMs, while the group of SMs has their local controllers. The controller of the RSMs continually monitors the voltage of all the SM sets in the arm. If there is any failure, the controller of the RSMs activates a requested number of SMs to help local controllers to generate the desired voltage level. The proposed control system significantly reduces local controllers’ computational and communication requirements compared to conventional redundant controllers. The proposed control system is based on a distributed structure, so it does not limit hardware flexibility, such as the scalability and modularity of an MMC system. Besides, the separate controller for the RSMs significantly helps increase the reliability of an MMC application.}, number={24}, journal={SUSTAINABILITY}, author={Alharbi, Mohammed and Isik, Semih and Bhattacharya, Subhashish}, year={2022}, month={Dec} }
 @article{madadi_zou_bhattacharya_2022, title={Unified Control Method for Seamless Transition of a Weak Grid Connected AC Microgrid to Islanded Mode}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947705}, abstractNote={A unified control approach for a weak-grid connection ac microgrid has been proposed that not only results in a seamless transition from grid following operation mode to grid forming operation mode, but also offers fast reference tracking and is highly robust to the sudden changes in the load. The effectiveness of the proposed controller has been evaluated by simulation in PLECS compared to a conventional control method with separate controllers for each mode of operation. The performance of the algorithm has been evaluated by simulation of a 100kW inverter in PLECS and controller hardware-in-the loop (CHIL) testbed setup under different operating conditions.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Madadi, Mehrnaz and Zou, Ke and Bhattacharya, Subhashish}, year={2022} }
 @article{prabowo_sharma_bhattacharya_tripathi_bhavaraju_2023, title={ZVS Boundary Analysis and Design Guideline of MV Grid-Compliant Solid-State Transformer for DC Fast Charger Applications}, volume={9}, ISSN={["2332-7782"]}, url={https://doi.org/10.1109/TTE.2022.3229223}, DOI={10.1109/TTE.2022.3229223}, abstractNote={A solid-state transformer (SST) comprising a cascaded H-bridge and a dual active bridge (DAB) converter is a promising solution for a megawatt medium-voltage dc fast charger application. The new IEEE Std 1547.9-2022 comprehensively discusses extending the minimum reactive power capability to electric vehicle chargers. This article analyzes the impact of operating the grid compliant single-phase SST on the overall system. The impact of the dc-link voltage due to the single-phase implementation of the H-bridges on the DAB converter zero-voltage switching (ZVS) mode at light-load operation is highlighted. The system’s operational boundary is analyzed, which defines the reactive power capability limit while ensuring the DAB converter ZVS mode operation for the defined operating points. This ZVS mode boundary analysis is then used to develop a design guideline as part of the SST design process. The proposed guideline allows a simultaneous design of a dc-link capacitor and DAB inductance to ensure the ZVS mode for the defined operating points. It leads to dc-link capacitance reduction that offers cost- and footprint-savings. The proposed concept is validated through simulations and experimental results. Furthermore, a potential benefit analysis is provided to emphasize the effectiveness of the proposed concept. A supplementary video is included to showcase the system’s dynamic active and reactive power operation.}, number={4}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Prabowo, Yos and Sharma, Shrivatsal and Bhattacharya, Subhashish and Tripathi, Awneesh Kumar and Bhavaraju, Vijay}, year={2023}, month={Dec}, pages={4964–4980} }
 @article{prabowo_sharma_bhattacharya_tripathi_bhavaraju_2022, title={ZVS Boundary Analysis and Design Guideline of MV Grid-Compliant Solid-State Transformer for DC Fast Charger Applications}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947559}, abstractNote={A solid-state transformer comprising a cascaded H-bridge followed by a dual-active bridge converter is a promising solution for a megawatt medium voltage DC fast charger application. Previously, IEEE Std 1547– 2018 mandates a system with the capability of exporting an active power to have a minimum continuous reactive power capability to comply with IEEE Std 1547–2018. An approved revision of IEEE Std 1547–2018 comprehensively discusses to extend the minimum reactive power capability of electric vehicle chargers. This paper analyzes the impact of operating the grid compliant single-phase solid-state transformer on the overall system. The impact of the double-line frequency component of DC-link voltage on the DAB converter zero-voltage switching mode is emphasized. The zero-voltage switching mode boundary analysis is used to propose the design guidelines as part of the single-phase solid-state transformer design process. The proposed design guidelines are validated using switching simulations and experimental results.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Prabowo, Yos and Sharma, Shrivatsal and Bhattacharya, Subhashish and Tripathi, Awneesh K. and Bhavaraju, Vijay}, year={2022} }
 @article{anurag_acharya_bhattacharya_weatherford_parker_2022, title={A Gen-3 10-kV SiC MOSFET-Based Medium-Voltage Three-Phase Dual Active Bridge Converter Enabling a Mobile Utility Support Equipment Solid State Transformer}, volume={10}, ISSN={["2168-6785"]}, url={https://doi.org/10.1109/JESTPE.2021.3069810}, DOI={10.1109/JESTPE.2021.3069810}, abstractNote={The emergence of medium-voltage silicon carbide (SiC) power semiconductor devices, in ranges of 10–15 kV, has led to the development of simple two-level converter systems for medium-voltage applications. A medium-voltage mobile utility support equipment-based three-phase solid state transformer (MUSE-SST) system, based on Gen3 10 kV SiC MOSFETs, is developed to interconnect a three-phase 4160 V/60 Hz grid to a three-phase 480 V/60 Hz grid to provide a shore-to-ship power interface for naval vessels. The MUSE-SST system consists of three power conversion stages, namely, MVac/MVdc stage (MV: active front-end converter), MVdc/LVdc stage (dual active bridge converter), and LVdc/LVac stage (LV: active front-end converter). The galvanic isolation is introduced in the MVdc/LVdc stage using MV/LV high-frequency transformers (HFTs). This article demonstrates the operation of the three-phase Y– $\Delta $ connected dual active bridge converter used in the MVdc/LVdc stage of the MUSE-SST system. Equations for phase currents, power flow, and zero-voltage switching (ZVS) boundaries are derived for all possible modes for the three-phase Y– $\Delta $ configuration. A detailed parasitic simulation model is derived by measuring and experimentally verifying the parasitic elements of the HFT. A brief discussion regarding the design considerations required for the hardware development of the medium- and low-voltage sides of the three-phase dual active bridge converter is also provided. Successful tests demonstrating the operation and feasibility of the medium-voltage dual active bridge converter, at medium-voltage levels (7.2 kV dc-link voltage), are shown. The results indicate that these devices can accelerate the growth and deployment of the medium-voltage SiC-based converter for isolated and bidirectional medium- to low-voltage dc systems.}, number={2}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Anurag, Anup and Acharya, Sayan and Bhattacharya, Subhashish and Weatherford, Todd R. and Parker, Andrew A.}, year={2022}, month={Apr}, pages={1519–1536} }
 @article{sharma_iyer_bhattacharya_2021, title={A Load Profile Based Optimized Piecewise Droop Control for DC Microgrids}, DOI={10.1109/ICDCM50975.2021.9504628}, abstractNote={Droop control is a commonly used method to parallel converters in a DC microgrid. However, the presence of non-idealities such as cable resistances can degrade the current sharing accuracy among the paralleled converters with the droop control approach. In this paper, an optimized piecewise droop-based control scheme is proposed to improve the current sharing accuracy. In the proposed method, the droop characteristics are optimized using the load current distribution. The proposed optimized piecewise droop control method is compared with both the linear and nonlinear droop based approaches over a wide range of load conditions. It is shown that the proposed piecewise droop control can achieve improved current sharing in a desired operating region based on the load distribution. The proposed control approach is verified using extensive switching circuit simulations. Further, a hardware-based experimental setup is used to validate the effectiveness of the proposed optimized piecewise droop control strategy.}, journal={2021 IEEE FOURTH INTERNATIONAL CONFERENCE ON DC MICROGRIDS (ICDCM)}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish}, year={2021} }
 @article{sharma_iyer_das_bhattacharya_2021, title={A Modified Droop Control Algorithm for DC Microgrids to Achieve Accurate Current Sharing and Improved Voltage Regulation}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487092}, abstractNote={Droop control is a commonly used method for load current sharing among the converters in DC microgrid applications. However, in this method, the current sharing and load voltage regulation are affected by cable resistances and other non-idealities. The conventional droop control method’s performance can be improved using secondary control algorithms that involve low-bandwidth communication channels. In this paper, an improved secondary control algorithm is proposed for a multi-source, single load bus DC microgrid system. In the proposed algorithm, the load voltage information is communicated to the individual converters, and there are no communication channels between individual converters. Thus the proposed algorithm achieves accurate current sharing and improved load voltage regulation with reduced communication channels compared to several state-of-the-art approaches. All the controllers in the proposed algorithm are implemented locally, and hence a decentralized control is achieved. The proposed algorithm’s effectiveness is validated using circuit simulations and hardware-based experiments on a two converter single load bus DC microgrid system.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Das, Partha Pratim and Bhattacharya, Subhashish}, year={2021}, pages={119–125} }
 @article{alharbi_isik_bhattacharya_2021, title={A Novel Submodule Level Fault-Tolerant Approach for MMC With Integrated Scale-Up Architecture}, volume={2}, url={https://doi.org/10.1109/JESTIE.2021.3061954}, DOI={10.1109/JESTIE.2021.3061954}, abstractNote={A submodule (SM) level fault-tolerant method for modular multilevel converters (MMCs) with a scalable control design for medium- and high-voltage applications is proposed in this article. A large number of SMs, which is typically required in high-power applications, is divided into sets with a smaller number of SMs. A local controller is assigned to each set for the capacitor voltage balancing (CVB) and switching signal generations, and the SM level protection. A CVB control method is proposed to maintain SM voltages among sets within a prespecified band under SM failures, in which an MMC arm can operate with unequal numbers of SMs among sets. The computational and communication burdens are reduced in each local controller. Most importantly, changing the number of SMs is achieved without significant modifications in the control system, which improves the expandability and flexibility of the MMC system to easily scale-up to higher voltage levels. A ±320 kV/1000 MW MMC system has been studied in a real-time digital simulator (RTDS) and field-programmable gate arrays boards to validate the proposed fault-tolerant control method under SM failures.}, number={3}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Alharbi, Mohammed and Isik, Semih and Bhattacharya, Subhashish}, year={2021}, month={Jul}, pages={343–352} }
 @article{anurag_acharya_kolli_bhattacharya_weatherford_parker_2022, title={A Three-Phase Active-Front-End Converter System Enabled by 10-kV SiC MOSFETs Aimed at a Solid-State Transformer Application}, volume={37}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2021.3131262}, DOI={10.1109/TPEL.2021.3131262}, abstractNote={The use of high-voltage silicon carbide (SiC) devices can eliminate multilevel and cascaded converters and their complicated control strategies, making converter systems simple and reliable. A three-phase two-level voltage-source converter system serves as a simple converter system for interfacing any dc source to a three-phase grid. However, when the high-voltage devices are used in two-level converters, they are exposed to a high-voltage peak stress and a high $dv/dt$ (up to 100 kV/$\mu$s). Operating these semiconductor devices at these stress levels requires careful design not only of the semiconductor die and the module, but also of the gate drivers, busbars, and passive filters. This article demonstrates the operation of 10-kV SiC mosfets and discusses the design considerations, advantages, and challenges associated with the operation of the three-phase two-level medium-voltage converter system used as the active-front-end converter system. Reliable operation of the medium-voltage converter system requires the development of reliable high-voltage modules and auxiliary parts, such as gate drivers, busbars, inductors, voltage and current sensors, and proper design of the controller system. Successful tests demonstrating continuous field operation of the medium-voltage active-front-end converter at a nominal rating of 7.2-kV dc-link voltage is demonstrated for the first time in the literature. The results indicate that these devices can accelerate the growth and deployment of medium-voltage SiC devices for field operation, as demonstrated by the operation inside the mobile container.}, number={5}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Anurag, Anup and Acharya, Sayan and Kolli, Nithin and Bhattacharya, Subhashish and Weatherford, Todd R. and Parker, Andrew A.}, year={2022}, month={May}, pages={5606–5624} }
 @article{miryala_dhanasekaran_ganesan_hatua_bhattacharya_2022, title={Active Gate Driving Technique for Series Connecting SiC MOSFETs in the Presence of Gate Pulse Delay Mismatch}, volume={69}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2021.3128907}, DOI={10.1109/TIE.2021.3128907}, abstractNote={In this article, series connection of SiC MOSFETs has been attempted with the help of an active gate driving (AGD) technique. The gate currents of SiC MOSFETs are actively controlled in such a way that several devices can switch fast (within 50 ns) even in the presence of a moderate amount of gate pulse delay mismatch and jitter in the gate pulse. This enables the AGD’s to share the gate pulse signal information among each other. Such a feature can reduce the cost of the net solution by reducing the number of optical cables required for the gate pulse transmission. In addition to this, the AGD is designed in such a way that fast switching can be achieved even in the presence of moderate parasitic inductance in the layout. The proposed AGD technique is experimentally verified in a double pulse test setup with two and four switching devices in series using 32 A, 1 kV CREE SiC MOSFETs. The experimental results show turn-on and turn-off switching times of 45 and 34 ns, respectively, at 35 A load current. The AGD has also shown 47% reduction in the turn-off switching losses compared to the passive gate driving technique.}, number={12}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Miryala, Vamshi Krishna and Dhanasekaran, Saravanan and Ganesan, P. and Hatua, Kamalesh and Bhattacharya, Subhashish}, year={2022}, month={Dec}, pages={12402–12413} }
 @article{madadi_bhattacharya_2021, title={Adaptive Nonlinear Droop Control with Dynamic State-of-Charge Balancing Capability for Batteries in DC Microgrids}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487320}, abstractNote={Droop control is one of the generally accepted methods for interfacing various voltage sources in a dc microgrid that could deal with challenges such as load-sharing accuracy and dc voltage regulation among the sources. This paper proposes a novel adaptive nonlinear droop control method based on dynamic state-of-charge (SOC) balancing of battery energy storage systems (BESSs) and the converters' output current in a dc microgrid. In this decentralized communication-less method, the BESS with higher SOC delivers more power with the minimum trade-off between the voltage regulation and current-sharing accuracy. The simulation and Hardware-in-the-loop (HIL) testbed results verify the stability and load-sharing, and voltage regulation capability of the proposed controller technique compared to other nonlinear and adaptive droop methods.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Madadi, Mehrnaz and Bhattacharya, Subhashish}, year={2021}, pages={55–61} }
 @article{iyer_gulur_bhattacharya_kikuchi_sridharan_zou_chen_2021, title={An Active Voltage Stabilizer for a DC Microgrid System}, volume={9}, ISSN={["2169-3536"]}, url={https://doi.org/10.1109/ACCESS.2021.3087543}, DOI={10.1109/ACCESS.2021.3087543}, abstractNote={This paper analyzes the low-frequency stability challenges that exist in a complex DC microgrid (MG) system. The converters that belong to a DC MG are categorized into different groups based on their control approach. The small-signal model of the DC MG is presented, and the conditions for system stability are derived. In some DC MG applications, there is the possibility of installing off-the-shelf converters with little flexibility and access for controller auto-tuning. To tackle this, a hardware-based active voltage stabilizer solution is proposed to stabilize the DC MG. The active stabilizer’s functionality, based on an isolated bidirectional DC-DC converter, is elucidated, and a suitable control strategy is proposed. The active stabilizer and its associated control configuration involve only local voltage sensing and are non-intrusive. A dual active bridge (DAB) converter-based active stabilizer is implemented, and hardware-based steady-state and transient experimental results from a DC MG test-bench are provided to validate the functionality and effectiveness of the proposed active stabilizer.}, journal={IEEE ACCESS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Iyer, Vishnu Mahadeva and Gulur, Srinivas and Bhattacharya, Subhashish and Kikuchi, Jun and Sridharan, Srikanthan and Zou, Ke and Chen, Chingchi}, year={2021}, pages={86786–86800} }
 @article{das_satpathy_bhattacharya_2021, title={An Improved PWM Method for Minimum Common-Mode Circulating Current Operation of Six Phase Three Level Inverter}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487259}, abstractNote={This paper presents a simple Pulse Width Modulation (PWM) technique to reduce the common-mode circulating current of a six-phase three-level inverter. Six-phase inverters generally suffer high common-mode circulating current when space vector PWM (SVPWM) or min-max method is used with a common neutral point. For common-mode circulating current reduction, Phase Disposition (PD) PWM with a compromised third harmonics injection method is proposed in this work. The selected third harmonics injection method removes the low-frequency common-mode circulating current. The absence of low frequency circulating current improves the THD of the load currents. Finally, the proposed method is tested in PLECS simulation with a 75KW system, and results are presented here.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Das, Partha Pratim and Satpathy, Subhransu and Bhattacharya, Subhashish}, year={2021}, pages={1070–1077} }
 @article{isik_alharbi_bhattacharya_2021, title={An Optimized Circulating Current Control Method Based on PR and PI Controller for MMC Applications}, volume={57}, ISSN={["1939-9367"]}, url={https://doi.org/10.1109/TIA.2021.3092298}, DOI={10.1109/TIA.2021.3092298}, abstractNote={Modular multilevel converter (MMC) is an excellent topology for medium- and high-voltage applications due to its advantages over other multilevel converters. However, the control algorithm design needs meticulous attention as each submodule (SM) capacitor voltage is balanced around their reference. Any voltage inequality between the SM voltage causes the second harmonic-dominated circulating current inside the MMC. The circulating current increases the rms value of the arm currents, component ratings, and the ripple in the capacitor voltages unless it is appropriately controlled. This article proposes an optimized closed-loop circulating current control method based on PR and PI controllers in abc reference frame to prevent high circulating current inside an MMC. The proposed method suppresses the magnitude of circulating current while reducing the ripple in capacitor voltages. The ripple in the dc link voltage is also reduced without any supplementary controller under balanced and unbalanced ac grid conditions. Thus, the proposed circulating current control method reduces the conduction losses and component ratings, while the converter's efficiency and reliability increase. The method's verification is tested on a point-to-point connected MMC-based high voltage direct current system in a real-time simulator with Xilinx FPGA-based MMC emulator and arm controller.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Isik, Semih and Alharbi, Mohammed and Bhattacharya, Subhashish}, year={2021}, month={Sep}, pages={5074–5085} }
 @article{agarwal_prabowo_bhattacharya_2021, title={Analysis and Design Considerations of Input Parallel Output Series-Phase Shifted Full Bridge Converter for a High-Voltage Capacitor Charging Power Supply}, ISSN={["2150-6078"]}, DOI={10.1109/ECCE-Asia49820.2021.9479247}, abstractNote={Capacitor charging power supplies (CCPS) are used for pulsed-power applications such as electromagnetic guns, radar applications, and pulsed lasers for aesthetic medicine, among many other application fields. This paper describes the design and analysis of an Input Parallel Output Series-Phase Shifted Full Bridge converter (IPOS-PSFB) for CCPS. In CCPS application, attaining long-lifetime of the high voltage (HV) pulsed capacitor is critical. The proposed system possesses low output current ripple to improve the lifetime of the pulsed capacitor. With the output voltage not being constant, modifications on the output current ripple equations for selecting an appropriate output inductor parameter is required. The proposed system employs a Constant Current - Constant Power (CC-CP) charging profile instead of a Constant-Current (CC) charging profile. Comparative evaluation of the CC-CP charging profile is presented to elucidate the advantage of employing CC-CP. Circuit simulation and experimental results from a hardware prototype are included to validate the design and to show the effectiveness of the proposed system.}, journal={2021 IEEE 12TH ENERGY CONVERSION CONGRESS AND EXPOSITION - ASIA (ECCE ASIA)}, author={Agarwal, Apoory and Prabowo, Yos and Bhattacharya, Subhashish}, year={2021}, pages={1068–1075} }
 @article{kim_anurag_acharya_bhattacharya_2021, title={Analytical Study of SiC MOSFET Based Inverter Output dv/dt Mitigation and Loss Comparison With a Passive dv/dt Filter for High Frequency Motor Drive Applications}, volume={9}, ISSN={["2169-3536"]}, url={https://doi.org/10.1109/ACCESS.2021.3053198}, DOI={10.1109/ACCESS.2021.3053198}, abstractNote={Fast switching characteristic of wide bandgap devices enables high switching frequency of power devices and thereby, can facilitate high fundamental frequency operation of electrical machines. However, with the switching transition times in orders of tens of nanoseconds, the high dv/dt is observed across the switching device. The high dv/dt experienced by the switches, and consequently by the machine, can degrade winding insulations or bearings over a period of time. Therefore, it is imperative to maintain the dv/dt below recommended values depending on the machine insulation. The dv/dt across the devices can be adjusted by varying the gate resistance. A high value of gate resistance, however, introduces additional switching losses on the device. Using different dv/dt filtering techniques can also help to control the dv/dt on the machine terminals. These techniques do not increase the switching losses on the device. However, it introduces additional losses in the filter resistors and also increases the cost of the system. In this paper, an analysis based on the impact of gate resistance on the dv/dt across the machine, and the corresponding losses is carried out. An analytical dv/dt filter design strategy is proposed to limit the dv/dt to a particular value. With the proposed design scheme, the value of each filter component can be easily obtained, and filter losses can be estimated accurately. Lastly, a comparison is performed on the basis of efficiency between these two techniques.}, journal={IEEE ACCESS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Kim, Heonyoung and Anurag, Anup and Acharya, Sayan and Bhattacharya, Subhashish}, year={2021}, pages={15228–15238} }
 @article{narasimhan_anurag_bhattacharya_2021, title={Comparative Study of a 3.3 kV SiC-based Voltage and Current Source Inverter for High-Speed Motor Drive Applications}, ISSN={["2150-6078"]}, DOI={10.1109/ECCE-Asia49820.2021.9479066}, abstractNote={Current source inverters (CSIs) is a technology typically used for high power medium voltage (MV) applications. With the emergence of wide-bandgap (WBG) technology, the CSI has been widely looked into for aerospace applications, MV solid-state transformers (SST), electric vehicles, traction applications, and renewable energy systems. This paper looks into the potential of MV-based CSI inverter for high-speed machine (HSM) applications compared to MV-based voltage source inverters (VSIs) inverter in terms of efficiency, reflected voltage, and sizing of passive components. It also compares the effects of dead-time in the VSI and effects of overlap-time in the CSI. The fault tolerance of permanent magnet motor-based HSM for VSI and CSI-based systems is discussed. The switch configuration required for a WBG based MV-based CSI is discussed.}, journal={2021 IEEE 12TH ENERGY CONVERSION CONGRESS AND EXPOSITION - ASIA (ECCE ASIA)}, author={Narasimhan, Sneha and Anurag, Anup and Bhattacharya, Subhashish}, year={2021}, pages={2211–2217} }
 @inproceedings{kanale_narasimhan_cheng_agarwal_shah_baliga_bhattacharya_hopkins_2021, title={Comparison of the Capacitances and Switching Losses of 1.2 kV Common-Source and Common- Drain Bidirectional Switch Topologies}, ISBN={9781665401821}, url={http://dx.doi.org/10.1109/WiPDA49284.2021.9645130}, DOI={10.1109/WiPDA49284.2021.9645130}, abstractNote={Bidirectional, or four-quadrant switches (FQS) can be designed as back-to-back MOSFETs connected in common-drain (CD) or common-source (CS) topologies. CDFQS and CS-FQS assembled from discrete 1.2 kV commercially available SiC power MOSFETs were characterized to obtain capacitance and switching loss values. The CD-FQS exhibited a 1. 17x larger turn-on loss compared to the CS-FQS, while the CS-FQS exhibited a 1. 52x larger turn-off loss compared to the CD-FQS. The CS-FQS exhibited a lower input capacitance, while the CD-FQS exhibited a lower output and reverse transfer capacitance.}, booktitle={2021 IEEE 8th Workshop on Wide Bandgap Power Devices and Applications (WiPDA)}, publisher={IEEE}, author={Kanale, Ajit and Narasimhan, Sneha and Cheng, Tzu-Hsuan and Agarwal, Aditi and Shah, Suyash Sushilkumar and Baliga, B. Jayant and Bhattacharya, Subhashish and Hopkins, Douglas C.}, year={2021}, pages={112–117} }
 @article{isik_alharbi_bhattacharya_2021, title={Comprehensive Analysis of the Control Structures for MMC Applications}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595092}, abstractNote={Early MMC applications are controlled with a centralized controller. However, recent MMC controllers are primarily based on a distributed control structure as modularity and scalability features of an MMC can be efficiently utilized with local controllers of the distributed control algorithm. However, the distributed control structure also has a centralized unit for coordinating its local controllers, and the chance of a single point of failure still exists. Therefore, in most recent MMC applications, decentralized control structures are adopted, eliminating the central control unit. Eliminating the central control unit eliminates a single point of failure risk, and the reliability of an MMC theoretically increases. However, this might not always be true for practical MMC applications, as the operation of an MMC relies overall structure of an MMC. Therefore, each arm of an MMC should operate appropriately for the safe and reliable operation of an MMC. This paper evaluates and compares the control structures for MMC applications regarding reliability and area of use.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Isik, Semih and Alharbi, Mohammed and Bhattacharya, Subhashish}, year={2021}, pages={2459–2466} }
 @article{prabowo_iyer_bhattacharya_aeloiza_2021, title={Controller Design for the Rating-Proportional Current Sharing in Modular Hybrid Critical Load Substation Transformers}, ISSN={["2150-6078"]}, DOI={10.1109/ECCE-Asia49820.2021.9479434}, abstractNote={Partially rated power electronic modules (PEMs) can be interfaced with conventional line-frequency transformers (LFTs) to realize hybrid transformers (HTs). Hybrid transformers possess higher controllability as compared to conventional LFTs. In this paper, the parallel operation of multiple such hybrid transformer systems to form a modular architecture is proposed. The proposed system utilizes back-to-back power converter units with a lead/follower (L/F) control strategy. It entails reliable and resilient operations for critical load substation deployment during disasters and emergencies. The partially-rated power electronic module is exploited to achieve rating-proportional current sharing and voltage regulation. The controller design for the rating-proportional current sharing is presented. The DC-side stability of the back-to-back power converter unit with the proposed current sharing controller is assessed. Simulation results are included to validate the proposed concept.}, journal={2021 IEEE 12TH ENERGY CONVERSION CONGRESS AND EXPOSITION - ASIA (ECCE ASIA)}, author={Prabowo, Yos and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish and Aeloiza, Eddy}, year={2021}, pages={899–905} }
 @article{kolli_parashar_kokkonda_anurag_kumar_bhattacharya_veliadis_2021, title={Design Considerations of Three Phase Active Front End Converter for 13.8 kV Asynchronous Microgrid Power Conditioning System enabled by Series Connection of Gen-3 10 kV SiC MOSFETs}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9594975}, abstractNote={The recent growth in power generation using renewable energy sources has led to extensive research and development of robust and resilient power converters, which can integrate them with the medium voltage (MV) grids (13.8 kV,60Hz). Conventional power converters need a line frequency transformer for their integration to the MV grid, which increases the overall footprint and installation cost of the system. Therefore, a compact and lightweight alternative are required for largescale integration of the renewable energy source to the MV grid. With the advent of high voltage SiC MOSFETs, the operating frequency of grid converter can be increased up to 10-20 kHz, thus significantly reducing the size of filter inductors. The use of these devices in multi-level configurations with series-connected devices facilitates the design of power converters that can interface directly with MV grid, eliminating the need for line frequency transformers. The converter presented in this paper is designed to interface a 13.8 kV three-phase grid to a dc link of 24 kV. A three-level neutral point clamped (3L-NPC) topology enabled by series-connected 10 kV 15 A SiC MOSFETs and 10 kV 15 A SiC JBS diodes is presented. This paper focuses on the advantages, design considerations, and challenges associated with a medium voltage 3L-NPC converter. Experimental results show the successful operation of series-connected 10 kV 15 A SiC MOSFETs and JBS Diodes at medium voltage levels and highlights the series connection that is realized with snubber circuits for voltage balancing.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Kolli, Nithin and Parashar, Sanket and Kokkonda, Raj Kumar and Anurag, Anup and Kumar, Ashish and Bhattacharya, Subhashish and Veliadis, Victor}, year={2021}, pages={1211–1218} }
 @article{wong_zhu_pahl_bhattacharya_2021, title={Design and Implementation of 50V/400A Single-Stage Full-Bridge Synchronous Rectifier for Data Center Application}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595179}, abstractNote={Synchronous rectification (SR) is widely adopted for low-voltage high-current applications to improve efficiency. However, most SR researches focus on low power levels at hundreds or several kilowatts, and there is yet any attempt to extend SR to tens of kilowatts. This paper presents the design and experimental results of a full-bridge SR using ON-Semi NCP4305 SR IC at 20kW for 48V data center application.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Wong, Isaac and Zhu, Guangqi and Pahl, Birger and Bhattacharya, Subhashish}, year={2021}, pages={2245–2250} }
 @article{agarwal_anurag_kolli_kumar_bhattacharya_2021, title={Design considerations of 6.5kV enabled three-level and 10kV enabled two-level medium voltage SST}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595367}, abstractNote={The advent of medium voltage silicon carbide (SiC) power semiconductor devices (6.5kV and 10 kV) has opened up the possibilities of looking into different converter topologies for the MV grid interfaced applications. A medium voltage mobile utility support equipment-based three-phase solid-state transformer (MUSE-SST) system is one such application aimed to interconnect a three-phase 4160 V/60 Hz grid to a three-phase 480 V/60 Hz grid to provide a shore-to-ship power interface for naval vessels. The system can be realized by both 10 kV SiC MOSFET and 6.5kV SiC MOSFET employing a two-level and three-level architecture respectively. The aim of this paper is to understand the thermal challenges and provides detailed design considerations of the two MV device-based architectures for a system scale-up to 500kVA rating. Device characteristics for both 6.5kV and 10kV SiC MOSFETs have been evaluated from experimental results. Based on these experimental data, the thermal performance of these devices enabled converter architecture is compared using elctro-thermal simulation-based loss comparison.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Agarwal, Apoorv and Anurag, Anup and Kolli, Nithin and Kumar, Ashish and Bhattacharya, Subhashish}, year={2021}, pages={282–289} }
 @article{isik_parashar_bhattacharya_2021, title={Design of a Fault-tolerant Controller for Three-phase Active front End Converter used for Power Conditioning Applications}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487291}, abstractNote={Recently, an asynchronous micro-grid PCS, enabled by 10kV SiC MOSFETs, has become an exciting research area. The PCS is lightweight and modular technology due to its high switching frequency, 10 kHz or more. Therefore, it can be manufactured and transported at a relatively lower cost. The integration of the PCS to an MV grid, 13.8kV or more, requires an electrical protection scheme to avoid the converter’s fault. Different types of faults might occur in the converter system, such as switch failures or grid side faults. The converter shut-off might lead to power loss to many customers and higher downtime costs for the utilities during a failure. Thus, alternative fault-tolerant techniques are necessary to sustain the converter operation under faulty conditions. This paper investigates short and open circuit switch conditions occurring in 3L-NPC converter topology. Large and small-signal converter models are derived for a given failure. A fault-tolerant controller is designed based on the symmetrical components, and it limits the fault current under the desired limit. A closed-loop simulation of the PCS at 22 kV DC bus and the 10A load current is performed at the RTDS and CHIL setup. Individual switch failures are tested in the RTDS and compared with offline simulation results. The effectiveness of the controller is validated in PLECS.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Isik, Semih and Parashar, Sanket and Bhattacharya, Subhashish}, year={2021}, pages={2804–2811} }
 @article{ghanbari_bhattacharya_2022, title={Disturbance Rejection Analysis of a Droop-Controlled DC Microgrid Through a Novel Mathematical Modeling}, volume={10}, ISSN={["2168-6785"]}, url={https://doi.org/10.1109/JESTPE.2021.3088777}, DOI={10.1109/JESTPE.2021.3088777}, abstractNote={DC microgrids are gaining interest by the increase in dc loads and renewable resource penetrations. Photovoltaic (PV) arrays are the primary renewable resources utilized in dc microgrids with variations in their productions. Power variations are seen as disturbances from other sources’ point of view. The droop control method is frequently used to control dc microgrids and assures power sharing among parallel-connected converters. It is of great interest to assess droop controller functionality in rejecting disturbances, and maintain constant output voltage. Therefore, there is a need for a comprehensive converter and controller modeling to study the effect of disturbances on the system behavior. In this article, the converter’s small-signal model is utilized in deriving the system state space model. Via the derived model, the effect of different circuit parameters on time and frequency responses is studied. The line resistances’ effect on the parallel operation of converters is also studied. To verify the droop controller’s functionality, the converter’s output impedance is derived. Disturbances are applied to the load current, and the system response is analyzed. Finally, the dc microgrid plug and play feature is addressed by proposing an algorithm for deriving the multiple converters’ mathematical model. Simulations and hardware-in-the-loop (HIL) experiments are conducted to verify the mathematical model and controllers’ performance.}, number={2}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Ghanbari, Niloofar and Bhattacharya, Subhashish}, year={2022}, month={Apr}, pages={1507–1518} }
 @article{pal_madadi_gulur_bhattacharya_2021, title={Grid Compliant Power Conditioning System for Solid Oxide Fuel Cells}, ISSN={["2329-5759"]}, DOI={10.1109/PEDG51384.2021.9494182}, abstractNote={Fuel Cell (FC) energy-based systems are a growing source of distributed generation (DG) and are typically connected through a power conversion system (PCS) to the ac distribution network. In this work, broad control guidelines are analyzed and discussed for interconnecting Solid Oxide Fuel Cells (SOFC) based distribution systems to the utility grid. A two-stage PCS (comprising of a Boost Converter and a 3ϕ, Voltage Source Converter) is designed and utilized for controlling the power being injected into the utility grid. Additionally, the PCS is equipped with an advanced supervisory control scheme to adhere to IEEE 1547 requirements for utility grid interconnection. The overall architecture, including the SOFC system along with the appropriate PCS is implemented on a Real-Time Digital Simulation (RTDS) platform to evaluate and demonstrate the usefulness of proposed supervisory control schemes.}, journal={2021 IEEE 12TH INTERNATIONAL SYMPOSIUM ON POWER ELECTRONICS FOR DISTRIBUTED GENERATION SYSTEMS (PEDG)}, author={Pal, Shruti and Madadi, Mehrnaz and Gulur, Srinivas and Bhattacharya, Subhashish}, year={2021} }
 @article{zhu_pahl_wong_samanta_bhattacharya_2021, title={High Efficiency Medium Voltage to Low Voltage Wireless Power Transformation for Data Centers}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487222}, abstractNote={Wireless power transfer (WPT) techniques have been widely explored for various applications including for electric vehicles (EVs) and mobile phones. Less attention has been paid to the use of WPT in power distribution applications. An isolated wireless power link enables a touch safe interface without electrically energized contacts eliminating any arc flash or electrocution hazards. This concept will for example enable safe medium voltage distribution inside data centers eliminating low voltage distribution with its large bus bars and cables and bring voltages larger than 1kV directly to the server rack. It has been demonstrated that a converter using a planar contactless transformer can directly convert the 1kV DC input to 48V over a wide load range. In this paper, the planar contactless transformer is optimized with 3D printed bobbins to improve the manufacturability and technology readiness level. A new synchronous rectifier architecture is developed with MOSFET drain-to-source voltage-sensing for an H-bridge rectifier to improve the DC-to-DC efficiency. An adaptive dead time control method is used to compensate for layout parasitic inductances, to maximize the synchronous rectifier efficiency, and to avoid premature turn-off of MOSFETs. The DC-to-DC power transfer efficiency and loss distribution are analyzed.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Zhu, Guangqi and Pahl, Birger and Wong, Isaac and Samanta, Suvendu and Bhattacharya, Subhashish}, year={2021}, pages={1580–1585} }
 @article{kumar_kokkonda_bhattacharya_baliga_veliadis_2021, title={High Voltage Output Characteristics and Short Circuit Robustness of HV SiC MOSFETs}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595821}, abstractNote={The short circuit characteristics of the recently developed high voltage (HV) SiC MOSFETs are essential to ensure the proper functioning of the power converters during the short circuit fault conditions. The short circuit failure time can be estimated using the HV output characteristics of the MOSFETs with reasonable assumptions. The HV output characteristics of the 3.3 kV, 6.5 kV, and 10 kV SiC MOSFETs, developed by Wolfspeed, are measured for the first time. The estimated short circuit failure time is 3.5 μs, 7.4 μs and 8.1 μs for the 3.3 kV, 6.5 kV, and 10 kV SiC MOSFETs, respectively at the gate bias of 15 V. The analytical results are closely matching with the experimental short circuit failure results of the 6.5 kV SiC MOSFET. The short circuit robustness of the single 6.5 kV SiC MOSFET is found to be superior to the two series-connected 3.3 kV SiC MOSFETs.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Kumar, Ashish and Kokkonda, Raj Kumar and Bhattacharya, Subhashish and Baliga, Jayant and Veliadis, Victor}, year={2021}, pages={5277–5282} }
 @article{miryala_pandey_hatua_bhattacharya_2021, title={Layout Inductance Assisted Novel Turn-on Switching Loss Recovery Technique for SiC MOSFETs}, volume={2}, url={https://doi.org/10.1109/JESTIE.2021.3105871}, DOI={10.1109/JESTIE.2021.3105871}, abstractNote={This article proposes a passive snubber circuit for achieving reliable zero voltage turn-on transition with the help of layout inductance in a dc–dc converter. A small assist inductance is inserted in the PCB layout for achieving this zero voltage turn-on. A new regenerative snubber circuit is designed to recover the switching loss corresponding to the voltage overshoots alone. This way energy storage requirement of the snubber circuit is minimized significantly. The proposed snubber circuit is experimentally verified using a 1 kV, 32 A SiC mosfet, and 1.2 kV, 30 A Schottky diode in a boost converter setup. For the same voltage overshoot, the proposed snubber circuit has achieved a ten times reduction (89.4%) in switching losses compared to the without snubber case in a boost converter setup at 600 V, 30 A load condition. At 200-kHz switching frequency, the designed boost converter registered a peak efficiency of 98.87% at 5.5 kW load and it achieved 98.45% efficiency at 10 kW load. At 10 kW load, the snubber inductor had an rms current of 0.45 A and a peak current of 4 A flowing through it. The diode and mosfet snubber capacitors had a peak voltage of 60 V and 190 V, respectively.}, number={4}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Miryala, Vamshi Krishna and Pandey, Vibhav and Hatua, Kamalesh and Bhattacharya, Subhashish}, year={2021}, month={Oct}, pages={513–525} }
 @article{kokkonda_kumar_anurag_kolli_parashar_bhattacharya_2021, title={Medium Voltage Shore-to-Ship Connection System Enabled by Series Connected 3.3 kV SiC MOSFETs}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487119}, abstractNote={Increasing concern about the environmental impact of ships has made Shore-to-Ship (STS) power an attractive solution for ship owners and port authorities worldwide in reducing emissions at ports. Existing shore-to-ship solutions for 0.1 MVA to 5 MVA applications employ silicon (Si) IGBT based static frequency converters. Recent developments in high voltage silicon carbide (SiC) devices have facilitated improvement in efficiency and power density of medium voltage (MV) converters in various applications. This paper proposes an MV STS system enabled by series connection of three 3.3 kV SiC MOSFETs, which shows the potential for improved power density and efficiency compared to existing Si IGBT based solutions. A 100 kVA 3-phase two-level voltage source converter (VSC) with series connected 3.3 kV SiC MOSFETs is designed and demonstrated. Experimental results for the series connected 3.3kV SiC MOSFET based converter is shown at 6 kV dc link voltage to validate the design and operation of such a system. Successful demonstration of a MV converter system enabled by series connection of high voltage SiC MOSFETs can open up opportunities to replace conventional Si IGBT based converters with SiC MOSFET based converters in applications interfacing with medium voltage grid.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Kokkonda, Raj Kumar and Kumar, Ashish and Anurag, Anup and Kolli, Nithin and Parashar, Sanket and Bhattacharya, Subhashish}, year={2021}, pages={1380–1387} }
 @article{zhu_pahl_fons_wong_bhattacharya_beddingfield_2021, title={Medium Voltage to Low Voltage Contactless Power Transformation for Data Centers}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595112}, abstractNote={Contactless power transfer (CPT) methods have widely been explored for many applications. An isolated wireless power link enables a touch-safe interface without electrically energized contacts eliminating any arc flash or electrocution hazard. The concept presented here will enable safe medium voltage distribution inside data centers eliminating low voltage distribution with bulky cables bringing voltages larger than 1kV directly to the server rack. This paper proposes high-efficiency single-stage contactless power conversion from medium voltage to low voltage for data center applications. The proposed solution is evaluated using a 10kW design example and verified by experimental tests. A plug-in contactless transformer is developed with customized nanocrystalline cores and 3D printed bobbins to improve the DC-to-DC efficiency and manufacturability. A high efficiency converter is developed to maintain a 48V output voltage with a IOOOV input voltage over a wide load range. The DC-to-DC efficiency and frequency modulation performance are analyzed.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Zhu, Guangqi and Pahl, Birger and Fons, Richard J. and Wong, Isaac and Bhattacharya, Subhashish and Beddingfield, Byron}, year={2021}, pages={5839–5844} }
 @article{rastogi_shah_singh_bhattacharya_2021, title={Mode Analysis and Identification Scheme of Open-Circuit Fault in a Three-phase DAB Converter}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595447}, abstractNote={The three-phase Dual Active Bridge (3$-\Phi$ DAB) is a popular DC-DC converter topology for high power applications; it provides high efficiency, bidirectional power transfer capability with galvanic isolation between the input/output terminals. With the wide-scale adoption of such power electronic converters, their reliability becomes increasingly important. A prominent failure mode in the high power converters is the open-circuit fault that occurs due to failure in a semiconductor device or its gate drive circuit. In this study, detailed waveform analyses are presented for the normal and the fault mode operation of the $3-\Phi$ DAB. Main symptoms of the converter during normal and fault conditions have been identified, and a unique pattern in the DC bias of phase currents under fault mode is noted. A logic-based fault diagnosis scheme is proposed to detect the fault and identify the faulty transistor. The scheme requires sensing of currents on only one side of the transformer to detect faults on either side. Therefore, lower-rated current sensors may be placed on the low current side of the high-gain converters, thereby reducing the cost. Moreover, the detection scheme relies only on the DC bias value of the phase currents, implying that low-bandwidth current sensors can be used. Experimental results at 5.5 kW rated power have been provided to verify the analyses and the proposed identification scheme. The study also reveals a new potential benefit of the 3$-\Phi$ DAB converter over the 1$-\Phi$ DAB; i.e., even in the presence of a secondary-side open-circuit fault, the 3$-\Phi$ converter may continue to operate normally. The analyses and the open-circuit fault diagnosis scheme proposed for the 3$-\Phi$ DAB converter will improve the system’s reliability.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Rastogi, Sagar Kumar and Shah, Suyash Sushilkumar and Singh, Brij N. and Bhattacharya, Subhashish}, year={2021}, pages={2762–2769} }
 @article{ghanbari_bhattacharya_2021, title={Modeling of Energy Source in DC Microgrids with Voltage Regulation Capability}, ISSN={["2329-5759"]}, DOI={10.1109/PEDG51384.2021.9494191}, abstractNote={DC microgrids gain interests due to the increase in the penetration of renewable resources with DC nature. In DC microgrids, renewable resources are connected in parallel to the DC bus. Droop control strategy is generally used for power sharing allocation among parallel-connected resources. Although its acceptable functionality, the droop control method has two main drawbacks. Line resistances affect the accuracy of power sharing. Moreover, DC bus regulation is deteriorated due to the voltage drop. Hierarchical platforms are introduced to restore power sharing accuracy and voltage level. In this paper, different methods of power sharing correction and voltage restoration are compared. A novel distributed method of voltage restoration is proposed to address the power sharing accuracy, as well as voltage restoration. Then, small-signal analysis is used to derive the hierarchical state space model. The mathematical model has an algorithm that addresses the DC microgrid’s plug and play feature. Through the derived model, functionalities of the studied methods are investigated. Stability analysis is done through the derived state space model for different loading conditions. Simulations and Hardware-In-the-Loop (HIL) experiments are conducted to verify the controllers’ functionalities.}, journal={2021 IEEE 12TH INTERNATIONAL SYMPOSIUM ON POWER ELECTRONICS FOR DISTRIBUTED GENERATION SYSTEMS (PEDG)}, author={Ghanbari, Niloofar and Bhattacharya, Subhashish}, year={2021} }
 @article{isik_burugula_alharbi_bhattacharya_2021, title={Modular Power Flow Enhancer for Transmission Networks under Unbalanced Power Grid Conditions}, ISSN={["1553-572X"]}, DOI={10.1109/IECON48115.2021.9589894}, abstractNote={The three-phase H-bridge or NPC converters are commonly adopted converter topologies for FACTS devices. Both the converters are classified as multilevel converters capable of producing a three-level AC voltage between the phase and the neutral terminals. Either topology is a good solution in the low voltage environment where it is possible to select a switch capable of blocking the required DC bus voltage. If the converter is designed for a high-voltage application, the design stage of these converters may be challenging due to making composite switches for voltage blocking requirements. Besides, there is a need for a large filter for interfacing these converters with the grid to meet the THD requirements as the operating frequency is the line frequency. Therefore, this paper adopts an MMC as an SSSC to enhance power flow in the transmission network and relieve the transmission line against abnormal situations. Besides, PR-based controllers are presented in αβ0 stationary reference frame to provide reliable operation under unbalanced grid conditions. The effectiveness of the MMC-based SSSC and its controller is modeled in FPGAs and integrated with the RTDS through fiber optic cables.}, journal={IECON 2021 - 47TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY}, author={Isik, Semih and Burugula, Vasishta and Alharbi, Mohammed and Bhattacharya, Subhashish}, year={2021} }
 @article{shah_narwal_bhattacharya_kanale_cheng_mehrotra_agarwal_baliga_hopkins_2021, title={Optimized AC/DC Dual Active Bridge Converter using Monolithic SiC Bidirectional FET (BiDFET) for Solar PV Applications}, ISSN={["2329-3721"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85123361428&partnerID=MN8TOARS}, DOI={10.1109/ECCE47101.2021.9595533}, abstractNote={Grid interface power conversion systems for commercial, industrial and residential solar power generation are becoming ubiquitous due to the competitive cost of solar energy. The AC/DC dual active bridge (DAB) converter is an upcoming topology in industrial PV energy and energy storage applications, providing bidirectional power transfer and galvanic isolation. In this paper, the properties of a DAB-type converter are leveraged to propose a design optimization process. It can optimize the high-frequency RMS current, size of magnetic elements and zero-voltage-switching (ZVS) region of the converter. The resulting design is compared against that derived from a conventional approach. In addition, an algorithm to compute the harmonic currents at the DC and line frequency AC ports of the system is proposed, and the respective filter designs are presented. The optimized design of the AC/DC DAB converter is implemented using the newly developed, 1200 V, $46 \mathrm{m}\Omega$, four quadrant, SiC-based monolithic bidirectional FETs (BiDFET). Experimental results from the 2.3 kW, $400\mathrm{V}/277\mathrm{V}_{{\mathrm {RMS}}}$ hardware prototype are finally presented to verify the design process.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Shah, Suyash Sushilkumar and Narwal, Ramandeep and Bhattacharya, Subhashish and Kanale, Ajit and Cheng, Tzu-Hsuan and Mehrotra, Utkarsh and Agarwal, Aditi and Baliga, B. Jayant and Hopkins, Douglas C.}, year={2021}, pages={568–575} }
 @article{das_satpathy_shah_bhattacharya_veliadis_2021, title={Paralleling of Four 650V/60A GaN HEMTs for High Power Traction Drive Applications}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595766}, abstractNote={This paper presents design considerations and experimental verification of a GaN-based half-bridge 650V/160A power converter block with four parallel 650V/60AGaN High Electron Mobility Transistors (HEMTs) for high-power traction drive applications. Paralleling of semiconductor devices is common for high power density applications. However, paralleling more than two GaN devices is challenging as parasitic inductances and resistances need to be well matched for all the devices. In addition, the DC loop inductances must be minimized to reduce the device voltage overshoot during turn-off. The gate loop inductances must also be matched and minimized to improve current sharing and reduce gate voltage oscillations. A detailed design method of a half-bridge with four parallel devices is discussed in this paper for matching gate and DC loop inductances. A half-bridge test circuit with four parallel enhancement-mode GaN (e-GaN) HEMTs is designed following the design method. The inductance matchings are verified with a detailed Q3D simulation. Finally, Double Pulse Test (DPT) results at 400V/160A are presented in this paper to demonstrate the half-bridge converter block’s current sharing and loss distributions.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Das, Partha Pratim and Satpathy, Subhransu and Shah, Suyash Sushilkumar and Bhattacharya, Subhashish and Veliadis, Victor}, year={2021}, pages={5269–5276} }
 @article{kolli_pramod_bhattacharya_2021, title={Performance Analysis of PMSM during Regeneration fed by Dual-Inverter System}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487450}, abstractNote={Fault mode operation of motor drives, especially in traction applications, is gaining ground. One of the common practices during fault mode is to turn off the inverter. If the inverter circuit is not electrically isolated from the machine, it acts as an uncontrolled rectifier, because of anti-parallel diodes, leading the machine to cause regenerative braking. In this paper, the performance analysis of PMSM during regeneration, which is fed by dual-inverter system, is studied in a synchronous reference frame as it gives better insight from the analysis and active compensation point of view. The harmonic analysis of all the currents and braking torque is also presented for all the operating modes during regeneration.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Kolli, Nithin and Pramod, Prerit and Bhattacharya, Subhashish}, year={2021}, pages={2200–2205} }
 @article{kumar_bhattacharya_baliga_veliadis_2021, title={Performance Comparison and Demonstration of 3-L Voltage Source Inverters Using 3.3 kV SiC MOSFETs for 2.3 kV High Speed Induction Motor Drive Applications}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487135}, abstractNote={Medium voltage direct-drive high-speed motor results in better efficiency and reduces the compressor system’s footprint in the oil and gas industry. This paper investigates the employment and the performance evaluation of the recently developed 3.3 kV SiC MOSFET power modules for a 2.3 kV three-phase high-speed motor drive application. Performance of the three popular three-level (3-L) converter topology, namely NPC, ANPC, and T-type, enabled by the 3.3 kV SiC MOSFETs and diodes is evaluated and compared with a 3.3 kV IGBT-based 2.3 kV drive system. At 10 kHz switching frequency, the test results show that the 3.3 kV SiC MOSFET-based 3-L NPC inverter has superior performance to the other 3-L converters at the motor frequency of 300 Hz. The 3.3 kV SiC MOSFET-based drive system is shown to have a significant improvement in reliability, power density, and efficiency in comparison to the 3.3 kV IGBT-based drive system. The 3.3 kV MOSFET module is demonstrated successfully using the heat run test in the 3-L inverter pole at 10 kHz switching frequency in the laboratory.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Kumar, Ashish and Bhattacharya, Subhashish and Baliga, Jayant and Veliadis, Victor}, year={2021}, pages={1103–1110} }
 @article{kumar_bhattacharya_baliga_veliadis_2021, title={Performance Evaluation of 10 kV SiC Current Switch Based PWM Current Source Inverter for 4.16 kV Motor Drive Applications}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487162}, abstractNote={Series-connected 6.5 kV symmetric gate-commutated thyristor (SGCTs) are widely used as the reverse blocking switch (referred to as the current switch in this paper) in 4.16 kV PWM current source inverter (CSI) based motor drive applications up to 420 Hz switching frequency. Modern 10 kV SiC MOSFETs and SiC diodes have the potential to be implemented as the current switch with lower switching loss and a smaller count of the active switches in the 4.16 kV CSI-based drives. In this paper, a 10 kV SiC current switch is presented to enable a medium voltage (MV) PWM-CSI for 4.16 kV motor drive applications. The higher switching frequency capability of the 10 kV SiC current switch reduces the output current harmonics and the dc link inductor size significantly. Experimental tests have shown that the electrical and thermal performance of the 10 kV SiC current switch-based CSI is shown to be reasonably acceptable and near to 10 kV SiC MOSFET-based VSI drives at 10 kHz switching frequency.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Kumar, Ashish and Bhattacharya, Subhashish and Baliga, Jayant and Veliadis, Victor}, year={2021}, pages={1219–1226} }
 @article{narasimhan_kanale_bhattacharya_baliga_2021, title={Performance Evaluation of 3.3 kV SiC MOSFET and Schottky Diode for Medium Voltage Current Source Inverter Application}, DOI={10.1109/WiPDA49284.2021.9645089}, abstractNote={This paper for the first time discusses the dynamic characterization of 3.3 kV SiC-based reverse-voltage blocking current switch for three different switch configurations - SiC MOSFET with a series diode, SiC MOSFETs connected in the common-source or common-drain configuration. The dynamic characterization of the current switch is performed using the conventional double-pulse test at different junction temperatures and different gate resistances. This paper also discusses the static characterization of the latest generation 3.3 kV SiC MOSFET and Schottky diode TO-247 packages. The static characterization of the MOS-FET includes output characteristics, transfer characteristics, junction capacitance measurement and 3rd quadrant characteristics. The static characteristics of the Schottky diode includes the on-state characteristics, and junction capacitance measurement. With the obtained static and dynamic characterization data, the three-phase current-source inverter losses is evaluated for the three different switch configurations and the preferred current switch configuration is selected for a medium voltage-based high-speed motor drive application.}, journal={2021 IEEE 8TH WORKSHOP ON WIDE BANDGAP POWER DEVICES AND APPLICATIONS (WIPDA)}, author={Narasimhan, Sneha and Kanale, Ajit and Bhattacharya, Subhashish and Baliga, Jayant}, year={2021}, pages={366–371} }
 @article{krishna_kumar_parashar_bhattacharya_2021, title={Performance Evaluation of a Novel High Voltage Monolithically Integrated SiC MOSFET-DIODE for Solar String Inverters}, ISSN={["2150-6078"]}, DOI={10.1109/ECCE-Asia49820.2021.9479330}, abstractNote={There has been an increase in large-scale solar power plants around the world. Most large-scale solar power plants operate at a DC bus voltage of 1000Vor less. It has been shown in current literature that an increase in DC bus voltage enhances the performance of the solar string inverters. The commercially available Si-based string inverters use complex multi-level inverter topologies to reduce the filtering requirements, eliminating the high-frequency operation of SiC MOSFETs. But SiC MOSFETs are associated with reverse recovery losses owed to its body diode. A novel device namely, Integrated MOSFET-DIODE was developed to eliminate this loss, where the reverse conduction is through a SiC diode rather than the MOSFET’s body diode. This paper demonstrates the advantages of a novel Integrated MOSFET-DIODE over Si devices and SiC MOSFETs in applying solar string inverters.}, journal={2021 IEEE 12TH ENERGY CONVERSION CONGRESS AND EXPOSITION - ASIA (ECCE ASIA)}, author={Krishna, Vineeth and Kumar, Ashish and Parashar, Sanket and Bhattacharya, Subhashish}, year={2021}, pages={2345–2351} }
 @article{isik_bhattacharya_2021, title={Reliability and Cost Modeling of a Modular Multilevel Converter}, ISSN={["2329-5759"]}, DOI={10.1109/PEDG51384.2021.9494184}, abstractNote={This paper presents an analytical expression to calculate the reliability, cost and loss for Modular Multilevel Converter (MMC) based high voltage applications. A three-terminal DC system is chosen as a case study with different terminal modeling. Terminal 1 is modeled with conventional vector current control and circulating current control. Terminal 2 is modeled with a Fault-Tolerant Controller and dq based circulating current control, and terminal 3 is modeled with a conventional vector current control with no circulating current control. In addition to the control structure, Nearest Level Modulation (NLM) is adopted for each terminal. The MTDC system is investigated based on the total reliability and availability of the terminals. Besides, analytical loss and cost calculations are performed for the three-terminal DC system. Different redundancy techniques for MMC arms are presented, but a 10% active redundancy scheme is adopted in the three-terminal DC system.}, journal={2021 IEEE 12TH INTERNATIONAL SYMPOSIUM ON POWER ELECTRONICS FOR DISTRIBUTED GENERATION SYSTEMS (PEDG)}, author={Isik, Semih and Bhattacharya, Subhashish}, year={2021} }
 @article{anurag_acharya_bhattacharya_2021, title={Solid State Transformer for Medium Voltage Grid Applications Enabled by 10 kV SiC MOSFET based Three-Phase Converter Systems}, ISSN={["2150-6078"]}, DOI={10.1109/ECCE-Asia49820.2021.9479336}, abstractNote={The emergence of wide bandgap semiconductors in power electronics has made it possible to manufacture medium voltage (MV) devices with low on-state resistance and offer fast switching transitions. This has enabled high switching frequencies in MV applications, which reduces the size and weight of the magnetic components and has opened up many opportunities in the field of power transmission and distribution. With the increasing popularity of MVac and MVdc microgrids, it has become necessary to have suitable MVac/MVdc, MVac/MVac, or MVac/LVac converters to integrate MVac systems with AC or DC microgrids. On account of this, an MV solid-state transformer (MV-SST) enabled by 10 kV SiC MOSFETs is developed to integrate an MV grid of 4.16 kV to a low voltage (LV) grid of 480 V. The MV-SST is divided into three stages: MVac/MVdc stage, MVdc/LVdc stage, and LVdc/LVac stage. These three stages ensure an SST operation to integrate MVac and LVac grids and provide an option to integrate DC loads or DC grids at the DC ports. This paper discusses the design, development, and operation of the 10 kV SiC MOSFETs based SST. A concise description of the hardware challenges in developing the MV-SST system is also shown. A brief description of the design aspects of different parts of the system (MVac/MVdc stage, MVdc/LVdc stage, and LVdc/LVac stage) is highlighted. Stability analysis for integrating the different converter systems is also provided to ensure that the system remains stable in its rated operating conditions. The operation and feasibility of the MV-SST system are demonstrated by experimental results.}, journal={2021 IEEE 12TH ENERGY CONVERSION CONGRESS AND EXPOSITION - ASIA (ECCE ASIA)}, author={Anurag, Anup and Acharya, Sayan and Bhattacharya, Subhashish}, year={2021}, pages={906–913} }
 @article{satpathy_das_bhattacharya_2021, title={Study of Switching Transients based on dv/dt and di/dt for a GaN-based Two-Level Pole}, ISSN={["2150-6078"]}, DOI={10.1109/ECCE-Asia49820.2021.9479426}, abstractNote={The faster switching transients of GaN devices lead to extremely low switching loss. This is a key feature that makes GaN devices a potential candidate for power converters driving high speed electric machines. The switching transients occur in tens of nanoseconds leading to very high dv/dt and di/dt. This leads to several challenges for both power converter as well as motor load. Switching device voltage overshoot and insulation stress for motors are key concerns among them. A practical operation of power converter needs to consider minimizing the losses while addressing these challenges. Analytical models for switching transient help in investigating the mitigation of these challenges from the gate drive side. This paper presents a systematic modeling approach that divides the turn-on and turn-off transient intervals of a GaN-based two-level pole into sub-intervals responsible for di/dt and dv/dt. The switching loss contribution of each sub-interval and their role in transient overshoot is highlighted. Using switching device voltage overshoot and motor dv/dt as two important constraints, an optimal gate drive is then proposed, which minimizes the switching loss. Spice simulation results are presented for the proposed optimal gate drive of 650 V, 60 A GaN device operating at 400 V DC bus voltage and 40 A device current.}, journal={2021 IEEE 12TH ENERGY CONVERSION CONGRESS AND EXPOSITION - ASIA (ECCE ASIA)}, author={Satpathy, Subhransu and Das, Partha Pratim and Bhattacharya, Subhashish}, year={2021}, pages={19–25} }
 @inproceedings{kanale_cheng_shah_han_agarwal_baliga_hopkins_bhattacharya_2021, title={Switching Characteristics of a 1.2 kV, 50 mΩ SiC Monolithic Bidirectional Field Effect Transistor (BiDFET) with Integrated JBS Diodes}, ISBN={9781728189499}, ISSN={["1048-2334"]}, url={http://dx.doi.org/10.1109/apec42165.2021.9487410}, DOI={10.1109/APEC42165.2021.9487410}, abstractNote={The switching performance of large area (1cm x 1cm) monolithic 1.2 kV 50 mΩ 4H-SiC bidirectional field effect transistor (BiDFET) with integrated JBS diodes is reported for the first time. The devices were fabricated in a 6-inch commercial foundry and then packaged in a custom-designed four-terminal module. The switching performance of the BiDFET has been observed to be 1.4x better than that of its internal JBSFETs. Dynamic characterization was performed at 800 V with different gate resistances, current levels and case temperatures. An increase in switching losses was observed for the BiDFET with increasing gate resistance and current level as observed for SiC power MOSFETs. The BiDFET showed a 9% reduction in total switching loss from 25 °C to 150 °C with a current of 10 A.}, booktitle={2021 IEEE Applied Power Electronics Conference and Exposition (APEC)}, publisher={IEEE}, author={Kanale, Ajit and Cheng, Tzu-Hsuan and Shah, Suyash Sushilkumar and Han, Kijeong and Agarwal, Aditi and Baliga, B. Jayant and Hopkins, Douglas and Bhattacharya, Subhashish}, year={2021}, month={Jun}, pages={1267–1274} }
 @article{pulakhandam_bhattacharya_2021, title={System-Level Common-Mode EMI Analysis for Drive Applications Using Unterminated Behavioral EMI Models}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487202}, abstractNote={As wide-bandgap (WBG) semiconductors continue to establish their superior performance in today’s power electronics industry, it is imperative that they are equipped with electromagnetic interference (EMI) solutions tailored for their performance characteristics. The increased switching frequency and switching speeds in WBG converters facilitates higher power densities but can adversely affect EMI filtering requirements. This study uses Unterminated Behavioral Models (UBM) to estimate the common-mode (CM) emissions of two individual SiC AC drive systems feeding of the same DC bus, i.e. the effective input CM emission of the system. An extraction procedure for calculating the worst-case emission in the CM range is presented, accounting for the asynchronized and independent operation of both drives. The extraction procedure is developed through experimental UBM development and subsequent frequency-domain, MATLAB script analyses. Experimental results to validate both the UBM and combined input CM noise at various operating points are provided along with details of the physical hardware setup used.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Pulakhandam, Harish and Bhattacharya, Subhashish}, year={2021}, pages={2357–2363} }
 @article{sharma_iyer_bhattacharya_kikuchi_zou_2021, title={Tertiary Control Method for Droop Controlled DC-DC converters in DC Microgrids}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595384}, abstractNote={Droop control is a commonly used method for load current sharing between the converters in DC microgrid applications. In droop control, the current sharing performance gets degraded due to the resistance of the cables and other non-idealities. Secondary control approaches are typically used along with droop control to achieve accurate current sharing among the converters. However, secondary control methods can result in the converter steady-state output voltages exceeding the design or permissible voltage limits. In this paper, a tertiary control method is proposed to ensure that the converter steady-state output voltages remain within the safe bounds under all operating conditions. The proposed tertiary control loop gets activated when any of the converter output voltages exceed the permissible limit, and modifies the current sharing ratio to ensure that the converter steady-state output voltages are bounded. The proposed tertiary control approach is verified using extensive switching circuit simulations. Further, a hardware-based experimental DC microgrid test-bench is used to validate the effectiveness of the proposed tertiary droop control.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish and Kikuchi, Jun and Zou, Ke}, year={2021}, pages={694–699} }
 @article{ghanbari_bhattacharya_2021, title={The Impact of PV Arrays Disturbances on the Performance of Droop Controllers in a DC Microgrid}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595066}, abstractNote={Photovoltaic (PV) arrays are frequently utilized in DC microgrids due to their DC power generations. These resources have unavoidable variations in their productions. These variations can be seen as disturbances to the DC bus voltage and other sources’ currents. The droop control algorithm is employed in such systems to assure current sharing among PV arrays and other sources such as Battery Energy Storage Systems (BESS). The droop control method functionality should be questioned in the existence of disturbances. Therefore, there is a need for a mathematical study to investigate the effect of PV arrays’ disturbances on the droop control functionality. Disturbances are applied to the PV arrays’ currents, and the system outputs are monitored. Simulations and Hardware-In-the-Loop (HIL) experiments are conducted to address the evaluation of the control method in the introduction of disturbances.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Ghanbari, Niloofar and Bhattacharya, Subhashish}, year={2021}, pages={1058–1064} }
 @article{kim_han_lee_bhattacharya_2020, title={A Sinusoidal Current Control Strategy Based on Harmonic Voltage Injection for Harmonic Loss Reduction of PMSMs With Non-Sinusoidal Back-EMF}, volume={56}, ISSN={["1939-9367"]}, url={https://doi.org/10.1109/TIA.2020.3016210}, DOI={10.1109/TIA.2020.3016210}, abstractNote={In permanent magnet synchronous machine design, a limited number of stator and rotor slots distorts the air-gap flux distribution and its effective length. It causes machine parameters to vary with the rotor position. The rotor flux linkage harmonics introduce nonsinusoidal back-EMF, which causes current harmonics when conventional PI current controller is adopted. Those machines suffer from high-frequency torque ripple due to air-gap flux harmonics in low-speed region. However, in high-speed region, where the torque ripple is filtered out by the mechanical system, the torque ripple may be disregarded. In this case, torque-ripple suppression methods and the associated harmonic current components generate losses. Therefore, a sinusoidal current control is required to reduce the undesired harmonic losses. In this manner, this article focuses on the sinusoidal current control strategy based on harmonic voltage injection, which requires knowledge of rotor magnet flux linkage harmonics. This article also proposes both off- and on-line schemes for the identification of rotor magnet flux linkage harmonics. These methods do not require any proprietary machine design details such as the shape of stator or rotor for finite element analysis. Commonly used PI plus resonant controller is also designed and its disadvantages in terms of speed-dependent gain and stability, in comparison to the proposed scheme, are highlighted. Finally, experimental results are presented to compare the proposed scheme with the conventional method at different operating conditions.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Kim, Heonyoung and Han, Yongsu and Lee, Kibok and Bhattacharya, Subhashish}, year={2020}, month={Nov}, pages={7032–7043} }
 @article{ghanbari_bhattacharya_2020, title={Adaptive Droop Control Method for Suppressing Circulating Currents in DC Microgrids}, volume={7}, ISSN={["2687-7910"]}, url={https://doi.org/10.1109/OAJPE.2020.2974940}, DOI={10.1109/OAJPE.2020.2974940}, abstractNote={DC microgrids are introduced to reduce the conversion stages needed for connection of DC sources to the DC loads. They employ the droop control algorithm for managing the power flow from sources to the loads. However, the droop control functionality is affected by circuit parameters, especially line resistances. As a consequence, load sharing as the primary objective of the droop controller lacks accuracy. Parallel-connected converters have mismatched output voltages, resulting in circulating currents. This paper proposes an adaptive droop control algorithm for suppressing circulating currents in a low voltage DC microgrid. Line resistances are estimated through mathematical calculations and droop parameters are adjusted accordingly. Moreover, a distributed secondary controller is proposed to improve the load sharing accuracy and eliminate the effect of line resistances. The secondary controller shifts the droop controller voltage setpoint according to the converter current. Both of the proposed methods result in an accurate load sharing; Each of the participating converters has the rated current and consequently circulating current is suppressed. The effectiveness of the proposed method is verified through simulation and hardware-in-the-loop (HIL) setup.}, journal={IEEE OPEN ACCESS JOURNAL OF POWER AND ENERGY}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Ghanbari, Niloofar and Bhattacharya, Subhashish}, year={2020}, pages={100–110} }
 @article{beddingfield_samanta_nations_wong_ohodnicki_bhattacharya_2020, title={Analysis and Design Considerations of a Contactless Magnetic Plug for Charging Electric Vehicles Directly From the Medium-Voltage DC Grid With Arc Flash Mitigation}, volume={1}, url={https://doi.org/10.1109/JESTIE.2020.2999589}, DOI={10.1109/JESTIE.2020.2999589}, abstractNote={Electric vehicle charging has shifted to higher voltages to achieve higher power for more rapid charging capabilities. This article provides a contactless magnetic plug solution that enables medium-voltage grid connections for electric vehicle charging to achieve 3.5-<inline-formula><tex-math notation="LaTeX">$\text{kV}_{\rm DC}$</tex-math></inline-formula>-to-400-<inline-formula><tex-math notation="LaTeX">$\text{V}_{\rm DC}$</tex-math></inline-formula>, 150-kW rapid charging capabilities. This novel magnetic plug improves upon existing electric vehicle charging solutions by guaranteeing safe operation and connection through galvanic and physical separation from the medium-voltage side. It achieves this with a gap and barrier in the transformer core. We introduce a unique asymmetry in the core to localize parasitic capacitance, fully separating the medium- and low-voltage regions. This approach eliminates arcing risk and allows rapid charging capabilities to be delivered to the general public. This gapped core constitutes the plug action of our proposed charging system. We present solutions for the unique challenges of this solution through a detailed analysis of the magnetic design. We confirm this analysis in finite-element analysis and experimentation. The solution is verified through a scaled laboratory prototype of 20 kW, 1 <inline-formula><tex-math notation="LaTeX">$\text{kV}_{\rm DC}$</tex-math></inline-formula> to 50 <inline-formula><tex-math notation="LaTeX">$\text{V}_{\rm DC}$</tex-math></inline-formula> that is representative of the proposed 150-kW design. We demonstrate safe, arc-free, disconnection in included active content, a new solution for high-power electric vehicle rapid charging.}, number={1}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Beddingfield, Richard B. and Samanta, Suvendu and Nations, Mark S. and Wong, Isaac and Ohodnicki, Paul R. and Bhattacharya, Subhashish}, year={2020}, month={Jul}, pages={3–13} }
 @article{anurag_acharya_kolli_bhattacharya_2021, title={Gate Drivers for Medium-Voltage SiC Devices}, volume={2}, url={https://doi.org/10.1109/JESTIE.2020.3039108}, DOI={10.1109/JESTIE.2020.3039108}, abstractNote={Extensive research in wide-bandgap material technology such as silicon carbide (SiC) has led to the development of medium-voltage (MV) power semiconductor devices with blocking voltages of 3.3 to 15 kV. When these devices are used in various applications, they are exposed to a high peak voltage stress and a very high $dv/dt$ (50–100 V/ns). These impose stringent requirements on the gate driving stage for these devices in terms of featuring a high isolation voltage capability along with a high $dv/dt$ ruggedness, which makes it necessary to have an ultralow coupling capacitance between primary and secondary sides of the gate drivers. One of the key issues in achieving this MV insulation pertains to the necessary clearance and creepage requirements, as defined in IEC 61800-5-1 standards. While the successful operation of these gate drivers is demonstrated in MV converter applications such as solid-state transformers, and MV grid-connected inverters, substantial research needs to be carried out to improve the gate drivers’ performance and provide a plug-and-play solution. This article aims to comprehensively review these gate drivers and consolidate various required design features concerning their galvanic isolation stage, based on normal and short-circuit operation of MV high-power converter systems. Different device short-circuit protection schemes for these gate drivers are explored in detail. Additional applications and functionalities of the gate drivers, including gate drivers used in the series-connection of MV devices and intelligent gate drivers, are also provided in brief. Based on prior research, this review aims to provide design choices and guidelines for the gate drivers, accelerating the growth and deployment of MV SiC devices for field applications.}, number={1}, journal={IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Anurag, Anup and Acharya, Sayan and Kolli, Nithin and Bhattacharya, Subhashish}, year={2021}, month={Jan}, pages={1–12} }
 @article{kim_bhattacharya_2020, title={Improved Rotor Position Estimation in Extended Back-EMF Based Position Sensorless Control for IPMSMs with Non-Sinusoidal Back-EMF}, ISSN={["0197-2618"]}, DOI={10.1109/IAS44978.2020.9334884}, abstractNote={In terms of permanent magnet synchronous machine (PMSM) design, the limited number of stator and rotor slots distort the air-gap flux distribution and its effective length. It results in machine parameters varying with respect to the rotor position. The non-sinusoidal back-EMF, induced from the rotor flux linkage harmonics, introduces current harmonics when conventional d-q axis current controller is adopted. Consequently, it deteriorates the performance of the rotor position estimation in extended back-EMF based position sensorless control. It is because rotor position is estimated assuming sinusoidal machine current. Additionally, the harmonic currents introduces undesired losses which do not contribute to torque production. In this manner, a harmonic voltage injection based current control scheme is presented that results in sinusoidal machine current. It improves the performance of extended back-EMF based position sensorless control and mitigates the harmonic copper losses}, journal={2020 IEEE INDUSTRY APPLICATIONS SOCIETY ANNUAL MEETING}, author={Kim, Heonyoung and Bhattacharya, Subhashish}, year={2020} }
 @article{shah_rastogi_bhattacharya_2021, title={Paralleling of LLC Resonant Converters}, volume={36}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2020.3040621}, DOI={10.1109/TPEL.2020.3040621}, abstractNote={The LLC resonant converter is a popular, variable switching frequency dc--dc converter that may be controlled using two methods: charge and frequency control. In this article, the application of LLC resonant converters to input-parallel, output-parallel system is studied. In this respect, the models of output-port I-V characteristics and small-signal output impedance of the charge controlled LLC converter are proposed. In addition, a mathematical framework is developed for droop-based paralleled dc--dc systems. It distinctly identifies the output dc voltage and circulating current modes of stability, even in systems comprising of nonidentical converters. The developed model and the analytical framework are utilized to study the two modes of stability in droop-based parallel-connected LLC converters. It finds the circulating current mode instability for both the charge and frequency control methods, despite a stable output dc bus voltage. The instability inhibits fast response and high closed-loop bandwidth, eroding the reported advantages of the charge control method over frequency control. Further investigation into the output port I-V characteristics reveals the superiority of charge-controlled LLC converters in paralleled systems than the conventional frequency-controlled converters. A novel application of “common inner reference” based “automatic load sharing” strategy is developed and uniquely applied to the charge controlled system. In addition, the effects of component tolerance and communication delay on this strategy are also briefly explored. The theoretical output-port models and the stability analyses of parallel-connected LLC resonant converters are validated through experiments on a hardware prototype. Further, the supplementary video files illustrate the advantage of the charge control method over frequency control in such system. Finally, the proposed automatic load sharing strategy is validated in steady-state and through a step-change in load.}, number={6}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Shah, Suyash Sushilkumar and Rastogi, Sagar Kumar and Bhattacharya, Subhashish}, year={2021}, month={Jun}, pages={6276–6287} }
 @article{hazra_kamat_bhattacharya_ouyang_englebretson_2020, title={Power Conversion With a Magnetically-Geared Permanent Magnet Generator for Low-Speed Wave Energy Converter}, volume={56}, url={https://doi.org/10.1109/TIA.2020.2997640}, DOI={10.1109/TIA.2020.2997640}, abstractNote={This article presents power conversion and control of a novel low-speed radial-flux magnetically-geared permanent magnet generator (MGPMG) for wave energy conversion. The generator designed and developed by ABB Corporate Research has a magnetic-gear integrated into the structure, which amplifies the low speed of a wave energy converter (WEC) to a high speed of a rotor facing the stator windings. The generator is designed with a large number of magnet poles and concentrated windings for a simpler and cost-effective design. However, due to the concentrated windings, the induced voltage contains a significant percentage of the harmonic component, which leads to the generation of harmonic power. The impact of the harmonic power on power conversion circuit design and ways to mitigate the effect is discussed. The power conversion system and controls are designed to experimentally verify the operation of a prototype 10-kW 30-r/min MGPMG, which is driven by an induction motor emulating the dynamics of an oscillating rotary WEC. Experimental results of power conversion including harmonic power, efficiency analysis, and energy storage integration are reported.}, number={5}, journal={IEEE Transactions on Industry Applications}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Hazra, Samir and Kamat, Prathamesh and Bhattacharya, Subhashish and Ouyang, Wen and Englebretson, Steven}, year={2020}, month={Sep}, pages={5308–5318} }
 @inproceedings{chattopadhyay_gulur_nair_bhattacharya_ohodnicki_2019, title={50kW Nano-Crystalline Core Based Three Port Transformer for Triple Active Bridge Converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076784147&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8912172}, abstractNote={This paper discusses a 50kW high frequency three port transformer made of Nano-Crystalline core, for three port phase shifted DC-DC converter integrating Renewable Energy Sources(RES) & Energy Storages(ES). Phase shifted DC-DC converters need an isolating transformer with series inductances or leakage inductances for power transfer among different ports. However, using leakage inductances for a tape wound or Nano-Crystalline transformer as energy transferring element, causes high leakage fluxes to induce significant eddy currents & related losses in transformer cores. At high switching frequency, this eddy current losses can go too high, reducing efficiency. In order to avoid the eddy current losses in cores, an external inductor based approach along with the concentric winding transformer is presented in this paper for Three Port Phase Shifted Triple Active Bridge(TAB) converter. The three port converter can use either a three inductor or two inductor approach, which is discussed in this paper. The TAB converter uses 1.2kV & 1.7kV SiC Mosfets as switching devices along with Nano-Crystalline core based transformer & ferrite based series inductors. In this paper, analysis & design for concentric winding transformer and experimental results are presented.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Chattopadhyay, R. and Gulur, S. and Nair, V. and Bhattacharya, S. and Ohodnicki, P.R.}, year={2019}, pages={4167–4173} }
 @article{gulur_iyer_bhattacharya_2020, title={A CM Filter Configuration for Grid-Tied Voltage Source Converters}, volume={67}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2019.2949530}, DOI={10.1109/TIE.2019.2949530}, abstractNote={Common mode (CM) filters play a crucial role in determining adherence to conducted emissions (CE) standards for grid-tied voltage source converters. Design and implementation of such filters can be challenging since they depend on several factors like identification of CM noise paths, fidelity of passive components and discerning the frequency and amplitude of CM noise sources. In this article, a CM filter has been proposed, which uses passive components along with the converter's heat sink as a circulating return path for the CM currents. Based on the presented CM circuit models with the proposed filter, a detailed design process has been delineated for selecting the passive components required to realize the CM filter. Additionally, the heat-sink potential has been shown to be touch safe during both ideal and nonideal grid conditions with the proposed CM filter. CE spectral results measured using a commercially procured line impedance stabilization network and captured time domain converter operational wave forms for a 2-level, 3$\phi$ grid-tied voltage source converter validate the functionality and effectiveness of the presented design.}, number={10}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Gulur, Srinivas and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish}, year={2020}, pages={8100–8111} }
 @inproceedings{singh_bhattacharya_white_2019, title={A DC circuit breaker with artificial zero current interruption}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076794399&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8912956}, abstractNote={A method for inducing a forced DC crossing applied to a Direct Current Circuit Breaker (DCCB) for High Voltage Direct Current (HVDC) applications is described. A low voltage prototype was developed, and theoretical analysis was done on the circuit to derive an expression for the fault clearance time. The circuit was modelled on PLECS for verification of the working principle. Hardware was fabricated for a 40 VDC, 2 A continuous current rating; the ideal analytical expression for fault clearance time was verified from the experimental value, which was observed to be 62.76 µs. Work described is covered by US Patent Publication No. 2017/0345587.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Singh, S. and Bhattacharya, S. and White, L.W.}, year={2019}, pages={1047–1051} }
 @article{gulur_iyer_bhattacharya_2019, title={A Dual Loop Current Control Structure With Improved Disturbance Rejection For Grid Connected Converters}, volume={34}, ISSN={0885-8993}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85068727943&partnerID=MN8TOARS}, DOI={10.1109/TPEL.2019.2891686}, abstractNote={The increase in renewable energy penetration in the past few years has led to grave power quality issues in the utility grid. This has ushered in the need for a robust and stable control system for reference tracking and disturbance rejection with respect to grid connected converters. Typically, a simple proportional integrator (PI) controller is used in the synchronous reference frame (dq) for current control of grid connected systems. However, the PI controller in itself may be insufficient for disturbance rejection, when the utility grid voltages contain other harmonics in addition to the fundamental component. This paper introduces and analyzes a dual loop current control structure which utilizes two independent controllers, one for reference tracking and the other for disturbance rejection in the dq frame. A small signal model of the dual loop current control has been presented and its robustness under grid inductance variation, examined. Simulation and experimental results are presented to validate the dual loop strategy for improved disturbance rejection capability and filtering action during the presence of grid voltage harmonics and unbalances, without compromising on the reference tracking performance.}, number={10}, journal={IEEE Transactions on Power Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Gulur, S. and Iyer, V. Mahadeva and Bhattacharya, S.}, year={2019}, pages={1–1} }
 @article{yadav_gopakumar_raj_umanand_bhattacharya_jarzyna_2019, title={A Hybrid 7-Level Inverter Using Low-Voltage Devices and Operation With Single DC-Link}, volume={34}, ISSN={["1941-0107"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85068675417&partnerID=MN8TOARS}, DOI={10.1109/TPEL.2018.2890371}, abstractNote={This paper proposes a new 7-level inverter topology for induction motor drives. It is a hybrid topology formed by cascading a 5-level active neutral-point-clamped inverter with a 3-level T-type converter. It is obtained using low-voltage semiconductor devices with voltage blocking capability of Vdc/3 and Vdc/6. The topology uses three floating capacitors per phase, which are balanced within a pulsewidth modulation (PWM) switching duration using switching-state redundancies for each pole-voltage level. Topology forms two stacks at the front-end, which requires individual symmetrical dc source. The analysis of switching loss and conduction loss is performed and compared with some of the existing 7-level multi-level inverters reported in various literatures to show the advantages of the proposed topology. Furthermore, the single dc source operation with two stacked capacitors and closed-loop control of neutral-point voltage using symmetrical six-phase induction motor is proposed. The voltage-control algorithms for floating capacitors and dc-link stacked capacitors are proposed, which are independent of load power factor and modulation index. Open-loop V/f and closed-loop rotor field oriented control are performed, and various results at steady and transient states are presented to validate the aforementioned claims.}, number={10}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Yadav, Apurv Kumar and Gopakumar, K. and Raj, Krishna R. and Umanand, Loganathan and Bhattacharya, Subhashish and Jarzyna, Wojciech}, year={2019}, month={Oct}, pages={9844–9853} }
 @inproceedings{kim_bhattacharya_2019, title={A Novel Current Control Strategy Based on Harmonic Voltage Injection for Power Losses Reduction of PMSMs with Non-Sinusoidal Back-EMF}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076759180&partnerID=MN8TOARS}, DOI={10.1109/IAS.2019.8912372}, abstractNote={In terms of permanent magnet synchronous machine (PMSM) design, high power density and a low manufacturing cost can be achieved by sacrificing sinusoidal back-EMF. Those machines suffer from higher torque ripple due to the flux harmonics. Additionally, the non-sinusoidal back-EMF introduces current harmonics in the case where the conventional d-q axis current controller is adopted. This introduces additional copper losses in machine stator windings and conduction losses in inverter switches. A novel current control strategy based on harmonic voltage injection is presented for PMSMs with non-sinusoidal back-EMF to reduce the copper losses due to harmonic current components in a high speed region. Based on the harmonic back-EMF information of the machine, the harmonic voltages are injected to cancel out the harmonic components in the back-EMF waveforms so that machine current can be controlled with lower THD and copper losses. This method can be easily applied to the conventional PI current controller without non-sinusoidal coordinate transformation.}, booktitle={2019 IEEE Industry Applications Society Annual Meeting, IAS 2019}, author={Kim, H. and Bhattacharya, S.}, year={2019} }
 @inproceedings{iyer_gulur_bhattacharya_ramabhadran_2019, title={A Partial Power Converter Interface for Battery Energy Storage Integration with a DC Microgrid}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076744535&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8912590}, abstractNote={A battery energy storage system (BESS) interface for a DC microgrid, featuring a partial rated power electronic converter, is proposed in this work. Universal schemes for implementing a partial rated BESS interface are discussed and a soft-switched, dual active bridge (DAB) converter-based solution is presented. The proposed scheme is analyzed and compared with a conventional full rated BESS interface converter to showcase its benefits. A control strategy that can enable multiple operating modes for the the partial rated power electronic BESS interface is discussed. Hardware prototypes of partial rated and full rated BESS interface converter solutions that are rated to transfer 3.3 kW to the BESS are developed and tested in the laboratory. Experimental evidence suggests that the partial rated BESS interface can improve the system efficiency by up to 3% while simultaneously reducing the converter rating by about 70% as compared to that of a full rated converter. Elimination of redundant power processing by the partial rated BESS interface offers tremendous potential to improve the efficiency and power density while drastically reducing the cooling overhead.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Iyer, V.M. and Gulur, S. and Bhattacharya, S. and Ramabhadran, R.}, year={2019}, pages={5783–5790} }
 @inproceedings{agashe_madadi_bhattacharya_2019, title={A Robust and Reliable IEEE1547 Compliant Communication System for High Penetrated Renewable Energy Sources}, volume={2019-August}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85079046983&partnerID=MN8TOARS}, DOI={10.1109/PESGM40551.2019.8973940}, abstractNote={A novel and robust communication platform, compliant with IEEE 1547.3 has been developed for a distribution system with high penetrated renewable energy resources. The proposed communication system not only provides the realtime data monitoring through a designed web interface but also makes possible to remotely regulate the output voltage of all interconnected renewable energy resources. The effect of the communication latency on the performance of the designed hierarchical controllers of the interconnected renewable energy resources has been thoroughly investigated and the contributing parameters on improving the performance of the system has been determined. The result of this analysis could be used to optimize the system controller to minimize the voltage sag of the dc link capacitor and also improving the power system operational planning. The feasibility and reliability of the proposed communication platform has been validated by simulation and experimental results.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Agashe, R. and Madadi, M. and Bhattacharya, S.}, year={2019} }
 @inproceedings{parashar_bhattacharya_2019, title={A novel gate driver for active voltage balancing in 1.7kV series connected SiC MOSFETs}, volume={2019-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85067121601&partnerID=MN8TOARS}, DOI={10.1109/APEC.2019.8722176}, abstractNote={This paper addresses active voltage balancing method for series connected 1.7 kV SiC MOSFETs. The series connection of 1.7 kV SiC MOSFETs have potential to replace medium voltage IGBTs (4.5 kV) due to their high switching speed and improved reliability. Series connection of SiC MOSFET is challenging due to possibility of voltage mismatch, voltage spike and device current spike in leg configuration. A novel gating technique has been introduced to reduce the voltage mismatch and voltage spike due to di/dt. Experimental results have been performed with series connection of two SiC MOSFETs and validated with theoretical calculations.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Parashar, S. and Bhattacharya, S.}, year={2019}, pages={2773–2779} }
 @inproceedings{beddingfield_bhattacharya_ohodnicki_2019, title={Accurate characterization and emulation of active bridge magnetic efficiencies with novel excitation circuit}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076794646&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8913154}, abstractNote={Significant research has sought to understand, predict and map passive device performance for high power converters. Magnetic component performance is paramount for proper operation, efficiency and power density requirements. This paper introduces a method to apply the complex, multilevel operational waveforms needed for exact magnetic component performance mapping while using traditional open secondary testing techniques and a simple configuration of WBG devices. This converter easily achieves the high voltages and currents at high bandwidth that are applicable to advanced power converters. The presented testing approach reduces mischaracterization errors by up to 400%. An example characterization case of magnetics for the three port active bridge is shown whereby the transformer design efficiency is measured over the entire converter operational space.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Beddingfield, R.B. and Bhattacharya, S. and Ohodnicki, P.}, year={2019}, pages={4117–4124} }
 @inproceedings{parashar_bhattacharya_2019, title={Active voltage balancing methodology for series connection of 1700V SiC MOSFETs}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081169018&partnerID=MN8TOARS}, DOI={10.1109/WiPDA46397.2019.8998794}, abstractNote={Series connection of 1.7kV Silicon Carbide (SiC) MOSFETs have potential to become a building block of compact and lightweight Megawatt power converters. These devices with high current carrying capability (56.5A/die) can be connected in series to develop high voltage and current rating power converters. Series connection of power devices generally involves passive voltage balancing methods, such as R-C snubbers, which increases the switching loss in power converters. Therefore, this paper describes the series connection of 1.7kV SiC MOSFETs using Active Voltage Balancing method. Active Voltage Balancing avoids R-C snubbers for minimizing voltage mismatch, thus reducing the switching loss in power converters. An alternative method of Active Voltage Balancing has been discussed in the paper for series connection of two 1.7kV SiC MOSFETs. The proposed method has been verified by simulation and experimental results.}, booktitle={2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019}, author={Parashar, S. and Bhattacharya, S.}, year={2019}, pages={430–437} }
 @inproceedings{agarwal_iyer_anurag_bhattacharya_2019, title={Adaptive Control of a Hybrid Energy Storage System for Wave Energy Conversion Application}, ISBN={9781728103952}, url={http://dx.doi.org/10.1109/ecce.2019.8912897}, DOI={10.1109/ECCE.2019.8912897}, abstractNote={A hybrid energy storage system (HESS), that comprises of a battery and a supercapacitor, is utilized to absorb the power and energy oscillations for a wave energy conversion system so as to inject a smooth power to the grid. Continuous variation in the wave profile presents a formidable challenge in terms of the power and energy allocation among the battery and supercapacitor. In this paper, an adaptive control strategy is proposed, wherein the power and energy sharing between the battery and super-capacitor are dynamically decided based on an optimization algorithm. The proposed algorithm is aimed at optimizing the total losses in the hybrid energy storage system while simultaneously maximizing the battery lifetime. Circuit simulation and experimental results from a hardware prototype are provided to validate the effectiveness of the proposed control scheme.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition (ECCE)}, publisher={IEEE}, author={Agarwal, Apoorv and Iyer, Vishnu Mahadeva and Anurag, Anup and Bhattacharya, Subhashish}, year={2019}, month={Sep}, pages={4994–5001} }
 @article{anurag_acharya_bhattacharya_2020, title={An Accurate Calorimetric Loss Measurement Method for SiC MOSFETs}, volume={8}, ISSN={2168-6777 2168-6785}, url={http://dx.doi.org/10.1109/jestpe.2019.2920935}, DOI={10.1109/JESTPE.2019.2920935}, abstractNote={An accurate measurement of conduction and switching losses in the power semiconductor devices is necessary in order to design and evaluate the thermal management system of modern converter systems. Conventionally, electrical measurement methods, such as the double-pulse tests (DPTs), are used for measuring the switching losses. However, with the advent of wide-bandgap (WBG) devices that have fast switching transients, it is rather difficult to capture the waveforms accurately during switching transitions, and consequently, the measurement of switching loss becomes inaccurate. In addition, the measurement of switching waveforms depends on the voltage and current probes, as well as the oscilloscope used for the measurement, which makes this method prone to errors. This necessitates the use of measurement methods, which can provide much higher accuracy than the existing conventional electrical methods. Calorimetric methods are based on comparatively slow temperature measurements and do not rely on the measurements of fast switching transitions of voltages and currents, thus eliminating the demand for measuring fast switching transitions. This paper presents an accurate calorimetric method for measuring the device losses, which can be used to determine individual loss components accurately (conduction, turn-on, and turn-off losses). In addition to the turn-on and turn-off losses, this method can evaluate the charging and discharging losses of the device. The novelty of the method lies in the fact that a single setup can be used to measure all possible losses that can occur in a device during converter operation. The calorimetric test setup is described, and a novel modulation scheme is introduced, which enables the segregation of the individual losses. The experimental test setup is built and the method is verified by measuring the losses of a 900-V, 23-A Wolfspeed C3M0120090D SiC MOSFET.}, number={2}, journal={IEEE Journal of Emerging and Selected Topics in Power Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Anurag, Anup and Acharya, Sayan and Bhattacharya, Subhashish}, year={2020}, month={Jun}, pages={1644–1656} }
 @article{iyer_gulur_gohil_bhattacharya_2020, title={An Approach Towards Extreme Fast Charging Station Power Delivery for Electric Vehicles with Partial Power Processing}, volume={67}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2019.2945264}, DOI={10.1109/TIE.2019.2945264}, abstractNote={This article proposes an approach for realizing the power delivery scheme for an extreme fast charging (XFC) station that is meant to simultaneously charge multiple electric vehicles (EVs). A cascaded H-bridge converter is utilized to directly interface with the medium voltage grid while dual-active-bridge based soft-switched solid-state transformers are used to achieve galvanic isolation. The proposed approach eliminates redundant power conversion by making use of partial power rated dc–dc converters to charge the individual EVs. Partial power processing enables independent charging control over each EV, while processing only a fraction of the total battery charging power. Practical implementation schemes for the partial power charger unit are analyzed. A phase-shifted full-bridge converter-based charger is proposed. Design and control considerations for enabling multiple charging points are elucidated. Experimental results from a down-scaled laboratory test-bed are provided to validate the control aspects, functionality, and effectiveness of the proposed XFC station power delivery scheme. With a down-scaled partial power converter that is rated to handle only 27% of the battery power, an efficiency improvement of 0.6% at full-load and 1.6% at 50% load is demonstrated.}, number={10}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Iyer, Vishnu Mahadeva and Gulur, Srinivas and Gohil, Ghanshyamsinh and Bhattacharya, Subhashish}, year={2020}, pages={8076–8087} }
 @inproceedings{alharbi_isik_bhattacharya_2019, title={An Optimized SM Fault-Tolerant Control Method for MMC-based HVDC Applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076736311&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8912483}, abstractNote={Modular Multilevel Converters (MMCs) are becoming a realistic alternative to the conventional voltage source converters (VSCs) for medium voltage (MV) and high voltage direct current (HVDC) applications. The MMC topologies utilize a large number of submodules (SMs) cascaded in series per phase arm to achieve desired high voltage levels. These SMs can be as high as 512 to synthesize a very low total harmonic distortion (THD) (e.g. < 0.1%) of the MMC AC side interface voltage. However, malfunction of any SM results in undesirable waveforms, and it may result in unstable operation of the entire MMC system. This paper proposes an optimized SM fault ride-through method and a capacitor voltage balancing (CVB) control for MMC-based HVDC applications. The proposed method can effectively improve the MMC performance and reliability under SM faults. The proposed approach is implemented in the Real-Time Digital Simulator (RTDS) and MMC support units based on FPGA boards. The results show that the proposed method can efficiently keep the MMC operation as normal and provide satisfactory performance under SM faults.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Alharbi, M. and Isik, S. and Bhattacharya, S.}, year={2019}, pages={1592–1597} }
 @inproceedings{iyer_gulur_bhattacharya_kikuchi_sridharan_zou_chen_2019, title={An active voltage stabilizer for a generic DC microgrid}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076730268&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8912949}, abstractNote={This paper analyzes the low frequency stability chal-lenges that exist in a generic DC microgrid system. The conditions for system stability are derived from fundamental principles. A capacitive energy storage system based active voltage stabilizer, that handles the power fluctuations within the system during transient conditions, is proposed to stabilize the DC microgrid. The functionality of the active stabilizer, based on a bidirectional DC-DC converter, is elucidated and a suitable control strategy is proposed. The proposed active stabilizer and its associated control system involves only local voltage sensing and does not alter the generic DC microgrid structure. The proposed approach is validated through analytical models and circuit simulations. A dual active bridge (DAB) converter based active stabilizer is implemented and hardware based experimental results from a laboratory test-bench are provided to validate functionality and effectiveness of the proposed approach.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Iyer, V.M. and Gulur, S. and Bhattacharya, S. and Kikuchi, J. and Sridharan, S. and Zou, K. and Chen, C.}, year={2019}, pages={462–468} }
 @inproceedings{kumar_bhattacharya_baliga_veliadis_2019, title={An experimental study of short circuit behavior and protection of 15 kV SiC IGBTs}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081171320&partnerID=MN8TOARS}, DOI={10.1109/WiPDA46397.2019.8998821}, abstractNote={15 kV SiC n-channel IGBTs have been successfully demonstrated earlier up to 10 kHz switching frequency in medium voltage (MV) power converters such as solid state transformer and transformerless intelligent power substation. Short circuit safe operating area (SC-SOA) of a power device is an essential requirement to assess the reliability of the converters. In this paper, for the first time, the short circuit (SC) behavior of the 15 kV SiC IGBT was investigated by a non-destructive experimental method under hard-switch fault (HSF) up to 8 kV dc bus. The high voltage output curve of the 15 kV SiC IGBT was obtained experimentally up to 8 kV in steps of 500 V. A TCAD model of the 15 kV IGBT was developed to understand the behavior of the IGBT in the current saturation region. The HV output characteristics was used in the estimation of the short circuit withstand time of the IGBT under HSF SC condition up to 12 kV dc bus. A desat diode based short circuit protection circuit was demonstrated successfully for the 15 kV IGBT. Performance of the desat protection circuit is compared with the 10 kV SiC MOSFETs. Behavior of the SiC IGBT in the saturation region was explained with the help of the TCAD model and the analytical equations.}, booktitle={2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019}, author={Kumar, A. and Bhattacharya, S. and Baliga, J. and Veliadis, V.}, year={2019}, pages={63–70} }
 @book{kumar_parashar_brunt_sabri_ganguly_bhattacharya_veliadis_2019, title={Avalanche ruggedness characterization of 10 KV 4H-SIC MOSFETS}, volume={963 MSF}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071879222&partnerID=MN8TOARS}, DOI={10.4028/www.scientific.net/MSF.963.773}, abstractNote={In this paper, single pulse unclamped inductive switching (UIS) test of Wolfspeed Gen-3 10 kV, 15 A 4H-SiC MOSFETs is performed for four operating conditions at room temperature. The avalanche energy is observed to be around 7.0 J. The measured values are in good agreement with expected behavior, which may be extrapolated beyond the experimentally measured range. Failure analysis was conducted after each device failure to observe the failure locations. Avalanche parameters of SiC MOSFETs with various voltage ratings are compared. The avalanche energy of the Gen-3 10 kV, 15 A 4H-SiC MOSFETs is obtained to be superior to earlier generations of 10 kV SiC MOSFETs.}, journal={Materials Science Forum}, author={Kumar, A. and Parashar, S. and Brunt, E.V. and Sabri, S. and Ganguly, S. and Bhattacharya, S. and Veliadis, V.}, year={2019}, pages={773–776} }
 @inproceedings{ghanbari_bhattacharya_2019, title={Battery State of Charge Management by Voltage Feedback Modification}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071297175&partnerID=MN8TOARS}, DOI={10.1109/ITEC.2019.8790549}, abstractNote={Due to increase in utilization of DC loads and renewable resources which mostly produce DC powers, there has been an increasing popularity in DC microgrids. In the previous research studies, the focus is more on power balancing among parallel voltage sources of the system while balancing the State of Charge (SoC) of batteries has been overlooked. In this paper, by modifying droop control method as the basis of power sharing in the DC microgrid, the objective of SoC equalization can be achieved. DC bus voltage scheduling is the core of modification to keep the batteries SoCs balanced. First, the paper discusses about an existing droop control based SoC balancing method with voltage scheduling. Then, it proposes a new DC bus voltage scheduling to overcome the drawback of the mentioned method. The methods have been simulated in MATLAB/Simulink and a comparison study has been performed.}, booktitle={ITEC 2019 - 2019 IEEE Transportation Electrification Conference and Expo}, author={Ghanbari, N. and Bhattacharya, S.}, year={2019} }
 @inproceedings{anurag_acharya_gohil_bhattacharya_2019, title={Benchmarking and Qualification of Gate Drivers for Medium Voltage (MV) Operation using 10 kV Silicon Carbide (SiC) MOSFETs}, volume={2019-March}, ISBN={9781538683309}, url={http://dx.doi.org/10.1109/apec.2019.8721799}, DOI={10.1109/APEC.2019.8721799}, abstractNote={Emergence of reliable medium voltage (MV) silicon carbide (SiC) devices, has made it possible to use these for MV applications, including grid interconnections, and medium voltage drives system. In a converter structure, the isolated power supplies of the gate drivers for these MV devices experience a peak stress up to 15 kV and a very high dv/dt (up to 100 kV/μs). Exposing the gate driver to such harsh conditions leads to various challenges in providing the required insulation, and maintaining the signal fidelity (due to common mode (CM) currents across the parasitic capacitance of the transformer). The failure of gate drivers at a converter level can lead to destructive damage to the converter. This calls for a methodology to design, test and qualify the gate drivers before implementing them in the field for long-term operation. This paper provides a detailed design methodology and analysis to qualify the gate drivers for a long-term operation. The analysis and design-phase ensures reliable operation of the gate driver, and the testing and qualifying phase ensures long-term operation of the gate driver. The experimental test setup has been built and test results have been provided based on a gate driver designed for 10 kV SiC MOSFETs.}, booktitle={2019 IEEE Applied Power Electronics Conference and Exposition (APEC)}, publisher={IEEE}, author={Anurag, Anup and Acharya, Sayan and Gohil, Ghanshyamsinh and Bhattacharya, Subhashish}, year={2019}, month={Mar}, pages={441–447} }
 @article{alfaris_bhattacharya_2019, title={Control and Real-Time Validation for Convertible Static Transmission Controller Enabled Dual Active Power Filters and PV Integration}, volume={55}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85068899634&partnerID=MN8TOARS}, DOI={10.1109/TIA.2019.2910782}, abstractNote={This paper proposes a versatile convertible static transmission controller, in shunt-shunt mode, with dual active filters and photovoltaic (PV) power integration. The combined system aims to back up and control the power of a transmission transformer, as well as, improve the transmitted power quality to meet the grid standards and codes, especially the recently revised IEEE 1547 standards. The filters are also designed to eliminate the current and voltage harmonics due to the fluctuation in the injected PV power and the use of the switching power converters. A new reference generation technique is proposed to inject the solar power into the grid and compensate the system reactive power and harmonics. Moreover, the varying nature of PV power, due to the intermittent solar radiation and temperature, is accounted with the online computation of the dc voltage and power references with the help of the system rectifier. A simulation study adopted by real-time digital simulator is used to validate the proposed system for the integration of an actual solar PV under normal and faulted conditions.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Alfaris, Faris E. and Bhattacharya, Subhashish}, year={2019}, pages={4309–4320} }
 @inproceedings{alharbi_isik_bhattacharya_2019, title={Control of circulating current to minimize the rating of the energy storage device in modular multilevel converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076773793&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8912773}, abstractNote={The circulating current is a negative sequence current at double the fundamental frequency in a Modular Multilevel Converter (MMC). Conventionally, many types of research are conducted to suppress the circulating current in an MMC to reduce the converter loading. However, this paper studies rather than suppressing the circulating current, decoupling control algorithm between circulating current and AC, DC sides of the converter improves the average and RMS current such that performance of the converter increases while rating of the devices minimize. The Sub-Module (SM) capacitor voltage ripple significantly reduces so that the cost of a large scale MMC application decrease. The proposed control algorithm uses AC power as a circulating current reference, so the amplitude and phase of the output currents need not to be calculated. The studies are performed in Real Time Digital Simulator (RTDS) with FPGA based MMC support unit.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Alharbi, M. and Isik, S. and Bhattacharya, S.}, year={2019}, pages={6041–6045} }
 @inproceedings{parashar_kumar_jakka_bhattacharya_veliadis_2019, title={Demonstration of new generation 10kV SiC MOSFET modules in medium voltage power converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081173124&partnerID=MN8TOARS}, DOI={10.1109/WiPDA46397.2019.8998836}, abstractNote={This paper reports a comprehensive analysis of three phase converter enabled by 10kV SiC based XHV-6 modules. A thorough explanation of converter based upon 10kV XHV-6 module has been carried out. The gate driver and converter structure used for carrying out the test have been explained in details. The assessment of MOSFET modules have been carried out in several steps till final implementation of three phase VSI (voltage source inverter). Step 1 involves double pulse test, which identifies the nominal Rg and switching losses for 10kV SiC MOSFET at specified current. Double pulse test is followed by continuous operation of single 10kV switch in buck-boost converter topology (Step 2). Operation of Single MOSFET switch in buck-boost topology 1) evaluates the capacity of modules for sustaining specified dv/dt without failure 2) provide the loss data for single MOSFET switch in continuous operation. After that, MOSFET modules are operated in Single pole configuration (building block for MV converters) as half bridge topology (Step 3) for evaluating their performance in terms of losses and dv/dt current (through base plates) for complementary switching. The single pole operation is demonstrated on 5:6kV voltage stress.}, booktitle={2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019}, author={Parashar, S. and Kumar, A. and Jakka, V. and Bhattacharya, S. and Veliadis, V.}, year={2019}, pages={208–213} }
 @inproceedings{acharya_anurag_kolli_bhattacharya_2019, title={Design and Performance Evaluation of 1.2 kV, 325 a SiC-MOSFET High Performance Module Based 100 kVA Three-Phase Two-Level Power Block}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071642137&partnerID=MN8TOARS}, booktitle={ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia}, author={Acharya, S. and Anurag, A. and Kolli, N. and Bhattacharya, S.}, year={2019}, pages={821–828} }
 @inproceedings{parashar_kokkonda_bhattacharya_2019, title={Design of modular auxiliary gate driver power supply for medium voltage converter system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076732434&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8912853}, abstractNote={Auxiliary Power supplies are necessary for powering the gate drivers and controller circuits used in converter operation. Designing auxiliary power supplies for generating very low voltage output (up to 20V) from medium voltage DC input (6kV to 10kV) is technically challenging. Currently, lot of research is being carried out in implementing grid level medium voltage converters using 6.5kV to 10kV SiC MOSFETs. Fast switching speed of SiC devices induces common mode noise into the gate driver system. Apart from generating a DC output for gate drivers, the power supplies also need to provide the necessary isolation and common mode current protection resulting from fast switching. This paper discusses a novel power supply topology to generate an isolated low Voltage output from a high voltage input up to 2kV. A scheme has been proposed to achieve low DC output from Medium Voltage input (6kV to 10kV) by series input and parallel output connection of auxiliary power supply modules. Theoretical analysis of proposed topology has been formulated and hardware implementation has been done to verify operation of the topology.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Parashar, S. and Kokkonda, R. and Bhattacharya, S.}, year={2019}, pages={5712–5719} }
 @inproceedings{kim_acharya_anurag_kim_bhattacharya_2019, title={Effect of Inverter Output dv/dt with Respect to Gate Resistance and Loss Comparison with dv/dt Filters for SiC MOSFET based High Speed Machine Drive Applications}, ISBN={9781728103952}, url={http://dx.doi.org/10.1109/ecce.2019.8912249}, DOI={10.1109/ECCE.2019.8912249}, abstractNote={Fast switching characteristic of wide band gap (WBG) devices enables high frequency switching of power devices and thereby, facilitates high fundamental frequency operation of a machine. However, with the switching transition times being in orders of tens of nanoseconds, a high dv/dt is observed across the switching device. The high dv/dt experienced by the switches, and consequently by the machine, can degrade winding insulations or bearings over a period of time. It is therefore imperative to maintain dv/dt below recommended values depending on the machine insulation. The dv/dt across the devices can be adjusted by using higher values of gate resistance. However, this introduces additional switching losses on the device. Using different dv/dt filtering techniques can also help to control the dv/dt on the machine terminals. These techniques do not increase the switching losses on the device. However, the filter circuits introduce losses in the circuit and additional costs. In this paper, an analysis based on the impact of gate resistance on the dv/dt across the machine, and the corresponding losses is carried out. In addition, a comparision is performed on the basis of efficiency between these two techniques. A SiC MOSFET based 3-phase inverter (CREE-CCS020M12CM2) is used for the analysis.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition (ECCE)}, publisher={IEEE}, author={Kim, Heonyoung and Acharya, Sayan and Anurag, Anup and Kim, Byeong-Heon and Bhattacharya, Subhashish}, year={2019}, month={Sep}, pages={2301–2306} }
 @inproceedings{samanta_beddingfield_wong_bhattacharya_2019, title={Efficient Power Transfer to Data Center Racks using Medium Voltage Inductive Coupling}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076792078&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8911899}, abstractNote={Usually, the data center racks are supplied power at or below 400V, primarily due to safety. However, because of rapid increase in size of data centers, the power demand is also rising sharply, which results in bulky power cables and inefficient power distribution. In this paper, the idea of inductive coupling is used to increase the distribution voltage level to kVs, while maintaining the required safety aspects of the system. Based on the defined problem, a suitable converter topology is selected, where safety issue are addressed with a gapped-core (or split-core) transformer isolation. The performance of this converter circuit is analyzed, and component ratings are derived. Soft-switching performance of inverter devices are also reported. Due to low voltage and high current at the output, synchronous rectification technique promises significant improvement in efficiency. To verify the performances of the converter circuit, numerical simulation is performed in PowerSIM 11. A 2.5kW lab-prototype is developed, where the input/ output voltage is 1.1kV / 48V, and experimental results are included to justify the suitability of the selected converter.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Samanta, S. and Beddingfield, R. and Wong, I. and Bhattacharya, S.}, year={2019}, pages={1125–1130} }
 @inproceedings{anurag_acharya_bhattacharya_2019, title={Evaluation of Extra High Voltage (XHV) Power Module for Gen3 10 kV SiC MOSFETs in a Mobile Utility Support Equipment based Solid State Transformer (MUSE-SST)}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071614810&partnerID=MN8TOARS}, booktitle={ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia}, author={Anurag, A. and Acharya, S. and Bhattacharya, S.}, year={2019} }
 @book{kanale_jayant baliga_han_bhattacharya_2019, title={Experimental study of high-temperature switching performance of 1.2kv sic JBSFET in comparison with 1.2kv sic MOSFET}, volume={963 MSF}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071889458&partnerID=MN8TOARS}, DOI={10.4028/www.scientific.net/MSF.963.625}, abstractNote={The high-temperature switching performance of a 1.2kV SiC JBSFET is compared with a 1.2kV SiC MOSFET using a clamped inductive load switching circuit representing typical H-bridge inverters. The switching losses of the SiC MOSFET are also evaluated with a SiC JBS Diode connected antiparallel to it. Measurements are made with different high-side and low-side device options across a range of case temperatures. The JBSFET is observed to display a reduction in peak turn-on current – up to 18.9% at 150°C and a significantly lesser turn-on switching loss – up to 46.6% at 150°C, compared to the SiC MOSFET.}, journal={Materials Science Forum}, author={Kanale, A. and Jayant Baliga, B. and Han, K. and Bhattacharya, S.}, year={2019}, pages={625–628} }
 @article{nazmunnahar_simizu_ohodnicki_bhattacharya_mchenry_2019, title={Finite-Element Analysis Modeling of High-Frequency Single-Phase Transformers Enabled by Metal Amorphous Nanocomposites and Calculation of Leakage Inductance for Different Winding Topologies}, volume={55}, ISSN={["1941-0069"]}, url={https://doi.org/10.1109/TMAG.2019.2904007}, DOI={10.1109/TMAG.2019.2904007}, abstractNote={The solid-state transformer (SST) is an emerging technology which is gaining increasing importance for future power distribution systems. Here, we present 2-D finite-element analysis (FEA) of single-phase SSTs for operating frequencies of 50 kHz. We consider designs to benchmark materials aimed at controlling high-frequency losses to achieve higher power densities. The FEA model is solved in the time domain for frequencies of 50 kHz, at a fixed 800 V input voltage and 10 kW output power for the first four cycles. This paper analyzes the influence of leakage inductance on the waveform with an increasing number of turns and discusses how to calculate the leakage inductance of the different winding topologies by FEA. In addition, transformer topologies are coupled to a power analysis using a Steinmetz parameterization of magnetic losses capturing induction and field scaling for transformer losses for FeNi-based metal amorphous nanocomposites (MANCs) for SST applications and their benchmarking with amorphous and other MANCs and ferrites. Recently, discovered FeNi-based MANCs allow smaller transformers at equivalent power as compared to Si steels, Metglas, and Co-based MANCs. These Fe-rich and non-Co containing MANCs also offer economies based on lower raw materials costs as compared with Co-based MANCs and significantly improved mechanical properties with respect to commercially available Fe-based MANCs.}, number={7}, journal={IEEE TRANSACTIONS ON MAGNETICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Nazmunnahar, M. and Simizu, S. and Ohodnicki, P. R. and Bhattacharya, S. and McHenry, M. E.}, year={2019}, month={Jul} }
 @book{bhattacharya_2019, title={Flexible Large Power Solid State Transformer (FLP-SST)}, url={https://doi.org/10.2172/1647580}, DOI={10.2172/1647580}, abstractNote={A large power transformer (LPT) is a major component in the electric power system grid. With the passage of time their reliability in terms of failure and service maintenance has been a big concern. According to a report by EPRI, various agencies have emphasized, and recent events have demonstrated, the critical nature of power transformers in the face of possible high-impact, low-frequency (HILF) events. The HILF events include intentional malicious events (e.g., physical attacks, cyber-attacks, coordinated attacks, electromagnetic pulse weapons, and others), natural disasters (e.g., hurricanes, earthquakes, severe geomagnetic disturbances, etc.), and non-intentional or accidental events such as nuclear power plant accidents. With aging, the line frequency transformers (LFTs) are also prone to failure due to insulation degradation, coolant leakage, mechanical failure, inadequate maintenance, etc. and thus poses a bigger threat to the electrical grid. Moreover, these transformers are custom made to fit the needs at the substation and weighs approximately between 100-400 tons, hence are neither interchangeable nor stored as a spare one. Hence reasonable efforts need to be made regarding the replacement of the LPT with a more feasible technology that does not pose similar issues. The concept of Flexible Large Power Solid-State Transformer (FLPSST) has addressed the aforementioned issues to provide an economical solutions for the failure of LPTs.}, institution={Office of Scientific and Technical Information (OSTI)}, author={Bhattacharya, Subhasish}, year={2019}, month={Feb} }
 @article{anurag_acharya_bhattacharya_2019, title={Gate Drivers for High-Frequency Application of Silicon-Carbide MOSFETs}, volume={6}, ISSN={["2329-9215"]}, url={https://doi.org/10.1109/MPEL.2019.2925238}, DOI={10.1109/MPEL.2019.2925238}, abstractNote={With the advent of wide-bandgap (WBG) semiconductor devices, silicon-carbide (SiC)-based MOSFETs for high voltage and current serve as a viable replacement for conventional Si-based IGBTs [1], [2]. SiC-based MOSFETs combine the advantages of both IGBTs and MOSFETs, have a low on-state resistance at a high-voltage rating (similar to IGBTs), and lower-switching losses than those of Si MOSFETs, thus making it closer to an ideal switch [3]. This makes it possible for SiC MOSFETs to process high power at high-switching frequencies without compromising the efficiency of the system [4]. Due to the inherent lower on-state specific resistance and faster switching speeds in SiC MOSFETs, it is also possible to develop and use medium-voltage (MV) power semiconductor devices greater than 6.5 kV without experiencing very high losses [5]. The SiC MOSFET design and development can be divided into two broad categories: low-voltage (LV)-blocking (<3.3-kV) and MV-blocking (>3.3-kV) SiC MOSFETs [6]. Although MV SiC MOSFETs can enable niche applications, there is widespread use of LV-blocking power devices in various applications such as renewable energy, drives for electrical machines, power converters for electric vehicles, and so on, whereas SiC MOSFETs can offer a multitude of advantages over Si IGBTs [7], [8].}, number={3}, journal={IEEE POWER ELECTRONICS MAGAZINE}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Anurag, Anup and Acharya, Sayan and Bhattacharya, Subhashish}, year={2019}, month={Sep}, pages={18–31} }
 @inproceedings{ghanbari_bhattacharya_2019, title={Hardware-In-The-Loop Implementation of a Grid Connected PV System}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076723972&partnerID=MN8TOARS}, DOI={10.1109/IAS.2019.8912363}, abstractNote={This paper presents a methodology and algorithm for validating the performance of a grid connected Photovoltaic (PV) system. The paper also aims at observing irradiance change of PV arrays and its effect on the load side of the converter using real time simulation. With this real time platform, it is possible to evaluate the system behavior with the uncertainties exist in PV production and the controller performance in maintaining DC bus voltage fixed. The methodology uses OPAL-RT as the Hardware-In-The-Loop (HIL) platform to model the system by means of its MATLAB based library. The power electronic elements are directly implemented in FPGA part of OPAL-RT, while the controller and mathematical model of PV arrays are implemented in its CPU part. The HIL results are presented to show the effect of irradiance change on the system variables. The presented HIL simulation platform also offers a verification for the system control algorithm design.}, booktitle={2019 IEEE Industry Applications Society Annual Meeting, IAS 2019}, author={Ghanbari, N. and Bhattacharya, S.}, year={2019} }
 @inproceedings{pulakhandam_bhattacharya_byrd_2019, title={Hybrid operation of a GaN-based three-level T-type inverter for pulse load applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081173145&partnerID=MN8TOARS}, DOI={10.1109/WiPDA46397.2019.8998812}, abstractNote={Pulsed-power loads are present in many industries such as defense, automotive, milling, etc. Performance benefits like reduced switching stress, lower losses, dV/dT, harmonic distortion, and smaller output filters have proven the viability of multi-level converters at medium voltages. Now, with the rise of Wide Bandgap (WBG) semiconductors, studies have shown their relevance at low voltages (<1000V). This study highlights a potential control issue with three-level converters for Pulsed-Load applications and demonstrates a novel modulation scheme as a solution. The converter actively switches between two-level (2L) and three-level (3L) operation to minimize neutral point (NP) deviation, output current distortion and may now increase overall system power density. This hybrid operation reduces the ripple current requirements for the DC bus capacitors. The NP deviation and current distortion of the Gallium Nitride (GaN) based T-type converter is compared with the conventional three-level (3L) control scheme for a continuous pulsed-load.}, booktitle={2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019}, author={Pulakhandam, H. and Bhattacharya, S. and Byrd, T.}, year={2019}, pages={378–383} }
 @inproceedings{agarwal_kanale_han_baliga_bhattacharya_2019, title={Impact of gate oxide thickness on switching and short circuit performance of 1200 v 4H-SiC inversion-channel MOSFETs}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081169610&partnerID=MN8TOARS}, DOI={10.1109/WiPDA46397.2019.8998839}, abstractNote={In this paper, we report successful fabrication of 1200 V 4H-SiC planar-gate inversion-channel power MOSFETs with 27 nm gate oxide thickness in a 6 inch commercial foundry. The static electrical characteristics, switching performance and short-circuit failure times for the 27 nm devices are compared with those of conventional 55 nm gate oxide devices. The specific on-state resistance of the 27 nm gate oxide devices at a gate voltage of 15 V was found to be 1.5x lower than the conventional 55 nm gate oxide devices at a gate bias of 20 V. The total switching energy loss (Etot) for the 27 nm device with Vgs of 15 V and Vgs of 10 is approximately equal and 1.4x larger than the 55 nm case with Vgs of 20 V. The short-circuit failure time (tsc) for the 27 nm device is 1.4× better than 55 nm device at Vgs of 10 V but 1.4× worse for Vgs of 15 V.}, booktitle={2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019}, author={Agarwal, A. and Kanale, A. and Han, K. and Baliga, B.J. and Bhattacharya, S.}, year={2019}, pages={59–62} }
 @inproceedings{jakka_nath_acharya_kadavelugu_madhusoodhanan_tripathi_patel_mainali_bhattacharya_2019, title={Implementation of Flexible Large Power Transformers Using Modular Solid State Transformer Topologies Enabled by SiC Devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076753041&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8912564}, abstractNote={Large power transformers (LPTs) have been a major concern of the electric power sector as a failure of a single unit can lead to temporary service interruption and utility damages. Replacement of such large and heavy transformer units is a challenging job as LPTs are custom-designed and hence entail long lead times due to its intricate manufacturing process and transportation. On the other hand, solid-state-transformer (SST) technology has evolved as an alternate option for the conventional line-frequency transformers, which offers comparatively reduced size and weight with the enhanced power quality features. With the advancement in wide-bandgap devices such as silicon carbide (SiC) and advanced power electronic converters, SSTs are able to deploy in medium voltage applications. Consequently, the utilization of SiC-SSTs for large power applications can mitigate some of the existing concerns of LPTs. In this paper, challenges and concerns associated with the existing LPTs are discussed. Possible SST modules/cells enabled by SiC devices, which can be connected in a modular structure to achieve multi-cell flexible large power SSTs (FLP-SST) are presented. The effectiveness of the discussed SST cells is validated using appropriate simulations and experimental results of the scaled SST prototypes.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Jakka, V.N. and Nath, H. and Acharya, S. and Kadavelugu, A. and Madhusoodhanan, S. and Tripathi, A. and Patel, D. and Mainali, K. and Bhattacharya, S.}, year={2019}, pages={4619–4626} }
 @article{baek_bhattacharya_2019, title={Isolation Transformer for 3-Port 3-Phase Dual-Active Bridge Converters in Medium Voltage Level}, volume={7}, ISSN={["2169-3536"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85062211518&partnerID=MN8TOARS}, DOI={10.1109/ACCESS.2019.2895818}, abstractNote={In this paper, an isolation transformer with integrated filter inductances for three-phase three-port dual-active bridge (DAB) converters in the wye-wye-delta (Yyd) configuration is introduced and designed. A large number of ports and phases in the application necessarily requires a proportionally increased number of components, accessories, and connections. These additional parts induce significant losses and electromagnetic interference during high-frequency operations. Hence, fully manipulating the parasitic components, especially the leakage inductances of the transformer as the circuit element in the interconnected multi-port configuration, is a key to reduce the system’s overall size and to improve its reliability. The proposed geometry and design method enables the full integration of a large number of otherwise bulky inductors to be included in the isolation transformers so that the latter function not only a step-up/down transformers but also as filter networks required for three-port DAB operations. The transformer is suitable for high-power and high step-up/down ratio dc-dc converters, which prefers a parallel combination of converters that share current, on the low-voltage side. The operating principles and steady-state analysis are presented with respect to power flow, and a three-winding shell-type isolation/filter transformer has been designed for a three-port three-phase Yyd DAB converter for solid state transformer applications. The finite element method simulations are used to validate the feasibility of the proposed approach. A prototype was fabricated and tested in an experimental setting.}, journal={IEEE ACCESS}, author={Baek, Seunghun and Bhattacharya, Subhashish}, year={2019}, pages={19678–19687} }
 @article{bhattacharya_2019, title={MV Power Conversion Systems Enabled by High-Voltage SiC Devices [Happenings]}, volume={6}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85078522992&partnerID=MN8TOARS}, DOI={10.1109/MPEL.2019.2947369}, abstractNote={The current electrical distribution system needs to adapt due to an increase in demand and requirements for a “smarter grid,” which are required because of the proliferation of distributed energy resources (DERs). Transformers form an integral part of these electrical grids, and an upgrade to handle the additional requirements that come along is imperative. Unfortunately, an upgrade in a conventional sense is not possible, so it is time to think beyond conventional transformers. Thanks to recent strides in power electronics research and the availability of high-voltage (HV) silicon carbide (SiC) power semiconductor devices, we can contemplate building a smart “solid-state transformer” to handle the demands of the smart grid. In electrical distribution systems, the transformers convert thousands of volts [medium voltage (MV)] into lower voltages that can be safely used in homes and businesses [1]. With emerging technologies in building and fabricating MV SiC-based power semiconductor devices, MV power conversion on a large-scale scenario seems feasible. While companies, such as Wolfspeed (CREE), General Electric, Infineon Technologies, Mitsubishi, and ROHM, continue to develop and improve these MV semiconductor devices, we at the FREEDM Systems Center are aiming at the application side of things to ensure a market for these power devices. We have been working with 15-kV SiC insulated-gate bipolar transistors (IGBTs) and 10-kV SiC MOSFETs to develop solid-state transformers to showcase the viability of a working MV solid-state transformer. In 2010, the U.S. Department of Energy’s (DOE’s) Advanced Research Projects Agency-Energy (ARPA-E) awarded our team US$4.2 million to build a three-phase solid-state transformer from the 15-kV SiC IGBTs. The project was called the Transformerless Intelligent Power Substation (TIPS) [2]. With the TIPS project, a successful demonstration of MV SST was carried out for the first time using these SiC devices. Several technical questions related to the viability of such an ap proach were answered. It was proven Digital Object Identifier 10.1109/MPEL.2019.2947369 Date of current version: 17 December 2019}, number={4}, journal={IEEE Power Electronics Magazine}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Bhattacharya, Subhashish}, year={2019}, pages={18–21} }
 @inproceedings{parashar_bhattacharya_2019, title={Medium Voltage Asynchronous Micro-grid Power Conditioning System Enabled by HV SiC Devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071638598&partnerID=MN8TOARS}, booktitle={ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia}, author={Parashar, S. and Bhattacharya, S.}, year={2019}, pages={1676–1681} }
 @inproceedings{chattopadhyay_gulur_nair_bhattacharya_ohodnicki_2019, title={Medium Voltage DC Bus Enabled by Series Connection of SiC Mosfet Based Three Port DC-DC Converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076790742&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8911893}, abstractNote={This paper presents development of Medium Voltage(MV) DC bus using series connection of Modular DC-DC Converter blocks. The MVDC bus is developed using Three Port Triple Active Bridge(TAB) DC-DC converter, which integrate Renewable Energy Sources(RES) and Energy Storages(ES). The TAB DC-DC converter units are three port high frequency transformer isolated phase shifted converters which integrate RES and ES with an output dc bus. Multiple of this DC-DC converter output dc buses can be connected in series to obtain a Medium Voltage DC Bus. The three port TAB converters for this series connection of converters, use 1200V & 1700V SiC Mosfets as switching devices with a three port high frequency transformer providing galvanic isolation among the three ports. In this paper, two laboratory prototypes of the three port TAB converters are connected in series to demonstrate MVDC bus(>2kV). Three port TAB converter, Gate Drivers for TAB converters, Three Port High Frequency transformer, along with independent power & voltage control for three port TAB Converter is discussed here in this paper with experimental verification.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Chattopadhyay, R. and Gulur, S. and Nair, V. and Bhattacharya, S. and Ohodnicki, P.R.}, year={2019}, pages={6231–6238} }
 @inproceedings{anurag_acharya_pal_bhattacharya_2019, title={Mission Profile based Reliability Analysis of a Three-Phase PV Inverter Considering the Influence of High dv/dt on Parasitic Filter Elements}, volume={2019-March}, ISBN={9781538683309}, url={http://dx.doi.org/10.1109/apec.2019.8721983}, DOI={10.1109/APEC.2019.8721983}, abstractNote={Silicon Carbide (SiC) power semiconductor devices in medium voltage (MV) applications have facilitated the use of power converters at distribution voltage level. In these applications, the semiconductor devices are exposed to a high peak stress (of up to 15 kV) and a very high dv/dt (of up to 100 kV/µs). The increasing use of these power devices has made the effects of the parasitic elements in the filter more prominent, due to the high dv/dt experienced by the passive filter elements during device switching transients. The parasitic elements in the filter inductors causes an increased switching loss in the devices. This paper analyses the effect of these additional losses on the lifetime of the device. A thermal analysis based on a mission profile (solar irradiance and temperature) is provided to account for the additional junction temperature rise due to the high dv/dt and the parasitic filter elements. Rainflow counting method has been used to identify the mean and amplitude of each thermal cycle. An analytical device model and Palgrem Miner rule is used to quantify the damage in the device. Comparisons have been carried out on basis of lifetime, for cases with and without the influence of parasitic capacitances. This analysis can be helpful in validating the importance of the design of filter inductors in these MV applications.}, booktitle={2019 IEEE Applied Power Electronics Conference and Exposition (APEC)}, publisher={IEEE}, author={Anurag, Anup and Acharya, Sayan and Pal, Shruti and Bhattacharya, Subhashish}, year={2019}, month={Mar}, pages={3490–3496} }
 @inproceedings{prabowo_iyer_kim_bhattacharya_2019, title={Modeling and Stability Assessment of Single-Phase Droop Controlled Solid State Transformer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071608538&partnerID=MN8TOARS}, booktitle={ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia}, author={Prabowo, Y. and Iyer, V.M. and Kim, B. and Bhattacharya, S.}, year={2019}, pages={3285–3291} }
 @article{acharya_anurag_bhattacharya_pellicone_2020, title={Performance Evaluation of a Loop Thermosyphon-Based Heatsink for High-Power SiC-Based Converter Applications}, volume={10}, ISSN={2156-3950 2156-3985}, url={http://dx.doi.org/10.1109/tcpmt.2019.2923332}, DOI={10.1109/TCPMT.2019.2923332}, abstractNote={Thermal management system (TMS) of a power converter directly dictates the available power rating, power density, semiconductor module reliability, and its operating lifetime. For the latest-generation wide bandgap (WBG) semiconductor device-based converters, it is challenging to extract the generated heat from the devices due to smaller die area as compared to its silicon (Si) counterparts. In this paper, the thermal performance of a new loop thermosiphon-based TMS for silicon carbide (SiC) semiconductor device-based power conversion system is presented. The working principle and design of the TMS are shown, and the performance of the designed TMS in both transient and steady-state conditions of power dissipation is evaluated. Furthermore, an accurate thermoelectrical model of the TMS is presented, and the circuit parameters are quantified by experimental results. This analysis helps to estimate the device junction temperature in real time during converter operation. Moreover, detailed simulations are carried out with the derived TMS thermal model to evaluate its performance at low fundamental frequencies at rated currents. The experimental results and the simulation studies indicate that the TMS offers a low thermal resistance and can extract a large amount of heat without increasing the device junction temperatures beyond their rated values. Furthermore, the designed TMS is able to maintain the junction temperature ripples at low fundamental frequencies within small values, which helps to increase the lifetime of the power modules significantly, as compared to conventional heatsinks.}, number={1}, journal={IEEE Transactions on Components, Packaging and Manufacturing Technology}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Acharya, Sayan and Anurag, Anup and Bhattacharya, Subhashish and Pellicone, Devin}, year={2020}, month={Jan}, pages={99–110} }
 @article{alharbi_bhattacharya_2019, title={Scale-Up Methodology of a Modular Multilevel Converter for HVdc Applications}, volume={55}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071334447&partnerID=MN8TOARS}, DOI={10.1109/TIA.2019.2925055}, abstractNote={Modular multilevel converters (MMCs) are a realistic alternative to the conventional voltage source converters for medium-voltage (MV) and high-voltage direct current (HVdc) applications. The number of submodules (SMs) per arm of the MMC can be as high as 512 to achieve desired high dc voltage levels required for HVdc with a very low total harmonic distortion (THD) (e.g., <0.1%) of the MMC ac-side interface voltage. Although the low THD of the MMC output voltage with a high number of SMs is desirable, the MMC control implementation and complexity is also important to be considered for the high number of SMs. The MMC control complexity significantly increases as the number of SMs increases. Redesigning the number of SMs in MMCs also becomes quite difficult and may require significant control upgrade, which in turn also needs additional tests and validations. This paper presents an MMC scale-up control methodology applicable for MV and HVdc applications. The number of SMs can be conveniently increased or reduced without any significant control modifications. The proposed control method and capacitor voltage balancing algorithm are implemented in the real-time digital simulator and MMC support units based on field-programmable gate array boards. The performance of the proposed MMC control method is investigated for a point-to-point MMC-based HVdc system under various operating conditions.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Alharbi, Mohammed and Bhattacharya, Subhashish}, year={2019}, pages={4974–4983} }
 @inproceedings{beddingfield_bhattacharya_ohodnicki_2019, title={Shielding of Leakage Flux Induced Losses in High Power, Medium Frequency Transformers}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076790212&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8911859}, abstractNote={Metal Amorphous Nanocrystalline core materials have shown great promise as the magnetic material for the isolation transformer used in high power, high frequency power converters. However, many current designs require special winding configurations that result in high parasitic capacitance. Similarly, when these designs are used in active bridge circuits where a certain minimum series inductance is required, auxiliary inductors are required. These dramatically reduce the power density and can have impacts on the efficiency. Designs that integrate the series inductance through inherently geometric approaches have resulted in catastrophic increases in losses that are not predicted by typical core magnetizing loss models and have not been viable as a result. This paper demonstrates a method of using a mix of materials to manage and direct the leakage flux through paths that are more efficient. Similarly, this approach enables deliberate tuning and design of the series inductance. This introduces a method to independently design the series inductance with the magnetizing inductance of the transformer. This will prove to enable high efficiency transformer designs with very high power density, empowering wide bandgap semiconductor-based converters to reach their full potential.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Beddingfield, R.B. and Bhattacharya, S. and Ohodnicki, P.}, year={2019}, pages={4154–4161} }
 @inproceedings{kumar_kokkonda_bhattacharya_veliadis_2019, title={Single shot avalanche characterization of series and parallel connection of SiC power MOSFETs}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081179636&partnerID=MN8TOARS}, DOI={10.1109/WiPDA46397.2019.8998886}, abstractNote={Power modules are connected in series and parallel combinations to meet the voltage and current requirements of various applications, especially in medium voltage high power applications. Avalanche ruggedness of the SiC power MOSFETs need to be established in these connections to assess the reliability of the converters in extreme transient conditions. 1700 V SiC MOSFET has potential to replace the conventional 1700 V silicon IGBT in medium voltage power converters such as 800 V and 1500 V railway traction applications. In this paper, single shot avalanche ruggedness of the series-connected and parallel-connected 1700 V SiC MOSFETs are characterized using the unclamped inductive test circuit. Single shot avalanche ruggedness of series connected SiC MOSFETs is reported for the first time. In both the connections, the failed MOSFET was observed to be the one which dissipated lower share of the total avalanche energy of the connection.}, booktitle={2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019}, author={Kumar, A. and Kokkonda, R.K. and Bhattacharya, S. and Veliadis, V.}, year={2019}, pages={438–443} }
 @inproceedings{acharya_anurag_bhattacharya_2019, title={Stability Analysis of a Medium Voltage Cascaded Converter System with Reduced DC-link Capacitance}, volume={2019-March}, ISBN={9781538683309}, url={http://dx.doi.org/10.1109/apec.2019.8722010}, DOI={10.1109/APEC.2019.8722010}, abstractNote={Recent development of Silicon Carbide (SiC) based Medium Voltage (MV) power semiconductor devices have paved ways to build high power MV power converters with simple two level structures. One of the critical applications of these converters are solid state transformers (SSTs) which interconnects MV grid to a low voltage (LV) grid with high frequency isolation. SSTs are usually built with multi-stage cascaded conversion structures which includes ac-dc, dc-dc, and dc-ac stages, respectively. These converter structures need an intermediate MV DC bus to function. For MV applications, the DC bus structure is designed with low inductance bus bar and MV capacitors. At medium voltage levels, it is difficult to manufacture capacitors with high capacitance values with low footprint. Therefore, MV polypropylene film capacitors with low equivalent series inductance (ESL) are often utilized to build the MV DC Bus to meet the power density requirements. The small values of the effective DC bus capacitance create stability issues for cascaded converter structures for SSTs as it becomes difficult to completely decouple different power conversion stages. This paper delves into the interaction between different power conversion stages of a MV SST while transferring power. The study shows that low capacitance value of the MV DC bus can cause instability which needs to be mitigated.}, booktitle={2019 IEEE Applied Power Electronics Conference and Exposition (APEC)}, publisher={IEEE}, author={Acharya, Sayan and Anurag, Anup and Bhattacharya, Subhashish}, year={2019}, month={Mar}, pages={1157–1164} }
 @inproceedings{kanale_han_jayant baliga_bhattacharya_2019, title={Stability of 4H-SiC JBS Diodes under Repetitive Avalanche Stress}, volume={2019-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85066751469&partnerID=MN8TOARS}, DOI={10.1109/IRPS.2019.8720431}, abstractNote={Silicon carbide (SiC) Junction Barrier Schottky (JBS) rectifiers, used as antiparallel diodes for silicon IGBTs, can be subjected to high current reverse avalanche stress (RAS) during operation in inductive load circuits. The stability of commercially available and NCSU SiC JBS rectifiers was investigated after repetitive RAS. No degradation was observed after 10,000 RAS pulses at the rated on-state current level. Numerical Simulations reveal that the degradation of JBS diodes is suppressed because: (a) the electric field at the Schottky contact is reduced by P+ shielding region, (b) the avalanche current primarily flows via the P+ shielding region and not the Schottky contact, and (c) the temperature rise is limited to less than 100°C during the stress. The avalanche energy for failure of the diodes was also obtained for three values of load inductance by increasing the avalanche current. The critical failure energy was found to be independent of the load inductance values leading to a reduction of the failure current with increasing load inductance.}, booktitle={IEEE International Reliability Physics Symposium Proceedings}, author={Kanale, A. and Han, K. and Jayant Baliga, B. and Bhattacharya, S.}, year={2019} }
 @inproceedings{ghanbari_shabestari_mehrizi-sani_bhattacharya_2019, title={State-space modeling and reachability analysis for a DC microgrid}, volume={2019-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85066759672&partnerID=MN8TOARS}, DOI={10.1109/APEC.2019.8721914}, abstractNote={In a DC microgrid containing parallel voltage sources, distributed control algorithms such as droop control methods are mainly employed. These controllers depend on the nominal bus voltage and the droop coefficients to operate properly. In the DC microgrid with PV arrays there are uncertainties in the PV current. To analyze the transient behavior of this uncertain system simulation-based techniques cannot be used, since they cannot consider the uncertainties. To analyze the uncertain DC microgrid, reachability analysis is used to find the limits of the system variables from a given state-space model of the system. In this paper, using the state-space model of the DC microgrid, reachability analysis is performed to analyze effectiveness of the droop control method in the existence of uncertainties. Simulation and experimental case studies are performed to verify the reachability analysis results.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Ghanbari, N. and Shabestari, P.M. and Mehrizi-Sani, A. and Bhattacharya, S.}, year={2019}, pages={2882–2886} }
 @inproceedings{han_kanale_baliga_bhattacharya_2019, title={Static, dynamic, and short-circuit performance of 1.2 kV 4H-SiC MOSFETs with various channel lengths}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081173165&partnerID=MN8TOARS}, DOI={10.1109/WiPDA46397.2019.8998803}, abstractNote={The impact of channel length on the static, dynamic, and short-circuit performance of 1.2 kV-rated 4H-SiC inversion-channel (Inv) power MOSFETs is reported for the first time. Devices were successfully fabricated with the various channel lengths (LCH=0.3 to 1.1 $\mu$ m) in a 6 inch commercial foundry and they were packaged in TO-247 cases for all the testing. The devices with 0.3 $\mu$ m channel length were found to have the lowest on-resistance, best High Frequency Figures-of-Merit (HF-FOMs), and fastest switching performance, but worst short-circuit (SC) capability. The SC capability improved with increasing channel length at the penalty of an increase in the on-resistance. The fabricated 1.2 kV SiC MOSFETs were compared with commercially available 1.2 kV Si IGBTs in terms of the power losses and short-circuit capability: the 1.2 kV SiC power MOSFETs with long channel length can outperform the Si IGBT with lower power losses and superior short-circuit capability.}, booktitle={2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019}, author={Han, K. and Kanale, A. and Baliga, B.J. and Bhattacharya, S.}, year={2019}, pages={47–52} }
 @book{kanale_han_baliga_bhattacharya_2019, title={Superior short circuit performance of 1.2KV SIC JBSFETs compared to 1.2KV SIC mosfets}, volume={963 MSF}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071847000&partnerID=MN8TOARS}, DOI={10.4028/www.scientific.net/MSF.963.797}, abstractNote={The high-temperature switching performance of a 1.2kV SiC JBSFET is compared with a 1.2kV SiC MOSFET using a clamped inductive load switching circuit representing typical H-bridge inverters. The switching losses of the SiC MOSFET are also evaluated with a SiC JBS Diode connected antiparallel to it. Measurements are made with different high-side and low-side device options across a range of case temperatures. The JBSFET is observed to display a reduction in peak turn-on current – up to 18.9% at 150°C and a significantly lesser turn-on switching loss – up to 46.6% at 150°C, compared to the SiC MOSFET.}, journal={Materials Science Forum}, author={Kanale, A. and Han, K. and Baliga, B.J. and Bhattacharya, S.}, year={2019}, pages={797–800} }
 @inproceedings{samanta_wong_beddingfield_bhattacharya_zhu_pahl_2019, title={Supplying medium voltage to data-center racks directly using SiC-based converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081182419&partnerID=MN8TOARS}, DOI={10.1109/WiPDA46397.2019.8998837}, abstractNote={With the increase in size of data centers and cloud computing, its power demand is also rising sharply. Traditionally, this power distribution is achieved at about 400VDC which is inconvenient because it requires very bulky conductor to prevent high copper loss. In this paper, a new power distribution architecture for data centers is reported where direct medium voltage distribution to data-center racks are achieved with SiC based inverter. The safety issues raised due to bringing medium voltage to the racks are addressed with contactless power transfer technology. The rectifier circuit handles a high current at 48V, and synchronous rectification would be suitable to boost the efficiency. In this paper, a GaN based synchronous rectification is studied. This proposed converter circuit is analyzed and simulated in PowerSim 11. A 3kW experimental setup is developed in the lab to verify the analysis and simulation performances of the converter, where the input is 1000V and the output is 48V.}, booktitle={2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019}, publisher={IEEE}, author={Samanta, Suvendu and Wong, Isaac and Beddingfield, Richard and Bhattacharya, Subhashish and Zhu, Guangqi and Pahl, Birger}, year={2019}, pages={85–92} }
 @misc{sonti_jain_agarwal_bhattacharya_2019, title={Terminal voltage analysis for the transformerless PV inverter topologies in a single-phase system}, volume={13}, ISSN={["1752-1424"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85075801817&partnerID=MN8TOARS}, DOI={10.1049/iet-rpg.2019.0106}, abstractNote={This study presents an analysis of the terminal voltage of the basic photovoltaic (PV) inverter topologies available in the literature. The presented analysis utilises the switching function concept. Use of switching function in the analysis enables the inclusion of the effect of the pulse-width modulation technique or the switching strategy on the terminal voltage of the reviewed configuration. It gives insight into the switching action effects on the terminal voltage and provides every detail of the high-frequency transitions in the terminal voltage for the given switching strategy. Using the terminal voltage expression derived in terms of switching function, the analytical waveforms are obtained for various configurations. These waveforms are compared with the simulation and experimental results waveforms to justify the analysis given. This study also presents a bar chart view of the switching and conduction losses of the switches in the reviewed PV inverter topologies. The magnitude of high-frequency components in the terminal voltage and the leakage current is also presented in this study. The PV inverter topologies are also compared in terms of other aspects such as a number of devices used, asymmetry in operation, filter requirement etc.}, number={15}, journal={IET RENEWABLE POWER GENERATION}, author={Sonti, Venu and Jain, Sachin and Agarwal, Vivek and Bhattacharya, Subhashish}, year={2019}, month={Nov}, pages={2723–2739} }
 @inproceedings{kim_kim_bhattacharya_2019, title={The Influence of the LC with Clamping Diodes dv/dt Filter on Current Control of PMSM Drives in Case of Inverter Output Current Sensing and Its Compensation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071614124&partnerID=MN8TOARS}, booktitle={ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia}, author={Kim, H. and Kim, B.-H. and Bhattacharya, S.}, year={2019}, pages={1280–1285} }
 @article{anurag_acharya_bhattacharya_weatherford_2020, title={Thermal Performance and Reliability Analysis of a Medium-Voltage Three-Phase Inverter Considering the Influence of High $dv/dt$  on Parasitic Filter Elements}, volume={8}, ISSN={2168-6777 2168-6785}, url={http://dx.doi.org/10.1109/jestpe.2019.2952570}, DOI={10.1109/JESTPE.2019.2952570}, abstractNote={In recent years, the use of silicon carbide (SiC) power semiconductor devices in medium-voltage (MV) applications has been made possible due to the development of high blocking voltage (10–15 kV)-based devices. While the use of these devices brings in a lot of advantages, the semiconductor devices are exposed to high peak stress (of up to 15 kV) and a very high <inline-formula> <tex-math notation="LaTeX">$dv/dt$ </tex-math></inline-formula> (of up to 100 kV/<inline-formula> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula>). The high <inline-formula> <tex-math notation="LaTeX">$dv/dt$ </tex-math></inline-formula> across the devices leads to a high <inline-formula> <tex-math notation="LaTeX">$dv/dt$ </tex-math></inline-formula> across other components connected to the system. This makes the effect of the parasitic capacitance across the components to be of paramount importance since an additional current flows through the components and, consequently, through the switching device. This additional current flows during each switching transition and leads to increased switching losses in the device. This article analyzes the effect of these additional losses on the lifetime of the device. The thermal performance of a three-phase inverter power block is provided, and a mission profile (solar irradiance and temperature)-based analysis is carried out to account for the additional junction temperature rise. The rainflow counting method is implemented to identify the mean and amplitude of each thermal cycle. An empirical device lifetime model is used to calculate the number of cycles to failure. Finally, the Palgrem Miner rule is used to quantify the total damage in the device. Comparisons have been carried out on basis of lifetime for both the cases (with and without the influence of parasitic capacitances). This analysis can be helpful in validating the importance of the design of filter inductors in these MV applications.}, number={1}, journal={IEEE Journal of Emerging and Selected Topics in Power Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Anurag, Anup and Acharya, Sayan and Bhattacharya, Subhashish and Weatherford, Todd R.}, year={2020}, month={Mar}, pages={486–494} }
 @inproceedings{jakka_kumar_parashar_rastogi_kolli_jaiswal_bhattacharya_2019, title={Voltage Balancing of Series Connected Clamping Diodes in Medium Voltage NPC Converter enabled by Gen-3 10 kV SiC MOSFETs for Asynchronous Micro-Grid Power Conditioning System (AMPCS)}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076718597&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2019.8911830}, abstractNote={Asynchronous micro-grid power conditioning system (AMPCS) had been proposed for integrating two medium voltage nonsynchronous grids. Neutral point clamped (NPC) converter based active front-end converters (AFECs) and three-phase dual active bridge (DAB) are used as basic building blocks for the AMPCS. Switching and voltage clamping operations of these NPCs are achieved using series connected 10 kV SiC MOSFETs and 10 kV SiC JBS diodes, respectively. In the earlier reported work on AMPCS, voltage balancing across the series connected MOSFETs is reported. It is observed that in a few cases voltage unbalance also appears across the series connected clamping diodes due to dissimilar nature of their characteristics. This voltage imbalance across the clamping diodes can affect the operation of AMPCS. In this digest, a balancing scheme for series connected clamping diodes of the AMPCS system using passive snubber circuit is presented. A systematic set of experiments have been reported which can be conducted to ensure the voltage balancing across the series connected clamping diodes before applying them in actual medium voltage AMPCS. The balancing scheme is validated using the experimental results.}, booktitle={2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019}, author={Jakka, V.N. and Kumar, A. and Parashar, S. and Rastogi, S.K. and Kolli, N. and Jaiswal, R. and Bhattacharya, S.}, year={2019}, pages={5798–5804} }
 @inproceedings{isik_alharbi_bhattacharya_2018, title={A Feedforward Current Control Strategy for a MMC Based Point to Point HVDC Systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85053832326&partnerID=MN8TOARS}, DOI={10.1109/PEDG.2018.8447601}, abstractNote={Voltage source converters (VSCs) have been commonly used due to their flexibility to control voltages and powers independently and bi-directionally. Typically, (e.g. two-level converter), the control system mainly consists of two parts; outer voltage or power flow (real and reactive power) controller and inner current controller. Vector current control based dq decoupling technique enables to control active and reactive power, DC voltage and AC voltage. The d- and q-axis of grid voltages and currents comprise AC and DC components under unbalanced grid conditions. The AC components of the d- and q-axis current have negative impact on the current control loop and converter performance. In this paper, a novel feed-forward current control has been presented and investigated under balanced and unbalanced grid modes for a Modular Multilevel Converter (MMC) system. The Real Time Digital Simulator (RTDS) demonstrates the results of proposed feedforward current control strategy, applied to the Point to Point MMC based High Voltage Direct Current (HVDC) system.}, booktitle={2018 9th IEEE International Symposium on Power Electronics for Distributed Generation Systems, PEDG 2018}, author={Isik, S. and Alharbi, M. and Bhattacharya, S.}, year={2018} }
 @inproceedings{anurag_acharya_gohil_bhattacharya_2018, title={A Gate Driver Design for Medium Voltage Silicon Carbide Power Devices with High dv / dt}, ISBN={9781509066841}, url={http://dx.doi.org/10.1109/iecon.2018.8591858}, DOI={10.1109/IECON.2018.8591858}, abstractNote={The use of silicon carbide (SiC) devices in medium voltage (MV) applications has become a possibility due to the development of reliable MV SiC power devices. However, when SiC devices are used in these MV applications, they are exposed to a high voltage peak stress (of up to 15 kV across the primary and secondary side of the gate driver) and a very high $dv/dt$ (of up to 100 kV/μs across the isolation transformer). The gate driver design is very critical for proper functioning of the MV devices under the presence of such high dv/dt. This paper presents a design of an improved gate driver power isolation method, with a low coupling capacitance between the primary and the secondary side. The footprint of the isolation transformer is minimized to meet the clearance and insulation requirements. Comparisons have been drawn with an existing gate driver topology, on the basis of size of the gate driver, and common mode performances for different $dv/dt$. Experimental results are provided to validate both the gate driver designs. The testing and analysis is carried out on a 10 kV SiC MOSFET developed and packaged by Wolfspeed. In addition, a brief discussion on the insulation standards for these kinds of applications is provided. The gate driver concept is aimed at providing a benchmark for building an efficient and reliable method to drive MV SiC devices.}, booktitle={IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society}, publisher={IEEE}, author={Anurag, Anup and Acharya, Sayan and Gohil, Ghanshyamsinh and Bhattacharya, Subhashish}, year={2018}, month={Oct}, pages={877–882} }
 @article{shah_bhattacharya_2019, title={A Simple Unified Model for Generic Operation of Dual Active Bridge Converter}, volume={66}, ISSN={["1557-9948"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85049465467&partnerID=MN8TOARS}, DOI={10.1109/TIE.2018.2850012}, abstractNote={This paper presents a simple and generic model of a dual active bridge converter valid throughout its range of operation. It is suitable for all operating modes and modulation strategies such as phase-shift, extended phase-shift, dual phase-shift, or triple phase-shift modulation. It hypothesizes that any mode of its operation characterized by the duty ratios (<inline-formula><tex-math notation="LaTeX">$d_1$</tex-math></inline-formula>, <inline-formula><tex-math notation="LaTeX">$d_2$</tex-math></inline-formula>) of the two full-bridge converter ac voltages and the phase shift (<inline-formula><tex-math notation="LaTeX">$\phi$</tex-math></inline-formula>) between them can be decomposed into four parallel dual active bridge circuits operating in simple phase-shift modulation. The hypothesis is proven mathematically; the average and small-signal models are derived and validated through simulations and experiments on a hardware prototype.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Shah, Suyash Sushilkumar and Bhattacharya, Subhashish}, year={2019}, month={May}, pages={3486–3495} }
 @inproceedings{yadav_gopakumar_krishna raj_umanand_bhattacharya_jarzyna_2018, title={A hybrid seven level inverter topology formed by cascading T-type and active neutral point clamped inverter for induction motor drives}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85061522542&partnerID=MN8TOARS}, DOI={10.1109/IECON.2018.8591579}, abstractNote={This paper proposes a hybrid 7-level inverter scheme formed by cascading basic inverter cells. The proposed inverter is realized by cascading basic 3-level T-type converter with 5-level active neutral point clamped inverter. The proposed topology uses low voltage semiconductor devices and floating capacitors which are balanced in every PWM switching cycle using pole voltage redundancies for every pole voltage levels. The balancing of capacitors are independent of modulation index and load power factor. The topology forms two stacks at the front-end which uses individual symmetrical reduced DC sources and each stack works only for half the fundamental period. The open loop V/f control is simulated as well as experimentally verified on induction machine using proposed inverter topology. The experimental and simulation results for transient and steady state operations are included in the paper. Further, a brief comparison of proposed topology with conventional 7-level topologies have also been included.}, booktitle={Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society}, author={Yadav, A.K. and Gopakumar, K. and Krishna Raj, R. and Umanand, L. and Bhattacharya, S. and Jarzyna, W.}, year={2018}, pages={4423–4428} }
 @inproceedings{ghanbari_mobarrez_bhattacharya_2018, title={A review and modeling of different droop control based methods for battery state of the charge balancing in DC microgrids}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85055090311&partnerID=MN8TOARS}, DOI={10.1109/IECON.2018.8591739}, abstractNote={Nowadays, DC microgrids by linking DC sources such as renewable resources directly to the DC loads and offering higher efficiency due to the elimination of conversion stages are gaining more and more popularity. In DC microgrids with renewable resources, there are stochastic behavior and uncertainties. Thus, energy storage use is unavoidable. Droop control as a well known method is used as the basis of the power sharing among different parallel voltage sources and battery energy storage systems (BESSs). In order to extend the lifetime of BESSs and avoid the overuse of a certain battery, the State of the Charge (SoC) of BESSs should be balanced. This paper presents a review on three different droop control based methods for balancing SoCs of different BESSs in DC microgrids. Moreover, the paper proposes a new droop control method for SoC balancing to overcome the drawbacks of the mentioned methods. The mathematical model of these different methods are derived using small signal state space modeling for a Photovoltaic (PV) grid-interactive DC microgrid consisting of two BESSs. Then, a comparison study has been performed for the mentioned four methods using MATLAB/Simulink.}, booktitle={Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society}, author={Ghanbari, N. and Mobarrez, M. and Bhattacharya, S.}, year={2018}, pages={1625–1632} }
 @inproceedings{sukhatme_krishna_ganesan_hatua_bhattacharya_2018, title={A simple reduced order model for switching dynamics of Silicon Carbide MOSFET power module}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85065964845&partnerID=MN8TOARS}, DOI={10.1109/PEDES.2018.8707647}, abstractNote={The problem of overshoot and oscillations in Silicon Carbide (SiC) MOSFET power converters is well known. A simplified second order model, whose response is well understood, is presented in this paper which helps in gaining an intuitive insight in the overshoot and ringing. The modelling is done with the assumption that the gate of the SiC MOSFET power module is driven by a current source of fixed magnitude. The model presented in this paper is experimentally verified on a SiC MOSFET power module with a current source driven gate driver.}, booktitle={Proceedings of 2018 IEEE International Conference on Power Electronics, Drives and Energy Systems, PEDES 2018}, author={Sukhatme, Y. and Krishna, V. and Ganesan, P. and Hatua, K. and Bhattacharya, S.}, year={2018} }
 @inproceedings{shah_iyer_bhattacharya_2018, title={An Approach to Unified Full-Order Modeling of Dual Active Bridge Type Converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85061537028&partnerID=MN8TOARS}, DOI={10.1109/IECON.2018.8591664}, abstractNote={Modeling of dual active bridge (DAB)type converters, and that of its single-phase form, is an active area of research. In this paper, a new modeling approach is proposed. It is theorised that single-phase DAB converter operating in any of its multiple modes and modulation may be modeled as four dual active half-bridge (DAHB)circuits operating in simple phase-shift modulation. It allows extension of the model developed for simple phase-shift modulated DAHB converter to any operating mode of the DAB converter. In this respect, the physical basis of the theory is first explained. Subsequently, the improved first harmonic approximation (I-FHA)model of the DAHB converter, developed a priori, is extended to the general operating case of the DAB converter. Finally, the model is validated through extensive simulation and hardware experiments proving the theoretical basis of the proposed approach.}, booktitle={IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society}, author={Shah, S. S. and Iyer, V. M. and Bhattacharya, S.}, year={2018}, month={Oct}, pages={986–992} }
 @inproceedings{chattopadhyay_viju nair_bhattacharya_2018, title={An Isolated DC-AC Converter Module Integrating Renewable Energy Source and Energy Storage for Cascaded Inverter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060272842&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2018.8557706}, abstractNote={Large scale grid integration of renewable energy sources demands the converter systems to work under varying nature of renewable energy source power availability, which can be smoothened and compensated by using an Energy Storage. The large scale integration for renewable energy sources at medium voltage grid level can be accomplished using cascaded modular converter. This paper work focuses on an isolated DC-AC converter module which integrates a renewable energy source, an energy storage and a single phase low frequency AC output port. The converter uses a high frequency transformer with four winding terminals to integrate the renewable energy source, energy storage and the AC output port. The high frequency transformer current control maintains the renewable energy source power output at a fixed dc level without any 2nd harmonic oscillations, while all the 2nd harmonic oscillating component of power is supplied by the energy storage. This paper focuses on the converter working principle, power control and soft-switching ZVS of the converter.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition, ECCE 2018}, author={Chattopadhyay, R. and Viju Nair, R. and Bhattacharya, S.}, year={2018}, pages={3647–3652} }
 @inproceedings{anurag_acharya_prabowo_gohil_kassa_bhattacharya_2018, title={An accurate calorimetrie method for measurement of switching losses in silicon carbide (SiC) MOSFETs}, volume={2018-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046966591&partnerID=MN8TOARS}, DOI={10.1109/APEC.2018.8341245}, abstractNote={An accurate measurement of switching losses in SiC MOSFETs is necessary in order to design and evaluate the thermal performance of modern converter systems. Conventionally, electrical measurement methods, such as the double-pulse test (DPT) are used for calculating the hard-switching losses. However, with the advent of wide-bandgap devices, which have fast switching transients, it is rather difficult to capture the waveforms accurately during switching transitions, and consequently the measurement of switch loss suffers. This paper presents an accurate calorimetric method for measuring the switching losses. The conventional calorimetric measurement methods can accurately measure the device losses. However, the segregation of the conduction, turn-on and turn-off loss is not possible. This paper addresses this issue and proposes a method that can be used to determine individual loss components. The calorimetric test setup is described and a novel modulation scheme is introduced which enables the separation of turn-on and turn-off switching losses. The experimental test setup has been built and the method has been verified by measuring the losses of a Wolfspeed CMF10120D device.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Anurag, A. and Acharya, Sayan and Prabowo, Y. and Gohil, G. and Kassa, H. and Bhattacharya, S.}, year={2018}, pages={1695–1700} }
 @inproceedings{kim_kim_bhattacharya_2018, title={An analytical design strategy and implementation of a dv/dt filter for wbg devices based high speed machine drives}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85061556212&partnerID=MN8TOARS}, DOI={10.1109/IECON.2018.8591737}, abstractNote={This paper presents a design strategy of a $dv/dt$ filter for high speed machine drives based on analytical analysis. Both a LCR filter and a LC with a diode bridge are studied and, a choice between two options can be made depending on a length of cable. The way of choosing the value of L, C, and R of the filter is proposed by analyzing the transfer function of the filter output voltage and the filter resonant current. In the same manner, filter characteristics such as $dv/dt$, rise time, peak voltage, and peak resonant current can be adjusted accurately. The power loss in damping resistors are discussed. The proposed design scheme is evaluated through simulations and experiments with a SiC inverter and high speed IPMSM.}, booktitle={Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society}, author={Kim, H. and Kim, B.-H. and Bhattacharya, S.}, year={2018}, pages={385–390} }
 @inproceedings{kumar_parashar_kolli_bhattacharya_2018, title={Asynchronous Microgrid Power Conditioning System Enabled by Series Connection of Gen-3 SiC 10 kV MOSFETs}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060216072&partnerID=MN8TOARS}, DOI={10.1109/WiPDA.2018.8569088}, abstractNote={Asynchronous interconnection of grids has advantage over synchronous interconnection in terms of fault clearance time, islanding operation and disturbance propagation. Presently, asynchronous interconnection of medium voltage microgrids is realized using AC-DC and DC-AC power converters with the galvanic isolation provided by the power frequency transformers connected to the grids. The converters are typically implemented using 3.3 kV–6.5 kV silicon IGBTs. In this paper, a novel topology is proposed for asynchronous interconnection of 13.8 kV grids enabled by series connection of latest Gen-3 10 kV, 15 A SiC MOSFETs. The asynchronous microgrid power conditioning system (AMPCS) uses three level neutral point clamped (3L-NPC) legs in AC-DC, DC-DC and DC-AC power stages. The DC-DC stage provides the galvanic isolation between the grids, and is realized by three phase dual active bridge (DAB). Simulation results are provided to validate the performance of the AMPCS in bidirectional power flow, low voltage ride through condition and interconnection of grids with different frequencies. The 3- L NPC leg is designed, fabricated and demonstrated experimentally at 2.5 kV dc bus and 10 kHz switching frequency in sine-triangle inverter mode.}, booktitle={2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2018}, author={Kumar, A. and Parashar, S. and Kolli, N. and Bhattacharya, S.}, year={2018}, pages={60–67} }
 @inproceedings{viju nair_chattopadhyay_parashar_bhattacharya_gopakumar_2018, title={Cascaded Active Neutral Point Clamped and Flying Capacitor Inverter Topology for Induction Motor Drives Applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060288355&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2018.8557745}, abstractNote={This paper proposes a novel multilevel architecture using active neutral point clamped inverter cascaded with a flying capacitor inverter to form a multilevel inverter topology with higher number of voltage levels for induction motor drives. All the capacitors in the topology can be balanced irrespective of any modulation index or power factor. This topology can be generalized for higher number of voltage levels. The front end DC sources required are of very low value and it can be further halved when using a reconfigured six phase induction machine for higher power. The low value DC sources can be stacked battery cells, hence the topology can find extensive applications in electric vehicles. Detailed experimental results are shown for the steady state and transient operations of the inverter. The proposed topology will be a viable scheme for high power applications.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition, ECCE 2018}, author={Viju Nair, R. and Chattopadhyay, R. and Parashar, S. and Bhattacharya, S. and Gopakumar, K.}, year={2018}, pages={6696–6702} }
 @inproceedings{mobarrez_ghanbari_bhattacharya_2018, title={Control Hardware-in-the-Loop Demonstration of a Building-Scale DC Microgrid Utilizing Distributed Control Algorithm}, volume={2018-August}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85057458275&partnerID=MN8TOARS}, DOI={10.1109/PESGM.2018.8586602}, abstractNote={DC microgrids and DC distribution power systems offer efficiency improvement, higher reliability, better expandability and stability over their equivalent AC systems. Despite the clear advantages of DC distribution systems, the deployment of such systems does not make economical sense due to high engineering, installation and commissioning costs. In this paper, we are proposing a platform that is designed to enable DC microgrids by simplifying project-specific design, installation, and commissioning, allowing designers to unlock the benefits of microgrids for the customers in an economic manner. The proposed platform, utilizes a distributed control algorithm and the concept of multiple slack sources (for power sharing). This core structure enables microgrid advantages of redundancy, simple plug-and-play, modularity and expandability. In this paper, the proposed control structure is explained in details. Then, analytical analysis is performed to ensure the stability of the system in all the operating modes. Finally, Control Hardware-in-the-Loop (C-HIL) simulations are used for demonstrating the effectiveness and feasibility of the proposed platform in a typical photovoltaic (PV) plus battery energy storage (BESS) grid-interactive DC microgrid.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Mobarrez, M. and Ghanbari, N. and Bhattacharya, S.}, year={2018} }
 @inproceedings{shah_bhattacharya_2018, title={Control of active component of current in dual active bridge converter}, volume={2018-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046963233&partnerID=MN8TOARS}, DOI={10.1109/apec.2018.8341030}, abstractNote={The paper presents a control strategy based on improved first harmonic approximation model of the single-phase dual active bridge (DAB) converter. The model consists of three state-variables: output DC voltage and two orthogonal components of first harmonic of transformer current, equivalent to active and circulating powers. Foremost, a strategy based on the conventional output voltage control is designed to regulate the output voltage. Subsequently, the first harmonic current control strategy, which aims to control the active power component of the current to regulate the output DC voltage, is introduced. Based on this strategy, a method to design the control system is suggested and its implementation in digital domain is described. The two control strategies are validated through time-domain simulations. Finally, the schemes are implemented for a prototype 500V/270V DC/DC converter. The experimental results are reported and compared against the developed control models for verification.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Shah, S.S. and Bhattacharya, Subhashish}, year={2018}, pages={323–330} }
 @inproceedings{alfaris_bhattacharya_2018, title={Current-Fed Quasi Z-Source Inverter Based PV Distributed Generation Controller}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060314788&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2018.8557759}, abstractNote={Recently, the renewable photovoltaic distributed generation (PV-DG) enjoys a rapid growth globally due to the advancement in solar systems and power electronics technologies. However, the intermittent nature of solar radiation and performance of the attached power converters, inevitably poses some challenges to the power grids integrated large-scale solar-farms (SF). These challenges include frequency oscillations, voltage variation and power quality issues. To overcome these problems, this study proposes a Current-Fed quasi Z-source Inverter (CF-qZSI) as an alternative converter for distribution generation controllers to facilitate the integration of a PV energy source into a weak power system. The detailed model of the CF-qZSI-based distribution controller (CqZDC) and its control system are developed. The dynamic performance of the CqZDC device is evaluated to validate different objectives using an actual field data and RTDS simulation platform.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition, ECCE 2018}, author={Alfaris, F.E. and Bhattacharya, S.}, year={2018}, pages={6249–6256} }
 @article{anurag_acharya_prabowo_gohil_bhattacharya_2019, title={Design Considerations and Development of an Innovative Gate Driver for Medium-Voltage Power Devices With High dv/dt}, volume={34}, ISSN={0885-8993 1941-0107}, url={http://dx.doi.org/10.1109/tpel.2018.2870084}, DOI={10.1109/TPEL.2018.2870084}, abstractNote={Medium-voltage (MV) silicon carbide (SiC) devices have opened up new areas of applications which were previously dominated by silicon-based IGBTs. From the perspective of a power converter design, the development of MV SiC devices eliminates the need for series connected architectures, control of multilevel converter topologies which are necessary for MV applications, and the inherent reliability issues associated with it. However, when SiC devices are used in these applications, they are exposed to a high peak stress (5–10 kV) and a very high <inline-formula><tex-math notation="LaTeX">$dv/dt$</tex-math></inline-formula> (10–100 kV/<inline-formula><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula>s). Using these devices calls for a gate driver with a dc–dc isolation stage that has ultralow coupling capacitance in addition to be able to withstand the high isolation voltage. This paper presents a new MV gate driver design to address these issues while maintaining a minimal footprint for the gate driver. An MV isolation transformer is designed with a low interwinding capacitance, while maintaining the clearance, creepage, as well as insulation standards. A dc isolation test has been performed to validate the integrity of the insulating material. The key features include low input common mode current, and a short-circuit protection scheme specifically designed for 10 kV SiC <sc>mosfet</sc>s. The performance of the gate driver is evaluated using double pulse tests and continuous tests. Experimental results validate the advantages of the gate driver and its application for MV SiC devices exhibiting very high <inline-formula><tex-math notation="LaTeX">$dv/dt$</tex-math></inline-formula>. The proposed gate driver concept is aimed at providing an efficient and reliable method to drive MV SiC devices.}, number={6}, journal={IEEE Transactions on Power Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Anurag, Anup and Acharya, Sayan and Prabowo, Yos and Gohil, Ghanshyamsinh and Bhattacharya, Subhashish}, year={2019}, month={Jun}, pages={5256–5267} }
 @inproceedings{anurag_acharya_prabowo_jakka_bhattacharya_2018, title={Design of a Medium Voltage Mobile Utilities Support Equipment based Solid State Transformer (MUSE-SST) with 10 kV SiC MOSFETs for Grid Interconnection}, ISBN={9781538667057}, url={http://dx.doi.org/10.1109/pedg.2018.8447766}, DOI={10.1109/PEDG.2018.8447766}, abstractNote={A conventional transformer can withstand multiple electrical, mechanical and thermal faults which enables it to have a long lifetime. However, its inability to control the power flow through it has led researchers to look for alternate options such as the solid-state transformers. With the Silicon Carbide (SiC) semiconductor devices, it is now possible to go to high switching frequencies in medium voltage applications, which helps in reducing the overall size and weight of the transformer. The advent of medium voltage (MV) SiC devices has enabled the use of simple two-level and three-level topologies for medium voltage power transfer. This paper discusses a basic power topology for a medium voltage mobile utilities support equipment based solid state transformer (MUSE-SST) with the new 10 kV SiC MOS-FETs. A design of the MUSE-SST is presented followed by some of the practical considerations that needs to be taken, including gate driver design and heat sink configurations. Simulation results for a 100 kW, MV MUSE SST system is presented. Experimental results are provided validating the operation of these 10 kV devices in double pulse tests, buck and boost operation. This research helps in providing an overview regarding the usage of the 10 kV SiC devices in grid-interconnection and also discusses various challenges that comes along with it.}, booktitle={2018 9th IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)}, publisher={IEEE}, author={Anurag, Anup and Acharya, Sayan and Prabowo, Yos and Jakka, Venkat and Bhattacharya, Subhashish}, year={2018}, month={Jun} }
 @inproceedings{isik_nath_alharbi_bhattacharya_2018, title={Direct PV Integration to MMC Based Point to Point HVDC Link}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85061508944&partnerID=MN8TOARS}, DOI={10.1109/eGRID.2018.8598692}, abstractNote={Increasing demand for energy has been growing very fast. Photovoltaic systems are good solution to provide energy since it is environmentally friendly, and it has zero variable cost. On the other hand, High Voltage Direct Current (HVDC) is gaining importance to transfer power from one grid to another. Modular Multilevel Converter (MMC) has made a great contribution for the development of HVDC since it is modular, scalable and cost-effective. Traditional HVDC system consists of two terminals. However, in the case of an unbalanced condition, HVDC lose stability, and it is a challenge to re-run the system if an MMC is built with high number of capacitors. In this study, large-scale PV plant is used as a backup terminal if a fault occurs on one of the grids, and one of the terminals is lost. The system has been built and tested on Real Time Digital Simulator (RTDS) with the help of FPGA based MMC support unit.}, booktitle={Conference Record of the 3rd IEEE International Workshop on Electronic Power Grid, eGrid 2018}, author={Isik, S. and Nath, H. and Alharbi, M. and Bhattacharya, S.}, year={2018} }
 @inproceedings{kim_kim_bhattacharya_2018, title={Discrete Diagonal State Estimator based Current Control for Grid Connected PWM Converter with an LCL filter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060286149&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2018.8557757}, abstractNote={In this paper, the control and state observer for grid connected PWM converter with LCL filter has been discussed. The discrete state-space observer is designed in the d-q synchronous reference frame. Using the coordinate change of the matrix, the alternative state equation, which has diagonal system matrix, is obtained. Discretization of alternative state equation using Zero-Order Hold method is suggested, and the discrete form is simpler than that derived by original system matrix. By considering control stability with respect to the relation between filter resonant frequency and sampling frequency, current control scheme with feedback signal from state observer is also proposed. The digital delay to the PWM and sampling is considered for digital implementations.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition, ECCE 2018}, author={Kim, B.-H. and Kim, H. and Bhattacharya, S.}, year={2018}, pages={3069–3075} }
 @inproceedings{chattopadhyay_gohil_acharya_nair_bhattacharya_2018, title={Efficiency improvement of three port high frequency transformer isolated triple active bridge converter}, volume={2018-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046944973&partnerID=MN8TOARS}, DOI={10.1109/apec.2018.8341262}, abstractNote={This paper discusses and compares few techniques for efficiency improvement of Three-port Triple Active Bridge(TAB) Converter. Transformer isolated three port phase shifted Triple Active Bridge dc-dc converters are very efficient in nature providing high efficiency, ZVS operation over wide range, galvanic isolation and bidirectional power flow capability. The natural turn-on ZVS for switching devices in DAB or TAB converters is a very useful property for using Mosfets, as it reduces the device losses by a huge margin. The natural ZVS is lost for phase shifted converters at low power operating regions, causing reduction in efficiency. This paper discusses a comparsion between phase shift operation at fixed frequency vs phase shift operation at varying frequency and varying duty cycle operation at fixed frequency, which leads to a greater operating range of natural turn-on ZVS thus improving the efficiency. A comparison of the three methods have been presented in this paper with experimental results from a 10kW hardware prototype made of SiC Mosfets.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Chattopadhyay, R. and Gohil, G. and Acharya, Sayan and Nair, V. and Bhattacharya, Subhashish}, year={2018}, pages={1807–1814} }
 @book{liu_baliga_jiang_sun_bhattacharya_huang_2018, title={Electrical performances and physics based analysis of 10kV SiC power MOSFETs at high temperatures}, volume={924 MSF}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85049019994&partnerID=MN8TOARS}, DOI={10.4028/www.scientific.net/MSF.924.719}, abstractNote={Silicon Carbide (SiC) power MOSFETs become more important in 10kV industrial application level, beginning to replace the silicon devices. Due to the harsh environments, high temperature performances of 10kV SiC MOSFETs must be concerned and understood. In this paper, comprehensive static and dynamic parameters of 10kV SiC MOSFETs have been measured up to 225°C. The device physics behind high temperature behaviors has been analyzed by using the basic analytical models.}, journal={Materials Science Forum}, author={Liu, S.Y. and Baliga, B.J. and Jiang, Y.F. and Sun, W.F. and Bhattacharya, S. and Huang, A.Q.}, year={2018}, pages={719–722} }
 @article{shah_iyer_bhattacharya_2018, title={Exact Solution of ZVS Boundaries and AC Currents in Dual Active Bridge Type DC-DC Converters}, volume={34}, ISSN={0885-8993}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85057892110&partnerID=MN8TOARS}, DOI={10.1109/TPEL.2018.2884294}, abstractNote={This letter presents an approach to develop an exact, unified model of zero voltage switching (ZVS) regions and ac-port currents (peak and RMS) in dual active bridge type dc–dc converters for all its operating modes and modulation strategies. It is executed for a single-phase system, where the method is used to compute closed-form expressions of ac current at switching instants. Then, exact formulae of ZVS regions for all devices, system peak, and RMS currents are derived. Simulation and hardware results for forward and reverse power transfer are reported to validate the proposed approach.}, number={6}, journal={IEEE Transactions on Power Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Shah, S. S. and Iyer, V. Mahadeva and Bhattacharya, S.}, year={2018}, pages={1–1} }
 @inproceedings{iyer_gulur_gohil_bhattacharya_2018, title={Extreme fast charging station architecture for electric vehicles with partial power processing}, volume={2018-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046972946&partnerID=MN8TOARS}, DOI={10.1109/apec.2018.8341082}, abstractNote={This paper introduces a power delivery architecture for an Extreme Fast Charging (XFC) station that is meant to simultaneously charge multiple electric vehicles (EVs) with a 300-mile range battery pack in about 15 minutes. The proposed approach can considerably improve overall system efficiency as it eliminates redundant power conversion by making use of partial power rated dc-dc converters to charge the individual EVs as opposed to a traditional fast charging station structure based on full rated dedicated charging converters. Partial power processing enables independent charging control over each EV, while processing only a fraction of the total battery charging power. Energy storage (ES) and renewable energy systems such as photovoltaic (PV) arrays can be easily incorporated in the versatile XFC station architecture to minimize the grid impacts due to multi-mega watt charging. A control strategy is discussed for the proposed XFC station. Experimental results from a scaled down laboratory prototype are provided to validate the functionality, feasibility and cost-effectiveness of the proposed XFC station power architecture.}, booktitle={2018 IEEE Applied Power Electronics Conference and Exposition (APEC)}, author={Iyer, V. M. and Gulur, S. and Gohil, G. and Bhattacharya, S.}, year={2018}, month={Mar}, pages={659–665} }
 @inbook{bhattacharya_2018, title={Gate drivers for wide bandgap power devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85082076239&partnerID=MN8TOARS}, DOI={10.1016/B978-0-08-102306-8.00007-1}, abstractNote={Wideband gap power devices (SiC) are becoming popular in the power electronics sector because their high switching performance and high temperature sustaining capabilities. Increase in switching frequency causes reduction in the size of energy storage components (inductors and capacitors) and the high temperature sustaining capacity reduces heat sink requirements for power electronic circuitry. Implementation of SiC devices on converter level requires properly designed gate drivers for switching operation. Apart from switching operation, gate drivers are also required for protection of device from short circuit and overvoltage operation. Design of gate driver for medium voltage Silicon carbide (SiC) devices have different specification from Silicon (Si) based devices. The gate drivers should be able to operate at higher switching frequency with adequate insulation between the low voltage and high voltage components. This makes the relevance of research and analysis of the gate driver design for the medium voltage level SiC devices. This chapter addresses the design issues and challenges required for designing the gate drivers at 1200V to 10kV level. The appropriate test results and detailed description have been given into the chapter regarding gate driver design.}, booktitle={Wide Bandgap Semiconductor Power Devices: Materials, Physics, Design, and Applications}, author={Bhattacharya, S.}, year={2018}, pages={249–300} }
 @inproceedings{acharya_chattopadhyay_anurag_rengarajan_prabowo_bhattacharya_2018, title={High Power Medium Voltage 10 kV SiC MOSFET Based Bidirectional Isolated Modular DC–DC Converter}, ISBN={9784886864055}, url={http://dx.doi.org/10.23919/ipec.2018.8507406}, DOI={10.23919/IPEC.2018.8507406}, abstractNote={Recent advancement in the packaging technology for the SiC MOSFETs with blocking voltage of 10 kV or higher have opened up opportunities to consider these devices for medium voltage and high power applications. This paper focuses on the design of a modular medium voltage, high power DC– DC converter enabled by 10 kV SiC MOSFETs which aims at increasing the efficiency, power density and inter-operability. The proposed DC–DC converter is suitable for applications like DC distribution for the data centres, sub-sea power transmission, offshore wind farms and photovolatic energy transmission -distribution - coordination, electric ship DC power transmission and distribution solid state transformer.}, booktitle={2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia)}, publisher={IEEE}, author={Acharya, Sayan and Chattopadhyay, Ritwik and Anurag, Anup and Rengarajan, Satish and Prabowo, Yos and Bhattacharya, Subhashish}, year={2018}, month={May}, pages={3564–3571} }
 @inproceedings{parashar_kumar_bhattacharya_2018, title={High Power Medium Voltage Converters Enabled by High Voltage SiC Power Devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85057294777&partnerID=MN8TOARS}, DOI={10.23919/IPEC.2018.8506674}, abstractNote={This paper presents the potential applications of HV SiC power devices for high power and medium voltage power conversion systems. The advantages and features enabled by HV SiC devices are experimentally validated by both device performance evaluations as well as operation and performance validations of MV power conversion systems. The potential application examples of Solid State Transformer (SST), Asynchronous Microgrid Power Conditioning Systems, MV motor drives, MV grid connected converters for integration of Distributed Renewable Energy Resources (DRER) and Distributed Energy Storage Devices (DESD) are presented as design case studies and experimental validations with their advantages and power conversion efficiency.}, booktitle={2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018}, author={Parashar, S. and Kumar, A. and Bhattacharya, S.}, year={2018}, pages={3993–4000} }
 @inproceedings{mobarrez_acharya_bhattacharya_2018, title={Impact of DC side fault protection on performance and operation of multi-Terminal DC (MTDC) systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85048564869&partnerID=MN8TOARS}, DOI={10.1109/EVER.2018.8362342}, abstractNote={With the development of modular structured Voltage Source Converters (VSC), Multi-Terminal DC (MTDC) transmission systems have now became a feasible solution to transmit power at high voltage levels which greatly improves the electric power transmission system. The MTDC grid has lower capital costs and lower losses than an equivalent AC transmission system. Thus for long distance power transmission, MTDC grid becomes a very attractive solution. Since the MTDC network is now built based on VSCs, it automatically offers better quality of transmitted power along with more flexibility in power transmission over the conventional current source converters. However, VSC based MTDC transmission systems are vulnerable to DC side fault and often expensive DC circuit breakers are required to protect them against DC fault. In this paper, we demonstrate the effect of DC Circuit Breaker (DCCB) performance on the rating, control and operation of modular multi-level converters (MMC) inside a MTDC system. Furthermore, it is established that depending on the type of DCCBs the converter component ratings can be reduced which contributes to the overall reduction in system cost. Performance analysis has been done to investigate the fault current limiting capabilities of each of the types of DCCBs. PSCAD and real-time control hardware-in-the loop (C-HIL) simulations are used to prove the relevance of the analysis.}, booktitle={2018 13th International Conference on Ecological Vehicles and Renewable Energies, EVER 2018}, author={Mobarrez, M. and Acharya, S. and Bhattacharya, S.}, year={2018}, pages={1–7} }
 @inproceedings{gulur_iyer_bhattacharya_2018, title={Improved Common Mode Noise Models for Three Level T-Type Neutral Point Clamped Converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060285297&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2018.8558405}, abstractNote={Three level $T$-type based converter (3LT2C) is becoming an attractive option in several grid connected power electronic applications as it offers several advantages like high efficiency, lower active component count compared to other three level converters and superior output ac voltage quality. Common mode (CM) based noise modeling for 3LT2C has not been thoroughly explored in literature. This work presents an improved CM noise model for a grid connected 3LT2C with an LCL filter. It is shown that the 3LT2C has two high frequency CM noise sources which are responsible for ground leakage current injection. The effect of both CM noise sources on the overall CM model has been examined under different switching frequencies using sine triangle pulse width modulation (SPWM). Along with detailed analysis, extensive simulation results have been provided to validate the presented CM noise model.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Gulur, S. and Iyer, V. M. and Bhattacharya, S.}, year={2018}, month={Sep}, pages={6398–6403} }
 @inproceedings{shah_raheja_bhattacharya_2018, title={Input Impedance Analyses of Charge Controlled and Frequency Controlled LLC Resonant Converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060306780&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2018.8558222}, abstractNote={LLC resonant converters are popular for point-of-load dc-dc conversion in applications such as data-centers and electric vehicles. In complex systems, where converters are cascaded to feed disparate loads, system stability issues related to the impedance interaction in converters may arise. At the very least, the designed system must satisfy Middlebrook's criterion for stable operation; therefore, the knowledge of input and output impedance of converters is essential. In this respect, the paper analyses the impact of two control strategies of LLC resonant converter on its input impedance. The two strategies are: conventional variable frequency control (VFC) and bang-bang charge control (BBCC). The input impedance models of LLC resonant converter in case of these two strategies are derived. The developed models are validated through impedance plots extracted from simulation. Further, the models are applied to a system comprising of a dual active bridge (DAB) converter feeding a single LLC resonant point-of-load converter to investigate the impact of two strategies on the stability of such cascaded systems.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition, ECCE 2018}, author={Shah, S.S. and Raheja, U. and Bhattacharya, S.}, year={2018}, pages={6822–6829} }
 @inproceedings{viju nair_gulur_chattopadhyay_beddingfield_mathur_bhattacharya_gohil_ohodnicki_2018, title={Large Scale Grid Integration of Photovoltaic and Energy Storage Systems Using Triple Port Dual Active Bridge Converter Modules}, volume={2018-August}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060816074&partnerID=MN8TOARS}, DOI={10.1109/PESGM.2018.8586158}, abstractNote={Integration of solar energy (PV) using isolated high frequency power electronic converters to the utility grid or microgrid is fast becoming an attractive option due to the improvement in power density and elimination of the bulky low frequency transformer. This paper presents and analyzes the integration of solar energy and battery based energy storage system (ESS) to the grid using a two stage topology which includes triple port dual active bridges (DABs) and a conventional 2-level inverter. This paper considers the triple port DABs as the basic building blocks which can be connected in different configurations to meet the voltage and power requirements. Detailed simulation results are provided, investigating various operating and control modes. Experimental result showing the triple port DC-DC converter waveforms are also included. This paper shows that the triple port DAB modules along with the inverter is a viable option for large scale PV-ESS grid integration.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Viju Nair, V. and Gulur, S. and Chattopadhyay, R. and Beddingfield, R. and Mathur, S. and Bhattacharya, S. and Gohil, G. and Ohodnicki, P.R.}, year={2018} }
 @article{byerly_ohodnicki_moon_leary_keylin_mchenry_simizu_beddingfield_yu_feichter_et al._2018, title={Metal Amorphous Nanocomposite (MANC) Alloy Cores with Spatially Tuned Permeability for Advanced Power Magnetics Applications}, volume={70}, ISSN={["1543-1851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046031173&partnerID=MN8TOARS}, DOI={10.1007/s11837-018-2857-5}, abstractNote={Metal amorphous nanocomposite (MANC) alloys are an emerging class of soft magnetic materials showing promise for a range of inductive components targeted for higher power density and higher efficiency power conversion applications including inductors, transformers, and rotating electrical machinery. Magnetization reversal mechanisms within these alloys are typically determined by composition optimization as well as controlled annealing treatments to generate a nanocomposite structure composed of nanocrystals embedded in an amorphous precursor. Here we demonstrate the concept of spatially varying the permeability within a given component for optimization of performance by using the strain annealing process. The concept is realized experimentally through the smoothing of the flux profile from the inner to outer core radius achieved by a monotonic variation in tension during the strain annealing process. Great potential exists for an extension of this concept to a wide range of other power magnetic components and more complex spatially varying permeability profiles through advances in strain annealing techniques and controls.}, number={6}, journal={JOM}, author={Byerly, K. and Ohodnicki, P. R. and Moon, S. R. and Leary, A. M. and Keylin, V. and McHenry, M. E. and Simizu, S. and Beddingfield, R. and Yu, Y. and Feichter, G. and et al.}, year={2018}, month={Jun}, pages={879–891} }
 @inproceedings{hazra_bhattacharya_2018, title={Minimizing Reactive Current of a High Gain Dual Active Bridge Converter for Supercapacitor Based Energy Storage System Integration}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060290492&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2018.8557580}, abstractNote={In this paper, a control strategy is presented to operate a dual active bridge (DAB) converter at optimal operating point in terms of minimized reactive component of current. To interface a supercapacitor based energy storage system with the dc grid to absorb oscillating energy a DAB can be used. A DAB can provide galvanic isolation and can cater high voltage gain required to integrate a low voltage supercapacitor module with a higher voltage dc-link (voltage ratio more than 5). During operation, the voltage of the supercapacitor varies in wide range due to storage of oscillating energy. Also, during charging of the supercapacitor from zero voltage at the start of the operation and discharging to zero voltage at the end of the operation the voltage ratio varies from $\infty$ to 1.0. Due to large deviation of the voltage ratio from unity the reactive power in the DAB is increased. To minimize the reactive power flow an optimization method based on fundamental components is presented in this paper. By reducing the reactive component of the current overall current of the DAB for a fixed power flow is reduced. Experimental results showing implementation of the optimal solution are presented.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition, ECCE 2018}, author={Hazra, S. and Bhattacharya, S.}, year={2018}, pages={1407–1414} }
 @inproceedings{acharya_anurag_gohil_hazra_bhattacharya_2018, title={Mission Profile based Reliability Analysis of a Medium Voltage Power Conversion Architecture for PMSG based Wind Energy Conversion System}, ISBN={9781538645369}, url={http://dx.doi.org/10.1109/ias.2018.8544579}, DOI={10.1109/IAS.2018.8544579}, abstractNote={The development of wide-bandgap (WBG) power semiconductor devices has opened up new areas of applications which were previously dominated by silicon based IGBTs. This paper presents one such application where a multi-megawatt permanent magnet synchronous generator based wind energy conversion system (PMSG-WECS) is used for medium voltage (MV) grid integration. The conversion of the low output voltage of the PMSG to medium voltage brings about a multitude of advantages including reduction in the cable diameter and consequently the cost and weight of the system. WBG devices enable the use of high frequency transformers which makes it possible to install the system on the tower of the wind turbine. With these kinds of installations, it becomes necessary to investigate the reliability of the system, since maintenance of the systems leads to additional incurred costs. This paper provides a mission-profile (i.e. wind speed and ambient temperature) based analysis, in order to determine the temperature rise in the devices and consequently, its effects on the lifetime of the devices. An analytical lifetime model has been used and the damage produced on the transistors has been quantified using Palgrem Miner rule. This analysis can be helpful in understanding the impacts of having a tower-top converter system on the overall cost.}, booktitle={2018 IEEE Industry Applications Society Annual Meeting (IAS)}, publisher={IEEE}, author={Acharya, Sayan and Anurag, Anup and Gohil, Ghanshyamsinh and Hazra, Samir and Bhattacharya, Subhashish}, year={2018}, month={Sep} }
 @inproceedings{anurag_acharya_prabowo_jakka_bhattacharya_2018, title={Mobile Utility Support Equipment based Solid State Transformer (MUSE-SST) for MV Grid Interconnection with Gen3 10 kV SiC MOSFETs}, ISBN={9781479973125}, url={http://dx.doi.org/10.1109/ecce.2018.8557388}, DOI={10.1109/ECCE.2018.8557388}, abstractNote={With the increasing maturity of Silicon Carbide (SiC) semiconductor devices at medium voltage (MV) level, high switching frequencies and low conduction losses in MV applications is possible. Higher switching frequency operation enables the reduction in size and weight of transformers. In an application such as MV-MV or MV-LV grid-interconnection, a solid state transformer offers a multitude of advantages compared to conventional transformers. A reduction in size and weight, in addition to having active and reactive power flow control have made SSTs a lucrative replacement to conventional low frequency (LF) transformers. Lower conduction losses exhibited by SiC devices (as compared to their silicon counterparts) have made it possible to achieve similar efficiencies as compared to conventional LF transformers. This paper aims at providing an overview of a MV MUSE-SST topology. A brief idea on control and monitoring is also provided. Practical design considerations that are required to build a MV system is provided to aid researchers in designing converters for MV applications. The protection aspects of the MV MUSE-SST system is also highlighted. Basic experimental results for the gate driver is also shown. Initial testing results with the Gen3 10 kV SiC MOSFETs and the challenges associated with it are also discussed. This research aims at being a building block for implementation and testing of the medium voltage converter systems.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition (ECCE)}, publisher={IEEE}, author={Anurag, Anup and Acharya, Sayan and Prabowo, Yos and Jakka, Venkat and Bhattacharya, Subhashish}, year={2018}, month={Sep}, pages={450–457} }
 @inproceedings{alharbi_bhattacharya_2018, title={Modeling and Control Method for MMC B2B System under Balanced and Unbalanced Grid Voltages}, volume={2018-August}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060798869&partnerID=MN8TOARS}, DOI={10.1109/PESGM.2018.8586493}, abstractNote={Voltage source converters (VSCs) have been widely used due to their flexibility to control voltages and power independently and bi-directionally. Typically, the control system of VSCs mainly consists of two parts; outer voltage and power controllers and inner current controllers. The vector current control based dq decoupling technique enables to control the active power, reactive power, DC voltage and AC voltage. However, the d- and q-axis of grid voltages and currents comprise AC and DC components under unbalanced grid conditions. The AC components of the d- and q-axis currents make the grid currents unbalanced. In this paper, a novel current control is presented and investigated under unbalanced grid condition for a Back-to-Back Modular Multilevel Converter (B2B-MMC) based HVDC system and validated using the Real Time Digital Simulator (RTDS). Further, the active power oscillation under fault is eliminated by controlling the AC component of grid currents in the dq frame. The RTDS results demonstrate the feasibility of the proposed controllers under unbalanced grid voltage conditions.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Alharbi, M. and Bhattacharya, S.}, year={2018} }
 @inproceedings{ghanbari_bhattacharya_mobarrez_2018, title={Modeling and Stability Analysis of a DC Microgrid Employing Distributed Control Algorithm}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85053832057&partnerID=MN8TOARS}, DOI={10.1109/PEDG.2018.8447707}, abstractNote={DC microgrids have higher efficiency, reliability and lower costs compared to the AC systems due to linking DC loads to the DC sources and reducing conversion stages. Thus, they are gaining more and more popularity and the interest in DC microgrids is increasing. In this paper, we are deriving mathematical model of a DC microgrid consisting of photovoltaic (PV) arrays, Battery Energy Storage Systems (BESS) and grid-tied converter, employing distributed control algorithm. The core structure of this work is mathematical modeling of all converters in the discussed microgrid with their voltage, current and droop controllers. Then, the stability analysis for the system and its control algorithm is performed to ensure the stability of DC microgrid in all operating modes. Finally, MATLAB/Simulink is used for demonstrating the capability of the mathematical model in modeling the DC microgrid and its control algorithm.}, booktitle={2018 9th IEEE International Symposium on Power Electronics for Distributed Generation Systems, PEDG 2018}, author={Ghanbari, N. and Bhattacharya, S. and Mobarrez, M.}, year={2018} }
 @inproceedings{alfaris_yousefpoor_bhattacharya_2018, title={Modular Static Distribution Controller for Distributed Energy Resource Generation Applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060294570&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2018.8557612}, abstractNote={Recently, renewable wind generations (WG) is enjoying a rapid growth globally amongst other renewable energy sources due to their lower cost and technology advancement. However, the intermittent nature of wind energy and performance of the attached induction generators inevitably poses some challenges to the power grid integrated large-scale wind-farms (WF), especially in case of weak power system. These challenges include frequency oscillations, voltage variation and power quality issues. To overcome these problems and facilitate the WF integration, this study proposes a modular static distribution controller (MSDC) at the WF point of interconnection (POI). The MSDC is composed of a dc-ac power converter connected to a dc/dc chopper converter and energy storage system. The overall power electronic system is considered as a versatile controller which is connected at the POI of WFs, and it can perform several tasks including frequency regulation, reactive power support, voltage control, harmonic filtering, power smoothing, and dynamic load balancing. The detailed model of the MSDC is presented and its control system is developed. In this paper, the dynamic performance of MSDC system is evaluated to achieve different objectives, and the operation of MSDC is validated in an actual weak power system under different modes of operation.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition, ECCE 2018}, author={Alfaris, F.E. and Yousefpoor, N. and Bhattacharya, S.}, year={2018}, pages={5857–5864} }
 @inproceedings{mokhtari_bhattacharya_2018, title={Optimal distributed generation allocation and sizing for minimizing losses and cost function}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85059949073&partnerID=MN8TOARS}, DOI={10.1109/IAS.2018.8544588}, abstractNote={The need for independent power generation has been increased in recent years specially with the growing demand in micro grid systems. In distribution networks with several DGs of different types and with all kinds of loads of variable nature, an optimal power balance in the system has to be achieved. This optimal objective, which results in minimal energy losses over a specific period of time, requires an optimal location and sizing of the DGs in a distribution network. This paper proposes a new optimization method in which both optimal location of the DGs and their generation profile according to the load demand profile are determined. The method is based on minimizing simultaneously the cost of investment and operation of the DGs, the cost of power delivered by the external grid as well as the cost of power losses in the network. The proposed method is tested on the IEEE standard radial distribution network considering time-varying loads.}, booktitle={2018 IEEE Industry Applications Society Annual Meeting, IAS 2018}, author={Mokhtari, N.G.H. and Bhattacharya, S.}, year={2018} }
 @article{ghanbari_mokhtari_bhattacharya_2018, title={Optimizing operation indices considering different types of distributed generation in microgrid applications}, volume={11}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046940383&partnerID=MN8TOARS}, DOI={10.3390/en11040894}, abstractNote={The need for independent power generation has increased in recent years, especially with the growing demand in microgrid systems. In a microgrid with several generations of different types and with all kinds of loads of variable nature, an optimal power balance in the system has to be achieved. This optimal objective, which results in minimal energy losses over a specific period of time, requires an optimal location and sizing of the distributed generations (DGs) in a microgrid. This paper proposes a new optimization method in which both optimal location of the DGs and their generation profile according to the load demand profile as well as the type of DG are determined during the life time of the DGs. The types of DGs that are considered in this paper are diesel generators and wind turbine. The method is based on simultaneously minimizing the cost of the investment and operation of the DGs, the cost of power delivered by the the external grid as well as the cost of power losses in the network. The proposed method is tested on the IEEE standard radial distribution network considering time-varying loads and the wind speed every hour of a day.}, number={4}, journal={Energies}, author={Ghanbari, N. and Mokhtari, H. and Bhattacharya, S.}, year={2018} }
 @inproceedings{isik_alharbi_acharya_bhattacharya_2018, title={Performance comparison of detailed and averaging model of a grid connected 401-level MMC system under system fault conditions}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85061551304&partnerID=MN8TOARS}, DOI={10.1109/IECON.2018.8592845}, abstractNote={The development of fully controlled power semiconductor devices has paved way the path for Voltage Source Converters (VSC) based High Voltage Direct Voltage (HVDC) transmission systems. For these high voltage applications, Modular Multilevel Converter (MMC) is a good candidate which utilizes interconnection of several Sub-Modules (SM). Furthermore, it provides several advantages including flexibility, scalability, better voltage quality etc. However, the MMC can be vulnerable to the DC short circuit faults. Different Sub-Module (SM) topology based MMCs exists which can suppress the DC short circuit current. The MMCs can be modelled with different modelling technics. This paper presents a comparative study of a point to point (PTP) MMC based HVDC system with feed-forward current control based on detailed and averaging modelling technics. Furthermore, the DC short circuit handling capabilities of Half Bridge SM (HBSM) and Full Bridge SM (FBSM) topologies are examined. Real time simulation results are provided to demonstrate the results of the study on FPGA based MMC support unit from Real Time Digital Simulator (RTDS).}, booktitle={Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society}, author={Isik, S. and Alharbi, M. and Acharya, S. and Bhattacharya, S.}, year={2018}, pages={3979–3984} }
 @inproceedings{ilango_viju nair_chattopadhyay_bhattacharya_2018, title={Photovoltaic and energy storage grid integration with fully modular architecture using triple port active bridges and cascaded H-bridge inverter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85061545306&partnerID=MN8TOARS}, DOI={10.1109/IECON.2018.8591763}, abstractNote={This paper presents a novel architecture to integrate the photovoltaic and energy storage to the grid. The modular approach is provided by using the triple port active bridge DC-DC converter modules and the cascaded H-Bridge multilevel inverter structures. The modular approach helps in easy scaling up, easy maintenance and better controllability of the available power. The triple port bridge is capable of supplying and receiving power in any of its ports, allowing various control modes. Also the voltage control mode at its output allows for additional grid services. The cascaded H-bridge is a multilevel inverter with higher number of voltage levels, reduced filter size, lower switching frequency, lower dv/dt and EMC issues. The experimental and simulation results presented in this paper ensures that the proposed architecture is suitable for large scale photovoltaic and energy storage grid integration.}, booktitle={Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society}, author={Ilango, S. and Viju Nair, R. and Chattopadhyay, R. and Bhattacharya, S.}, year={2018}, pages={1400–1405} }
 @inproceedings{acharya_anurag_prabowo_bhattacharya_2018, title={Practical Design Considerations for MV LCL Filter Under High dv/dt Conditions Considering the Effects of Parasitic Elements}, ISBN={9781538667057}, url={http://dx.doi.org/10.1109/pedg.2018.8447701}, DOI={10.1109/PEDG.2018.8447701}, abstractNote={For high power medium voltage (MV) grid connected applications LCL filter proves to be an attractive solution to filter out the current harmonics when compared to $L$ or LC filters. The inductance requirement reduces drastically to meet the same Total Harmonic Distortion (THD) standards for grid connections for LC L filters compared to $L$ filter which makes the system dynamics much faster. The increasing use of Silicon Carbide (SiC) based power devices for MV applications has made the effects of the parasitic elements in the filter more prominent, due to the high dv / dt experienced by the passive filter elements during device switching transients. This paper addresses the issues associated with the high dv / dt experienced by the LC L filters for SiC-based MV applications. In order to study these effects, the parasitic elements of the inductor are modeled and analyzed. A suitable solution is proposed to improve the overall system performance. The effect of high dv / dt on the filter and the effectiveness of the proposed solution are validated using simulation. Experimental data is also provided to validate the proposed concept.}, booktitle={2018 9th IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG)}, publisher={IEEE}, author={Acharya, Sayan and Anurag, Anup and Prabowo, Yos and Bhattacharya, Subhashish}, year={2018}, month={Jun} }
 @inproceedings{gulur_iyer_bhattacharya_2018, title={Proportional integral — Resonant and dual loop current control structure comparison for grid connected converters in the rotating frame}, volume={2018-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046961004&partnerID=MN8TOARS}, DOI={10.1109/apec.2018.8341233}, abstractNote={Over the past few years, due the increasing penetration of renewable energy, there has been a steady rise in the harmonic content in grid voltages. In such circumstances, a proportional integral (PI) based current control in the synchronous reference rotating frame (dq) for a grid connected voltage source converter may not be adequate to suppress the harmonic components and to precisely follow the fundamental frequency component with zero steady state error. Several current control structures have been proposed, with proportional integral — resonant controller (PI-RES) based structure being one of the most popular. In this paper, the PI-RES has been compared to the recently introduced dual loop current control structure. Both these current control structures have been compared in terms of their tracking, filtering and disturbance rejection capability. Robustness of both these structures has also been analyzed under a grid impedance variation. Simulation and experimental results have been provided to validate the analysis presented.}, booktitle={2018 IEEE Applied Power Electronics Conference and Exposition (APEC)}, author={Gulur, S. and Iyer, V. M. and Bhattacharya, S.}, year={2018}, month={Mar}, pages={1617–1623} }
 @inproceedings{jakka_acharya_anurag_prabowo_kumar_parashar_bhattacharya_2018, title={Protection Design Considerations of a 10 kV SiC MOSFET Enabled Mobile Utilities Support Equipment Based Solid State Transformer (MUSE-SST)}, ISBN={9781509066841}, url={http://dx.doi.org/10.1109/iecon.2018.8592886}, DOI={10.1109/IECON.2018.8592886}, abstractNote={Solid state transformers (SSTs) are evolved as an emerging technology which offer several key features in integrating different grids, storage devices, and renewable energy sources, etc. In this paper, a 10 kV SiC MOSFET enabled Mobile Utility Support Equipment based SST (MUSE-SST) is presented for integrating a medium voltage (MV) AC grid (4.16 kV L-L, 60 Hz) and a low voltage (LV) AC grid (480 V L-L, 60 Hz). The MUSE-SST consist of three power conversion stages: MV side active front end converter (AFEC: MV), dual active bridge (DAB), and LV side active front end converter (AFEC: LV). In order to protect MUSE-SST from various abnormal operating conditions, different protection schemes are discussed. Dedicated gate drivers incorporating device short-circuit protection are implemented for both the MV and the LV SiC MOSFETs. It is observed that the MV short circuit faults are found to be severe and resulting in very high inrush currents from the MV grid which can lead to the impairment of entire SST system. A bi-directional switch in parallel with a high impedance resistor (BSPHR) circuit based protection scheme is presented to limit the grid currents during MV dc-link short circuit conditions. The BSPHR scheme and efficacy of gate drivers are validated through simulations and experimental results, respectively. The avalanche ruggedness of 10kV, SiC MOSFETs is established experimentally using a single shot unclamped inductive switching (UIS) test and the critical avalanche energy for the MOSFET failure is obtained.}, booktitle={IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society}, publisher={IEEE}, author={Jakka, Venkat N. and Acharya, Sayan and Anurag, Anup and Prabowo, Yos and Kumar, Ashish and Parashar, Sanket and Bhattacharya, Subhashish}, year={2018}, month={Oct}, pages={5559–5565} }
 @inproceedings{parashar_kumar_bhattacharya_2018, title={Qualification of Gate drivers for Operation of High Voltage SiC MOSFETs and IGBTs}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85053846508&partnerID=MN8TOARS}, DOI={10.1109/PEDG.2018.8447879}, abstractNote={Smaller switching loss at higher switching frequency makes the 10kV and 15kV SiC MOSFETs and IGBTs competent to the medium voltage application. Due to exposure to fast voltage transitions at such high voltage level (10kV and 15kV), the gate drivers used in operation suffer through various challenges including insulation problems and common mode currents in power supply. Failure of gate drivers at such a high voltage may lead to catastrophic damage to the converter and surroundings. Therefore, it requires to qualify the gate drivers performance at 10kV to 15kV voltage level before implementing them in field operation. This paper describes an organized methodology for the qualification of gate drivers for High voltage SiC MOSFETs and IGBTs at higher switching frequency up to 20kHz.}, booktitle={2018 9th IEEE International Symposium on Power Electronics for Distributed Generation Systems, PEDG 2018}, author={Parashar, S. and Kumar, A. and Bhattacharya, S.}, year={2018} }
 @inproceedings{alharbi_isik_bhattacharya_2018, title={Reliability Comparison and Evaluation of MMC Based HVDC Systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85061495086&partnerID=MN8TOARS}, DOI={10.1109/eGRID.2018.8598662}, abstractNote={Modular Multilevel Converters (MMC) based High Voltage Direct Current (HVDC) systems utilize a large number of submodules (SMs). Failure of any SM may lead to shut-down of the entire system or seriously affect the converter performance. The fault-tolerant design approach can dominate faults and improve the system performance and reliability. The $N+1$ redundancy design is a well-known technique to improve the MMC reliability. However, this approach requires additional SMs, and accordingly higher cost. The reliability of an MMC can be improved using the MMC scale-up control method, which a large number of SMs can be predicated by a smaller cumulative set of SMs. In this paper, the reliability analysis is performed to compare the reliability performance of the MMC based conventional and scale-up control methods with and without redundant designs. The MMC control designs are presented and assessed using Markov reliability model for $\pm 320 kV$ and 1000 MVA MMC system. The comparative evaluation shows that the reliability of an MMC with the scale-up approach is higher than that of the $N+1$ redundancy design.}, booktitle={Conference Record of the 3rd IEEE International Workshop on Electronic Power Grid, eGrid 2018}, author={Alharbi, M. and Isik, S. and Bhattacharya, S.}, year={2018} }
 @inproceedings{shah_bhattacharya_2018, title={Reliability Oriented Design of Dual Active Bridge Converter for Power Supply on Heavy-Vehicles}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060306997&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2018.8558046}, abstractNote={The design of power electronic converters is often driven by goals such as full-load efficiency, power density or cost per watt of power transferred. In the paper, application of power electronic conversion system in heavy-duty vehicle industry is considered; in this low-volume industry, system reliability and availability along with economies of scale are also crucial. In this respect, a dual active bridge (DAB) based dc-dc power electronic building block (PEBB) is considered to supply an auxiliary load. Economies of scale are achieved by designing the PEBB for its reliable operation across different vehicle platforms of the original equipment manufacturers (OEM), while catering to their disparate specifications. A method is proposed in the paper to realise a design of a DAB based PEBB for maximum system availability by minimising the lifetime consumption of the semiconductor device for a defined load-cycle. It is illustrated for a load-cycle of air-conditioning compressors in heavy vehicles.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition, ECCE 2018}, author={Shah, S.S. and Bhattacharya, S.}, year={2018}, pages={4102–4109} }
 @inproceedings{kumar_parashar_sabri_van brunt_bhattacharya_veliadis_2018, title={Ruggedness of 6.5 kV, 30 a SiC MOSFETs in extreme transient conditions}, volume={2018-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85049938983&partnerID=MN8TOARS}, DOI={10.1109/ISPSD.2018.8393693}, abstractNote={6.5 kV silicon IGBTs are used in multi-megawatt medium voltage power converters for rail traction applications, AC drives and grid-connected power converters. The 6.5 kV, 30 A SiC MOSFETs, recently launched by Wolfspeed, have the potential to replace Si IGBTs. Static and dynamic characteristics of the 6.5 kV SiC MOSFETs have been reported earlier. During the extreme transient conditions, the SiC MOSFETs can be subjected to high voltage overshoot and high short circuit current. In this work, ruggedness of these MOSFETs is established by short-circuit tests and single shot avalanche tests at room temperature. The 6.5 kV SiC MOSFET is observed to withstand 7.75 J of short-circuit energy at 20 V gate voltage with a stress withstanding time of 6 μs. The single shot avalanche test result shows an avalanche energy of 5.0 J. The increase in junction temperature of the SiC MOSFET at the avalanche failure is estimated from the experimental results.}, booktitle={Proceedings of the International Symposium on Power Semiconductor Devices and ICs}, author={Kumar, A. and Parashar, S. and Sabri, S. and Van Brunt, E. and Bhattacharya, S. and Veliadis, V.}, year={2018}, pages={423–426} }
 @inproceedings{ghanbari_bhattacharya_2018, title={SOC balancing of different energy storage systems in DC microgrids using modified droop control}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85061544369&partnerID=MN8TOARS}, DOI={10.1109/IECON.2018.8592890}, abstractNote={Droop control as a well known approach is used as the basis of the power sharing among different paralleled voltage sources and battery energy storage systems (BESS). In order to extend the lifetime of BESS and avoid the overuse of a certain battery, the State of the Charge (SoC) of BESS should be balanced. This paper reviews and compares three different droop control methods in an islanded DC microgrid that are based on balancing the SoC of different BESS. All of the presented methods are compared together and the best one is selected. The feasibility of the selected method is verified through computer simulations in MATLAB/Simulink for a DC microgrid consisting of three BESS, PV (Photovoltaic) arrays and DC load.}, booktitle={Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society}, author={Ghanbari, N. and Bhattacharya, S.}, year={2018}, pages={6094–6099} }
 @inproceedings{alharbi_bhattacharya_2018, title={Scale-up methodology of a Modular Multilevel Converter for HVDC applications}, volume={2018-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046960862&partnerID=MN8TOARS}, DOI={10.1109/apec.2018.8341349}, abstractNote={Modular Multilevel Converters is developing a realistic alternative to the conventional converters for Medium Voltage (MV) and High Voltage Direct Current (HVDC) applications. The MMC topologies utilize a high number of submodule (SM) cascaded in series per phase arm to achieve the desired high voltage level. These SMs can be as high as 512 SMs to produce a very low Total Harmonics Distortion (THD) (e.g. < 0.1%) of the MMC AC side interface voltage. However, employing a large number of SMs in the converter to synthesize a very low THD of an AC voltage with a high number of levels increases the control complexity. Typically, the MMC AC side interface voltage THD requirements are < 3% which can be achieved by 48-pulse stepped AC waveform. This paper presents the first step towards MMC scale-up control and performance analysis such that the behavior of a high number of SMs can be predicted by a cumulative set of a smaller number of SMs. A Back-to-Back (B2B) MMC based on the scale-up method is implemented in a Real Time Digital Simulator (RTDS) and MMC support units based FPGAs. The results demonstrate that the scale-up control method is providing a satisfactory performance and other features for HVDC systems such as a stable operation under multiple faulty SMs.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Alharbi, M. and Bhattacharya, Subhashish}, year={2018}, pages={2379–2386} }
 @inproceedings{chattopadhyay_raheja_gohil_nair_bhattacharya_2018, title={Sensorless phase shift control for phase shifted DC-DC converters for eliminating DC transients from transformer winding currents}, volume={2018-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046958041&partnerID=MN8TOARS}, DOI={10.1109/apec.2018.8341274}, abstractNote={The paper presents a two phase shift control strategy for Dual Active Bridge(DAB) and Triple Active Bridge(TAB) converter to eliminate the dc transients from the high frequency transformer winding currents during operating phase angle change from one cycle to the next cycle. The proposed two phase shift method controls the alternating nature of high frequency current in transformer windings in one switching cycle without using any high frequency current sensor. The proposed control strategy applies two different phase shift angles during positive and negative half cycles in order to eliminate the dc transients from transformer winding currents during steady state phase angle change. The control strategy is analyzed and applied for power flow direction reversal of Dual Active Bridge Converter and for changing power flow mode from three port scenario to two port scenario in case of Triple Active Bridge converter. The proposed control strategy study has been verified by performing experimental study on a hardware prototype.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Chattopadhyay, R. and Raheja, U. and Gohil, G. and Nair, V. and Bhattacharya, Subhashish}, year={2018}, pages={1882–1889} }
 @inproceedings{kumar_parashar_baliga_bhattacharya_2018, title={Single shot avalanche energy characterization of 10kV, 10A 4H-SiC MOSFETs}, volume={2018-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046957199&partnerID=MN8TOARS}, DOI={10.1109/apec.2018.8341404}, abstractNote={Higher switching frequency capability and lower switching loss associated with 10kV 4H-SiC MOSFETs make them attractive for medium voltage applications, mostly in inductive circuits e.g. solid state transformers, grid connectors and high speed machine drives. Due to exposure to inductive circuits, avalanche ruggedness of these MOSFETs needs to be established to improve their reliability in case of unintended unclamped inductive switching. In this paper, the avalanche ruggedness of 10kV, 10A 4H-SiC MOSFETs is established experimentally using single shot unclamped inductive switching. The minimum and the maximum energy is found out for the MOSFET to remain in avalanche without being failed permanently. The junction temperature at the permanent failure is estimated using semiconductor device physics.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Kumar, A. and Parashar, S. and Baliga, J. and Bhattacharya, Subhashish}, year={2018}, pages={2737–2742} }
 @inproceedings{wiemer_iyer_hinz_bhattacharya_doncker_2018, title={Small-Signal Modeling and Controller Design Considerations for Dyna-C AC-DC Converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060316581&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2018.8558281}, abstractNote={The Dyna-C ac-dc converter is a current-source-based topology featuring medium-frequency galvanic isolation. This paper presents the state-space based average and small signal modeling of Dyna-C ac-dc converter. A space vector based modulation strategy is developed, presented and validated by simulation. Based on the proposed small signal model for Dyna-C ac-dc converter, a two stage closed loop control approach is developed. The proposed approach comprises of an outer loop to regulate the transformer magnetizing-current and an inner $\boldsymbol{d}\boldsymbol{q}$-based vector control strategy for regulating the grid currents. Circuit simulation results are presented to validate the proposed models and the closed loop control scheme for the Dyna-C ac-dc converter.}, booktitle={2018 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Wiemer, A. and Iyer, V. M. and Hinz, A. and Bhattacharya, S. and Doncker, R. W. De}, year={2018}, month={Sep}, pages={1513–1520} }
 @article{iyer_gulur_bhattacharya_2019, title={Small-Signal Stability Assessment and Active Stabilization of a Bidirectional Battery Charger}, volume={55}, ISSN={0093-9994}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85053610599&partnerID=MN8TOARS}, DOI={10.1109/TIA.2018.2871101}, abstractNote={A two-stage electric vehicle (EV) battery charger typically consists of an ac–dc converter cascaded with a dc–dc converter. In such a cascaded system, maintaining stability at the intermediate dc link is imperative for reliable operation of the battery charger under different operating modes. This paper addresses the intermediate dc-link stability challenges that exist in a bidirectional two-stage grid connected single-phase battery charger. It is delineated that the small-signal load-dependent resistance of the ac–dc converter plays a crucial role in determining the stability of the bidirectional battery charger. A virtual-resistor-based active damping control strategy that does not require any additional sensors is explored for the ac–dc converter to stabilize the cascaded system under all operating modes irrespective of the power flow direction. Experimental results on a grid-connected single-phase battery charger hardware prototype are presented to validate the proposed models and showcase the improvement in the dc-link stability due to the virtual-resistance-based active damping approach.}, number={1}, journal={IEEE Transactions on Industry Applications}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Iyer, V. M. and Gulur, S. and Bhattacharya, S.}, year={2019}, month={Jan}, pages={563–574} }
 @article{kashani_mobarrez_bhattacharya_2019, title={Smart Inverter Volt-Watt Control Design in High PV-Penetrated Distribution Systems}, volume={55}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85055894035&partnerID=MN8TOARS}, DOI={10.1109/TIA.2018.2878844}, abstractNote={Advanced control techniques such as volt-watt and volt-VAR control have been developed for high integration of distributed renewable energy, such as photovoltaic (PV) resources, on an electric distribution system. However, designing these control parameters, which yields the best results in the system, is complicated and depends on feeder conditions. This paper proposes a method to properly design the volt-watt control parameters in smart PV inverters to increase the benefit of their control action. The intention of this control design is to mitigate the voltage violations in a high PV-penetrated distribution feeder, while evenly distributing the weight of energy curtailment among all PV systems. Test results are provided from simulation-only scenarios and a hardware-in-the-loop test platform.}, number={2}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Kashani, Mahsa Ghapandar and Mobarrez, Maziar and Bhattacharya, Subhashish}, year={2019}, pages={1147–1156} }
 @article{anurag_gohil_acharya_han_vechalapu_baliga_bhattacharya_van brunt_sabri_hull_et al._2018, title={Static and Dynamic Characterization of a 3.3 Kv, 45 A 4H-Sic MOSFET}, volume={924}, ISSN={1662-9752}, url={http://dx.doi.org/10.4028/www.scientific.net/msf.924.739}, DOI={10.4028/www.scientific.net/MSF.924.739}, abstractNote={Wide bandgap materials such as Silicon Carbide (SiC) has enabled the use of medium voltage unipolar devices like Metal-Oxide Field Effect Transistors (MOSFETs) and Junction Field Effect Transistors (JFETs), which can switch at much higher frequencies as compared to their silicon counterparts. It is therefore imperative to evaluate the performance of these medium voltage devices. In this paper, the static characterization and the switching performance of the new single die 3.3 kV, 45 A 4H-SiC MOSFET developed by Cree Inc are presented. The switching performance is measured through the conventional Double Pulse Test. Testing is done at a dc-link voltage of 1.5 kV for different values of current, and gate resistances.}, journal={Materials Science Forum}, publisher={Trans Tech Publications, Ltd.}, author={Anurag, Anup and Gohil, Ghanshyamsinh and Acharya, Sayan and Han, Ki Jeong and Vechalapu, Kasunaidu and Baliga, B. Jayant and Bhattacharya, Subhashish and van Brunt, Edward and Sabri, Shadi and Hull, Brett and et al.}, year={2018}, month={Jun}, pages={739–742} }
 @inproceedings{gulur_iyer_bhattacharya_2018, title={Stationary reference frame based current control structure with improved disturbance rejection for grid connected converters}, volume={2018-March}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046936440&partnerID=MN8TOARS}, DOI={10.1109/apec.2018.8341142}, abstractNote={A proportional resonant (PR) controller is commonly used for tracking the reference current with zero steady state error in the stationary reference frame (abc or αβ) for the voltage source converter. Such a structure suffers from poor disturbance rejection capability when the grid voltages contain harmonic components. This results in higher harmonic distortion in the grid currents which is not desirable. This paper introduces a virtual loop based current control structure for improving the voltage and the current disturbance rejection capability. The virtual loop based current control structure also decouples the reference tracking and disturbance rejection leading to simpler controller designs. Frequency domain plots and analysis have been provided to validate the presented control structure. Detailed circuit simulation results have been used to verify the presented analysis.}, booktitle={2018 IEEE Applied Power Electronics Conference and Exposition (APEC)}, author={Gulur, S. and Iyer, V. M. and Bhattacharya, S.}, year={2018}, month={Mar}, pages={1031–1035} }
 @article{beddingfield_bhattacharya_byerly_simizu_leary_mchenry_ohodnicki_2018, title={Thermal profile shaping and loss impacts of strain annealing on magnetic ribbon cores}, volume={33}, ISSN={["2044-5326"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85047850891&partnerID=MN8TOARS}, DOI={10.1557/jmr.2018.157}, abstractNote={Abstract}, number={15}, journal={JOURNAL OF MATERIALS RESEARCH}, publisher={Cambridge University Press (CUP)}, author={Beddingfield, Richard and Bhattacharya, Subhashish and Byerly, Kevin and Simizu, Satoru and Leary, Alex and McHenry, Mike and Ohodnicki, Paul}, year={2018}, month={Aug}, pages={2189–2206} }
 @article{boby_arun rahul_gopakumar_umanand_blaabjerg_bhattacharya_2018, title={A Low-Order Harmonic Elimination Scheme for Induction Motor Drives Using a Multilevel Octadecagonal Space Vector Structure With a Single DC Source}, volume={33}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85038920155&partnerID=MN8TOARS}, DOI={10.1109/TPEL.2017.2695660}, abstractNote={Conventional voltage-source inverters used for induction motor drives generate a hexagonal space vector structure. In the overmodulation range, the hexagonal space vector structure generates low-order harmonics in the phase voltage resulting in low-order torque ripple in the motor. Inverter topologies with an octadecagonal (18 sided) space vector structure eliminate fifth-, seventh-, eleventh-, and thirteenth-order harmonics from the phase voltage, and hence, the dominant sixth- and twelfth-order torque ripple generation is eliminated. Octadecagonal space vector structures proposed in the past require multiple dc sources, which makes four-quadrant operation of the drive system difficult and costly. In this paper, the formation of a multilevel nine-concentric octadecagonal space vector structure using a single dc source is proposed. Detailed experimental results, using open-loop  $V/f$ control and rotor field-oriented control, are presented to validate the effectiveness of the proposed drive scheme.}, number={3}, journal={IEEE Transactions on Power Electronics}, author={Boby, M. and Arun Rahul, S. and Gopakumar, K. and Umanand, L. and Blaabjerg, F. and Bhattacharya, S.}, year={2018}, pages={2430–2437} }
 @inproceedings{alfaris_bhattacharya_2017, title={A current-fed quasi Z-Source inverter with SiC power modules for EV/HEV applications}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041320132&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096910}, abstractNote={This paper presents a comparative study between a conventional boosted-VSI electric/hybrid electric vehicle (EV/HEV) powertrain converter with alternative topologies including bidirectional CSI, Silicon (Si)-based current-fed Quasi Z-Source Inverter (CF-qZSI), and Silicon Carbide (SiC)-based CF-qZSI. The higher switching frequency operation of SiC MOSFETs enables the size reduction of reactive elements necessary for bi-directional power flow through the input Z-network, and results in higher efficiency and power density of the overall system. Research results support this claim, bolstering the possibility to replace conventional VSIs with CSIs in the future using wide bandgap (WBG) devices.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Alfaris, F.E. and Bhattacharya, Subhashish}, year={2017}, pages={5445–5452} }
 @inproceedings{gulur_iyer_bhattacharya_2017, title={A dual loop current control structure with improved disturbance rejection for grid connected converters in the synchronous rotating reference frame}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041457092&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096684}, abstractNote={Increase in renewable energy penetration, in the recent past, has been one of the primary causes for serious issues in power quality of the utility grid. This has ushered in the need for a robust and stable control system for reference tracking and disturbance rejection of grid-connected converters. Conventionally, due to its simplicity and ability to achieve zero steady-state error, a simple proportional integral (PI) controller is used in the synchronous reference frame ($dq$) for current control of voltage-source based grid-connected systems. However, the PI controller by itself, may not suffice for adequate disturbance rejection, especially when the utility grid voltages contain other harmonics in addition to the fundamental component. This paper introduces and analyzes a dual-loop current control structure, which utilizes two independent controllers, one for reference tracking and the other for disturbance rejection in the $dq$ frame. A small signal model of the dual-loop current control has been presented and its robustness under grid impedance variation, examined. Extensive experimental results are presented to validate the dual-loop control strategy for improved disturbance rejection capability and filtering action during the presence of grid voltage disturbances and grid impedance variations, without compromising the reference tracking performance.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Gulur, S. and Iyer, V.M. and Bhattacharya, Subhashish}, year={2017}, pages={3890–3896} }
 @inproceedings{cho_mobarrez_bhattacharya_2017, title={A multi-loop controller for LCL-filtered grid-connected converters integrated with a hybrid harmonic compensation and a novel virtual impedance}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85020026025&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7931074}, abstractNote={The LCL-filtered converter is widely adapted to interface renewable energy sources and energy storage devices to the grid. While the LCL filter is capable of eliminating current harmonics caused by the high-frequency PWM of the converter, low-order current harmonics are reduced selectively by the stationary-frame resonant harmonic compensators (HCs). There are two types of the harmonic compensator, namely, harmonic current compensator (HCC) and harmonic voltage compensator (HVC). HCCs are in general embedded in parallel with conventional grid current controllers by which the active and reactive power are regulated. If autonomous islanding operation is required, the active and reactive power are controlled by a V-f droop method and a filter capacitor voltage controller with which HCCs or HVCs are added in parallel. In this paper, a multi-loop controller is proposed as one possible alternative to the conventional grid current controller to improve the harmonic compensation performance by using both HCCs and HVCs, which is a hybrid harmonic compensation (HHC). In addition, a novel virtual impedance implementation technique which fits to the multi-loop frame is presented to maintain stability of the controller in case of large grid impedance.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Cho, Y. and Mobarrez, M. and Bhattacharya, Subhashish}, year={2017}, pages={2658–2663} }
 @inproceedings{mobarrez_fregosi_jalali_bhattacharya_bahmani_2017, title={A novel control method for preventing the PV and load fluctuations in a DC microgrid from transferring to the AC power grid}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85028632617&partnerID=MN8TOARS}, DOI={10.1109/icdcm.2017.8001069}, abstractNote={DC microgrids are gaining popularity due to the higher efficiency, reliability, lower costs and better compatibility with DC loads compared to their AC counterparts. Large-scale deployment of distributed renewable energy resources like solar in the microgrids, has to provide utilities and grid operators the capability to safely and reliably mitigate the impact of solar and loads intermittency on the main AC power grid. In this paper, a novel control method is proposed to prevent solar and load variations inside a DC microgrid from transferring to the AC power grid while the microgrid is operating in grid-tied mode. The control method works based on having multiple slack terminals with different voltage controller response times in parallel. The response times can be adjusted such that the battery converters of the microgrid absorb solar and load fluctuations while the grid-tied inverters contribute to their voltage regulation's shares smoothly according to their droop parameters. This method improves upon previously discussed methods in literature in that it does not require single slack terminal, DC bus signaling or converter mode changes.}, booktitle={2017 IEEE 2nd International Conference on Direct Current Microgrids, ICDCM 2017}, author={Mobarrez, M. and Fregosi, D. and Jalali, G. and Bhattacharya, Subhashish and Bahmani, M.A.}, year={2017}, pages={352–359} }
 @inproceedings{alharbi_alfaris_bhattacharya_2017, title={A novel current control strategy for a back-to-back HVDC applications under unbalanced operation conditions}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041445826&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8095934}, abstractNote={Voltage unbalance in a three-phase system introduces oscillations to the DC Link voltage and power. Moreover, it causes performance deterioration of a pulsewidth modulation (PWM) of the back-to back voltage source converter systems (BTB-VSC) by producing the double-line-frequency ripples in the dc link voltage and power. This paper proposes a new control strategy by developing the conventional vector current controller relying on the DC and AC components of voltages and currents. The proposed controller utilized for the three-level voltage-source converters as a building block of the Convertible Static Transmission controller (CSTC) system in shunt-shunt mode. The proposed control strategy aims to suppress the oscillations in DC Link voltage and converters power under system disturbances and faults. The simulation tests is realized by PSCAD-EMTDC environment software. The simulation result shows the feasibility of the proposed controller under normal and unbalanced AC conditions with the CSTC application system.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Alharbi, M. and Alfaris, F.E. and Bhattacharya, Subhashish}, year={2017}, pages={1263–1269} }
 @inproceedings{beddingfield_storelli_bhattacharya_2017, title={A novel dual voltage source converter for magnetic material characterization with trapezoidal excitation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85020117541&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7930922}, abstractNote={A magnetic core testbed is intended to provide a variety of induction curves to fully characterize a magnetic material. Off the shelf solutions are prohibitively expensive and limited in testing range for research purposes. Mainly, high voltages and/ or currents and the ability to create a variety of induction profiles, beyond sinusoidal, is needed for full core characterization. This paper establishes the need for a novel magnetic core testing apparatus to explore high frequency trapezoidal excitation. Then a solution is presented using a novel dual voltage source converter circuit. The authors validate the topology in simulation and present a laboratory prototype. Specifically, the induction profile seen in many dual active bridges is of immediate interest and generated with this approach.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Beddingfield, R. and Storelli, D. and Bhattacharya, Subhashish}, year={2017}, pages={1659–1666} }
 @inproceedings{beddingfield_storelli_bhattacharya_2017, title={Active elimination of DC bias flux in series DC active filter coupling transformer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85020036855&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7930897}, abstractNote={The Medium-voltage DC amplifier is a thyristor based power converter with a series DC active filter that provides a highly controllable and responsive platform to establish a high power dc bus. Having bulk power flow through the thyristor converter offers an economical and high power density solution over PWM converters. By designing the system to meet standards requested by the US Navy for the Next Generation Intelligent Power System, this paper will show a platform applicable to many high power DC microgrid fields. In particular, there are promising applications in mobile mining equipment, electric aircraft and ships. This paper proposes a novel control technique to actively mitigate the DC flux that is generated by the load current. This control approach yields significant reductions in the core volume and required transformer turns. The proposed solutions will be evaluated in a 4 kVA 400 VDC laboratory scale test-bed.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Beddingfield, R. and Storelli, D. and Bhattacharya, Subhashish}, year={2017}, pages={1498–1505} }
 @inproceedings{alfaris_bhattacharya_2017, title={Advanced control strategies for convertible static transmission controller enabled dnal active power filters and PV-power integration}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85044177872&partnerID=MN8TOARS}, DOI={10.1109/ias.2017.8101773}, abstractNote={This paper proposes a hybrid convertible static transmission controller (CSTC), in shunt-shunt mode, with dual active filters and photovoltaic (PV) power integration. The combined system aims to back up and control the power of the transmission transformer, as well as, improve the transmitted power quality. The filters are also designed to eliminate the harmonics due to the injected renewable energy. A new reference generation technique is proposed to inject the solar power into the grid and compensate the system reactive power and current harmonics. Moreover, the varying nature of PV power due to the change in solar radiation and temperature is accounted with the online computation of the DC voltage and power references with the help of the system rectifier. A simulation study adopted by PSCAD-EMTDC environment software is used to validate the proposed system with integration of a solar PV under normal and fault conditions.}, booktitle={2017 IEEE Industry Applications Society Annual Meeting, IAS 2017}, author={Alfaris, F.E. and Bhattacharya, Subhashish}, year={2017}, pages={1–7} }
 @inproceedings{kumar_ravichandran_singh_shah_bhattacharya_2017, title={An intelligent medium voltage gate driver with enhanced short circuit protection scheme for 10kV 4H-SiC MOSFETs}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041440358&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096486}, abstractNote={Designing of gate drivers for high voltage SiC power devices in medium voltage applications is challenging due to high dv/dt and di/dt at the switching instants. During short circuit fault, the device current rises with high di/dt, and eventually the device fails within few of micro seconds if not protected. Short circuit protection of power devices is an essential feature to improve reliability of converters. In this paper, a novel gate driver is developed with short circuit protection scheme, suitable for 10kV, 10A 4-H SiC MOSFETs. It utilizes the de-sat sensing scheme to detect the fault, and clears the fault by turning off the gate pulse in two stages. The trip time at the short circuit fault is much smaller than the short circuit withstanding time of 10kV 4H-SiC MOSFETs. The gate driver is qualified with appropriate experimental test bench for validation of short circuit protection feature, over-current limit and continuous operation for the 10kV MOSFETs.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Kumar, A. and Ravichandran, A. and Singh, S. and Shah, S. and Bhattacharya, Subhashish}, year={2017}, pages={2560–2566} }
 @article{baek_bhattacharya_2018, title={Analytical Modeling and Implementation of a Coaxially Wound Transformer With Integrated Filter Inductance for Isolated Soft-Switching DC-DC Converters}, volume={65}, ISSN={["1557-9948"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85028532226&partnerID=MN8TOARS}, DOI={10.1109/tie.2017.2740855}, abstractNote={In this paper, we propose an approach for integrating a series filter inductance in a coaxially wound transformer (CWT) as a potential alternative to conventional solenoidally wound transformers (SWT) for high-power isolated soft-switching dc–dc converters. The critical elements that determine the size and the performance of soft-switching dc–dc converters are the isolation transformer and the filter elements. While conventional SWTs using a stray magnetic field as a filter inductance often suffer from a considerably increased loss, heat congestion, and electromagnetic interference, a CWT is rarely affected by high frequency and fringing effects. The desired properties are still valid while the required filter inductance is fully integrated with an isolation transformer using the proposed method. In addition, the evenly distributed magnetic fields in a concentric geometry enable accurate electrical and mechanical analysis and a specific application-oriented design. In this paper, the operating principles, design procedure, and loss modeling of a CWT with an integrated filter inductance are introduced. Its functionality and suitability for high-frequency applications were proven by theoretical analysis and experiments. A prototype transformer with an integrated inductance 4 mH was facilitated and evaluated in a 15 kV-SiC  mosfet-based 6 k–400 Vdc stage for a solid-state transformer of up to 6.5 kW at a switching frequency of 20 kHz.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Baek, Seunghun and Bhattacharya, Subhashishi}, year={2018}, month={Mar}, pages={2245–2255} }
 @inproceedings{raheja_gohil_han_acharya_baliga_battacharya_labreque_smith_lal_2017, title={Applications and characterization of four quadrant GaN switch}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041481367&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096397}, abstractNote={Bi-directional switches, also called four quadrant switches (FQS), are the basic building blocks in many power converter circuits, such as cyclo-converters, matrix converters etc. Conventional approaches to realize bi-directional switch involves combination of unidirectional controllable blocking device (IGBT or MOSFET) and diode. In this approach, current flows through multiple devices for any direction of current flow. This leads to higher conduction losses. Moreover, use of multiple devices increases system size. The die size and semiconductor losses can be reduced by realizing a bi-directional switch using a single die. Further improvement can be achieved by using Gallium Nitride (GaN) semiconductor. This paper discusses characterization of such a four quadrant GaN switch, made using a single die. Static characterization is performed, where the on-state resistances are obtained along with the output characteristics. A double pulse test setup has been built for characterizing FQS's and the experiments were performed to obtain the turn-on and turn-off switching energies.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Raheja, U. and Gohil, G. and Han, K. and Acharya, Sayan and Baliga, B.J. and Battacharya, S. and Labreque, M. and Smith, P. and Lal, R.}, year={2017}, pages={1967–1974} }
 @article{kashani_bhattacharya_matamoros_kaiser_cespedes_2018, title={Autonomous Inverter Voltage Regulation in a Low Voltage Distribution Network}, volume={9}, ISSN={["1949-3061"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85028800997&partnerID=MN8TOARS}, DOI={10.1109/TSG.2017.2728661}, abstractNote={Inverter voltage control techniques, including Volt-Watt and Volt-VAR, have been developed to support higher penetration integration of photovoltaic (PV) generation. These techniques typically focus on voltage regulation as measured at the point of common coupling (PCC). Implementing voltage control with distributed inverters within a low voltage network is challenging due to voltage rise between the PCC and the electrical connection point (ECP). This paper proposes a voltage correction and control method for distributed PV microinverters in a low voltage network by utilizing readily available data measurements, i.e., voltage and power at the ECP of inverters. It is shown that this method could reduce unnecessary PV microinverter tripping and power curtailment while supporting voltage control schemes at the PCC. Test results are provided from simulation-only scenarios and a power-hardware-in-the-loop test platform.}, number={6}, journal={IEEE TRANSACTIONS ON SMART GRID}, author={Kashani, Mahsa Ghapandar and Bhattacharya, Subhashish and Matamoros, Joseph and Kaiser, David and Cespedes, Mauricio}, year={2018}, month={Nov}, pages={6909–6917} }
 @inproceedings{alharbi_mobarrez_bhattacharya_2017, title={Control and performance analysis methodology for scale-up of MMC submodules for back-to-back HVDC applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85020008754&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7930731}, abstractNote={The modular multilevel converter (MMC) is a promising topology for both Medium Voltage (MV) and High Voltage Direct Current (HVDC) applications. The MMC employs a large number of “submodule” (SM) cascaded in series per phase arm to achieve the MV- or HVDC voltage. The SM numbers per phase arm can be as high as 256 or 512 SMs for +/− 300kV DC bus voltage for typical 300–600MW Back-to-Back (B2B) and also point to point HVDC applications. The MMC AC side interface voltage Total Harmonics Distortion (THD) requirements are normally < 3% which can be achieved by 48-pulse stepped AC waveform. This paper addresses the first step towards scale-up control and performance analysis such that the behavior of a large number of SMs can be predicted by a cumulative set of a smaller number of SMs. The SM capacitor voltage control is analyzed for scale-up of MMC. Simulation results of B2B HVDC application based MMC system with minimum values of MMC components (SMs capacitors and arms inductors) based on a parametric search are performed using Real Time Digital Simulator (RTDS) system.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Alharbi, M. and Mobarrez, M. and Bhattacharya, Subhashish}, year={2017}, pages={440–447} }
 @inproceedings{alfaris_bhattacharya_2017, title={Convertible static transmission controller model and supervisory vector control for operation under unbalanced grid conditions}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041464084&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096817}, abstractNote={This paper proposes an electromagnetic transient model of the Convertible Static Transmission Controller (CSTC) system in shunt-shunt operation mode. This proposed transient model is used for dynamic analysis and system design. Two recently proposed control structures, which aim to suppress the DC link voltage oscillations under unbalanced AC grid, are applied and compared to the conventional state feedback control method. The simulation tests for a CSTC transmission system connect two active networks are adopted by PSCAD-EMTDC and MATLAB/Simulink. The results verify the validity of the mathematical model and the feasibility of the applied control strategies for the studied system under normal and fault/unbalanced AC conditions.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Alfaris, F.E. and Bhattacharya, Subhashish}, year={2017}, pages={4806–4812} }
 @inproceedings{chavan_acharya_bhattacharya_inam_2017, title={Damping of power oscillations induced by photovoltaic plants using distributed series-connected FACTS devices}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85044191968&partnerID=MN8TOARS}, DOI={10.1109/ias.2017.8101759}, abstractNote={This paper demonstrates the capability of distributed series-connected Flexible AC Transmission Systems (FACTS) devices in damping power oscillations. Large power systems have resonant frequencies which result from the electro-mechanical power balance equations of synchronous generators connected to the power network. Transient events that affect power flow, like the loss of a transmission line, switching of loads, changes in renewable energy output can excite these resonant frequencies, referred to as modes, leading to power oscillations within the network. This paper proposes a power oscillation damping (POD) controller using multiple Static Series Synchronous Compensators (SSSC) connected in series on a single transmission line. The power oscillation frequencies in New York Power Authority's (NYPA) three-bus power system network are identified using the Matrix Pencil method, and a controller is designed to block the most prominent frequencies from them. The controller is implemented in PSCAD to damp power oscillations in NYPA's network and its performance while damping power oscillations is recorded.}, booktitle={2017 IEEE Industry Applications Society Annual Meeting, IAS 2017}, author={Chavan, G. and Acharya, Sayan and Bhattacharya, Subhashish and Inam, H.}, year={2017}, pages={1–7} }
 @inproceedings{kashani_pulakhandam_bhattacharya_katiraei_kaiser_2017, title={Design considerations and test setup assessment for power hardware in the loop testing}, DOI={10.1109/ias.2017.8101770}, abstractNote={Power Hardware in the Loop (PHIL) simulations have recently been developed as a substitution for traditional methods of testing and analyzing real and physical electric power apparatus, especially power electronic based devices. However, due to some inherent characteristics of the PHIL test setup — such as use of power amplifiers, software/hardware interfaces, and real time simulations — there are certain operating constraints and implementation challenges that need to be considered and incorporated in the design. This work provides an overview of design and implementation of a PHIL platform for electrical power system testing. A frequency-domain stability analysis and a time-domain accuracy assessment of several PHIL test setups using different approaches have been presented. PHIL simulation and experimental results have been provided to demonstrate the effectiveness and functionality of each approach.}, booktitle={2017 ieee industry applications society annual meeting}, author={Kashani, M. G. and Pulakhandam, H. and Bhattacharya, Subhashish and Katiraei, F. and Kaiser, D.}, year={2017} }
 @article{de_morgan_iyer_ke_zhao_vechalapu_bhattacharya_hopkins_2018, title={Design, Package, and Hardware Verification of a High-Voltage Current Switch}, volume={6}, ISSN={2168-6777}, url={http://dx.doi.org/10.1109/JESTPE.2017.2727051}, DOI={10.1109/jestpe.2017.2727051}, abstractNote={In this paper, an attempt has been made to demonstrate various package design considerations to accommodate series connection of high voltage Si-IGBT (6500V/25A die) and SiC-Diode (6500V/25A die). The effects of connecting the cathode of the series diode to the collector of the IGBT versus connecting the emitter of the IGBT to the anode of the series diode have been analyzed in regards to parasitic line inductance of the structure. Various simulation results have then been used to redesign and justify the optimized package structure for the final current switch design. The package is fabricated using the optimized parameters. A double pulse test-circuit has been assembled. Initial hardware results have been shown to verify functioning. The main motivation of this work is to enumerate detailed design considerations for packing a high voltage current switch package.}, note={\urlhttps://ieeexplore.ieee.org/document/7981339/}, number={1}, journal={IEEE Journal of Emerging and Selected Topics in Power Electronics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={De, A. and Morgan, A. J. and Iyer, V. Mahadeva and Ke, H. and Zhao, X. and Vechalapu, K. and Bhattacharya, S. and Hopkins, D. C.}, year={2018}, month={Mar}, pages={441–450} }
 @inproceedings{kumar_vechalapu_bhattacharya_veliadis_brunt_grider_sabri_hull_2017, title={Effect of capacitive current on reverse recovery of body diode of 10kV SiC MOSFETs and external 10kV SiC JBS diodes}, volume={2017-December}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046697191&partnerID=MN8TOARS}, DOI={10.1109/wipda.2017.8170548}, abstractNote={The body diodes of 10kV SiC MOSFETs can be used as anti-parallel diodes in medium voltage converters instead of widely used SiC JBS and PiN diodes. Characterization of switching loss of the body diodes is required to evaluate its candidature for replacement of JBS/PiN diodes. Normally, double pulse test setup is used to observe the reverse recovery behavior of the diodes. But, in high voltage diodes, due to large dv/dt the capacitive current becomes significant, and it superimposes on the reverse recovery current waveform of the diode, misleading the reverse recovery loss data, if the capacitive current is ignored. In this paper, contribution of the capacitive current in the reverse recovery is segregated, which helps in determining actual reverse recovery loss of the diode in double pulse test circuit. Two-slope turn-on characteristic of 15kV SiC IGBT is employed to support the existence of this capacitive current. Using the proposed segregation technique, reverse recovery of the body diode of 10kV SiC MOSFETs is compared with that of 10kV SiC JBS diode.}, booktitle={2017 IEEE 5th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2017}, author={Kumar, A. and Vechalapu, K. and Bhattacharya, Subhashish and Veliadis, V. and Brunt, E. Van and Grider, D. and Sabri, S. and Hull, B.}, year={2017}, pages={208–212} }
 @inproceedings{azidehak_hwang_agarwal_bhattacharya_yousefpoor_2017, title={Fault-tolerant controller architecture for cascaded multi-level converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85019991207&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7931086}, abstractNote={Voltage source multi-level converters (MC) are one of the options for rectifying and inverting in high power applications. Each converter consists of several modules connected together to form a single converter. Power rating of the converter is usually more than the desired rating and it is possible to continue operation by bypassing the failed modules. This capability increases the reliability of this category of converters compared to other type of converters. In this paper, a distributed controller has been proposed that implements hot standby techniques to increase reliability and availability of the converter. Each slave controller is directly connected to the power electronic module with data link to neighbor controllers and all of the controllers are being synchronized through a master controller. At the end, reliability assessment of the proposed controller based on Markov modeling has been represented and experimental result approves the feasibility of the control method.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Azidehak, A. and Hwang, M. and Agarwal, R. and Bhattacharya, Subhashish and Yousefpoor, N.}, year={2017}, pages={2738–2744} }
 @inproceedings{bahmani_vechalapu_mobarrez_bhattacharya_2017, title={Flexible HF distribution transformers for inter-connection between MVAC and LVDC connected to DC microgrids: Main challenges}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85028634559&partnerID=MN8TOARS}, DOI={10.1109/icdcm.2017.8001022}, abstractNote={Solid-state transformers or so called flexible high-frequency (HF) distribution transformers are likely to become a more efficient inter-connection between medium voltage (MV) AC grids and low voltage (LV) DC grids which can eventually be connected to DC microgrids. This paper addresses the main challenges in order to implement this technology. High-Frequency Transformers (HFTs) are one of the key elements of such converters which are the main contributor to realize the voltage adaption, isolation requirements, as well as high-power density. This paper addresses the essential design considerations taking into account the magnetic materials, leakage inductance integration as well as thermal management of such transformers. Moreover, the limitations of the currently available semiconductors are discussed and the applicability and performance of the latest generations of 10 kV SiC MOSFETs are discussed. The highlighted design considerations within both the transformer and HV SiC devices are then demonstrated using experimental results.}, booktitle={2017 IEEE 2nd International Conference on Direct Current Microgrids, ICDCM 2017}, author={Bahmani, M.A. and Vechalapu, K. and Mobarrez, M. and Bhattacharya, Subhashish}, year={2017}, pages={53–60} }
 @inproceedings{hazra_vechalapu_madhusoodhanan_bhattacharya_hatua_2017, title={Gate driver design considerations for silicon carbide MOSFETs including series connected devices}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041439258&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8095954}, abstractNote={In this study, design considerations of gate driver for silicon carbide (SiC) power devices is discussed. The work is focused in minimizing the common-mode current injection into the control circuit, thereby adapting the gate circuit to operate at higher dv/dt of fast switching transients. By reducing the common-mode interference with the control circuit, the signal integrity can be increased, spurious faults in the converter can be minimized and the reliability of the converter operation can be enhanced. The effect of the coupling capacitance of the isolation transformer in the gate driver design is taken into account. The shoot-through protection of the device is ensured based on device voltage measurement. The operation of the designed gate driver is validated through double pulse switching as well as continuous operation of various converters. All the corresponding test results are reported.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Hazra, S. and Vechalapu, K. and Madhusoodhanan, S. and Bhattacharya, Subhashish and Hatua, K.}, year={2017}, pages={1402–1409} }
 @inproceedings{mobarrez_fregosi_bhattacharya_bahmani_2017, title={Grounding architectures for enabling ground fault ride-through capability in DC microgrids}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85028640244&partnerID=MN8TOARS}, DOI={10.1109/icdcm.2017.8001026}, abstractNote={Distributed generation in the power grid will result in considerable efficiency improvement and increase in reliability and stability of the grid. And DC microgrids have clear benefits such as higher reliability, higher efficiency, better compatibility with DC loads, expandability and etc., over their AC equivalent systems. Although DC microgrids have clear advantages over the AC microgrids, but there is not sufficient information available on their grounding. Realizing the grounding of DC systems would accelerate employing of these systems in the power grid. Grounding is a complex topic involving many design considerations and trade-offs and it is needed to ensure the safety of personnel and equipment as well as detection of ground fault in the system. Grounding of DC power system should be designed to 1) minimize the leakage current during normal operation, 2) maximize the safety of personnel and equipment under fault conditions. This work examines the different grounding methods and system architectures and discusses the design trade-offs in terms of safety, reliability, detection, mitigation, noise, and cost. We examine impedance grounding, isolation, and bi-polar architectures and discuss their benefits with respect to these criteria.}, booktitle={2017 IEEE 2nd International Conference on Direct Current Microgrids, ICDCM 2017}, author={Mobarrez, M. and Fregosi, D. and Bhattacharya, Subhashish and Bahmani, M.A.}, year={2017}, pages={81–87} }
 @article{madhusoodhanan_mainali_tripathi_patel_kadavelugu_bhattacharya_hatua_2017, title={Harmonic Analysis and Controller Design of 15 kV SiC IGBT-Based Medium-Voltage Grid-Connected Three-Phase Three-Level NPC Converter}, volume={32}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85012231749&partnerID=MN8TOARS}, DOI={10.1109/tpel.2016.2582803}, abstractNote={Cascaded converters are generally used for medium-voltage (MV) grid-connected applications due to the limitation in the voltage rating of available silicon (Si) power devices. These converters find application in active power filters, STATCOM or as the active front end converters for solid state transformers at the distribution voltage levels. The high voltage wide bandgap semiconductor devices have enabled the grid connected operation of noncascaded converters. This results in high power density, less number of switching devices, and high efficiency for three-phase MV grid interface. This also results in control simplicity without the need for complex dc bus balancing algorithms otherwise needed for cascaded converters. However, such noncascaded, grid-connected converters introduce challenges in maintaining power quality at low currents. This paper investigates the harmonic performance and current distortion of the grid-connected, three-level neutral point clamped converter using 15 kV silicon carbide Insulated Gate Bipolar Transistor (IGBTs). A suitable control scheme for stable harmonic compensation is proposed. The challenges and control performance are explained through frequency domain analysis, simulations, and experimental validation on a developed prototype of the three-phase converter up to 4.16 kV, three-phase MV grid-connected operation.}, number={5}, journal={IEEE Transactions on Power Electronics}, author={Madhusoodhanan, S. and Mainali, K. and Tripathi, A. and Patel, D. and Kadavelugu, A. and Bhattacharya, Subhashish and Hatua, K.}, year={2017}, pages={3355–3369} }
 @inproceedings{vechalapu_hazra_raheja_negi_bhattacharya_2017, title={High-Speed medium voltage (MV) drive applications enabled by series connection of 1.7 kV SiC MOSFET devices}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041387373&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8095868}, abstractNote={The medium voltage (MV) high-speed drives are required for traction, wind energy, marine, aerospace, oil, and gas compressors applications. The MV converter must be able to switch at higher switching frequencies (> 5 kHz) to generate higher fundamental frequency AC input voltages for the motor (≥ 500 Hz) and thereby achieving high speed at the motor output (≥ 15000 rpm). This paper presents the series connection of 1.7 kV SiC MOSFET devices to enable simple two level MV converter for high-speed drive and grid connected applications. Experimental switching characterization of a phase leg (one pole of a three-phase converter) with the series connection of four devices per arm (or eight per leg) has been presented. It also presents the experimental results of a DC-AC half-bridge inverter with four devices in series per arm at 3kV dc bus, at different fundamental frequencies. It also includes the experimental endurance test results of phase-leg (pole) in a DC-DC converter at 100 kW, 3kV dc bus. Furthermore, it also presents the performance evaluation of a 3-phase voltage source inverter (VSI) efficiency using four series connected devices for 3.6 kV dc bus, 2.1 kV AC(L-L), 720 kW output power and its comparison with single 6.5 kV Si IGBT.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Vechalapu, K. and Hazra, S. and Raheja, U. and Negi, A. and Bhattacharya, Subhashish}, year={2017}, pages={808–815} }
 @inproceedings{iyer_gulur_bhattacharya_2017, title={Hybrid control strategy to extend the ZVS range of a dual active bridge converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85020000052&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7930979}, abstractNote={This paper presents a hybrid control strategy for a dual active bridge (DAB) based dc-dc converter which combines the benefits of traditional phase shift and burst mode modulation schemes. The advantage of using such a control strategy stems from the fact that it can extend the zero voltage switching (ZVS) range of all power switches in both the primary and secondary bridges when there is a wide variation in input or output voltage. In addition, the hybrid control strategy improves the light load efficiency of the DAB converter. The paper focuses on the development of the average and small signal models for the DAB converter with the hybrid modulation scheme. Digital implementation considerations of the hybrid control scheme are discussed. The effectiveness of the proposed control strategy has been tested and validated through simulations and experiments.}, booktitle={2017 IEEE Applied Power Electronics Conference and Exposition (APEC)}, author={Iyer, V. M. and Gulur, S. and Bhattacharya, S.}, year={2017}, month={Mar}, pages={2035–2042} }
 @inproceedings{mobarrez_bhattacharya_fregosi_2017, title={Implementation of distributed power balancing strategy with a layer of supervision in a low-voltage DC microgrid}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85019987939&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7930855}, abstractNote={Low-voltage DC microgrids are gaining popularity due to the higher efficiency, reliability, lower costs and better compatibility with DC loads compared to their AC counterparts. One of the challenges associated with employing DC microgrids is to design and implement a reliable control algorithm that ensures all the power converters maintain the power balance in normal operating condition as well as emergency condition. In this paper, a novel power balancing strategy is proposed to harvest maximum power from the solar and minimize the effect of solar output variations on the AC power grid. Moreover, a layer of communication is proposed that can be added to the control algorithm to optimize the usage of battery energy storage systems (BESS) and compensate for voltage drop/rise due to the implementation of linear droop. The feasibility and effectiveness of the proposed power balancing strategy is verified by a lab-scale DC microgrid test bed.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Mobarrez, M. and Bhattacharya, Subhashish and Fregosi, D.}, year={2017}, pages={1248–1254} }
 @inproceedings{pinares_bongiorno_acharya_bhattacharya_2017, title={Investigation of dc-network resonance-related instabilities in VSC-based multi-terminal HVDC systems with tests in a real-time digital simulator}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85042029234&partnerID=MN8TOARS}, DOI={10.23919/epe17ecceeurope.2017.8099114}, abstractNote={A simplified method is proposed to investigate potential instabilities originated from dc-side resonances in multi-terminal HVDC systems. The method consists of identifying the resonances from the points to where the converters are connected. The method is applied to a four-terminal HVDC system, and the analysis indicates there are two resonance phenomena and a group of converters have the most significant impact on the first resonance, while the others on the second resonance. The four-terminal HVDC system is implemented in a Real-Time Digital Simulator and three dc-network configurations are investigated through the proposed method. The test results show the validity of the theoretical findings.}, booktitle={2017 19th European Conference on Power Electronics and Applications, EPE 2017 ECCE Europe}, author={Pinares, G. and Bongiorno, M. and Acharya, Sayan and Bhattacharya, Subhashish}, year={2017}, pages={P1–P10} }
 @inproceedings{batra_gohil_sesham_rodriguez_bhattacharya_2017, title={Isolation design considerations for power supply of medium voltage silicon carbide gate drivers}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041441713&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096485}, abstractNote={Single switch capable of blocking 10 kV and higher voltages are presently being developed and demand improved gate drivers for their functioning. Induction based gate drivers have been the foremost solutions in this regard. Design challenges that have been outlined for these drivers are low coupling capacitance, strong magnetic coupling and smaller dimensions with isolation not considered in depth. In this paper, first isolation requirements and its physical realization guidelines are provided from IEC 61800-5-1 for electric drives application. Based on study, two system insulation designs: single and double PCB are derived for lower MV and higher MV system respectively. Current loop gate driver with double PCB design is found to be practical and economical solution for higher MV power electronics systems. Afterwards, shortcomings of three state of art induction solutions at both system and magnetic link level is discussed. Improved transformers with primary MV cable providing mandatory solid insulation are fabricated. It is shown through impedance measurements that the cable has negative effect on the magnetizing inductance and coupling capacitance compared to state of art transformer solution. At the end, both set of transformers are tested with 64 kV impulse and 32 kV overvoltage with only improved transformers showing positive results.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Batra, T. and Gohil, G. and Sesham, A.K. and Rodriguez, N. and Bhattacharya, Subhashish}, year={2017}, pages={2552–2559} }
 @inproceedings{shah_bhattacharya_2017, title={Large & small signal modeling of dual active bridge converter using improved first harmonic approximation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85020017857&partnerID=MN8TOARS}, DOI={10.1109/APEC.2017.7930844}, abstractNote={The paper derives a technique to develop large and small signal state-space models of a single-phase dual active bridge (DAB) based DC-DC converter operated in phase-shift mode. An improved first harmonic approximation (I-FHA) method is proposed by introducing a correction factor to the conventional first harmonic approximation (FHA) technique. The output DC voltage and the two orthogonal components of first harmonic of transformer current, corresponding to active and circulating powers, are used as state-variables. The large-signal model, thus derived, is of simple form and accurate for ideal converter. A small-signal model is also developed from the I-FHA model. Finally, the large and small signal models are validated through time-domain simulations and experimental results.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Shah, S.S. and Bhattacharya, S.}, year={2017}, pages={1175–1182} }
 @inproceedings{acharya_hazra_vechalapu_bhattacharya_2017, title={Medium voltage power conversion architecture for high power PMSG based wind energy conversion System (WECS)}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041435472&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096600}, abstractNote={This paper presents a medium voltage power conversion architecture for grid integration of multi-MW permanent magnet synchronous generator (PMSG) based wind energyc-conversion system (WECS). Converting the low voltage power output of the generator to medium voltage, can reduce the diameter of the power cable significantly. As a result, power loss and the overall cost of the system can be minimized. With high frequency transformer based design, the weight of the power conversion system can be kept low, making it feasible to install the system on the tower of the wind turbine itself. The architecture is built upon modular concept which facilitates to operate the system under partial fault condition. Also, it has the advantage of reaching to a better efficiency by operating part of the conversion system at partial generation condition. Recent advances in wide bandgap (WBG) based switching devices can further enhance the efficiency of the system. The overall control system is designed and the operation of the proposed architecture is validated through simulation and the feasibility of system design is addressed based on the available power devices.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Acharya, Sayan and Hazra, S. and Vechalapu, K. and Bhattacharya, Subhashish}, year={2017}, pages={3329–3336} }
 @inproceedings{gohil_teodorescu_kerekes_blaabjerg_battacharya_2017, title={Mission-profile based multi-objective optimization of power electronics converter for wind turbines}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041430970&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096627}, abstractNote={To help mitigate some of the challenges associated with the wide spread adoption of the stochastic wind power, wind turbine with full-scale power converter (Type D) is preferred. Since full power is processed by the power converter in a type D wind turbine, it is important to improve its efficiency and reduce the cost per kW to achieve lower cost of energy. The power produced by the wind turbine varies in a wide range and the conventional design approach of optimizing converter at a specific loading condition may be sub-optimal. To overcome this challenge, a mission-profile based multi-objective optimization approach for designing power converter is presented. The objective is to minimize the energy loss for a given load profile as against the conventional approach of minimizing power loss at specific loading conditions. The proposed approach is illustrated by designing a grid-side power converter for 2 MW, 690 V wind turbine. The loss and volume models of the semiconductor and passive components have been discussed and design procedure has been demonstrated.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Gohil, G. and Teodorescu, R. and Kerekes, T. and Blaabjerg, F. and Battacharya, S.}, year={2017}, pages={3514–3521} }
 @article{hazra_bhattacharya_2018, title={Modeling and Emulation of a Rotating Paddle Type Wave Energy Converter}, volume={33}, ISSN={["1558-0059"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85037655176&partnerID=MN8TOARS}, DOI={10.1109/tec.2017.2778312}, abstractNote={Torque-speed characteristics of an oscillating wave energy converter (WEC) is necessary to determine its optimal power point and to extract the corresponding design parameters for the generator and power converters used to generate power from the WEC. In this paper, analytical expressions for the mechanical torque on the WEC due to the oscillating surge of seawater are derived, and the dynamic model of the WEC is developed. A method for hardware emulation of the WEC is proposed by controlling the torque of an electric motor. The reference torque of the motor is derived by solving the mechanical dynamics of the WEC system in a real-time computing device considering a typical sea wave input. The emulated WEC dynamics is validated through variable loading on a generator coupled with the emulator. Experimental results support the existence of an optimal power point of the derived WEC model.}, number={2}, journal={IEEE TRANSACTIONS ON ENERGY CONVERSION}, author={Hazra, Samir and Bhattacharya, Subhashish}, year={2018}, month={Jun}, pages={594–604} }
 @inbook{beddingfield_bhattacharya_2017, title={Multi-Parameter Magnetic Material Characterization for High Power Medium Frequency Converters}, volume={Part F6}, ISBN={9783319514925 9783319514932}, ISSN={2367-1181 2367-1696}, url={http://dx.doi.org/10.1007/978-3-319-51493-2_67}, DOI={10.1007/978-3-319-51493-2_67}, abstractNote={With the rapid availability of new magnetic materials and even more options in post-processing techniques such as field and strain annealing, full property maps of materials and final fabricated components are needed for proper system design. This is especially critical in modern wide bandgap power electronics based converters where medium switching frequencies are used to deliver high power. In these systems, the magnetic design has a significant impact in the overall losses. The magnetics constitute a majority of the losses and magnetic properties have a defining influence on the overall systems, e.g. available power flow and soft switching regions. A new lossless structural harness that allows easy testing of cores and the development of property maps is presented. The harness also enables the testing of mechanical variations such as gapping and clamping pressure on the core.}, booktitle={TMS 2017 146th Annual Meeting & Exhibition Supplemental Proceedings}, publisher={Springer International Publishing}, author={Beddingfield, Richard and Bhattacharya, Subhashish}, year={2017}, pages={693–708} }
 @inproceedings{beddingfield_bhattacharya_2017, title={Multi-parameter magnetic material characterization for high power medium frequency converters}, booktitle={Tms 2017 146th annual meeting & exhibition supplemental proceedings}, author={Beddingfield, R. and Bhattacharya, S.}, year={2017}, pages={693–708} }
 @inproceedings{chattopadhyay_acharya_gohil_bhattacharya_2017, title={One switching cycle current control strategy for Triple Active Bridge phase-shifted DC-DC converter}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85044242331&partnerID=MN8TOARS}, DOI={10.1109/ias.2017.8101785}, abstractNote={The paper presents two types of one cycle current control method for Triple Active Bridge(TAB) phase-shifted DC-DC converter integrating Renewable Energy Source(RES), Energy Storage System(ESS) and a output dc bus. The main objective of the current control methods is to control the transformer current in each cycle so that dc transients are eliminated during phase angle change from one cycle to the next cycle. In the proposed current control methods, the transformer currents are sampled within a switching cycle and the phase shift angles for the next switching cycle are generated based on sampled current values and current references. The discussed one cycle control methods also provide an inherent power decoupling feature for the three port phase shifted triple active bridge converter. Two different methods, (a) sampling and updating twice in a switching cycle and (b) sampling and updating once in a switching cycle, are explained in this paper. The current control methods are experimentally verified using digital implementation technique on a laboratory made hardware prototype.}, booktitle={2017 IEEE Industry Applications Society Annual Meeting, IAS 2017}, author={Chattopadhyay, R. and Acharya, Sayan and Gohil, G. and Bhattacharya, Subhashish}, year={2017}, pages={1–8} }
 @inproceedings{iyer_gulur_bhattacharya_2017, title={Optimal design methodology for dual active bridge converter under wide voltage variation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85028592472&partnerID=MN8TOARS}, DOI={10.1109/itec.2017.7993306}, abstractNote={Dual active bridge (DAB) converter is a popular topology for bidirectional on-board electric vehicle (EV) charger systems and other energy storage applications. In such systems, wide variation in the battery voltage makes design of the DAB converter non-trivial. The focus of this paper is on the optimal selection of DAB parameters when there is a wide variation in the output voltage. Different optimal strategies based on a minimal Euclidean norm approach, namely ‘minimal rms current design’, ‘minimal peak current design’ and ‘minimal power loss design’ are compared to illustrate the effect on system performance with output voltage variation. The proposed optimal design approaches are shown to be superior to a conventional design approach. A loss model for the DAB converter that can be used in the optimal design process is presented. The proposed optimal strategies are validated with experimental results using a laboratory prototype.}, booktitle={2017 IEEE Transportation and Electrification Conference and Expo, ITEC 2017}, author={Iyer, V.M. and Gulur, S. and Bhattacharya, Subhashish}, year={2017}, pages={413–420} }
 @inproceedings{chattopadhyay_juds_gohil_gulur_ohodnicki_bhattacharya_2017, title={Optimized design for three port transformer considering leakage inductance and parasitic capacitance}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041441738&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096588}, abstractNote={The power flow capability of high frequency phase-shifted dc-dc converter depends on transformer leakage inductance and switching frequency. The design of multi-port transformer requires optimized volume and losses with required leakage inductance for rated power flow. Use of fast-switching SiC devices also demand low inter-winding parasitic capacitance for reduced common mode current. The work in this paper focuses on loss-volume optimized design of three port high frequency transformer integrating PV and Energy Storage(ES) based on leakage inductance and parasitic capacitance model. Two laboratory prototypes of 50kHz and 100kHz operating frequency have been designed to verify the leakage and parasitic capacitance model based design and the losses of the transformers.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Chattopadhyay, R. and Juds, M.A. and Gohil, G. and Gulur, S. and Ohodnicki, P.R. and Bhattacharya, Subhashish}, year={2017}, pages={3247–3254} }
 @inproceedings{beddingfield_storelli_mirzaee_bhattacharya_2017, title={Performance investigation of hybrid active filter during low load condition}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041316593&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096877}, abstractNote={A hybrid active filter with a new voltage synchronization control loop is proposed to improve the harmonic content of nonlinear active front end converters for mobile mining equipment. This hybrid filter topology utilizes the DC bus established by the AFE and provides load harmonics at the PCC. Unlike traditional hybrid active filters, this topology uses no real power or control loops to maintain a DC link as this is provided by the AFE. This paper investigates the hybrid active filters performance in two compensation modes, harmonic current only, and both harmonic current and reactive power injection. Necessary considerations for the medium voltage dc testbed topology, real power flow minimization, and the active filter control during worst case load harmonic currents are also discussed.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Beddingfield, R. and Storelli, D. and Mirzaee, H. and Bhattacharya, Subhashish}, year={2017}, pages={5222–5228} }
 @inproceedings{hazra_kamat_bhattacharya_ouyang_englebretson_2017, title={Power conversion and control of a magnetic gear integrated permanent magnet generator for wave energy generation}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041291493&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096854}, abstractNote={This paper presents results of the control of a magnetic gear integrated permanent magnet synchronous generator (MG-PMSG) using a dedicated power conversion system to deliver power from an oscillating, low speed wave energy converter (WEC). The generator has two rotors and one stator. By magnetic gearing, the low speed of the outer rotor is amplified to the high speed of the inner rotor, which faces the stator winding. The machine is designed with a large number of poles and concentrated winding for simpler and cheaper design. However, concentrated winding can have harmonics in the induced electromotive force (emf), which causes harmonic power flow into the dc link of the power converter. In this work, the control system for power conversion from the MG-PMSG is developed and the harmonic content in the power is analyzed. Since, the generator is driven with oscillating speed to generate oscillating power, an energy storage system is integrated to supply smooth power from the system. All corresponding experimental results are provided.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Hazra, S. and Kamat, P. and Bhattacharya, Subhashish and Ouyang, W. and Englebretson, S.}, year={2017}, pages={5065–5072} }
 @inproceedings{hazra_kamat_bhattacharya_ouyang_englebretson_2017, title={Power conversion and control of a pole-modulated permanent magnet synchronous generator for wave energy generation}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041462066&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096928}, abstractNote={This paper presents test results of the control of a pole-modulated permanent magnet synchronous generator (PM-PMSG) using a dedicated power conversion system to deliver power from an oscillating, low speed wave energy converter (WEC). Due to the low speed of the WEC, the size of the generator is increased and the machine is designed with large number of poles and concentrated winding. The electromotive force (emf) induced in the concentrated and not sufficiently distributed stator winding contains harmonic components which generate harmonic active power. Since the harmonic active power flows through the dc bus capacitor of the power converter, the frequency of the harmonic power can be the deciding factor for selecting the size of the capacitor. Lower frequency of the harmonic power can lead to large dc link capacitor. Since the concentrated winding is more economical with the simpler design and faster manufacturing, increasing the emf frequency is a better option to reduce the size of the capacitor. The fundamental frequency of the generator is increased by pole modulation. In this work, the control system for power conversion by the PM-PMSG is developed and the harmonic content in the power is analyzed. The generator is driven by a dc motor which emulates the characteristics of an oscillating WEC. An energy storage system is integrated at the dc link to smooth the output power. All corresponding experimental results are provided.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Hazra, S. and Kamat, P. and Bhattacharya, Subhashish and Ouyang, W. and Englebretson, S.}, year={2017}, pages={5572–5578} }
 @inproceedings{alharbi_bhattacharya_yousefpoor_2018, title={Reliability comparison of fault-tolerant HVDC based modular multilevel converters}, volume={2018-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046374267&partnerID=MN8TOARS}, DOI={10.1109/PESGM.2017.8274712}, abstractNote={The reliability of Modular Multilevel Converters (MMC) is a significant issue as a large number of semiconductor devices are equipped with each converter. Failure of one switching device in the converter may lead to shut-down of the entire system The fault-tolerant design approach can dominate faults and improve the system safety and reliability. In this paper, the reliability analysis is performed to compare the reliability performance of the half-bridge (HB) and the high-frequency isolation (HFI) based MMC converters. The N+1 redundancy designs are presented and assessed using Markov reliability model. A comparative evaluation of the HB-MMC and HFI-MMC topologies shows that the reliability of HB-MMC converter is much higher than that of the HFI-MMC converter.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Alharbi, M. and Bhattacharya, Subhashish and Yousefpoor, N.}, year={2018}, pages={1–5} }
 @inproceedings{azidehak_agarwal_yousefpoor_dean_bhattacharya_2017, title={Resilient two dimensional redundancy based fault-tolerant controller array for modular multi-level converters}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041490609&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8095856}, abstractNote={In this paper, a state-of-the-art controller architecture for controlling modular multi-level converter (MMC) family is proposed. By using this controller architecture, single point of failure in the power converter, controller board or the communication network does not interrupt the functionality of the system. In order to achieve that, a two-dimensional array of controllers are formed to handle the MMC. In this architecture, a selected master controller is synchronizing slave controllers. In addition, adjacent slave controllers check the internal functionality of each other. In case of failure detection, the failed component will be isolated from system and the converter may continue its operation without interruption. This paper covers synchronization mechanism for slave controllers, master controller selection, and presents experimental results for the proposed controller.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Azidehak, A.H. and Agarwal, R. and Yousefpoor, N. and Dean, A.G. and Bhattacharya, Subhashish}, year={2017}, pages={722–729} }
 @inproceedings{iyer_gulur_bhattacharya_2017, title={Small-signal modeling and stability analysis of a bidirectional electric vehicle charger}, DOI={10.1109/icrera.2017.8191214}, abstractNote={This paper addresses the stability challenges that exist in a bidirectional grid connected electric vehicle (EV) charger. The EV charger under consideration comprises of an ac-dc single phase active rectifier stage followed by a dc-dc dual active bridge (DAB) stage. small-signal models suited for stability analysis of this charger are derived. Controller design considerations are discussed in order to ensure closed loop stability of individual stages and to prevent any instability due to interaction between the stages. Experimental results on an EV charger hardware prototype are presented to validate the proposed models and control design considerations.}, booktitle={2017 ieee 6th international conference on renewable energy research and applications (icrera)}, author={Iyer, V. M. and Gulur, S. and Bhattacharya, Subhashish}, year={2017}, pages={1030–1035} }
 @inproceedings{iyer_gulur_bhattacharya_2017, title={Small-signal modeling and stability analysis of a bidirectional electric vehicle charger}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85042707603&partnerID=MN8TOARS}, DOI={10.1109/DISTRA.2017.8191214}, booktitle={2017 6th International Conference on Renewable Energy Research and Applications, ICRERA 2017}, author={Iyer, V.M. and Gulur, S. and Bhattacharya, S.}, year={2017}, pages={1030–1035} }
 @inproceedings{kashani_mobarrez_bhattacharya_2017, title={Smart inverter volt-Watt control design in high PV penetrated distribution systems}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041461425&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8096764}, abstractNote={Advanced control techniques such as Volt-Watt and Volt-VAR Control have been developed for high integration of distributed renewable energy, such as Photovoltaic (PV) resources, on an electric distribution system. However, designing these control parameters which yields the best results in the system is complicated and depends on feeder conditions. This paper proposes a method to properly design the Volt-Watt control parameters in smart PV inverters to increase the benefit of their control action. The intention of this control design is to mitigate the voltage violations in a high PV penetrated distribution feeder, while evenly distributing the weight of energy curtailment among all PV systems. Test results are provided from simulation-only scenarios and a Hardware-In-The-Loop (HIL) test platform.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Kashani, M. Ghapandar and Mobarrez, M. and Bhattacharya, Subhashish}, year={2017}, pages={4447–4452} }
 @inproceedings{chattopadhyay_gohil_bhattacharya_2017, title={Split-winding type three limb core structured HF transformer for integrating PV and energy storage(ES)}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85020040493&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7931123}, abstractNote={The work presented in this paper focuses on the drawbacks of three limb three winding transformer for use in three port dc-dc converter and proposes a split-winding type transformer approach using three limb core for use in three port dc-dc converter. The three limb three winding type transformer has drawback due to limitation of power flow when one port is idle and also has a very limited ZVS operating region for phase shift control. The proposed split-winding type transformer has the equivalent circuit of single core based transformer, has no limitation of power flow when one of the three port is idle and has wide ZVS range. Detailed analysis for idle condition operation, equivalent circuit derivation and ZVS operating range analysis is carried out in this paper.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Chattopadhyay, R. and Gohil, G. and Bhattacharya, Subhashish}, year={2017}, pages={2997–3004} }
 @inproceedings{kamat_hazra_bhattacharya_2017, title={Stand-alone low-cost wave energy generation with energy storage integration}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85019993307&partnerID=MN8TOARS}, DOI={10.1109/apec.2017.7930905}, abstractNote={Ocean wave energy is an emerging renewable source of energy which can be used for generation of electricity for sustainable development. In this work, a wave energy generation system for the paddle type of wave energy converter in standalone system, is discussed. The wave energy is generated by a permanent magnet synchronous generator (PMSG) with low cost power architecture. To smooth the oscillating output power from the generator a hybrid energy storage system comprising of battery and super-capacitor is proposed. Smooth dc power can be directly fed to the load or can be controverted to ac to supply to the ac load. The system control is simulated and experimentally validated with an emulated wave energy converter in experimental setup. The driving speed for the WEC emulator is chosen to be a sinusoidal wave with dominant frequency of actual sea-wave.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Kamat, P. and Hazra, S. and Bhattacharya, Subhashish}, year={2017}, pages={1550–1557} }
 @article{bhattacharya_2017, title={Transforming the transformer}, volume={54}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85021279757&partnerID=MN8TOARS}, DOI={10.1109/MSPEC.2017.7951721}, abstractNote={It would be hard to overstate the importance of transformers in our electrical networks. They’re literally everywhere: on poles and pads, in substations and on private property, on the ground and under it. There are probably dozens in your neighborhood alone. It’s hard to imagine a world without them. But my colleagues and I are doing just that.}, number={7}, journal={IEEE Spectrum}, author={Bhattacharya, S.}, year={2017}, pages={38–43} }
 @inproceedings{beddingfield_vora_storelli_bhattacharya_2017, title={Trapezoidal characterization of magnetic materials with a novel dual voltage test circuit}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041485580&partnerID=MN8TOARS}, DOI={10.1109/ecce.2017.8095816}, abstractNote={Magnetic Core Characterization is returning as a critical area of research. This is due in part to the rise of wide bandgap semiconductors that have enabled new applications, new converter topologies and system designs that are pushing the limits of passive components. Similarly, new core materials are opening design spaces previously unfilled by legacy cores. With all of these new opportunities, it is important to fully understand the magnetic core behavior within a wide operating window. This will enable a better understanding of the materials and better approaches that leads to more globally optimized designs. This paper demonstrates core material characterizations utilizing a new test circuit. It focuses on the excitation profiles of magnetic devices, inductors and transformers, typically utilized in dual and multi-port active bridges. However, the presented characterization methods are applicable to a wide variety of power converter topologies and applications.}, booktitle={2017 IEEE Energy Conversion Congress and Exposition, ECCE 2017}, author={Beddingfield, R. and Vora, P. and Storelli, D. and Bhattacharya, Subhashish}, year={2017}, pages={439–446} }
 @inproceedings{iyer_gulur_bhattacharya_2017, title={Variable DC bus control for a bidirectional on-board electric vehicle charger}, DOI={10.1109/icrera.2017.8191216}, abstractNote={In this paper, a variable dc bus control strategy is evaluated for a bidirectional grid connected electric vehicle (EV) charger topology. The EV charger under consideration comprises of an ac-dc 3-φ active rectifier stage followed by a dc-dc dual active bridge (DAB) converter. The voltage of the common dc-link between the ac-dc stage and the dc-dc stage is regulated such that it follows the voltage variations of the battery pack. The proposed control strategy helps to minimize circulating reactive currents in the DAB converter and extends the soft-switching operating range of the same to achieve high system efficiency. An optimal design approach is presented to select the DAB converter parameters that can be used in conjunction with the variable dc bus control strategy. Experimental results on a 3.3 kW EV charger hardware prototype validate the benefits of the variable dc bus control and proposed optimal design methodology.}, booktitle={2017 ieee 6th international conference on renewable energy research and applications (icrera)}, author={Iyer, V. M. and Gulur, S. and Bhattacharya, Subhashish}, year={2017}, pages={1041–1046} }
 @inproceedings{iyer_gulur_bhattacharya_2017, title={Variable DC bus control for a bidirectional on-board electric vehicle charger}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85042717867&partnerID=MN8TOARS}, DOI={10.1109/DISTRA.2017.8191216}, booktitle={2017 6th International Conference on Renewable Energy Research and Applications, ICRERA 2017}, author={Iyer, V.M. and Gulur, S. and Bhattacharya, S.}, year={2017}, pages={1041–1046} }
 @inproceedings{kashani_bhattacharya_matamoros_kaiser_cespedes_2018, title={Voltage regulation with autonomous distributed smart inverters in a low voltage network}, volume={2018-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046350614&partnerID=MN8TOARS}, DOI={10.1109/PESGM.2017.8273934}, abstractNote={Advanced control techniques including Volt-Watt and Volt-VAR have been developed for high penetration integration of photovoltaic (PV) inverters. These techniques typically focus on voltage regulation as measured at the Point of Common Coupling (PCC). Designing advanced control functions is challenging in applications with distributed inverters not installed at the PCC due to the voltage rise in the low voltage network. This work proposes a method for control for distributed microinverters by utilizing readily available data. It is shown that this approach could reduce unnecessary PV microinverter tripping and power curtailment while supporting voltage control schemes as measured at the PCC. Test results are provided from simulation-only scenarios and a Power-Hardware-In-The-Loop (PHIL) test platform.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Kashani, M.G. and Bhattacharya, Subhashish and Matamoros, J. and Kaiser, D. and Cespedes, M.}, year={2018}, pages={1–5} }
 @article{dutta_hazra_bhattacharya_2016, title={A Digital Predictive Current-Mode Controller for a Single-Phase High-Frequency Transformer-Isolated Dual-Active Bridge DC-to-DC Converter}, volume={63}, ISSN={["1557-9948"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84983050259&partnerID=MN8TOARS}, DOI={10.1109/tie.2016.2551201}, abstractNote={This paper presents predictive current-mode control for a single-phase high-frequency transformer-isolated dual-active bridge dc-to-dc converter. The predictive control algorithm increases the bandwidth of the current loop of the converter which enables tracking of the current reference within one switching cycle. The paper further demonstrates that the application of the predictive control algorithm can remove transient dc offset from the current in high-frequency isolation transformer within one switching cycle. Direct control of the converter current protects the transformer from saturation even at transient conditions. The control algorithm has been implemented on an experimental setup and transient tests have been performed to validate controller performance. Since the predictive control algorithm is dependent on the measured value of the leakage inductance of the transformer, a compensator has been implemented to improve the parameter insensitivity of the proposed controller.}, number={9}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Dutta, Sumit and Hazra, Samir and Bhattacharya, Subhashish}, year={2016}, month={Sep}, pages={5943–5952} }
 @inproceedings{tripathi_mainali_madhusoodhanan_yadav_vechalapu_bhattacharya_2016, title={A MV intelligent gate driver for 15kV SiC IGBT and 10kV SiC MOSFET}, volume={2016-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84973596466&partnerID=MN8TOARS}, DOI={10.1109/apec.2016.7468153}, abstractNote={This paper presents an Intelligent Medium-voltage Gate Driver (IMGD) for 15kV SiC IGBT and 10kV SiC MOSFET devices. The high voltage-magnitude and high dv/dt(> 30kV/μs) of these MV SiC devices, pose design challenge in form of isolation and EMI. This problem is solved by development of a <; 1pF isolation capacitance power-supply. But due to applied high stress, smaller short-circuit withstand time and the criticality of the application, these devices need to be monitored, well protected, active gate-driven and safely shut-down. This paper presents an EMI hardened IMGD built around a CPLD, sensing and optical interfacing unit. It provides advanced gate-driving, added protection and optically isolated state-monitoring features. The device operating conditions such as module temperature and Vds(on) can be data-logged. They can be used for diagnosis/prognosis purposes such as to predict failure and safely shut-down the system. This paper describes the functionality of different building blocks. The 15kV SiC IGBT has higher second switching slope above its punch-through level which is moderated without increasing losses by using digitally controlled active gate-driving. The shoot-through protection time can be reduced below withstand time by advanced gate driving. Soft turn-on and over-current triggered gate-voltage reduction helps reducing blanking time and quick turn-off reduces the protection response time. In this paper, the IMGD is high side tested at 5kV with device state monitoring on. The active gate-driving is tested at 6kV.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Tripathi, A. and Mainali, K. and Madhusoodhanan, S. and Yadav, A. and Vechalapu, K. and Bhattacharya, Subhashish}, year={2016}, pages={2076–2082} }
 @article{mobarrez_kashani_bhattacharya_2016, title={A Novel Control Approach for Protection of Multiterminal VSC-Based HVDC Transmission System Against DC Faults}, volume={52}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84988908478&partnerID=MN8TOARS}, DOI={10.1109/tia.2016.2565458}, abstractNote={Overall performance of the voltage source converters (VSCs) has improved during the recent years. Improvement of the VSCs along with the attractive features of the VSC-based high-voltage direct current (HVdc) transmission systems over the thyristor-based HVdc transmission systems make it possible to build multiterminal VSC HVdc transmission systems. However, the VSCs are vulnerable against dc-side faults and a method needs to be employed to interrupt the dc fault current. In this paper, three different configurations of solid-state dc circuit breakers (CB) for protection purposes are studied. Moreover, a new control method to protect the VSCs against the dc-side fault is proposed. The new method makes it possible to interrupt the dc fault current with the existing ac breakers on the ac-side or with the lower rating solid-state (SS) direct current circuit breakers (DCCBs). The performance of the SS DCCBs and the proposed method are studied using real-time digital simulator.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Mobarrez, Maziar and Kashani, Mahsa Ghapandar and Bhattacharya, Subhashish}, year={2016}, pages={4108–4116} }
 @article{tripathi_mainali_madhusoodhanan_kadavelugu_vechalapu_patel_hazra_bhattacharya_hatua_2017, title={A Novel ZVS Range Enhancement Technique of a High-Voltage Dual Active Bridge Converter Using Series Injection}, volume={32}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85013096132&partnerID=MN8TOARS}, DOI={10.1109/TPEL.2016.2602285}, abstractNote={In this paper, a novel technique is proposed to extend the region of zero voltage switching (ZVS) of a dual active bridge (DAB) dc–dc converter using an auxiliary series injection transformer. The series voltage injection by the series transformer helps us to maintain ZVS by controlling the reactive power flow through the main converter of the DAB. A model for the series compensation is developed to compute the phase angle of the series voltage to obtain the optimum efficiency over the entire region of operation. The proposed technique is validated through simulations and the corresponding converter loss reduction is presented. The system is implemented on a high-voltage hardware with <inline-formula><tex-math notation="LaTeX">$6$</tex-math></inline-formula>kV-<inline-formula> <tex-math notation="LaTeX">$270$</tex-math></inline-formula>V DAB using 10-kV SiC <sc>mosfet</sc>-based converter in the primary and 1200-V SiC <sc>mosfet</sc> on the secondary side of the transformer and the corresponding results are presented.}, number={6}, journal={IEEE Transactions on Power Electronics}, author={Tripathi, A.K. and Mainali, K. and Madhusoodhanan, S. and Kadavelugu, A. and Vechalapu, K. and Patel, D.C. and Hazra, S. and Bhattacharya, S. and Hatua, K.}, year={2017}, pages={4231–4245} }
 @inproceedings{chavan_bhattacharya_2016, title={A novel control algorithm for a static series synchronous compensator using a Cascaded H-bridge converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85002406485&partnerID=MN8TOARS}, DOI={10.1109/ias.2016.7731874}, abstractNote={This paper presents a novel control scheme for a Cascaded H-bridge (CHB) converter-based Static Series Synchronous Compensator (SSSC). The SSSC is a Flexible AC Transmission Systems (FACTS) device which is a Voltage Source Converter (VSC) connected in series with the transmission line and is primarily used for real power flow control over that transmission line. SSSCs can find applications in integration of renewable energy resources within modern power systems since they can allow transmission lines to transfer power beyond their stability limits. Further, SSSCs can be used as power oscillation damping (POD) controllers within an area. CHB-based SSSCs are advantageous as compared to conventional SSSCs since they eliminate the series transformer which usually interconnects the VSC with the transmission line. This paper proposes a DC capacitor charge-balancing algorithm for the CHB VSC specific to the SSSC operation. An eleven-level CHB-based SSSC was implemented in PSCAD along with the proposed voltage-balancing algorithms and its performance was evaluated in controlling real power flow along the transmission line.}, booktitle={IEEE Industry Application Society, 52nd Annual Meeting: IAS 2016}, author={Chavan, G. and Bhattacharya, Subhashish}, year={2016} }
 @inproceedings{hazra_kamat_bhattacharya_2016, title={A partially-rated active filter enabled power architecture to generate oscillating power from wave energy converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015361074&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7854754}, abstractNote={This paper proposes an active filter (AF) enabled power architecture to harness oscillating power from wave energy converter (WEC). The proposed power architecture consisting of a diode rectifier and a dc-dc converter along with the partially-rated active filter, is cost-effective compared to conventional fully-rated power converter in generating oscillating power. The architecture is suitable to generate power using both squirrel-cage induction generator (SCIG) as well as permanent magnet synchronous generator (PMSG). In the current work, over all system modeling and control strategy is described for a SCIG based system. Feasibility of the proposed system is validated through experimental implementation with an emulated WEC excited by practical ocean wave data. The proposed system can also be effectively utilized to generate varying power from the tidal energy converter (TEC).}, booktitle={ECCE 2016 - IEEE Energy Conversion Congress and Exposition, Proceedings}, author={Hazra, S. and Kamat, P. and Bhattacharya, Subhashish}, year={2016} }
 @article{hazra_bhattacharya_2017, title={An Active Filter-Enabled Power Architecture for Oscillating Wave Energy Generation}, volume={5}, ISSN={["2168-6777"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85019126683&partnerID=MN8TOARS}, DOI={10.1109/jestpe.2016.2613081}, abstractNote={This paper proposes an active filter-enabled power architecture to harness oscillating power from wave energy converter (WEC). The power architecture consists of a diode rectifier and a dc–dc converter to extract active power and a partially rated active filter to supply harmonic and reactive power. The proposed power conversion system is cost-effective compared with a conventional, fully rated power converter in generating oscillating power from the WEC, using both squirrel-cage induction generator (SCIG) and permanent magnet synchronous generator. Analytically, it is shown that the low switching frequency of the active filter is adequate to absorb the harmonic current generated due to the diode rectification. Overall system modeling and control strategy are described for the SCIG-based system. The feasibility of the proposed system is validated through experimental implementation with an emulated WEC. A design guideline of the proposed system for high-power applications is elaborated.}, number={2}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Hazra, Samir and Bhattacharya, Subhashish}, year={2017}, month={Jun}, pages={723–734} }
 @article{sonti_jain_bhattacharya_2017, title={Analysis of the Modulation Strategy for the Minimization of the Leakage Current in the PV Grid-Connected Cascaded Multilevel Inverter}, volume={32}, ISSN={["1941-0107"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84999264517&partnerID=MN8TOARS}, DOI={10.1109/tpel.2016.2550206}, abstractNote={This paper presents a pulse width modulation (PWM) technique for the minimization of the leakage current in the grid-connected/stand-alone transformerless photovoltaic (PV)-cascaded multilevel inverter (CMLI). The proposed PWM technique is integrated with the MPPT algorithm and is applied to the five-level CMLI. Furthermore, using the proposed PWM technique the high-frequency voltage transitions in the terminal and common mode voltages are minimized. Thus, the proposed PWM technique minimizes the leakage current of the PV array and electromagnetic interference filter requirement in the system without addition of any extra switches. Furthermore, this paper also presents the analysis for the terminal voltage across the PV array and the common mode voltage of the inverter based on the switching function. Using the given analysis, the effect of the PWM technique can be analyzed, as it directly links the switching function with the common mode voltage and leakage current. Also, the proposed PWM technique requires reduced number of carrier waves compared to the conventional sinusoidal pulse width modulation technique for the given CMLI. Complete details of the working principle and analysis with the support of simulation and experimental results of the proposed PWM technique are presented in this paper.}, number={2}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Sonti, Venu and Jain, Sachin and Bhattacharya, Subhashish}, year={2017}, month={Feb}, pages={1156–1169} }
 @inproceedings{chavan_acharya_bhattacharya_das_inam_2016, title={Application of static synchronous series compensators in mitigating Ferranti effect}, volume={2016-November}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85001960773&partnerID=MN8TOARS}, DOI={10.1109/pesgm.2016.7741380}, abstractNote={This paper discusses a novel application of the SSSC which is a VSC-based FACTS device connected in series with the transmission line. An unloaded transmission line experiences Ferranti effect, i.e. the unloaded end of the transmission line experiences a voltage rise, which increases in magnitude as the length of the line increases. The SSSC can inject a controllable voltage in quadrature with the line current. Since the transmission line current is also in quadrature with the line voltage in the unloaded condition, the SSSC can take advantage of this to reduce the line voltage magnitude by injecting a voltage in phase with it. To verify this effect, the system is implemented in PSCAD along with a two-level VSC based SSSC with slightly altered controls. Voltage reduction at the receiving end was achieved when the SSSC was put in operation.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Chavan, G. and Acharya, Sayan and Bhattacharya, Subhashish and Das, D. and Inam, H.}, year={2016} }
 @article{khan_norris_chattopadhyay_husain_bhattacharya_2017, title={Autoinspection and Permitting With a PV Utility Interface (PUI) for Residential Plug-and-Play Solar Photovoltaic Unit}, volume={53}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85018514651&partnerID=MN8TOARS}, DOI={10.1109/tia.2016.2631135}, abstractNote={Renewable energy resources are becoming popular with mass adoption in residential and commercial applications because of gradual cost reduction along with continuous technical advancements. Photovoltaic (PV) energy is one of the biggest players of renewable energy installations although soft costs remain as the major barrier for higher penetration of PV systems. To address the cost challenges, a plug-and-play (PnP) system for a quick, low-cost installation is proposed and designed. The method is much less invasive and labor intensive than the traditional installation methods. This paper presents the PnP electrical system, with emphasis on the controls, software, and system-level communications within the system. A PV utility interface circuit has been developed for automated electrical safety checks and authentication for the PnP PV system. A data protocol has been used to deal with the master–slave controller setup in the system. This research has the potential to reduce the residential PV system price by $0.6/W.}, number={2}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Khan, Md Tanvir Arafat and Norris, Gregory and Chattopadhyay, Ritwik and Husain, Iqbal and Bhattacharya, Subhashish}, year={2017}, pages={1337–1346} }
 @article{vechalapu_bhattacharya_van brunt_ryu_grider_palmour_2017, title={Comparative Evaluation of 15-kV SiC MOSFET and 15-kV SiC IGBT for Medium-Voltage Converter Under the Same dv/dt Conditions}, volume={5}, ISSN={["2168-6777"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85012177488&partnerID=MN8TOARS}, DOI={10.1109/jestpe.2016.2620991}, abstractNote={The 15 kV SiC MOSFET and 15 kV SiC IGBT are two state-of-the-art high voltage SiC devices. These high voltage SiC devices enable simple two level converters for medium voltage source converter compared to the complex three level and multilevel topologies with Silicon devices. This paper presents the detailed experimental results for the characterization of 15 kV SiC MOSFET module at 10 kV and 12 kV DC bus for two different configuration of device under test. This paper also presents the switching loss comparison of 15 kV SiC MOSFET with 15 kV SiC IGBT for the same dv/dt. Based on loss data obtained from experiments, this paper finally reports the switching frequency limits of 15 kV SiC MOSFET for 10 kV DC bus, 3-Phase two level converter and Bi-directional DC-DC phase leg converter with 10 kV output voltage and comparative evaluation of 15 kV SiC MOSFET and 15 kV SiC IGBT for the same dv/dt in a unidirectional DC-DC boost hard switching converter for 10 kV output voltage.}, number={1}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Vechalapu, Kasunaidu and Bhattacharya, Subhashish and Van Brunt, Edward and Ryu, Sei-Hyung and Grider, Dave and Palmour, John W.}, year={2017}, month={Mar}, pages={469–489} }
 @inproceedings{madhusoodhanan_mainali_tripathi_kadavelugu_vechalapu_patel_bhattacharya_2016, title={Comparative evaluation of 15 kV SiC IGBT and 15 kV SiC MOSFET for 3-phase medium voltage high power grid connected converter applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015416448&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7854933}, abstractNote={The advent of high voltage (HV) wide band-gap power semiconductor devices has enabled the medium voltage (MV) grid tied operation of non-cascaded neutral point clamped (NPC) converters. This results in increased power density, efficiency as well as lesser control complexity. The multi-chip 15 kV/40 A SiC IGBT and 15 kV/20 A SiC MOSFET are two such devices which have gained attention for MV grid interface applications. Such converters based on these devices find application in active power filters, STATCOM or as active front end converters for solid state transformers. This paper presents an experimental comparative evaluation of these two SiC devices for 3-phase grid connected applications using a 3-level NPC converter as reference. The IGBTs are generally used for high power applications due to their lower conduction loss while MOSFETs are used for high frequency applications due to their lower switching loss. The thermal performance of these devices are compared based on device loss characteristics, device heat-run tests, 3-level pole heat-run tests, PLECS thermal simulation based loss comparison and MV experiments on developed hardware prototypes. The impact of switching frequency on the harmonic control of the grid connected converter is also discussed and suitable device is selected for better grid current THD.}, booktitle={ECCE 2016 - IEEE Energy Conversion Congress and Exposition, Proceedings}, author={Madhusoodhanan, S. and Mainali, K. and Tripathi, A. and Kadavelugu, A. and Vechalapu, K. and Patel, D. and Bhattacharya, Subhashish}, year={2016} }
 @inproceedings{vechalapu_negi_bhattacharya_2016, title={Comparative performance evaluation of series connected 15 kV SiC IGBT devices and 15 kV SiC MOSFET devices for MV power conversion systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015367464&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7854936}, abstractNote={The 10–15kV SiC MOSFET and 15kV SiC IGBT (2 μm and 5 μm buffer layer) are the state of the art high voltage devices designed by Cree Inc. These devices are expected to increase the power density of converters and the demonstration of these devices in applications like Solid State Transformers (SST) have been reported up to 4.16 kV–13.2 kV grid connection. It is interesting to investigate the performance of the devices in very high voltage (≥13.2 kV) application, where the series connection of devices is required. Therefore, this paper addresses design considerations of the series connection of 15 kV Silicon Carbide (SiC) IGBT devices and a series connection of 10 kV/15 kV Silicon Carbide (SiC) MOSFET devices in two separate independent cases and their experimental comparison.}, booktitle={ECCE 2016 - IEEE Energy Conversion Congress and Exposition, Proceedings}, author={Vechalapu, K. and Negi, A. and Bhattacharya, Subhashish}, year={2016} }
 @inproceedings{chattopadhyay_bhattacharya_2016, title={Decoupled power flow using phase shift control and ZVS cases for a three limb high frequency transformer based three-port DAB integrating PV and energy storage}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85002213818&partnerID=MN8TOARS}, DOI={10.1109/ias.2016.7731872}, abstractNote={The work presented in this paper focuses on the decoupled power flow control using phase shift control technique and resulting ZVS scenarios for three-limb high frequency transformer enabled three port Dual Active Bridge(DAB) converter, integrating PV and Energy Storage(ES). The advantage of using three-limb transformer is the low inter-winding parasitic capacitances due to positioning of windings on different limbs and elimination of high insulation requirements unlike concentric windings. The focus of the paper is based on decoupled power flow control of three port DAB using phase shift control, and ZVS scenario study under the phase shift control. Detailed analysis for power flow control and turn-on/turn-off ZVS conditions have been realized. Detailed Simulation Studies have been done and comprehensive results have been obtained for 700V dc PV//ES voltage and 1200V dc output voltage.}, booktitle={IEEE Industry Application Society, 52nd Annual Meeting: IAS 2016}, author={Chattopadhyay, R. and Bhattacharya, Subhashish}, year={2016} }
 @article{hazra_madhusoodhanan_moghaddam_hatua_bhattacharya_2016, title={Design Considerations and Performance Evaluation of 1200-V 100-A SiC MOSFET-Based Two-Level Voltage Source Converter}, volume={52}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84988904992&partnerID=MN8TOARS}, DOI={10.1109/tia.2016.2587098}, abstractNote={Silicon carbide (SiC) MOSFET is capable of achieving better efficiency and better power density of power converters due to its low on-state resistance and lower switching losses compared to silicon (Si) Insulated Gate Bipolar Transistor. Operation of power converters at higher switching frequency using SiC devices allows reduction in filter size and hence improves the power to weight ratio of the converter. This paper presents switching characterization of 1200-V 100-A SiC MOSFET module and compares the efficiency of a two-level voltage source converter (2L-VSC) using SiC MOSFETs and Si IGBTs. Also, various design considerations of the 1200-V 100-A SiC MOSFET-based 2L-VSC including gate drive design, bus bar packaging, and thermal management have been elaborated. The designed and developed 2L-VSC is operated to supply 35 kVA load at 20-kHz switching frequency with dc bus voltage of 800 V and the corresponding experimental results are presented.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Hazra, Samir and Madhusoodhanan, Sachin and Moghaddam, Giti Karimi and Hatua, Kamalesh and Bhattacharya, Subhashish}, year={2016}, pages={4257–4268} }
 @inproceedings{mainali_madhusoodhanan_tripathi_vechalapu_de_bhattacharya_2016, title={Design and evaluation of isolated gate driver power supply for medium voltage converter applications}, volume={2016-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84973644285&partnerID=MN8TOARS}, DOI={10.1109/apec.2016.7468085}, abstractNote={The commercial gate drivers are available upto 6.5 kV IGBTs. With the advances in the SiC, power devices rated beyond 10 kV are being researched. These devices will have use on medium voltage power converters. Commercial gate drivers rated for such high voltages are not available. These power devices have very high dv/dts (30-100 kV/μs) at switching transitions. Such high dv/dts bring in challenges in the gate driver design. The isolation stage of the gate power supply needs to have very low coupling capacitance to limit the high frequency circulating currents from reaching the gate driver control circuits. Also, the isolation stage has to be designed with insulation several times higher than the peak system voltage level. In this paper, design, development and evaluation of the gate power supply for medium voltage level applications have been investigated. Several isolation transformer designs have been investigated and optimum design, with very low coupling capacitance ≈ 0.5 pF, has been identified and used in the gate driver design. Experimental characterization of the transformer has been done. The performance of the gate driver power supply has been evaluated in several MV power converters, using 10 kV SiC MOSFETs.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Mainali, K. and Madhusoodhanan, S. and Tripathi, A. and Vechalapu, K. and De, A. and Bhattacharya, Subhashish}, year={2016}, pages={1632–1639} }
 @inproceedings{kashani_cho_bhattacharya_2016, title={Design consideration of volt-VAR controllers in distribution systems with multiple PV inverters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015376247&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7855012}, abstractNote={Advanced control techniques such as Volt-VAR Control (VVC) are required for integration of multiple distributed renewable energy, such as Photovoltaic (PV) resources, on an electric distribution system. However, undesired interactions have been observed among these Volt-VAR controlled PV inverters which leads to oscillation and instability of the system. In this paper, an analytical approach to study the stability of local voltage control in high PV penetrated distribution systems with advanced Volt-VAR control functions is employed. The transient of inverter Volt-VAR Control interactions and dynamics of the interconnected feed-back loops in the distribution circuits are investigated. It is shown analytically that the Grid impedances, droop slope, PI controller parameters, response time and delay time in the VVC are the main factors affecting the dynamic response of the system, and the absence of a standard selection criteria for inverter and controller parameters under different Grid impedances results in undesired potential interactions among the PV inverters and distribution power system.}, booktitle={ECCE 2016 - IEEE Energy Conversion Congress and Exposition, Proceedings}, author={Kashani, M.G. and Cho, Y. and Bhattacharya, Subhashish}, year={2016} }
 @inproceedings{de_morgan_iyer_ke_zhao_vechalapu_bhattacharya_hopkins_2016, title={Design, package, and hardware verification of a high voltage current switch}, volume={2016-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84973664278&partnerID=MN8TOARS}, DOI={10.1109/apec.2016.7467887}, abstractNote={This paper demonstrates various electrical and package design considerations in series connecting a high-voltage (HV) silicon (Si)-IGBT (6500-V/25-A die) and a silicon carbide-junction barrier Schottky diode (6500-V/25-A die) to form an HV current switch. The effects of connecting the cathode of the series diode to an IGBT collector, versus connecting the IGBT emitter to the anode of the series diode, are analyzed in regards to minimizing the parasitic inductance. An optimized package structure is discussed and an HV current switch module is custom fabricated in the laboratory. An HV double pulse test circuit is used to verify the switching performance of the current switch module. Low-voltage and HV converter prototypes are developed and tested to ensure thermal stability of the same. The main motivation of this paper is to enumerate detailed design considerations for packaging an HV current switch.}, note={\urlhttps://ieeexplore.ieee.org/document/7467887/}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={De, A. and Morgan, A. and Iyer, V.M. and Ke, H. and Zhao, X. and Vechalapu, K. and Bhattacharya, Subhashish and Hopkins, D.C.}, year={2016}, pages={295–302} }
 @inproceedings{shrivastav_singh_mahajan_bhattacharya_2016, title={Effective control & software techniques for high efficiency GaN FET based flexible electrical power system for cube-satellites}, volume={2016-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84973650201&partnerID=MN8TOARS}, DOI={10.1109/apec.2016.7467933}, abstractNote={This paper investigates an intelligent and configurable electric power system (EPS) for CubeSats and small satellites built using Silicon and GaN FETs at high switching frequency. The EPS is the power source of CubeSat which harnesses power from solar panels and includes battery charging and multi-domain voltage output regulation within the CubeSat. The electrical power system of a Cube-Satellite is developed and is used as a test bed for implementation of the various control algorithms necessary for such photovoltaic - battery based power management systems. The introduction of a digital controller to such power systems provides the system added flexibility and intelligence but also introduces controller design challenges with many control loops running simultaneously and being controlled by a single controller. Efficiency of power converter is increased using pulse frequency modulation (PFM) at light load. For moderate load, higher efficiency can be achieved with comparatively lower Rds-ON based GaN FETs. In this paper we have implemented a control scheme that takes into account various parameters like load transients, control loop update rate and sampling intervals that have an effect on the system performance. Power loss analysis is done for EPS using silicon devices. Simulation and experimental results are presented in this paper using both Silicon and 100V EPC Gallium Nitride Mosfets in PFM and PWM mode for EPS.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Shrivastav, A. and Singh, S. and Mahajan, A. and Bhattacharya, Subhashish}, year={2016}, pages={601–608} }
 @inproceedings{tripathi_madhusoodhanan_mainali_vcchalapu_chattopadhyay_bhattacharya_2016, title={Enabling DC microgrids with direct MV DC interfacing DAB converter based on 15 kV SiC IGBT and 15 kV SiC MOSFET}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015358617&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7855078}, abstractNote={The 15 kV SiC IGBT and 15 kV SiC MOSFET have been recently developed to enable non-cascaded high-frequency (HF) MV converters. Such direct MV DC interfacing Dual Active Bridge (DAB) converter is getting popular for DC micro-grid application due to higher efficiency, higher power-density and higher MTBF over the cascaded DAB topology. The high dv/dt in these devices on hard-switching with their inherent parasitics, causes increased EMI and switching loss. The suitability of the two family of SiC devices for an application, depends on the switching frequency, load range and magnitude of power, operating temperature and converter power density. This paper compares the two devices for a MV DAB application for dc micro-grid based on simulation and also with supporting MV side converter experiments up to 10kV DC bus and under 5–20kHz switching frequencies.}, booktitle={ECCE 2016 - IEEE Energy Conversion Congress and Exposition, Proceedings}, author={Tripathi, A. and Madhusoodhanan, S. and Mainali, K. and Vcchalapu, K. and Chattopadhyay, R. and Bhattacharya, Subhashish}, year={2016} }
 @article{bhattacharya_saha_hossain_2016, title={Fault contribution from large photovoltaic systems in building power supply networks}, volume={5}, ISSN={2352-7102}, url={http://dx.doi.org/10.1016/J.JOBE.2016.01.005}, DOI={10.1016/J.JOBE.2016.01.005}, abstractNote={This paper presents a detailed analysis for determining the impact of adding large three phase photovoltaic (PV) systems in secondary (building) power distribution networks. The analysis highlights the protection relay coordination problems arising due to the increase in network fault levels caused due to the contribution from PV generators. A typical distribution network for power supply to large buildings with multiple apartments in a housing complex has been modeled and used as a test network. Simulation result shows that the magnitude of fault current contribution from PV system depends on a number of different factors, not only on the size of the PV system. The analysis emphasizes the requirement to review protection settings of similar installations prior to connection of PV generators to the network and suggests a method of protection coordination to minimize the requirement of reviewing the protection setting every time a new PV system is connected to the distribution network. It is found that fault current contribution from PV systems, depending on the size, can cause significant relay coordination problems in terms of discrimination and thereby reduce system reliability.}, journal={Journal of Building Engineering}, publisher={Elsevier BV}, author={Bhattacharya, Subhashish and Saha, Tapan and Hossain, M.J.}, year={2016}, month={Mar}, pages={222–230} }
 @inproceedings{hazra_bhattacharya_2016, title={Hybrid energy storage system comprising of battery and ultra-capacitor for smoothing of oscillating wave energy}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015425966&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7855172}, abstractNote={In this work, a hybrid energy storage system (HESS) comprising of ultra-capacitor and battery is proposed for smoothing oscillating power from wave energy conversion system (WECS). Using generated power data from an installed wave energy converter (WEC), each component of the proposed HESS is sized to optimize the cost of the energy storage. A control scheme is designed to regulate the power into battery and ultra-capacitor to deliver smoothed average power to the grid. Energy storage minimizes the grid side converter (GSC) rating and also improves the stability of the grid by not injecting the oscillating power. The control scheme is verified through MATLAB simulation using the power data from field with maximum power reaching around 500-kW and a combination of available ultra-capacitors and batteries. An experimental validation of the control scheme is presented with an ultra-capacitor based energy storage system in a grid-connected wave energy conversion system (WECS) with an induction motor emulating as WEC to drive an induction generator.}, booktitle={ECCE 2016 - IEEE Energy Conversion Congress and Exposition, Proceedings}, author={Hazra, S. and Bhattacharya, Subhashish}, year={2016} }
 @article{chavan_weiss_chakrabortty_bhattacharya_salazar_ashrafi_2017, title={Identification and Predictive Analysis of a Multi-Area WECC Power System Model Using Synchrophasors}, volume={8}, ISSN={1949-3053 1949-3061}, url={http://dx.doi.org/10.1109/tsg.2016.2531637}, DOI={10.1109/TSG.2016.2531637}, abstractNote={This paper describes the construction of a reduced-order five-machine dynamic equivalent electro-mechanical model of the Western Electricity Coordinating Council (WECC) 500 kV power system network using slow mode oscillations of power flows derived from phasor measurement unit data. We first extract the slow oscillations using modal decomposition, and use them to estimate four key parameters of the reduced-order system, namely, the inter-area transmission line impedances, intra-area Thevenin reactances, rotational inertia, and damping of the aggregated synchronous generators. The resulting five-machine equivalent model is validated using different ranges of contingencies such as generation loss and line loss, and thereafter used for accurate prediction of oscillation mode frequencies and their damping factors. Finally, we present an algorithm by which this reduced-order model can be used to determine the criticality of line loss events within any area based on the divergence of load flow. The conclusions are drawn with the possible applications of the model for transient stability assessment, and prediction of stability limits needed to sustain increasing wind power penetration in the WECC.}, number={4}, journal={IEEE Transactions on Smart Grid}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Chavan, Govind and Weiss, Matthew and Chakrabortty, Aranya and Bhattacharya, Subhashish and Salazar, Armando and Ashrafi, Farrokh-Habibi}, year={2017}, month={Jul}, pages={1977–1986} }
 @inproceedings{madhusoodhanan_mainali_tripathi_vechalapu_bhattacharya_2016, title={Medium voltage (≥ 2.3 kV) high frequency three-phase two-level converter design and demonstration using 10 kV SiC MOSFETs for high speed motor drive applications}, volume={2016-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84973597838&partnerID=MN8TOARS}, DOI={10.1109/apec.2016.7468066}, abstractNote={High speed variable frequency motor drives are required for marine applications, compressors for oil and gas industries, wind energy generation systems etc. Traditionally, low voltage high speed motor drives are used in such applications. This results in large currents at high power levels leading to large copper loss in the motor winding. Therefore, medium voltage (MV) drives are being considered. The silicon (Si) based MV drives need gears to increase the speed due to low switching frequency operation of Si devices in the converter. Gears reduce both efficiency and power density. With the development of 10 kV SiC MOSFET, high switching frequency at MV is possible, which has enabled the scope of high power density MV direct drive variable speed controlled motors. In this paper, the design of a three-phase, 2-level, ≥ 2.3 kV MV, high frequency converter based on 10 kV SiC MOSEFT is explained. Performance analysis is presented along with experimental demonstration.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Madhusoodhanan, S. and Mainali, K. and Tripathi, A. and Vechalapu, K. and Bhattacharya, Subhashish}, year={2016}, pages={1497–1504} }
 @inproceedings{chattopadhyay_juds_ohodnicki_bhattacharya_2016, title={Modelling, design and analysis of three limb high frequency transformer including transformer parasitics, for SiC Mosfet based three port DAB}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85010028398&partnerID=MN8TOARS}, DOI={10.1109/iecon.2016.7793593}, abstractNote={The work presented in this paper focuses on the transformer modelling, design and parasitic capacitances' effect on transformer operation for three-limb high frequency transformers designed for three port Dual Active Bridge(DAB) converter, using 1200V and 1700V SiC devices. The effects of parasitic capacitance due to high speed and high frequency switching enabled by SiC Mosfet devices are investigated in this paper for three limb transformer of DAB converter. The focus of the paper is based on design, estimation and measurement of parasitic capacitance and leakage inductance for three limb high frequency transformer. Detailed transformer model analysis has been realized for three port DAB operation with parasitics included. Two different transformer design approaches for 10kW, 50kHz rating have been carried out and comparative results have been analyzed in this paper.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Chattopadhyay, R. and Juds, M.A. and Ohodnicki, P.R. and Bhattacharya, Subhashish}, year={2016}, pages={4181–4186} }
 @inproceedings{vechalapu_bhattacharya_2016, title={Performance comparison of 10 kV#x2013;15 kV high voltage SiC modules and high voltage switch using series connected 1.7 kV LV SiC MOSFET devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015454079&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7855339}, abstractNote={. The 10 kV to 15 kV SiC MOSFET and 15 kV SiC IGBT are state of the art high voltage (HV) devices designed by Cree Inc. These devices are expected to increase the power density of converters and are expected to replace 4.5 kV/6.5 kV Si IGBTs. However, these are not commercially available. On the other hand low voltage (LV) 1.7 kV SiC MOSFET is commercially available, and it is replacing existing 1.7 kV Si-IGBT and it can meet immediate need of medium or high voltage (MV or HV) converter applications with series connection of these devices and can replace existing 4.5 kV/6.5 kV Silicon (Si) IGBT. Therefore, 10 kV-15 kV SiC modules and series connected 1.7 kV SiC MOSFET will be competing with each other for MV and HV converter applications. Hence, to explore the capability of low voltage SiC devices for MV or HV applications, a HV switch (10 kV-15 kV) using the series connection of 1.7 kV/300 A SiC MOSFET modules has been investigated. For making HV switch using series connected 1.7 kV SiC MOSFET, a simple RC snubber method has been used for dynamic voltage sharing to offset the turn-off delays due to mismatch of device characteristics and gate signals. Experimental switching characterization with different values of RC snubbers has been carried out, and a methodology has been outlined to find the optimal RC snubber which gives minimum voltage sharing difference, snubber losses and total semiconductor losses. In addition, experimental switching characterization of 10 kV-15 kV SiC modules is presented. Furthermore, a performance comparison of HV 10 kV-15 kV SiC modules and HV switch using series connected 1.7 kV SiC MOSFETs is presented in this paper.}, booktitle={ECCE 2016 - IEEE Energy Conversion Congress and Exposition, Proceedings}, author={Vechalapu, K. and Bhattacharya, Subhashish}, year={2016} }
 @inproceedings{vechalapu_negi_bhattacharya_2016, title={Performance evaluation of series connected 15 kV SiC IGBT devices for MV power conversion systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015420529&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7855343}, abstractNote={The 15kV SiC IGBT (2 μm buffer layer) with chip area of 8.4 × 8.4 mm2 is the state of the art high voltage device designed by Cree Inc. This device is expected to increase the power density of converters and the demonstration of the device in applications like Solid State Transformers has been published. Therefore, it is interesting to investigate the performance of the device in very high voltage (HV) application, where the series connection of devices is required. This paper addresses design considerations of the series connection of 15kV SiC IGBT devices for high voltage converter applications. A simple RC snubber has been used to control both ‘dv/dt’ and dynamic voltage balancing during turn-off. The experimental results show that there is a significant difference in the static and dynamic voltage sharing between two unmatched 15kV SiC IGBTs without active compensation method. With external RC snubber at total DC bus voltage of 10 kV, the difference in dynamic voltage between the two 15 kV SiC IGBT devices during turn-off transition nearly negligible. Also with external snubber, the total turn-off dv/dt of less than ‘5 kV/ μs’ is achieved across each device of two series connected 15kV SiC IGBTs. Furthermore, optimization of RC snubber to minimize semiconductor switching losses and total losses per device including the snubber resistor losses in series connection has been presented.}, booktitle={ECCE 2016 - IEEE Energy Conversion Congress and Exposition, Proceedings}, author={Vechalapu, K. and Negi, A. and Bhattacharya, Subhashish}, year={2016} }
 @article{madhusoodhanan_mainali_tripathi_kadavelugu_patel_bhattacharya_2016, title={Power Loss Analysis of Medium-Voltage Three-Phase Converters Using 15-kV/40-A SiC N-IGBT}, volume={4}, ISSN={["2168-6777"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84982806206&partnerID=MN8TOARS}, DOI={10.1109/jestpe.2016.2587666}, abstractNote={Medium-voltage (MV) silicon carbide (SiC) devices such as the 15-kV SiC N-insulated gate bipolar transistor (IGBT) have better thermal withstanding capability compared with silicon (Si)-based devices. These devices also have lower switching and conduction losses at high switching frequencies and high power levels, respectively. The maximum safe operating junction temperature for the 15-kV SiC IGBT is 175 °C. This enables high power density design of the MV converters using this device. Heat sink with forced air cooling is considered for dissipating the heat generated during converter operation. In this paper, the power loss analysis of three-phase MV converters based on 15-kV/40-A SiC N-IGBT is discussed. The converter thermal analysis is carried out based on the experimental loss data and the continuous heat-run test of the device. It is supported by analytical calculations, PLECS thermal simulations, and FEM simulations in COMSOL Multiphysics software. Hardware prototypes of the converters are developed and the experimental results support the analysis. Experimental results are given for both hard-switched grid-connected converter and soft-switched dual active bridge converter. The paper mainly focuses on the semiconductor losses in the converter.}, number={3}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Madhusoodhanan, Sachin and Mainali, Krishna and Tripathi, Awneesh Kumar and Kadavelugu, Arun and Patel, Dhaval and Bhattacharya, Subhashish}, year={2016}, month={Sep}, pages={902–917} }
 @inproceedings{chattopadhyay_bhattacharya_2016, title={Power flow control and ZVS analysis of three limb high frequency transformer based three-port DAB}, volume={2016-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84973597860&partnerID=MN8TOARS}, DOI={10.1109/apec.2016.7467960}, abstractNote={The work presented in this paper focuses on the power flow control and study of three-limb high frequency transformer enabled three port Dual Active Bridge(DAB) converter, using 1200V and 1700V SiC devices. The advantage of using three-limb transformer is given by the low inter-winding parasitic capacitances due to placement of windings on different limbs and elimination of inter-winding insulations unlike concentric windings. The focus of the paper is based on power characterization for independent power flow of three port DAB using modulation control, and ZVS scenario study under the modulation control. Detailed analysis for power flow control and turn-on/turn-off ZVS conditions have been realized. A laboratory scale prototype using SiC Mosfets has been made and experimental results have been obtained for 500V dc input voltages and 1000V dc output voltage at 8.2kW of power.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Chattopadhyay, R. and Bhattacharya, Subhashish}, year={2016}, pages={778–785} }
 @inproceedings{cho_han_beddingfield_ha_bhattacharya_2016, title={Seamless black start and reconnection of LCL-filtered solid state transformer based on droop control}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015434753&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7855416}, abstractNote={The solid state transformer (SST) is an emerging technology that can replace conventional passive transformers and actively manage renewable energy resources, energy storage devices, and loads. In this paper, a seamless black start control strategy is proposed for an SST-based smart grid system that has fault ride-through capability when it is islanded from the grid. Also, a method is developed to achieve smooth reconnection to the grid after a fault is cleared. The main component of the proposed control strategy is control of the high-voltage side converter of the SST (HV SST), which is based on a combination of droop control and an LCL filter. A single-loop controller for the capacitor voltage of the LCL filter is proposed, and simple criteria for setting compensator gains are provided. A low-voltage scaled SST system is introduced, and the controllers of the converters within the system are described. The proposed control strategy has been tested in simulation and experimentally on a low-voltage scaled testbed.}, booktitle={ECCE 2016 - IEEE Energy Conversion Congress and Exposition, Proceedings}, author={Cho, Y. and Han, Y. and Beddingfield, R.B. and Ha, J.-I. and Bhattacharya, Subhashish}, year={2016} }
 @inproceedings{tripathi_madhusoodhanan_mainali_vechalapu_bhattacharya_2016, title={Series injection enabled full ZVS light load operation of a 15kV SiC IGBT based dual active half bridge converter}, volume={2016-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84973607429&partnerID=MN8TOARS}, DOI={10.1109/apec.2016.7467976}, abstractNote={The 15kV SiC IGBT has second higher dv/dt turn-off slope above the punch-through level resulting in EMI. Increasing gate-resistance also slows the first dv/dt causing increased switching loss. A snubber capacitor assisted turn-off solves these issues for a high power dual active bridge (DAB) converter based on this device, but the light load turn-on ZVS becomes hard to achieve. This paper proposes a series injection enabled triangular current shaping at the light load turn-off instant in the DAB to create enough current for smooth free-wheeling transition of device voltage during the dead-time period for ZVS turn-on. The proposed technique is validated through simulations followed by experiments on a medium voltage DAB hardware implementation of this technique.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Tripathi, A. and Madhusoodhanan, S. and Mainali, K. and Vechalapu, K. and Bhattacharya, Subhashish}, year={2016}, pages={886–892} }
 @inproceedings{cho_han_madhusoodhanan_ha_bhattacharya_2016, title={Synchronous frame full-order observer design for three-phase buck-type PWM rectifier}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85010078135&partnerID=MN8TOARS}, DOI={10.1109/iecon.2016.7794059}, abstractNote={This paper presents a synchronous reference frame full-order observer for a three-phase buck-type PWM rectifier that estimates both the currents of the input filter inductors and the voltages of the input filter capacitors. Either the currents or the voltages are needed in most cases to control the input grid power factor and the output dc voltage or current. For example, multiloop control strategies, which have been widely used for power rectifiers that are equipped with higher order LC or LCL input filters, require input filter currents or voltages. Using the proposed observer, the number of actual sensors needed for a buck-type rectifier control system can be reduced while maintaining fast dynamic performance and steady-state accuracy. The feasibility of the proposed technique is verified through MATLAB/PLECS simulations and experiments.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Cho, Y. and Han, Y. and Madhusoodhanan, S. and Ha, J.-I. and Bhattacharya, Subhashish}, year={2016}, pages={3618–3622} }
 @inproceedings{chattopadhyay_bhattacharya_2016, title={ZVS analysis and power flow control for three limb transformer enabled SiC Mosfet based three port DAB integrating PV and Energy Storage(ES)}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015404568&partnerID=MN8TOARS}, DOI={10.1109/ecce.2016.7855565}, abstractNote={Multi-port dc-dc converters are the modular power electronic building blocks for integration of PV and Energy Storages(ES). The work in this paper focuses on ZVS characteristics for independent power flow control of three port DAB converter integrating PV and Energy Storage(ES), using three limb high frequency transformer. The independent power flow control discussed here, focuses on ES charging scenario for the converter using two different modulation techniques. ZVS scenario variations for two different modulation control technique for two different designs of three limb transformers, are discussed in the paper. A laboratory scale prototype using 1200V and 1700V SiC Mosfets has been made and preliminary results have been obtained for experimental validation of the ZVS scenarios.}, booktitle={ECCE 2016 - IEEE Energy Conversion Congress and Exposition, Proceedings}, author={Chattopadhyay, R. and Bhattacharya, Subhashish}, year={2016} }
 @article{mainali_tripathi_madhusoodhanan_kadavelugu_patel_hazra_hatua_bhattacharya_2015, title={A Transformerless Intelligent Power Substation: A three-phase SST enabled by a 15-kV SiC IGBT}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84960131504&partnerID=MN8TOARS}, DOI={10.1109/MPEL.2015.2449271}, abstractNote={The solid-state transformer (SST) is a promising power electronics solution that provides voltage regulation, reactive power compensation, dc-sourced renewable integration, and communication capabilities, in addition to the traditional step-up/step-down functionality of a transformer. It is gaining widespread attention for medium-voltage (MV) grid interfacing to enable increases in renewable energy penetration, and, commercially, the SST is of interest for traction applications due to its light weight as a result of medium-frequency isolation. The recent advancements in silicon carbide (SiC) power semiconductor device technology are creating a new paradigm with the development of discrete power semiconductor devices in the range of 10-15 kV and even beyond-up to 22 kV, as recently reported. In contrast to silicon (Si) IGBTs, which are limited to 6.5-kV blocking, these high-voltage (HV) SiC devices are enabling much simpler converter topologies and increased efficiency and reliability, with dramatic reductions of the size and weight of the MV power-conversion systems. This article presents the first-ever demonstration results of a three-phase MV grid-connected 100-kVA SST enabled by 15-kV SiC n-IGBTs, with an emphasis on the system design and control considerations. The 15-kV SiC n-IGBTs were developed by Cree and packaged by Powerex. The low-voltage (LV) side of the SST is built with 1,200-V, 100-A SiC MOSFET modules. The galvanic isolation is provided by three single-phase 22-kV/800-V, 10-kHz, 35-kVA-rated high-frequency (HF) transformers. The three-phase all-SiC SST that interfaces with 13.8-kV and 480-V distribution grids is referred to as a transformerless intelligent power substation (TIPS). The characterization of the 15-kV SiC n-IGBTs, the development of the MV isolated gate driver, and the design, control, and system demonstration of the TIPS were undertaken by North Carolina State University's (NCSU's) Future Renewable Electrical Energy Delivery and Management (FREEDM) Systems Center, sponsored by an Advanced Research Projects Agency-Energy (ARPA-E) project.}, number={3}, journal={IEEE Power Electronics Magazine}, author={Mainali, K. and Tripathi, A. and Madhusoodhanan, S. and Kadavelugu, A. and Patel, D. and Hazra, S. and Hatua, K. and Bhattacharya, S.}, year={2015}, pages={31–43} }
 @article{babaei_bhattacharya_2015, title={A control structure for PWM-controlled static synchronous compensators under unbalanced conditions and grid faults}, volume={71}, ISSN={["1879-3517"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84925149499&partnerID=MN8TOARS}, DOI={10.1016/j.ijepes.2015.02.035}, abstractNote={Grid connected Voltage Source Converters (VSCs) are the heart of many applications with power quality concerns due to their reactive power controllability. Among the widely used grid-connected applications of the VSCs, the Static Synchronous Compensators (STATCOMs) are commonly used for compensating the voltage quality problems that come from voltage sag and swell. In spite of superior feature of fast voltage regulation and reactive power support functionality, VSC-based STATCOMs have the major drawback of being sensitive to the grid disturbances, especially the unbalanced condition and faults. Moreover, when the STATCOMs are used in the Distributed Generation (DG) applications or reactive power support of the sensitive industrial load, the unbalanced condition becomes even more intolerable. Protection system usually trips due to over current or highly distorted current caused by negative sequence current flow under unbalanced conditions and system faults. This paper propose an alternative control structure to keep the VSC-based STATCOM online during the unbalanced condition and system faults by limiting the negative sequence current. This eliminates the need to redesign/overdesign of the STACOM power components and over rating of the semiconductor switches to operate under fault current. Converter MVA rating reduction will decrease the cost significantly. Proposed controller performance has been verified by simulation and Hardware-In-the-Loop test.}, journal={INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS}, author={Babaei, Saman and Bhattacharya, Subhashish}, year={2015}, month={Oct}, pages={160–173} }
 @inproceedings{mobarez_kashani_chavan_bhattacharya_2015, title={A novel control approach for protection of multi-terminal VSC based HVDC transmission system against DC faults}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963632405&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310254}, abstractNote={Overall performance of the voltage source converters (VSCs) has improved during the recent years. Improvement of the VSCs along with the attractive features of the VSC based high voltage direct current (HVDC) transmission systems over the thyristor based HVDC transmission systems make it possible to build multiterminal (MT) VSC HVDC transmission systems. However, the VSCs are vulnerable against dc side faults and a method needs to be employed to extinguish the dc fault current. In this paper, three different configurations of solid state dc circuit breakers (CB) for protection purposes are studied. Moreover, a new control method to protect the VSCs against the dc side fault is proposed, the new method makes it possible to extinguish the dc fault current with the existing ac breakers on the ac side or with the lower rating solid state (SS) DCCBs. The performance of the SS DCCBs and the proposed method are studied using Real Time Digital Simulator (RTDS).}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Mobarez, M. and Kashani, M.G. and Chavan, G. and Bhattacharya, Subhashish}, year={2015}, pages={4208–4213} }
 @inproceedings{khan_norris_chattopadhyay_husain_bhattacharya_2015, title={Auto-inspection and permitting with a PV Utility Interface (PUI) for residential plug-and-play solar photovoltaic unit}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963549051&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310469}, abstractNote={Renewable energy resources are becoming popular with mass adoption in residential and commercial applications because of gradual cost reduction along with continuous technical advancements. Photovoltaic (PV) energy is one of the biggest players of renewable energy installations although soft costs remain as a major barrier for higher penetration of PV systems. To significantly lower the soft costs related to residential photovoltaic system installations, a Plug-and-Play (PnP) system has been designed which allows for a quick, low-cost installation. The method is much less invasive and labor intensive than traditional installation methods involving drilling holes through walls and installing additional panel boxes within the house. This paper presents the PnP electrical system, with emphasis on the controls, software, and system level communications within the system. A PV Utility Interface (PUI) circuit has been developed for automated electrical safety checks and authentication for implementing the PnP PV system. A data protocol has been used to deal with the master-slave controller setup in the system.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Khan, M.T.A. and Norris, G. and Chattopadhyay, R. and Husain, I. and Bhattacharya, Subhashish}, year={2015}, pages={5763–5770} }
 @inproceedings{vechalapu_bhattacharya_brunt_ryu_grider_palmour_2015, title={Comparative evaluation of 15 kV SiC MOSFET and 15 kV SiC IGBT for medium voltage converter under same dv/dt conditions}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963553261&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7309787}, abstractNote={The 15-kV silicon carbide (SiC) MOSFET and 15-kV SiC IGBT are the two state-of-the-art high-voltage SiC devices. These high-voltage SiC devices enable simple two-level converters for a medium-voltage (MV) voltage source converter (VSC) topology compared with the complex three-level neutral point clamped and other multilevel topologies, which, otherwise, is required to realize for MV VSC with silicon devices. This paper characterizes the 15-kV SiC MOSFET module at 10- and 12-kV dc bus for two different configurations of the device under test. This paper also presents endurance test (continuous switching-mode experimental demonstration) of 15-kV SiC MOSFET for 10-kV output voltage for both a bidirectional and unidirectional dc–dc boost converter. Furthermore, this paper presents: 1) the switching loss comparison of 15-kV SiC MOSFET with 15-kV SiC IGBT for the same dv/dt condition; 2) the switching frequency limits of 15-kV SiC MOSFET for a dc–dc boost converter with a phase leg configuration at 10-kV output voltage; and 3) comparative evaluation of 15-kV SiC MOSFET and 15-kV SiC IGBT in a unidirectional dc–dc boost converter for 10 V output voltage.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Vechalapu, K. and Bhattacharya, Subhashish and Brunt, E. Van and Ryu, S.-H. and Grider, D. and Palmour, J.W.}, year={2015}, pages={927–934} }
 @inproceedings{acharya_vechalapu_bhattacharya_yousefpoor_2015, title={Comparison of DC fault current limiting capability of various modular structured multilevel converters within a multi-terminal DC grid}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963525471&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310107}, abstractNote={With the development of Modular structured Voltage Source Converters (VSC), Multi-Terminal DC (MTDC) transmission systems have now become a feasible solution to transmit power at high voltage which greatly improves the electric power transmission system. The MTDC grid has lower capital costs and lower losses than an equivalent AC transmission system. Thus for long distance power transmission MTDC grid becomes a very attractive solution. Since the MTDC network is now built based on VSCs, it automatically offers better quality of transmitted power along with more flexibility in power transmission over the conventional current source converters. However, VSC based MTDC transmission systems are vulnerable to DC side fault and expensive DC circuit breakers are required to protect them against DC fault. This paper compares the DC short circuit fault response of different modular multi-level converters (MMC) inside a MTDC system. For the comparison purpose two different kind of MMC topologies have been considered namely, Modular Multi-level Converter (MMC) with High Frequency DC/DC Isolation Stage and MMC with full bridge sub modules. The paper analyzes the fault current limiting capabilities of each of the converters. PSCAD simulation is also done to prove the relevance of the analysis.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Acharya, Sayan and Vechalapu, K. and Bhattacharya, Subhashish and Yousefpoor, N.}, year={2015}, pages={3184–3191} }
 @inproceedings{yousefpoor_bhattacharya_2015, title={Control and dynamic performance evaluation of Multi-Terminal DC grid}, volume={2015-September}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84956855351&partnerID=MN8TOARS}, DOI={10.1109/pesgm.2015.7286382}, abstractNote={In this paper, the operation of Voltage Source Converter (VSC) based Multi-Terminal DC (MTDC) transmission system consisting of three different power converter topologies is evaluated. The high frequency isolated modular converter is used as the VSC configuration for two terminals. The Modular Multi-level Converter (MMC) and three-phase AC/DC converters are also used as the VSC configuration for the other two terminals. In the high frequency isolated modular converter configuration, several H-bridge modules are connected in cascade. From the MTDC system control point of view, a droop control structure with dead-band controller is proposed for MTDC grid control. The dynamic performance of a four-terminal DC grid is further investigated in PSCAD/EMTDC environment. Simulation results are presented to verify the performance of multi-terminal DC grid based on the proposed control method.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Yousefpoor, N. and Bhattacharya, Subhashish}, year={2015} }
 @article{yousefpoor_parkhideh_azidehak_kim_bhattacharya_2015, title={Control of High-Frequency Isolated Modular Converter}, volume={51}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84957878360&partnerID=MN8TOARS}, DOI={10.1109/tia.2015.2457402}, abstractNote={Recently, voltage-source converter (VSC)-based high-voltage dc (HVDC) transmission systems have gained more attention. In this paper, a control method for a modular VSC-based HVDC transmission system with high-frequency isolation referred to as high-frequency isolated modular converter is proposed. In the high-frequency isolated modular converter configuration, several floating dc capacitors in all three phases are connected in series, and voltage balancing control of these floating dc capacitors is required. In this paper, an appropriate control structure with the capacitor voltage balancing controller is proposed. The proposed control scheme consists of three layers to control terminal dc bus voltage and balance dc capacitor voltages of each building block. Detailed PSCAD simulation results are presented to evaluate the performance of high-frequency isolated modular converter. Controller hardware-in-the-loop simulation of the high-frequency isolated modular converter is also performed by real-time digital simulator (RTDS), and RTDS results are presented to verify the control structure. Finally, laboratory-scale experimental results are presented to validate the proposed control method.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Yousefpoor, Nima and Parkhideh, Babak and Azidehak, Ali and Kim, Sungmin and Bhattacharya, Subhashish}, year={2015}, pages={4634–4641} }
 @inproceedings{de_bhattacharya_2015, title={Control of dynamic VAR compensator based on current source converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963625762&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310146}, abstractNote={The paper proposes a current source based Dynamic VAR Compensator (DVC) control strategy. The switching unit in this DVC topology is composed of series connected switch and diode also termed as the “current switch”. The proposed controller has been designed to force discontinuous conduction mode operation thus fundamentally different from the traditional constant current source based control system operation. This naturally facilitates zero current turn-on, zero voltage switch overlap and zero current turn off. Two of the switches undergo hard switched turn off only once in a switching time period. The switching scheme has been managed in such a way that the diodes are always turned off at zero voltage thereby minimizing the reverse recovery loss and stress. This effectively reduces the switching losses and allows the switching frequency to be designed considerably higher. High Switching frequency facilitates faster response and high power density. An average model of this DVC converter has been used in an IEEE-34 BUS system to validate the VAR compensation capability. It has been shown that this effectively improves the feeder voltage profile. The ill effects of partial clouding over roof-top PV cells have also been shown, and its mitigation by the DVC. The proposed VAR compensator algorithm can adjust capacitive reactive power as well as inductive reactive power, which can be adapted to a wide range of load.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={De, A. and Bhattacharya, Subhashish}, year={2015}, pages={3442–3448} }
 @inproceedings{azidehak_chattopadhyay_acharya_tripathi_kashani_chavan_bhattacharya_2015, title={Control of modular dual active bridge DC/DC converter for photovoltaic integration}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963537568&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310140}, abstractNote={The DC transmission system provides a cost effective solution for long distance power transmission compared to the AC transmission system. Hence, this has increased the emphasis on the development of the DC transmission system. Development of power converter with modular structure has now made it possible to achieve higher voltage and power level. This opens the possibility for further development of a multi-terminal DC grid. Now once the DC grid system has been formed, it is also important to include more renewable energy sources directly to the DC grid. Therefore, a power conversion stage is required to condition the available power from a source to the grid. This paper shows the operation and control of such a kind of converter system which integrates the solar cell to the DC grid directly. The paper mainly focuses on control of the series connected DAB that have been integrated to HVDC power network. In order to deliver power in HVDC system, the total number of DABs must be high enough to achieve the DC link voltage. The control in that case must be a combination of current and voltage control. In order to validate the proposed control, complete system has been implemented on Opal-RT™ and hardware in the loop (HIL) using external controller has also been implemented to show the system operation.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Azidehak, A. and Chattopadhyay, R. and Acharya, Sayan and Tripathi, A.K. and Kashani, M.G. and Chavan, G. and Bhattacharya, Subhashish}, year={2015}, pages={3400–3406} }
 @article{tripathi_mainali_patel_kadavelugu_hazra_bhattacharya_hatua_2015, title={Design Considerations of a 15-kV SiC IGBT-Based Medium-Voltage High-Frequency Isolated DC-DC Converter}, volume={51}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937876123&partnerID=MN8TOARS}, DOI={10.1109/tia.2015.2394294}, abstractNote={A dual active bridge (DAB) is a zero-voltage switching (ZVS) high-power isolated dc-dc converter. The development of a 15-kV SiC insulated-gate bipolar transistor switching device has enabled a noncascaded medium voltage (MV) isolated dc-dc DAB converter. It offers simple control compared to a cascaded topology. However, a compact-size high frequency (HF) DAB transformer has significant parasitic capacitances for such voltage. Under high voltage and high dV/dT switching, the parasitics cause electromagnetic interference and switching loss. They also pose additional challenges for ZVS. The device capacitance and slowing of dV/dT play a major role in deadtime selection. Both the deadtime and transformer parasitics affect the ZVS operation of the DAB. Thus, for the MV-DAB design, the switching characteristics of the devices and MV HF transformer parasitics have to be closely coupled. For the ZVS mode, the current vector needs to be between converter voltage vectors with a certain phase angle defined by deadtime, parasitics, and desired converter duty ratio. This paper addresses the practical design challenges for an MV-DAB application.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Tripathi, Awneesh K. and Mainali, Krishna and Patel, Dhaval C. and Kadavelugu, Arun and Hazra, Samir and Bhattacharya, Subhashish and Hatua, Kamalesh}, year={2015}, pages={3284–3294} }
 @inproceedings{de_morgan_bhattacharya_hopkins_2015, title={Design considerations of packaging a high voltage current switch}, volume={3}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84953889244&partnerID=MN8TOARS}, DOI={10.1115/IPACK2015-48714}, abstractNote={In this paper an attempt has been made to demonstrate various package design considerations to accommodate series connection of high voltage Si-IGBT (6500V/25A die) and SiC-Diode (6500V/25A die). The effects of connecting the cathode of the series diode to the collector of the IGBT versus connecting the emitter of the IGBT to the anode of the series diode has been analyzed in regards to gate terminal operation and the parasitic line inductance of the structure. ANSYS Q3D/MAXWELL software have been used to analyze and extract parasitic inductance and capacitances in the package along with electromagnetic fields, electric potentials, and current density distributions throughout the package for variable parameters. SIMPLIS-SIMETRIX is used to simulate typical switch behavior for different parasitic parameters under hard switched conditions. Various simulation results have then been used to redesign and justify the optimized package structure for the final current switch design. The thermal behavior of such a package is also conducted in COMSOL in order to ensure that the thermal ratings of the power devices is not exceeded, and to understand where potentially harmful hotspots could arise and estimate the maximum attainable frequency of operation. The main motivation of this work is to enumerate detailed design considerations for packing a high voltage current switch package.}, booktitle={ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2015, collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels}, author={De, A. and Morgan, A. and Bhattacharya, Subhashish and Hopkins, D.C.}, year={2015} }
 @inproceedings{beddingfield_de_mirzae_bhattacharya_2015, title={Design methodology of series DC coupling transformer in a medium-voltage DC amplifier system}, volume={2015-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937857830&partnerID=MN8TOARS}, DOI={10.1109/apec.2015.7104350}, abstractNote={The medium-voltage dc amplifier is a controllable dc source for the purpose of testing medium-voltage dc system technologies for shipboard applications. In a medium-voltage dc amplifier system, a dc active filter with a series dc coupling transformer is an integral component of the system required for both steady-state and dynamic voltage injection. This paper describes the design aspects and methodology for the series dc coupling transformer in such a system. The design of the transformer is one of the most critical aspects of this system as it has to withstand large continuous dc current offset without saturating. Based on system performance requirements, design criteria for the transformer is defined and two transformer designs based on two Iron-based magnetic materials are evaluated for a 12 kVA, 300 Vdc laboratory-scale amplifier test bed. An optimal design methodology is also proposed in this paper. Various design compromises have been studied and reported. The practical transformer design considerations and feasibility study for a medium-voltage dc amplifier system are given.}, number={May}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Beddingfield, R. and De, A. and Mirzae, H. and Bhattacharya, Subhashish}, year={2015}, pages={183–190} }
 @inproceedings{de_bhattacharya_2015, title={Design, analysis and implementation of discontinuous mode Dyna-C AC/AC converter for solid state transformer applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963520581&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310369}, abstractNote={The paper presents an improved control strategy for Dynamic Current (Dyna-C) Converter. Dyna-C is a bidirectional current-source based AC/AC converter for Solid State Transformer (SST) application. The proposed controller facilitates discontinuous mode operation which leads to zero current turn on and turn off. A non-linear average phase charge based controller is presented which ensures zero harmonic current in the input phase currents. The switching scheme has been so arranged that the diodes always turn off at zero voltage thereby reducing the reverse recovery stress and losses. These modifications lead to a considerable reduction of switching loss and device stress as compared to the conventional control scheme of Dyna-C. Owing to soft switching states, the frequency of operation can therefore be pushed further higher thereby reducing the size of the passive components. An alternate switching pattern has also been discussed which enables soft switched turn off of active switches. Design Considerations of packaging such a switch structure has also been discussed. It has been shown that direct connection of Emitter of IGBT to the Anode of the Diode leads to considerably lower parasitic inductance. Design guidelines to construct an optimized inductor has also been discussed. Simulation and experimental results are presented to validate operation of the control scheme. A comparison study has been carried out to choose the appropriate set of devices for this application. It has been shown that SiC-MOS with low cost Si-PiN Diode shows impressive reduction in overall losses.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={De, A. and Bhattacharya, Subhashish}, year={2015}, pages={5030–5037} }
 @inproceedings{de_bhattacharya_2015, title={Discontinuous mode sparse Dyna-C rectifier for efficient AC/DC power conversion}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963576495&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310606}, abstractNote={The paper investigates a soft-switching buck-boost AC/DC converter. The proposed converter uses 4 active switches and overcomes the various shortcomings of conventional rectifiers. The proposed controller facilitates discontinuous mode of operation that leads to zero current turn on and turn off. A nonlinear average phase charge based controller is presented which ensures zero harmonic current in the input phases. The switching scheme has been so arranged that the diodes always turn off at zero voltage thereby reducing the reverse recovery stress and losses. These modifications lead to a considerable reduction of switching loss and device stress as compared to the conventional control scheme of Dyna-C. Owing to soft switching states, the frequency of operation can be pushed even higher thereby reducing the size of the passive components. An alternate switching pattern has also been discussed which enables soft switched turn off of active switches. Design guidelines to construct an optimized inductor has also been discussed. Simulation and initial experimental results are presented to validate operation of the control scheme. A comparison study has been carried out to choose the appropriate set of devices for this application. The research shows that SiC-MOS with low cost Si-PiN Diode results in impressive reduction in overall losses. The topology is expected to offer compact, fast, efficient and inexpensive solution to the present AC/DC power conversion requirements.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={De, A. and Bhattacharya, Subhashish}, year={2015}, pages={6762–6769} }
 @inproceedings{madhusoodhanan_tripathi_mainali_patel_kadavelugu_bhattacharya_2015, title={Distributed Energy Storage Device integration with three phase distribution grid using a Transformerless Intelligent Power Substation}, volume={2015-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937940471&partnerID=MN8TOARS}, DOI={10.1109/apec.2015.7104422}, abstractNote={The advent of SiC devices has resulted in the development of 3-phase, Medium Voltage (MV) grid tied Solid State Transformers (SSTs). One such SST is the 100 kVA Transformerless Intelligent Power Substation (TIPS) based on 15 kV SiC IGBTs and 1200 V SiC MOSFETs which interconnects the 13.8 kV distribution grid with the 480 V utility grid. TIPS has an ac-dc-dc-ac multi-module configuration. The availability of 800 V dc and 480 V ac terminals in the system allows for the integration of Distributed Energy Storage Devices (DESDs) with the 13.8 kV MV grid. These DESDs store the energy derived from the renewable sources like solar, wind and wave. The complex nature of the overall system makes the power flow control very challenging during integration. This paper investigates the steady state and transient behavior of the TIPS system when integrated with a battery model representing the DESD. Complete system simulation is carried out using the switching model of the converters along with the dynamic model of the battery and a feeder model similar to IEEE-34 bus system. Experimental verification is done on TIPS prototype at scaled down voltage and power levels.}, number={May}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Madhusoodhanan, S. and Tripathi, A. and Mainali, K. and Patel, D. and Kadavelugu, A. and Bhattacharya, Subhashish}, year={2015}, pages={670–677} }
 @inproceedings{hazra_dean_bhattacharya_2015, title={Doubly-fed induction generator enabled power generation in ocean wave energy conversion system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963576837&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310637}, abstractNote={This paper proposes a power architecture to utilize doubly-fed induction generator (DFIG) for power generation from oscillating wave energy converter (WEC). Unlike in wind energy conversion system, the stator circuit of the DFIG can not be tied directly with the grid in wave energy conversion system (WECS). In WECS, the speed of the DFIG oscillates from one direction to another. Due to the change of direction of the speed, the stator of the DFIG is proposed to be connected with the grid with switched phase sequence. Also, at low operating speed the DFIG slip speed increases which requires higher voltage rating of the rotor side converter. Therefore, to operate the DFIG with limited rotor side voltage the stator circuit is short circuited at low speed. With these modifications, the DFIG based power architecture is proposed to generate power from WECS. In this paper, the overall hardware and control architecture and system operation are presented. System operation is validated through simulation in MATLAB-Simulink platform. For simulation of the whole system, a WEC model is considered.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Hazra, S. and Dean, A.G. and Bhattacharya, Subhashish}, year={2015}, pages={6978–6985} }
 @inproceedings{acharya_bhattacharya_yousefpoor_2015, title={Dynamic performance evaluation of hybrid multi-terminal HVAC/HVDC grid}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963549008&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7309982}, abstractNote={The multi-terminal DC grid can be integrated to the existing meshed AC grid system to provide back-up in case of transmission line failure and enhance power transmission capacity and flexibility in existing ac grids. In addition to that, Power oscillations can also be damped effectively through modulation of both active and reactive power of a voltage source converter (VSC) based multi-terminal DC grid. In this paper, the ability of the multi-terminal DC grid to effectively damp the power oscillation in an interconnected AC grid has been investigated. Also, VSC based MTDC transmission systems are vulnerable to DC side fault. This paper demonstrates a control method of a dc fault resilient voltage source converter that has ultra-fast electronic isolation capability following dc fault which can be protected against dc fault. To verify the control structure, the dynamic performance of the integrated multi-terminal DC grid in a reduced order three-bus AC equivalent power system is investigated through hardware-in-the-loop testing. Controller hardware-in-the-loop simulation of the embedded multi-terminal DC grid in a meshed AC power system is performed by Real Time Digital Simulator (RTDS), and RTDS results are presented to verify the control structure.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Acharya, Sayan and Bhattacharya, Subhashish and Yousefpoor, N.}, year={2015}, pages={2287–2293} }
 @inproceedings{hazra_bhattacharya_2016, title={Electrical machines for power generation in oscillating wave energy conversion system - A comparative study}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84965138416&partnerID=MN8TOARS}, DOI={10.1109/IEMDC.2015.7409267}, abstractNote={In this paper, system level design of an oscillating wave energy conversion system (WECS) using doubly-fed induction generator (DFIG) is compared with systems using squirrel-cage induction generator (SCIG) and permanent magnet synchronous generator (PMSG). The comparative study is carried out considering major hardware components and their rating requirements for each system. Although, SCIG and PMSG based systems are more simple and reliable, DFIG can enable compact and cost effective systems especially for high power WECS design. DFIG can generate power above its nominal rating at super-synchronous rotor speed and hence can offer an attractive solution for the oscillating power pattern of WECS. Moreover, rotor side control of the DFIG enables one to work with lower voltage and power level which effectively reduces the ratings of the power converters and other passive elements in the system. The system design comparison is performed with a wave energy converter (WEC) modeled for maximum power output around 500 kW. System operation with singly-fed generator (SCIG) and doubly-fed generator (DFIG) have been studied through simulation in real time simulator (OPAL-RT). The results of the comparison are shown with details of the major component rating of each system.}, booktitle={Proceedings - 2015 IEEE International Electric Machines and Drives Conference, IEMDC 2015}, author={Hazra, S. and Bhattacharya, Subhashish}, year={2016}, pages={1538–1544} }
 @inproceedings{singh_shrivastav_bhattacharya_2015, title={GaN FET based CubeSat Electrical Power System}, volume={2015-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937840289&partnerID=MN8TOARS}, DOI={10.1109/apec.2015.7104529}, abstractNote={This paper deals with the development of high efficiency, compact and flexible Electrical Power System (EPS) for a Cube Satellite (CubeSat). The EPS is responsible for harnessing power from solar panels, battery charging and multi-domain voltage output regulation within the CubeSat. This work builds upon the results and learnings obtained from an EPS which uses Silicon MOSFETs. The hardware and software aspects of the development of such photovoltaic battery based power management systems are examined. The introduction of digital controller provides flexibility and intelligence but also introduces controller design challenges with simultaneous execution of multiple control loops. The EPS behaves like a standalone photo-voltaic battery charging system that harnesses solar energy to charge the battery banks. This entails the development of maximum power point tracking techniques as well as battery charging methods such as constant-current/constant-voltage charging. A dual loop control methodology with output current control is implemented to regulate the output current when charging the battery. This new EPS uses GaN FETs with an aim to increase efficiency and have all the functionalities of its silicon counterpart in smaller dimensions.}, number={May}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Singh, S. and Shrivastav, A. and Bhattacharya, Subhashish}, year={2015}, pages={1388–1395} }
 @inproceedings{tripathi_madhusoodhanan_mainali_kadavelugu_patel_bhattacharya_hatua_2015, title={Grid connected CM noise considerations of a three-phase multi-stage SST}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84961872947&partnerID=MN8TOARS}, DOI={10.1109/icpe.2015.7167873}, abstractNote={Solid State Transformer (SST) is an alternative to the conventional distribution transformer for smart grid applications. By employing a compact Medium-Frequency (MF) transformer for isolation, the SST has merits on size and weight. It also provides flexible utilization as a FACTS component. The switching converters are a potential source of Common-Mode (CM) and HF EMI noises. These noises are more nuisance in a SiC device based SST which switches at a high dV/dT at the Medium-Voltage (MV) level resulting in high CM voltages. The SST floating metalic surfaces such as heatsink and the output must be grounded for safety and smooth operation. However there are various significant low impedance paths present, including the parasitics of the compact transformer, which may conduct CM noise to the grid. The generated CM noise may affect the controls. This paper presents the CM and grounding challenges in the multistage integration of a three-phase SST system based on 15kV SiC IGBTs termed as Transformerless Intelligent Power Substation (TIPS). The TIPS interfaces MV 13.8kV and LV 480V grids using MV ac-dc, MV to LV dc-dc dual active bridge and LV dc-ac inverter stages. A study on the CM noise in the TIPS and a passive filter solution for its attenuation is presented in this paper. A time domain simulation considering the passive filter specification is also presented. The experimental results for line to line 3.64kV MV grid integration are presented. A LV prototype is used to verify the complete grounding and the CM choke design at a scaled-down condition.}, booktitle={9th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2015-ECCE Asia}, author={Tripathi, A. and Madhusoodhanan, S. and Mainali, K. and Kadavelugu, A. and Patel, D. and Bhattacharya, Subhashish and Hatua, K.}, year={2015}, pages={793–800} }
 @article{hazra_de_cheng_palmour_schupbach_hull_allen_bhattacharya_2016, title={High Switching Performance of 1700-V, 50-A SiC Power MOSFET over Si IGBT/BiMOSFET for Advanced Power Conversion Applications}, volume={31}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84962338926&partnerID=MN8TOARS}, DOI={10.1109/TPEL.2015.2432012}, abstractNote={Due to wider band gap of silicon carbide (SiC) compared to silicon (Si), MOSFET made in SiC has considerably lower drift region resistance, which is a significant resistive component in high-voltage power devices. With low on-state resistance and its inherently low switching loss, SiC MOSFETs can offer much improved efficiency and compact size for the converter compared to those using Si devices. In this paper, we report switching performance of a new 1700-V, 50-A SiC MOSFET designed and developed by Cree, Inc. Hard-switching losses of the SiC MOSFETs with different circuit parameters and operating conditions are measured and compared with the 1700-V Si BiMOSFET and 1700-V Si IGBT, using same test set-up. Based on switching and conduction losses, the operating boundary of output power and switching frequency of these devices are found out in a dc-dc boost converter and compared. The switching dv/dts and di/dts of SiC MOSFET are captured and discussed in the perspective of converter design. To validate the continuous operation, three dc-dc boost converters using these devices, are designed and tested at 10 kW of power with 1 kV of output voltage and 10 kHz of switching frequency. 1700V SiC Schottky diode is used as the blocking diode in each case. Corresponding converter efficiencies are evaluated and the junction temperature of each device is estimated. To demonstrate high switching frequency operation, the SiC MOSFET is switched upto 150 kHz within permissible junction temperature rise. A switch combination of the 1700-V SiC MOSFET and 1700-V SiC Schottky diode connected in series is also evaluated for zero voltage switching turn-ON behavior and compared with those of bipolar Si devices. Results show substantial power loss saving with the use of SiC MOSFET.}, number={7}, journal={IEEE Transactions on Power Electronics}, author={Hazra, S. and De, A. and Cheng, L. and Palmour, J. and Schupbach, M. and Hull, B.A. and Allen, S. and Bhattacharya, Subhashish}, year={2016}, pages={4742–4754} }
 @inproceedings{beddingfield_davis_mirzaee_bhattacharya_2015, title={Investigation of series DC active filter and hybrid AC active filter performance in medium voltage DC amplfier}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84945919142&partnerID=MN8TOARS}, DOI={10.1109/ests.2015.7157880}, abstractNote={To further improve energy management, the US navy is exploring medium-voltage DC as the power supply of choice for next generation integrated power systems (NGIPS). Using the mature technology of multi-pulse thyristor bridge rectifiers, viable topologies are proposed that meet power density expectations. However, due to the non-linear ripple associated with thyristor commutations in such active front-ends (AFEs), a high bandwidth series AC active filter is used to smooth out the current harmonics. Similarly, a high bandwidth hybrid DC active filter is used for DC bus smoothing and improved dynamic performance. This paper will investigate the combined performance and consequential interactions of both active filters.}, booktitle={2015 IEEE Electric Ship Technologies Symposium, ESTS 2015}, author={Beddingfield, R. and Davis, A. and Mirzaee, H. and Bhattacharya, Subhashish}, year={2015}, pages={161–166} }
 @article{chattopadhyay_bhattacharya_foureaux_pires_de paula_moraes_cortizio_silva_filho_brito_2015, title={Low-voltage PV power integration into medium voltage grid using high-voltage SiC devices}, volume={4}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015067417&partnerID=MN8TOARS}, DOI={10.1541/ieejjia.4.767}, abstractNote={High voltage high power semiconductor devices are being used for grid integration of renewable energy sources. 1200V/100A SiC-MOSFETs, 1700V SiC-MOSFETs, 1700V SiC-Schottky diodes, 10kV SiC-MOSFETs, and 10kV JBS diodes have proved to be useful for high-voltage applications. High-voltage SiC devices enable high-switching frequency operation thus reducing the size of the parasitic element. This paper focuses on an alternative approach to the 0.9MW PV power plant currently being constructed in Brazil. The objective of the use of high power SiC devices for integration of the PV power plant into 13.8kV grid is to provide higher efficiency and reduced size and volume.}, number={6}, journal={IEEJ Journal of Industry Applications}, author={Chattopadhyay, R. and Bhattacharya, S. and Foureaux, N.C. and Pires, I.A. and De Paula, H. and Moraes, L. and Cortizio, P.C. and Silva, S.M. and Filho, B.C. and Brito, J.A.D.S.}, year={2015}, pages={767–775} }
 @inproceedings{tripathi_mainali_madhusoodhanan_patel_kadavelugu_hazra_bhattacharya_hatua_2015, title={MVDC microgrids enabled by 15kV SiC IGBT based flexible three phase dual active bridge isolated DC-DC converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963593747&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310462}, abstractNote={The Dual Active Bridge (DABC) dc-dc converter is an integral part of the recently popular Medium-Voltage (MV) dc micro-grid application due to its high-power density. The advent of 15kV SiC IGBT and 10kV SiC MOSFET, has enabled a non-cascaded MV and Medium-Frequency (MF) DABC converter which is expected to have higher MTBF than the cascaded H-bridge topology due to relatively small number of switches. A composite DABC three-level three-phase topology earlier proposed for MV-MF application, has dual secondary side bridges to meet the rated load conditions. The duty-ratio control of the primary and the independent operation of dual secondary bridges as a single active bridge, can be utilized to solve the light load ZVS problem. This paper presents flexible operating modes of this MV DABC for ZVS and higher efficiency. The MV DABC simulations are presented to bring out the advantages of this topology in wide range load and voltage-ratio conditions. This paper reports 8kV experimental validation of this DABC while using 15kV/40A SiC IGBTs on the MV side.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Tripathi, A. and Mainali, K. and Madhusoodhanan, S. and Patel, D. and Kadavelugu, A. and Hazra, S. and Bhattacharya, Subhashish and Hatua, K.}, year={2015}, pages={5708–5715} }
 @inproceedings{kadavelugu_mainali_patel_madhusoodhanan_tripathi_hatua_bhattacharya_ryu_grider_leslie_2015, title={Medium voltage power converter design and demonstration using 15 kV SiC N-IGBTs}, volume={2015-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937857287&partnerID=MN8TOARS}, DOI={10.1109/apec.2015.7104530}, abstractNote={This paper summarizes the different steps that have been undertaken to design medium voltage power converters using the state-of-the-art 15 kV SiC N-IGBTs. The 11 kV switching characterization results, 11 kV high dv/dt gate driver validation, and the heat-run test results of the SiC IGBT at 10 kV, 550 W/cm2 (active area) have been recently reported as individual topics. In this paper, it is attempted to link all these individual topics and present them as a complete subject from the double pulse tests to the converter design, for evaluating these novel high voltage power semiconductor devices. In addition, the demonstration results of two-level H-Bridge and three-level NPC converters, both at 10 kV dc input, are being presented for the first-time. Lastly, the performance of two-chip IGBT modules for increased current capability and demonstration of three-level poles, built using these modules, at 10 kV dc input with sine-PWM and square-PWM modulation for rectifier and dc-dc stages of a three-phase solid state transformer are presented.}, number={May}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Kadavelugu, A. and Mainali, K. and Patel, D. and Madhusoodhanan, S. and Tripathi, A. and Hatua, K. and Bhattacharya, Subhashish and Ryu, S.-H. and Grider, D. and Leslie, S.}, year={2015}, pages={1396–1403} }
 @inproceedings{chattopadhyay_bhattacharya_2015, title={Modular isolated DC-DC converter with multi-limb transformer for interfacing of renewable energy sources}, volume={2015-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937960339&partnerID=MN8TOARS}, DOI={10.1109/apec.2015.7104785}, abstractNote={This paper presents a modular isolated scalable three phase dual active bridge(DAB) DC-DC converter configuration using three multi limb high frequency transformers. The proposed converter has the advantage of having multiple low and high voltage dc links, which can be used at different power levels. The converter has three high voltage dc links which can be used for cascaded inverters or can be connected in series to provide a high dc link voltage for medium voltage grid-tie inverter. Multiple number of renewable energy sources(RES) can be connected to the low voltage side dc links to feed power to the grid. The paper work contains converter configuration, equivalent circuit of multi limb transformer, control of converter for a single renewable energy source and multiple renewable energy sources.}, number={May}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Chattopadhyay, R. and Bhattacharya, Subhashish}, year={2015}, pages={3039–3046} }
 @inproceedings{vechalapu_bhattacharya_2015, title={Modular multilevel converter based medium voltage DC amplifier for ship board power system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84954128604&partnerID=MN8TOARS}, DOI={10.1109/PEDG.2015.7223098}, abstractNote={In this paper, the Modular Multilevel Cascaded Converter based on Double-Star Bridge Cells(MMCC-DSBC) for Medium Voltage DC (MVDC) amplifier is proposed. The medium voltage DC (MVDC) amplifier system is required to validate new technologies, new high power non-linear loads based on power electronics, in all electric ships as part of the proposed medium voltage (MVDC) ship power system. Thyristor based medium voltage DC amplifier (6 kV to 24 kV DC from 4.2 kV (L-L) AC three phase system) with Series Active Inverter (SAI) and DC side transformer in series with DC bus has been reported in the literature, where the series active Inverter compensates the slow dynamics of the Thyristor converter and facilitates fast dynamic response for step changing loads. However, this system has disadvantages as shown in Table III. This paper first shows a control method for AC to DC operation of MMCC-DSBC converter to control the wide DC output voltage in both buck and boost modes from fixed AC source. The simulation results show that the MMCC-DSBC converter provides a variable DC voltage from 6 kV to 24 kV DC and also the extended wide range of output DC voltage - 1 kV to 24 kV - from fixed 4.2 kV (L-L) AC three phase system. It is also shown that this topology will provide fast dynamic response compared to Thyristor based Line Commutated Converter (LCC) without the need of Series Active Inverter, DC side transformer in series with DC bus. This paper also shown the the control method to operate the MMCC-DSBC converter in STATCOM mode-to provide reactive power support to the AC side grid-during DC side pole to pole fault. Simulation results are presented on EMTDC/PSCAD platform to validate the controls.}, booktitle={2015 IEEE 6th International Symposium on Power Electronics for Distributed Generation Systems, PEDG 2015}, author={Vechalapu, K. and Bhattacharya, Subhashish}, year={2015}, pages={419–426} }
 @inproceedings{acharya_azidehak_vechalapu_kashani_chavan_bhattacharya_yousefpoor_2015, title={Operation of hybrid multi-terminal DC system under normal and DC fault operating conditions}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963585191&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310417}, abstractNote={Recently, multi-terminal DC (MTDC) system has received more attention in the power transmission areas. Development of modular structured power converter topologies has now enabled the power converter technology to attain high voltage high power ratings. Compared to current source converter technology, voltage source converters have several benefits including higher power quality, independent control of active and reactive power etc. This paper focuses on a unique MTDC system consisting of terminals with different converter topologies especially considering the fact that each of the terminals may be manufactured by different vendors. In this particular configuration, the MTDC system consists of four terminals namely two advanced modular multi-level converter with high frequency isolation, one standard modular multi-level converter (MMC) with half bridge sub modules and the fourth terminal is modular DC-DC converter which integrates PV along with a Battery energy storage system with the DC grid directly. This paper presents a system level study of hybrid MTDC System. Also the DC fault contingency case has been explored thoroughly. An algorithm has been proposed to prevent the system damage. All the cases have been demonstrated with the PSCAD simulation results. To show the system practically works in real time, the system is also evaluated in a unique real time platform, consisting of interconnected RTDS and OPAL RT systems.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Acharya, Sayan and Azidehak, A. and Vechalapu, K. and Kashani, M. and Chavan, G. and Bhattacharya, Subhashish and Yousefpoor, N.}, year={2015}, pages={5386–5393} }
 @inproceedings{de_bhattacharya_singh_2015, title={Performance evaluation and characterization of 6500V asymmetric SiC NPNP Thyristor based current switch}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963613100&partnerID=MN8TOARS}, DOI={10.1109/wipda.2015.7369324}, abstractNote={The main motivation of this work is to evaluate performance and characteristics of a 6.5kV SiC Thyristor based current switch (series connected active switch and diode). A unique series resonant testing circuit has been proposed to characterize this switch. The device has been tested in several soft and hard turn on and off transitions. Conceptual simulation and hardware results have been presented. It has been shown that SiC Thyristor exhibit fast turn-on transitions (~200ns). This coupled with the fact that SiC-JBS Diode (connected in series) has fast reverse voltage commutation leads to an efficient and robust switch combination for a high voltage, high power and high frequency converter. The collected data has been used to estimate overall device losses of a high voltage and high power resonant soft-switched converter.}, booktitle={WiPDA 2015 - 3rd IEEE Workshop on Wide Bandgap Power Devices and Applications}, author={De, A. and Bhattacharya, Subhashish and Singh, R.}, year={2015}, pages={10–15} }
 @inproceedings{madhusoodhanan_mainali_tripathi_patel_kadavelugu_bhattacharya_hatua_2015, title={Performance evaluation of 15 kV SiC IGBT based medium voltage grid connected three-phase three-level NPC converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963604269&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310184}, abstractNote={Cascaded converters are generally used for Medium Voltage (MV) grid connected applications due to the limitation in the voltage rating of available Silicon (Si) power devices. These converters find application in Active Power Filters, STATCOM or as Active Front End Converters for Solid State Transformers at the distribution voltage levels. The wide bandgap semiconductor devices have enabled the grid connected operation of non-cascaded converters. This results in high power density, less number of switching devices, high efficiency and control simplicity for three-phase MV grid interface. 15 kV SiC IGBT is one such device which can be switched at 5 kHz between MV and zero levels with forced air cooling. However, this device in a grid connected non-cascaded converter introduces few additional challenges which are analyzed in this paper. The paper investigates the performance of the grid connected converter using 15 kV SiC IGBT through simulations and experiments till 4.16 kV, 3-phase operation. The concerned areas of study are Total Harmonic Distortion (THD) at low currents, effect of practical sensor-feedback path errors, effect of switching ripple on the distribution transformer, effect of filter parasitic capacitance and elimination of high common mode current.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Madhusoodhanan, S. and Mainali, K. and Tripathi, A. and Patel, D. and Kadavelugu, A. and Bhattacharya, Subhashish and Hatua, K.}, year={2015}, pages={3710–3717} }
 @inproceedings{vechalapu_bhattacharya_aleoiza_2015, title={Performance evaluation of series connected 1700V SiC MOSFET devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963541072&partnerID=MN8TOARS}, DOI={10.1109/wipda.2015.7369327}, abstractNote={The low voltage SiC (Silicon carbide) MOSFET (1.2 kV to 1.7 kV) increases the switching frequency limits of a power electronic converter several folds compared to low voltage Si IGBTs. Significant increase in efficiency and power density of voltage source converters can be achieved. However, for medium-voltage high-power converter applications Silicon (Si) devices (4.5 kV and 6.5 kV IGBT) are still dominant. To explore the capability of low voltage SiC devices for medium or high voltage applications, series connection of 1.7 kV/300 A SiC MOSFET modules has been investigated in this paper. A simple RC snubber method has been used for dynamic voltage sharing to offset the turn-off delays due to mismatch on device's characteristics and/or gate signals. Experimental switching characterization with different values of RC snubbers have been carried out to find the optimal RC snubber which gives minimum voltage sharing difference, snubber losses and total semiconductor losses. This paper also intends to show an optimization of the RC snubber for series connection of a limited number of 1.7kV SiC MOSFETs for 6 kV dc bus and for a generalized dc bus voltage.}, booktitle={WiPDA 2015 - 3rd IEEE Workshop on Wide Bandgap Power Devices and Applications}, author={Vechalapu, K. and Bhattacharya, Subhashish and Aleoiza, E.}, year={2015}, pages={184–191} }
 @inbook{kadavelugu_hazra_madhusoodhanan_tripathi_vechalapu_de_mainali_patel_hatua_bhattacharya_2016, title={Semiconductor power devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85014146789&partnerID=MN8TOARS}, DOI={10.1049/PBPO074E_ch1}, abstractNote={In this chapter, the characteristics of high-voltage SiC IGBT, SiC MOSFET, SiC junction gate field-effect transistor (JFET), and low-voltage SiC MOSFET are discussed.}, booktitle={Power Electronic Converters and Systems: Frontiers and Applications}, author={Kadavelugu, A. and Hazra, S. and Madhusoodhanan, S. and Tripathi, A. and Vechalapu, K. and De, A. and Mainali, K. and Patel, D. and Hatua, K. and Bhattacharya, S.}, year={2016}, pages={3–42} }
 @inproceedings{vechalapu_tripathi_mainali_baliga_bhattacharya_2015, title={Soft switching characterization of 15 kV SiC n-IGBT and performance evaluation for high power converter applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963579482&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310246}, abstractNote={The 15 kV SiC IGBT with 2 μm and 5 μm field-stop buffer layer thicknesses are two state of the art HV SiC devices. These 15 kV SiC IGBTs generate high dv/dt with two slopes in punch through and non-punch through regions. To design 15 kV SiC IGBT with reduced dv/dt and single slope dv/dt similar to 10-15 kV SiC MOSFET, requires significantly larger drift epitaxial layer thickness and it increases the size and cost of the 15 kV SiC IGBT. This paper presents the zero voltage switching (ZVS) characteristics of 15 kV SiC N-IGBTs to reduce the dv/dt at switching pole along with reduction in the switching losses and increase in the switching frequency limits with external snubber capacitor. The ZVS characteristics are reported up to 9 kV dc bus voltage at 25°C and 150°C for both IGBTs. This paper also reports continuous mode experimental demonstration of zero voltage switching (ZVS) of 5 μm 15 kV IGBT in a medium voltage half bridge converter up to 7 kV dc bus voltage and calculation of power dissipation per IGBT module and its comparison of switching frequency limits with hard switching of half bridge converter.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Vechalapu, K. and Tripathi, A. and Mainali, K. and Baliga, B.J. and Bhattacharya, Subhashish}, year={2015}, pages={4151–4158} }
 @article{madhusoodhanan_tripathi_patel_mainali_kadavelugu_hazra_bhattacharya_hatua_2015, title={Solid-State Transformer and MV Grid Tie Applications Enabled by 15 kV SiC IGBTs and 10 kV SiC MOSFETs Based Multilevel Converters}, volume={51}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937880113&partnerID=MN8TOARS}, DOI={10.1109/tia.2015.2412096}, abstractNote={Medium-voltage (MV) SiC devices have been developed recently which can be used for three-phase MV grid tie applications. Two such devices, 15 kV SiC insulated-gate bipolar transistor (IGBT) and 10 kV SiC MOSFET, have opened up the possibilities of looking into different converter topologies for the MV distribution grid interface. These can be used in MV drives, active filter applications, or as the active front end converter for solid-state transformers (SSTs). The transformerless intelligent power substation (TIPS) is one such application for these devices. TIPS is proposed as a three-phase SST interconnecting a 13.8 kV distribution grid with a 480 V utility grid. It is an all SiC device-based multistage SST. This paper focuses on the advantages, design considerations, and challenges associated with the operation of converters using these devices keeping TIPS as the topology of reference. The efficiency of the TIPS topology is also calculated using the experimentally measured loss data of the devices and the high-frequency transformer. Experimental results captured on a developed prototype of TIPS along with its measured efficiency are also given.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Madhusoodhanan, Sachin and Tripathi, Awneesh and Patel, Dhaval and Mainali, Krishna and Kadavelugu, Arun and Hazra, Samir and Bhattacharya, Subhashish and Hatua, Kamalesh}, year={2015}, pages={3343–3360} }
 @inproceedings{mainali_madhusoodhanan_tripathi_patel_bhattacharya_2015, title={Start-up scheme for solid state transformers connected to medium voltage grids}, volume={2015-May}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937922109&partnerID=MN8TOARS}, DOI={10.1109/apec.2015.7104473}, abstractNote={The development of the high voltage wideband gap semiconductor SiC power devices has enabled the solid state transformer (SST) technology in connecting a medium voltage grid to a low voltage grid. Though, these power devices have superior loss and switching characteristics compared to Si power devices, they have limited inrush current handling capability. The large inrush currents that flow into the SST from the grids when commissioning the SST system can be detrimental to the SiC devices. A proper start-up scheme is required to address this issue. Reported literatures on SST are focused on different topologies and their control aspects. This paper is focused in developing the safe start-up schemes for SST system connecting medium voltage grid to low voltage grid. The paper presents the simulation results and experimental verifications of the proposed SST start-up scheme.}, number={May}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Mainali, K. and Madhusoodhanan, S. and Tripathi, A. and Patel, D. and Bhattacharya, Subhashish}, year={2015}, pages={1014–1021} }
 @article{rocha_bhattacharya_moghaddam_gould_paula_cardoso filho_2016, title={Thermal Stress and High Temperature Effects on Power Devices in a Fault-Resilient NPC IGCT-Based Converter}, volume={31}, ISSN={["1941-0107"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84960155689&partnerID=MN8TOARS}, DOI={10.1109/tpel.2015.2452262}, abstractNote={The integrated gate-commutated thyristor and presspack power diodes have been successfully applied in medium-voltage neutral point-clamped converters in the power range from hundreds of kilowatt to tenths of megawatt. Responsible for driving key processes in the industry, high reliability and availability are crucial for these converters, since their repair or replacement after failure events may take too long. Given the vital importance of such equipment for the drive systems, they are equipped with protection schemes that are usually reliable, but not infallible. If the protection scheme of the converter does not work properly in a short-circuit situation, serious damages may be expected on its power semiconductor devices. In this paper, the power semiconductors thermal behavior is investigated using finite-element models in the COMSOL Multiphysics software. Three-dimensional thermal models of the power devices were raised by industrial radiography techniques, aiming to expand the information provided by the manufacturers. The authors show how these results can be used in a real equipment to attenuate the catastrophic effects of the protection scheme malfunction, so limiting the damage pattern within the converter to their least complex power devices.}, number={4}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Rocha, Anderson Vagner and Bhattacharya, Subhashish and Moghaddam, Giti Karimi and Gould, Richard D. and Paula, Helder and Cardoso Filho, Braz de Jesus}, year={2016}, month={Apr}, pages={2800–2807} }
 @inproceedings{madhusoodhanan_mainali_tripathi_kadavelugu_patel_bhattacharya_2015, title={Thermal design considerations for medium voltage power converters with 15 kV SiC IGBTs}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84954159835&partnerID=MN8TOARS}, DOI={10.1109/PEDG.2015.7223105}, abstractNote={Medium Voltage (MV) Silicon Carbide (SiC) devices such as the 15 kV SiC IGBT have better thermal handling capability compared to Silicon (Si) based devices. These devices also have lower switching and conduction losses, at high switching frequencies and high power levels, respectively. The maximum safe operating junction temperature for the 15 kV SiC IGBT is 175 °C. This enables high power density design of the MV converters using this device. Heat sink with forced air cooling is sufficient for dissipating the heat generated during converter operation. In this paper, the thermal design of 3-phase MV converters based on 15 kV/40 A SiC N-IGBT is discussed. The design is carried out based on experimental loss data and the continuous heat-run test of the device. It is supported by analytical calculations and FEM simulations in COMSOL Multiphysics simulation software. Hardware prototypes of the converters are developed and experimental results are given.}, booktitle={2015 IEEE 6th International Symposium on Power Electronics for Distributed Generation Systems, PEDG 2015}, author={Madhusoodhanan, S. and Mainali, K. and Tripathi, A. and Kadavelugu, A. and Patel, D. and Bhattacharya, Subhashish}, year={2015}, pages={265–272} }
 @inproceedings{karimi-moghaddam_gould_bhattacharya_2016, title={Thermomagnetic liquid cooling: A novel variable speed motor drives thermal management solution}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84965183324&partnerID=MN8TOARS}, DOI={10.1109/IEMDC.2015.7409303}, abstractNote={Liquid cooling for thermal management has been extensively applied in high power electronic systems. However, the use of pumps may introduce reliability and mechanical limitations such as vibration, noise, leakage, and considerable power consumption. It has been shown that temperature sensitive ferrofluids in the presence of temperature field and magnetic field gradients are able to produce a liquid flow without a mechanical pump. This paper presents results from experiments using a single-phase, Mn-Zn ferrite based ferrofluid operating under transient and steady laminar flow conditions in a partially heated thermomagnetic circulation loop under the influence of an external magnetic field created by a solenoid. The effects of several operational factors on the system performance are discussed. Additionally, the self-regulating feature of this cooling system is demonstrated as the heat load is increased a larger heat dissipation rate can be managed due to a stronger thermomagnetic convection effect.}, booktitle={Proceedings - 2015 IEEE International Electric Machines and Drives Conference, IEMDC 2015}, author={Karimi-Moghaddam, G. and Gould, R.D. and Bhattacharya, Subhashish}, year={2016}, pages={1768–1773} }
 @inproceedings{madhusoodhanan_tripathi_mainali_kadavelugu_patel_bhattacharya_hatua_2015, title={Three-phase 4.16 kV medium voltage grid tied AC-DC converter based on 15 kV/40 a SiC IGBTs}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963600033&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310594}, abstractNote={Recently, with the emergence of Wide Bandgap semiconductor devices having higher blocking voltage capabilities and higher switching speed, ac-dc converters for Medium Voltage (MV) and Low Voltage (LV) dc micro-grid applications are becoming popular. In this paper, the first time experimental demonstration of such a 3-phase, isolated ac-dc power converter based on the newly developed 15 kV/40 A SiC IGBT is presented for 4.16 kV ac distribution grid interface. The presented converter consists of two bidirectional stages - the 4.16 kV ac to 8 kV dc front end converter followed by an 8 kV dc to 480 V dc dual active bridge converter with high frequency isolation. These stages are switched at 5 kHz and 10 kHz respectively. The converter design is presented along with experimental validation on a prototype at 9.6 kW.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Madhusoodhanan, S. and Tripathi, A. and Mainali, K. and Kadavelugu, A. and Patel, D. and Bhattacharya, Subhashish and Hatua, K.}, year={2015}, pages={6675–6682} }
 @inproceedings{juneja_dean_bhattacharya_2015, title={Using real-time system design methods to integrate SMPS control software with application software}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963563112&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310485}, abstractNote={A switch-mode power supply (SMPS) converts power efficiently between different voltage levels, making power optimizations through voltage scaling feasible. SMPS controllers are generally dedicated hardware (analog/digital circuits, microcontroller (MCU), digital signal processor (DSP)), and so are expensive to add to very low cost embedded applications. In this work, we show how to integrate SMPS control software into the MCU running application software, which reduces system cost while increasing the design space and flexibility for developers. Real-time system design methods are employed to ensure SMPS voltage regulation quality, while retaining the original embedded application behavior. Our methods apply to a wide range of software task schedulers, from simple interrupt-based foreground/background systems to sophisticated preemptive real-time kernels (RTOS). We demonstrate our methods on a position-logging embedded system, with multiple voltage domains controlled in software, resulting in power savings.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Juneja, A. and Dean, A.G. and Bhattacharya, Subhashish}, year={2015}, pages={5880–5887} }
 @book{ryu_capell_jonas_o’loughlin_clayton_van brunt_lam_richmond_kadavelugu_bhattacharya_et al._2014, title={20 kV 4H-SiC N-IGBTs}, volume={778-780}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84896069796&partnerID=MN8TOARS}, DOI={10.4028/www.scientific.net/MSF.778-780.1030}, abstractNote={A 1 cm x 1 cm 4H-SiC N-IGBT exhibited a blocking voltage of 20.7 kV with a leakage current of 140 μA, which represents the highest blocking voltage reported from a semiconductor power switching device to this date. The device used a 160 μm thick drift layer and a 1 μm thick Field-Stop buffer layer, and showed a VF of 6.4 V at an IC of 20 A, and a differential Ron,sp of 28 mΩ-cm2. Switching measurements with a supply voltage of 8 kV were performed, and a turn-off time of 1.1 μs and turn-off losses of 10.9 mJ were measured at 25°C, for a 8.4 mm x 8.4 mm device with 140 μm drift layer and 2 μm F-S buffer layer. The turn-off losses were reduced by approximately 50% by using a 5 μm F-S buffer layer. A 55 kW, 1.7 kV to 7 kV boost converter operating at 5 kHz was demonstrated using the 4H-SiC N-IGBT, and an efficiency value of 97.8% was reported.}, journal={Materials Science Forum}, author={Ryu, S. and Capell, C. and Jonas, C. and O’Loughlin, M. and Clayton, J. and Van Brunt, E. and Lam, K. and Richmond, J. and Kadavelugu, A. and Bhattacharya, S. and et al.}, year={2014}, pages={1030–1033} }
 @article{karimi-moghaddam_gould_bhattacharya_2014, title={A Nondimensional Analysis to Characterize Thermomagnetic Convection of a Temperature Sensitive Magnetic Fluid in a Flow Loop}, volume={136}, ISSN={["1528-8943"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84904479914&partnerID=MN8TOARS}, DOI={10.1115/1.4027863}, abstractNote={This paper presents results from theoretical and numerical studies of a single-phase, temperature sensitive magnetic fluid operating under steady-state laminar flow conditions in a partially heated thermomagnetic circulation loop under the influence of an external magnetic field (created by a solenoid). A one-dimensional theoretical model has been developed using scaling arguments to characterize thermomagnetic circulation in this loop in terms of the geometric length scales, magnetic fluid properties, and the strength of the imposed magnetic field. In parallel to this theoretical analysis, supporting numerical simulations using Comsol Multiphysics simulation software have been undertaken to obtain data for use in this 1D model. Comparison between experimental data and numerical simulation results and also a grid sensitivity analysis was carried out to validate the numerical simulation. A correlation for the nondimensional heat transfer (Nusselt number) as a function of the appropriate magnetic Rayleigh number and a correlation for the mass flow rate based on the system's properties are developed.}, number={9}, journal={JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME}, author={Karimi-Moghaddam, Giti and Gould, Richard D. and Bhattacharya, Subhashish}, year={2014}, month={Sep} }
 @inproceedings{dutta_bhattacharya_2014, title={A method to measure the DC bias in high frequency isolation transformer of the dual active bridge DC to DC converter and its removal using current injection and PWM switching}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934343862&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953527}, abstractNote={The Dual Active Bridge (DAB) bidirectional dc to dc converter has gained a significant popularity in high voltage, high power due to its several topological advantages. Due to non-ideal switching characteristics and delays in gating, DC bias may be generated in the high frequency transformer leading to increased loses and eventually saturation and failure of the transformer and the switches. This paper proposes a simple way to measure the dc bias in the transformer flux using the primary and secondary winding current. A simple duty cycle modulation of the primary bridge is proposed to eliminate the DC bias in lower power topologies. This method has been verified through experimental results. For high power applications a current injection method through a separate tertiary winding is proposed, and verified such that the magnetizing current is supplied separately by the tertiary winding eliminating the possibility of transformer saturation.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Dutta, S. and Bhattacharya, S.}, year={2014}, pages={1134–1139} }
 @inproceedings{dutta_roy_bhattacharya_2014, title={A mode switching, multiterminal converter topology with integrated fluctuating renewable energy source without energy storage}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900400574&partnerID=MN8TOARS}, DOI={10.1109/apec.2014.6803342}, abstractNote={An important functionality of the Solid State Transformer (SST) is the integration of renewable energy sources within the topology itself, acting as a renewable energy hub. Due to the fluctuating nature of the renewable energy source, such integration becomes a challenge and energy storage becomes a requirement. In this paper a topology variant of single phase SST with multi limb magnetic core is proposed which directly integrates the renewable energy source in the high frequency magnetic stage and uses the grid as the energy buffer eliminating the requirement of energy storage.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Dutta, S. and Roy, S. and Bhattacharya, Subhashish}, year={2014}, pages={419–426} }
 @inproceedings{tripathi_mainali_bhattacharya_2014, title={A series compensation enabled ZVS range enhancement of a dual active bridge converter for wide range load conditions}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934301547&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6954139}, abstractNote={A novel ZVS range control technique using an auxiliary series transformer for a Dual Active Bridge (DAB) DC-DC converter is proposed. The auxiliary transformer fed with an additional H-bridge at the secondary, adds a phase-controlled voltage in series with the main converter voltage either at the primary or secondary. This addition helps to control the reactive power flowing through the main converters of the DAB. Hence the power-factor of the main converters can be controlled in such a way that the DAB can maintain ZVS even at light loads. Also it operates at minimum reactive power at higher loads while it still operates in ZVS and thus results in higher efficiency on both extremes. The series transformer carries dominantly reactive power since the compensation angle is most often near quadrature. For medium/high power DAB, the cost and additional losses associated with the series circuit can be neglected due to significant efficiency improvement. The external inductor can be eliminated by using a series transformer designed with enough leakage inductance hence saving the additional magnetic cost. The proposed technique is validated with simulations followed by experiment on a hardware implementation. The technique is also simulated for a medium voltage DAB system with actual switching and magnetic data to bring out the efficiency improvements.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Tripathi, A. and Mainali, K. and Bhattacharya, S.}, year={2014}, pages={5384–5391} }
 @inproceedings{ramachandran_kuvar_singh_bhattacharya_baran_2014, title={A system level study employing improved solid state transformer average models with renewable energy integration}, volume={2014-October}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84930989275&partnerID=MN8TOARS}, DOI={10.1109/PESGM.2014.6939922}, abstractNote={Solid State Transformer (SST) average models are needed to enable system and protection studies. This paper focuses on fine tuning existing average models to replicate their switching counterparts and also discusses and validates control modifications required for successful grid integration. A 3 phase test system comprised of Substation SSTs and load SSTs of different ratings has been developed in PSCAD. The SST's response under fault conditions and its ability to integrate distributed resources in a seamless manner are shown. In addition other features such as the SST's internal over-current and over-voltage protection and its ride through capabilities are discussed..}, number={October}, booktitle={IEEE Power and Energy Society General Meeting}, author={Ramachandran, V. and Kuvar, A. and Singh, U. and Bhattacharya, S. and Baran, M.}, year={2014} }
 @inproceedings{madhusoodhanan_bhattacharya_hatua_2014, title={A unified control scheme for harmonic elimination in the front end converter of a 13.8 kV, 100 kVA transformerless intelligent power substation grid tied with LCL filter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900448559&partnerID=MN8TOARS}, DOI={10.1109/apec.2014.6803424}, abstractNote={This paper proposes a simple control scheme to eliminate the lower order harmonics in the line currents of the Front End Converter (FEC) of a 100 kVA Transformerless Intelligent Power Substation (TIPS) connected to the medium voltage (13.8 kV) grid through an LCL filter. Due to medium voltage (13.8 kV) and low power (100 kVA) specification for the FEC, the control technique needs to be specially designed to control very low magnitude of line current (4.2 A rms). Lower order harmonics are present in the grid current due to dead time in the FEC and grid voltage harmonics. Low switching frequency along with the medium voltage and low power levels results in a filter capacitor value that offers low impedance to the lower order harmonic currents. This lower order harmonic current flow through the filter capacitor limits the power that can be delivered by the converter due to lower current rating of the FEC. It also pollutes the control loop and affect system stability. This paper proposes a simple unified control scheme with harmonic current elimination under such conditions. The control scheme eliminates these harmonics in the grid current by regulating the harmonics in the filter capacitor voltage and inductor currents, both on grid side and converter side. System modeling, simulation and experimental results validate the proposed control scheme.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Madhusoodhanan, S. and Bhattacharya, Subhashish and Hatua, K.}, year={2014}, pages={964–971} }
 @inproceedings{yousefpoor_parkhideh_fardanesh_bhattacharya_2014, title={Algebraic model and control of embedded multi-terminal DC network in meshed AC power system}, volume={2014-October}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84930989260&partnerID=MN8TOARS}, DOI={10.1109/pesgm.2014.6939351}, abstractNote={Multi-terminal DC grid can be embedded in meshed AC grid to increase power transmission capability and control power flow of AC grid. In addition to economic benefits especially in congested areas, the proposed solution can provide back-up for the AC grid and enhance power transmission capacity and flexibility. From the supervisory control point of view, a control algorithm is required to set the reference values for controlling the DC grid power flow based on the desired operating points of meshed AC grid. In this paper, the algebraic model of the DC grid is derived and validated in meshed AC power systems. Algebraic model will present the behavior of AC grid with respect to various operating points of the DC grid, and it is used for steady state analysis. This paper also proposes a droop control structure with dead-band controller for the DC grid. To verify the algebraic model and the control structure, dynamic performance of the embedded multi-terminal DC grid in a reduced order three-bus AC equivalent NYPA power system is investigated in PSCAD/EMTDC environment.}, number={October}, booktitle={IEEE Power and Energy Society General Meeting}, author={Yousefpoor, N. and Parkhideh, B. and Fardanesh, B. and Bhattacharya, Subhashish}, year={2014} }
 @inproceedings{dutta_ramachandaran_bhattacharya_2014, title={Black start operation for the Solid State Transformer created micro-grid under islanding with storage}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934343864&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953936}, abstractNote={The Solid State Transformer (SST) enables intelligent integration of renewable resources with the grid. The rectifier, grid tie inverter and black start modes of SST operation are discussed in this paper. A previous study [3], did a preliminary investigation of the black start capabilities of the SST. This paper further investigates the control structures and validates them through PSCAD simulations and with experimental results.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Dutta, S. and Ramachandaran, V. and Bhattacharya, S.}, year={2014}, pages={3934–3941} }
 @inproceedings{mobarrez_kashani_bhattacharya_adapa_2014, title={Comparative study of DC circuit breakers using realtime simulations}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84949926464&partnerID=MN8TOARS}, DOI={10.1109/IECON.2014.7049056}, abstractNote={One of the main limitations in using high voltage and medium voltage DC grids is the issues related to the current-limiting devices and circuit breakers. These devices should be able to handle large currents in the normal operation condition and block high DC currents in a few microseconds in the case of DC faults. Moreover, they are required to dissipate huge amounts of energy stored in the transmission line inductances. In this paper, four configurations of DC circuit breakers from three general groups are evaluated and the results are compared in terms of the time required by the breakers to interrupt the current, maximum DC breaking current, rated voltage, efficiency and current state of development. The performance of DC circuit breakers is evaluated when a line to ground DC fault happens in a 9 module/2 terminal DC system. Simulation results were obtained using Real Time Digital Simulator (RTDS) and PSCAD.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Mobarrez, M. and Kashani, M.G. and Bhattacharya, S. and Adapa, R.}, year={2014}, pages={3736–3742} }
 @inproceedings{de_roy_bhattacharya_2014, title={Comparative suitability evaluation of reverse-blocking IGBTs for current-source based converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906662202&partnerID=MN8TOARS}, DOI={10.1109/ipec.2014.6869950}, abstractNote={In this paper, a Reverse Blocking IGBT is compared with various other combinations of switches and diodes keeping Current Source based Converter application in mind. The devices are tested under Reverse Voltage Commutation, Switch Overlap (turn on at non-zero current but zero voltage), Hard Switching, and Zero Current Switching condition. Test Circuits have been constructed and tested at various voltage levels with various combinations of devices. Forward Characteristics have also been compared. The main motivation of the paper is to make a fair judgment on device selection for Partial Resonant Link AC/AC Converter (soft-switched) and Isolated Dynamic Current Converter (hard switched). As for soft switched, majority of the losses are caused due to conduction loss. Therefore, RB-IGBT leads to a huge reduction of losses owing to better forward characteristics (lower conduction loss) as compared to the rest of the set. SiC-MOS and SiC-JBS Diode combination showed significant loss reduction for hard switched converter.}, booktitle={2014 International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014}, author={De, A. and Roy, S. and Bhattacharya, Subhashish}, year={2014}, pages={2562–2568} }
 @inproceedings{chattopadhyay_de_bhattacharya_2014, title={Comparison of PR controller and damped PR controller for grid current control of LCL filter based grid-tied inverter under frequency variation and grid distortion}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934324314&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953895}, abstractNote={Voltage Source Inverters (VSIs) are essential component for integration of renewable energy sources into utility grid or microgrid. Most of the utility grid regulation standards demand high quality sinusoidal current regulation by these inverters with renewable sources, which necessitates the use of LCL filters at the output of VSIs. Different load conditions and other factors influence grid conditions, such as voltage profile, harmonic distortion and frequency variation. The scope of this paper include comparison of effects on grid current of LCL filter based inverter while using PR controller and damped PR controller under distorted grid voltage and frequency variation conditions. The effects are analyzed through simulation studies in MATLAB/PLECS and real time simulation studies are carried out in Typhoon HIL environment.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Chattopadhyay, R. and De, A. and Bhattacharya, S.}, year={2014}, pages={3634–3641} }
 @inproceedings{yousefpoor_parkhideh_azidehak_kim_bhattacharya_2014, title={Control and experiment of high frequency isolated modular converter under normal and AC fault operating condition}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934301194&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6954199}, abstractNote={Recently, Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) transmission systems have gained more attention. In this paper, a control method for a modular VSC based HVDC transmission system with high frequency isolation referred to as high frequency isolated modular converter is proposed. In the high frequency isolated modular converter configuration, several floating DC capacitors in all three phases are connected in series, and voltage balancing control of these floating dc capacitors is required. In this paper, an appropriate control structure with the capacitor voltage balancing controller is proposed. The proposed control scheme consists of three layers to control terminal DC bus voltage and balance DC capacitor voltages of each building block. Detailed PSCAD simulation results are presented to evaluate the performance of high frequency isolated modular converter under normal and AC fault operating conditions. Finally, lab-scale experimental results are presented to validate the proposed control method.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Yousefpoor, N. and Parkhideh, B. and Azidehak, A. and Kim, S. and Bhattacharya, S.}, year={2014}, pages={5813–5820} }
 @inproceedings{tripathi_mainali_patel_bhattacharya_hatua_2014, title={Control and performance of a single-phase dual active half bridge converter based on 15kV SiC IGBT and 1200V SiC MOSFET}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900413266&partnerID=MN8TOARS}, DOI={10.1109/apec.2014.6803599}, abstractNote={A single-phase Dual Active Half Bridge (DAHB) DC-DC converter topology is evaluated for medium voltage (MV) application. A 15kV SiC-IGBT based three-level half-bridge is connected to the high voltage (HV) primary side of a high frequency (HF) transformer operating at 10kHz link-frequency. A 1200V SiC-MOSFET based two-level H-bridge is connected on the low voltage (LV) secondary side. This topology requires fewer switches and is suitable for MV application particularly with high step-down ratio where HF transformer may have considerable parasitics. It offers advantage of half blocking voltage requirement per device on the HV side and a simpler transformer saturation protection implementation. This paper also presents a robust D-Q based inner current control technique for the single phase DAB. The converters on both HV and LV side of the DAHB, can also be switched in 60° zero quasi-square mode to eliminate 3rd harmonic voltage. The square and 60° modes of operation are compared. The DAHB converter topology and controls are validated with simulation results followed by experimental results.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Tripathi, A. and Mainali, K. and Patel, D. and Bhattacharya, Subhashish and Hatua, K.}, year={2014}, pages={2120–2125} }
 @inproceedings{azidehak_yousefpoor_bhattacharya_2014, title={Control and synchronization of distributed controllers in modular converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84983134528&partnerID=MN8TOARS}, DOI={10.1109/IECON.2014.7049041}, abstractNote={In order to synchronize the distributed control systems (DCS) in modular converters such as Advanced Modular Multi-level Converters (AMMC) and Modular Transformer Converter (MTC) to the supervisory controller, a network layer must be established, and appropriate control architecture must be designed. In this paper, different control architectures for DCS with application in AMMC and MTC including series (daisy chain), parallel, and parallel-daisy (using both serial and parallel setup) are explored. There are practical issues in synchronization of modules in modular converters that have been addressed by and given solution to in the paper. The laboratory experimental test beds for MTC and AMMC configurations with distributed control systems (series (daisy chain), and parallel) architectures are implemented and experimental results are presented to validate the distributed control configurations.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Azidehak, A. and Yousefpoor, N. and Bhattacharya, S.}, year={2014}, pages={3644–3650} }
 @article{yousefpoor_narwal_bhattacharya_2015, title={Control of DC-fault-resilient voltage source converter-based HVDC transmission system under DC fault operating condition}, volume={62}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84929378724&partnerID=MN8TOARS}, DOI={10.1109/TIE.2014.2371431}, abstractNote={Voltage source converter (VSC)-based high-voltage direct current (HVDC) transmission systems have attractive advantages compared to classical thyristor-based HVDC transmission systems. However, VSC-based HVDC transmission systems are vulnerable to dc side fault, and expensive dc circuit breakers are required to protect them against dc fault. This paper proposes a control method of a dc fault-resilient VSC which can be protected against dc fault without using expensive dc circuit breakers. In the VSC configuration, several H-bridge modules are connected in cascade, so the voltage balancing control of several floating dc capacitors is required. In this paper, an appropriate control structure with the capacitor voltage balancing controller is proposed. The appropriate control algorithm for dc fault operation and recovery after dc fault is also proposed. PSCAD simulation results are presented to validate the proposed control structure under normal and dc fault operating conditions. Real-time-digital-simulator results are also presented to verify the control structure.}, number={6}, journal={IEEE Transactions on Industrial Electronics}, author={Yousefpoor, N. and Narwal, A. and Bhattacharya, Subhashish}, year={2015}, pages={3683–3690} }
 @inproceedings{hazra_bhattacharya_2014, title={Control of squirrel cage induction generator in an oscillating point absorber based wave energy conversion system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900444261&partnerID=MN8TOARS}, DOI={10.1109/apec.2014.6803759}, abstractNote={This paper presents operation and control of a Squirrel Cage Induction Generator (SCIG) to generate power from an oscillating point absorber based wave energy conversion (WEC) system. The oscillating point absorber buoy is assumed to be connected with the SCIG through a rack and pinion gear arrangement, thus converting the linear motion of the buoy to rotary motion of the generator. Proper gear ratio is assumed to amplify the low speed of the buoy to the standard rpm of the rotary generator. An equivalent mechanical model of the buoy is presented. The SCIG is controlled with indirect field oriented control (IFOC) method to extract power from the buoy. It is assumed that the SCIG is operated below its rated speed and the air gap flux is maintained at its rated value in all operating conditions. The torque component of the current is varied in proportion with the buoy speed to harvest variable power from the buoy. The system control is validated through simulation in MATLAB-Simulink platform and corresponding results are presented. A discussion on the peak to average power generation ratio and its impact on the machine rating is also provided.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Hazra, S. and Bhattacharya, Subhashish}, year={2014}, pages={3174–3180} }
 @inproceedings{yousefpoor_kim_bhattacharya_2014, title={Control of voltage source converter based multi-terminal DC grid under DC fault operating condition}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934300161&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6954183}, abstractNote={Recently, Voltage Source Converter (VSC) based Multi-Terminal DC (MTDC) transmission systems have gained more attention. Compared to current source converter technology, voltage source converters have several benefits including higher power quality, lower power transmission losses, and higher voltage capability. Flexibility in bidirectional power flow control is the main advantage of voltage source converters in large scale MTDC power transmission systems. However, VSC based MTDC transmission systems are vulnerable to DC side fault, and expensive DC circuit breakers are required to protect them against DC fault. This paper proposes a control method of a dc fault resilient voltage source converter that has ultra-fast electronic isolation capability following dc fault which can be protected against dc fault without using expensive DC circuit breakers. In this paper, the control scheme of MTDC grid based on droop control method with dead-band controller is proposed. The appropriate control algorithm of VSC based MTDC transmission system for DC fault operation and recovery after DC fault is also proposed. Finally, PSCAD simulation results are presented to evaluate the dynamic performance of VSC based MTDC grid with the proposed control algorithm under DC fault operating condition.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Yousefpoor, N. and Kim, S. and Bhattacharya, S.}, year={2014}, pages={5703–5708} }
 @inproceedings{babaei_chavan_bhattacharya_2014, title={Control structures for the unified power flow controller}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84949927799&partnerID=MN8TOARS}, DOI={10.1109/IECON.2014.7049137}, abstractNote={The basic principles of UPFC operation are discussed and the series inverter dynamics are explained. Two control strategies - the Cross-Coupling method and the Advanced Control method are discussed in detail and their bode plots are analyzed. The two control methods are implemented in PSCAD for the NYPA UPFC at Marcy substation. The performance of the two methods is observed for step changes in active power reference and the results are compared.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Babaei, S. and Chavan, G. and Bhattacharya, S.}, year={2014}, pages={4224–4230} }
 @inproceedings{yousefpoor_parkhideh_azidehak_bhattacharya_2014, title={Convertible Static Transmission Controller (CSTC) system model validation by controller hardware-in-the-loop-simulation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934325982&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953801}, abstractNote={Convertible Static Transmission Controller (CSTC) is a versatile power electronic system which is installed across a transmission transformer. The proposed solution provides several integration options with multiple operational modes. The CSTC can be used to control the power flow in a meshed transmission grid or to extend the life time of existing transformers by partially bypassing and conditioning the substation throughput power. From the supervisory control point of view, a control algorithm is required to set the reference values of active and reactive power flow of the CSTC converters based on the desired operating points for the transformer and the grid active and reactive power flows. In this paper, a generalized algebraic model of the CSTC in three different modes of operation is derived. The proposed algebraic model presents the behavior of transformer power flow with respect to various operating points of the CSTC. Therefore, the P-Q transformer operating range can be obtained. To verify the control structure and algorithm of the CSTC as a transmission asset, an ultra-high fidelity Controller Hardware-in-the-Loop (CHIL) experimentation will be explained and comparative results will be presented.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Yousefpoor, N. and Parkhideh, B. and Azidehak, A. and Bhattacharya, S.}, year={2014}, pages={2960–2966} }
 @inproceedings{roy_de_bhattacharya_2014, title={Current source inverter based cascaded solid state transformer for AC to DC power conversion}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906690154&partnerID=MN8TOARS}, DOI={10.1109/ipec.2014.6869656}, abstractNote={There are applications like railway traction system where power converters for HVAC to MVDC or MDAC to LVDC are required with a high power/weight ratio. The conventional way is to use heavy line frequency or medium frequency transformers followed by a controlled rectifier. The availability of high voltage SiC devices has made it possible to raise the switching frequency to higher value and hence the size and weight of the transformer can be reduced. This paper proposes a cascaded current source converter based topology with high frequency isolation as a replacement of the huge line frequency transformer. The paper also presents experimental results as a validation of the functionality of the converter.}, booktitle={2014 International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014}, author={Roy, S. and De, A. and Bhattacharya, Subhashish}, year={2014}, pages={651–655} }
 @article{mirzaee_de_tripathi_bhattacharya_2014, title={Design Comparison of High-Power Medium-Voltage Converters Based on a 6.5-kV Si-IGBT/Si-PiN Diode, a 6.5-kV Si-IGBT/SiC-JBS Diode, and a 10-kV SiC-MOSPET/SiC-JBS Diode}, volume={50}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84904684358&partnerID=MN8TOARS}, DOI={10.1109/tia.2014.2301865}, abstractNote={In this paper, a comparative design study of high-power medium-voltage three-level neutral-point-clamped converters with a 6.5-kV Si-IGBT/Si-PiN diode, a 6.5-kV Si-IGBT/SiC-JBS diode, and a 10-kV SiC-MOSFET/SiC-JBS diode is presented. A circuit model of a 100-A power module, including packaging parasitic inductances, is developed based on device die SPICE-based circuit models for each power device. Switching waveforms, characteristics, and switching power and energy loss measurements of the power modules, including symmetric/asymmetric parasitic inductances, are presented. High-power converter designs and SPICE circuit simulations are carried out, and power loss and efficiencies are compared for a pulsewidth-modulated (PMW) 1-MW power converter at 1-, 5-, and 10-kHz switching frequencies for application in shipboard power system and a PWM vector-controlled and a line-frequency angle-controlled 20- to 40-MVA power converter at 60-Hz, 540-Hz, and 1-kHz switching frequencies for active mobile substation application. It is shown that the 6.5-kV Si-IGBT incorporating an antiparallel SiC-JBS diode, with its high efficiency performance up to 5-kHz switching frequency, is a strong candidate for megawatt-range power converters. The 10-kV SiC-MOSFET/SiC-JBS diode remains an option for higher switching frequency (5-10 kHz) high-power converters.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Mirzaee, Hesam and De, Ankan and Tripathi, Awneesh and Bhattacharya, Subhashish}, year={2014}, pages={2728–2740} }
 @inproceedings{kadavelugu_bhattacharya_2014, title={Design considerations and development of gate driver for 15 kV SiC IGBT}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900410469&partnerID=MN8TOARS}, DOI={10.1109/apec.2014.6803505}, abstractNote={The 15 kV SiC N-IGBT is the state-of-the-art high voltage power semiconductor device developed by Cree. The SiC IGBT is exposed to a peak stress of 10-11 kV in power converter systems, with punch-through turn-on dv/dt over 100 kV/μs and turn-off dv/dt about 35 kV/μs. Such high dv/dt requires ultralow coupling capacitance in the dc-dc isolation stage of the gate driver for maintaining fidelity of the signals on the control-supply ground side. Accelerated aging of the insulation in the isolation stage is another serious concern. In this paper, a simple transformer based isolation with a toroid core is investigated for the above requirements of the 15 kV IGBT. The gate driver prototype has been developed with over 100 kV dc insulation capability, and its inter-winding coupling capacitance has been found to be 3.4 pF and 13 pF at 50 MHz and 100 MHz respectively. The performance of the gate driver prototype has been evaluated up to the above mentioned specification using double-pulse tests on high-side IGBT in a half-bridge configuration. The continuous testing at 5 kHz has been performed till 8 kV, and turn-on dv/dt of 85 kV/μs on a buck-boost converter. The corresponding experimental results are presented. Also, the test methodology of evaluating the gate driver at such high voltage, without a high voltage power supply is discussed. Finally, experimental results validating fidelity of the signals on the control-ground side are provided to show the influence of increased inter-winding coupling capacitance on the performance of the gate driver.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Kadavelugu, A. and Bhattacharya, Subhashish}, year={2014}, pages={1494–1501} }
 @inproceedings{tripathi_mainali_patel_kadavelugu_hazra_bhattacharya_hatua_2014, title={Design considerations of a 15kV SiC IGBT enabled high-frequency isolated DC-DC converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906658515&partnerID=MN8TOARS}, DOI={10.1109/ipec.2014.6869673}, abstractNote={The advent of the 15kV SiC IGBT device has made a single series stage medium-voltage (MV) and high-frequency (HF) DC-DC Dual Active Bridge (DAB) converter application viable. The Y: Y/Δ three-phase DAB is a high-power isolated DC-DC converter based on three-level neutral-point clamped (NPC) on the MV side. A MV/HF transformer used in the DAB, has significant parasitic capacitances, which cause ringing in the DAB current under high dV/dT switching. In addition, the converters need sufficient dead-time between complimentary switches to avoid possibility of any shoot-through. The length of the dead-time depends on switching characteristics. Both the dead-time and transformer parasitics affect zero voltage switching (ZVS) performance of the DAB. Thus, the DAB design has to be closely coupled with the switching characteristics of the devices and MV/HF transformer parasitics. For the ZVS mode, the current-vector needs to be between converter voltage vectors with a certain margins defined by dead-time, parasitics and desired duty ratio of three-level MV converter. This paper addresses these design challenges for the MV DAB application.}, booktitle={2014 International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014}, author={Tripathi, A. and Mainali, K. and Patel, D. and Kadavelugu, A. and Hazra, S. and Bhattacharya, Subhashish and Hatua, K.}, year={2014}, pages={758–765} }
 @inproceedings{mainali_tripathi_patel_bhattacharya_challita_2014, title={Design, measurement and equivalent circuit synthesis of high power HF transformer for three-phase composite dual active bridge topology}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900457176&partnerID=MN8TOARS}, DOI={10.1109/apec.2014.6803331}, abstractNote={High voltage high frequency (HF) transformer provides the isolation between high and low dc link voltages in dual active bridge (DAB) converters. Such DAB converters are finding wide applications as an intermediate DC-DC converter in transformerless intelligent power substation (TIPS), which is proposed as an alternative for conventional distribution-transformer connecting 13.8 kV and 480 V grids. The design of HF transformer used in DAB stage of such application is very challenging considering the required isolation, size and cost. In this paper, the specification generation, design, characterization, test and measurement results on a 10kHz HF transformer are presented, highlighting the above challenges.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Mainali, K. and Tripathi, A. and Patel, D.C. and Bhattacharya, Subhashish and Challita, T.}, year={2014}, pages={342–349} }
 @inproceedings{hazra_shrivastav_gujarati_bhattacharya_2014, title={Dynamic emulation of oscillating wave energy converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934343027&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953645}, abstractNote={This paper presents emulation of dynamic behavior of a wave energy converter in test bed condition. To evaluate performance of the electrical generator and associated power electronic converter in wave energy conversion (WEC) system, it is important to have the WEC device driving the generator. However, in test bed, the actual WEC device can not be installed. Rather, it is convenient to have an electrical motor working as the WEC device, driving the generator to be tested. Therefore, electrical motor needs to emulate the dynamic behavior of the WEC device closely to have the actual system conditions. In this paper, a point absorber buoy modeling is presented and emulation methods are described. The model is simulated in MATLAB-Simulink as well as real-time NI CompactRIO platform. The real time controller can generate the torque reference for an electrical motor to drive the generator. Thus NI CompactRIO emulates the behavior of the WEC system. All corresponding results are presented and discussed.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Hazra, S. and Shrivastav, A.S. and Gujarati, A. and Bhattacharya, S.}, year={2014}, pages={1860–1865} }
 @inproceedings{moballegh_madhusoodhanan_bhattacharya_2014, title={Evaluation of high voltage 15 kV SiC IGBT and 10 kV SiC MOSFET for ZVS and ZCS high power DC -DC converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906713623&partnerID=MN8TOARS}, DOI={10.1109/IPEC.2014.6869657}, abstractNote={The advent of Silicon Carbide (SiC) devices has made possible high switching frequency operation of PWM power converters. In this paper, SiC devices are compared in detail with Si devices in a high power (1 MW) DC -DC converter application. The converter is designed as the building block for traction drives which requires it to operate at high power, high input voltage (11 kV) and low output voltage (800 V) levels. A dual active bridge (DAB) and a series resonant converter (SRC) topology are compared to achieve highly efficient operation. The performance and efficiency of these converters are compared by simulations using two different combinations of switches; the SiC combination consists of 10 kV/10 A SiC MOSFET at High Voltage (HV) side and 1200 V/100 A SiC MOSFET at Low Voltage side (LV), and the Silicon combination consists of 6.5 kV/10 A Si IGBT at HV side and 1200 V/100 A Silicon IGBT at LV side. For further understanding, efficiency analysis using the newly developed 15 kV/20 A SiC IGBT on the HV side is also carried out.}, booktitle={2014 International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014}, author={Moballegh, S. and Madhusoodhanan, S. and Bhattacharya, Subhashish}, year={2014}, pages={656–663} }
 @inproceedings{kadavelugu_bhattacharya_ryu_brunt_grider_leslie_2014, title={Experimental switching frequency limits of 15 kV SiC N-IGBT module}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906675160&partnerID=MN8TOARS}, DOI={10.1109/ipec.2014.6870034}, abstractNote={This paper presents extensive experimental switching characteristics of a state-of-the-art 15 kV SiC N-IGBT (0.32 cm2 active area) up to 10 kV, 10 A and 175°C. The influence of the thermal resistance of the module package, cooling mechanism, and the increased energy loss with temperature are investigated for determining the switching frequency limits of the IGBT. Detailed FEM analysis is conducted for extracting the thermal resistance of each layer in the 15 kV module from the IGBT junction to the base plate, and then down to the ambient. Using this thermal information and the experimental switching data, the inductive switching frequency limits are analytically evaluated for liquid and air cooling cases with 660 W/cm2 and 550 W/cm2 power dissipation densities respectively, considering 150°C as maximum junction temperature. The air cooling power dissipation density of the 15 kV IGBT is experimentally validated using a dc-dc boost converter at 10 kV, 6.4 kW output and 550 W/cm2 under steady state operating conditions. The gate resistances used for the entire experiments are RG(ON) = 20 Ω and RG(OFF) = 10 Ω.}, booktitle={2014 International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014}, author={Kadavelugu, A. and Bhattacharya, Subhashish and Ryu, S.-H. and Brunt, E. Van and Grider, D. and Leslie, S.}, year={2014}, pages={3726–3733} }
 @inproceedings{madhusoodhanan_tripathi_kadavelugu_hazra_patel_mainali_bhattacharya_hatua_2014, title={Experimental validation of the steady state and transient behavior of a transformerless intelligent power substation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900439832&partnerID=MN8TOARS}, DOI={10.1109/apec.2014.6803809}, abstractNote={Transformerless Intelligent Power Substation (TIPS) is a 3-phase Solid State Transformer (SST) to interconnect 13.8 kV, 3-phase distribution grid with 480 V, 3-phase utility grid. The concept of TIPS was proposed as a solid state alternative to the conventional line frequency transformer. Various advantages of TIPS include unity power factor operation, controlled bidirectional power flow capability, reactive power compensation to improve grid voltage profile under necessary conditions, high frequency d.c link based isolation, small size and weight due to Silicon Carbide (SiC) devices, and renewable energy integration. This paper focuses on the system integration and hardware demonstration of the functions of TIPS at lower voltage and power levels. In addition, it focuses on various operational strategies like smooth start-up/shut-down scheme, stability criteria at the high voltage d.c link, fault protection for the various modules of TIPS, power quality improvement and performance under sudden load transients. Experimental results are given for each module separately and for fully integrated TIPS.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Madhusoodhanan, S. and Tripathi, A. and Kadavelugu, A. and Hazra, S. and Patel, D. and Mainali, K. and Bhattacharya, Subhashish and Hatua, K.}, year={2014}, pages={3477–3484} }
 @inproceedings{tripathi_shah_madhusoodhanan_bhattacharya_hatua_2014, title={FPGA based control board development for medium-voltage high-power three-phase dual active bridge converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84983164692&partnerID=MN8TOARS}, DOI={10.1109/IECON.2014.7048698}, abstractNote={A high power Y : Y/Δ three-phase Dual Active Bridge (DAB) topology offers higher power density, smaller switching stress, smaller volume of magnetics and smaller DC capacitor over single phase DAB. Therefore this topology is suitable for medium voltage (MV) applications. The high-frequency DAB currents are nearly sinusoidal suited for D-Q transformation which enables fast average mode current control for device protection. But it requires fast ADC conversions and processing speed to implement this control. Also the PWM channel requirement for this topology is high. A DSP repeats an infinite loop of calculations serially. Thus it has limited loop speed in case of longer algorithm size which limits the control bandwidth. An FPGA based control is suitable as it can process the algorithm in programmable combinational logic circuits which offer few nano-seconds of propagation delay. And thus the only speed limitation is the ADC conversion speed. But an FPGA board does not readily offer all the features required for this application. Therefore an ultra-fast 2 MSPS parallel ADC interface board has been developed to achieve the control objectives for the topology in this paper.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Tripathi, A.K. and Shah, M. and Madhusoodhanan, S. and Bhattacharya, S. and Hatua, K.}, year={2014}, pages={1487–1493} }
 @inproceedings{zhang_baran_de_bhattacharya_2014, title={Fast Volt-VAR control on PV dominated distribution systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84908428584&partnerID=MN8TOARS}, booktitle={Proceedings of the IEEE Power Engineering Society Transmission and Distribution Conference}, author={Zhang, W. and Baran, M. and De, A. and Bhattacharya, S.}, year={2014} }
 @inproceedings{patel_chattopadhyay_madhusoodhanan_bhattacharya_sawant_chandorkar_2014, title={Flux vector modulation for single-phase inverter with LC output filter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900463911&partnerID=MN8TOARS}, DOI={10.1109/apec.2014.6803510}, abstractNote={The inverter often connects to load or grid through inductor-capacitor (LC) filter for feeding the filtered voltage and current. The carrier based modulation techniques, such as sinusoidal pulse width modulation (SPWM) and space vector modulation (SVM), require some kind of current control in LC filter connected inverter to damp out the LC resonance. The major advantage of flux vector modulation for the inverter with output LC filter is that the voltage control loop alone can damp out the resonance of LC filter. Hence, there is no need to use extra passive components or active damping controller. In this paper, the flux vector modulation for single-phase voltage source inverter (VSI) is proposed. The theoretical development and the digital implementation steps of flux vector modulation are described. The synchronously rotating reference frame (SRRF) proportional-integral (PI) controller is used for output voltage control for stand-alone operation of inverter. The single-phase inverter with output LC filter in stand-alone mode controlled by only voltage control loop with the flux vector modulation is validated through laboratory experiments.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Patel, D.C. and Chattopadhyay, R. and Madhusoodhanan, S. and Bhattacharya, Subhashish and Sawant, R.R. and Chandorkar, M.C.}, year={2014}, pages={1530–1536} }
 @inproceedings{hazra_de_bhattacharya_cheng_palmour_schupbach_hull_allen_2014, title={High switching performance of 1.7kV, 50A SiC power MOSFET over Si IGBT for advanced power conversion applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906693633&partnerID=MN8TOARS}, DOI={10.1109/ipec.2014.6869991}, abstractNote={Silicon Carbide (SiC) has wider band gap compared to Silicon (Si) and hence MOSFET made in SiC has considerably lower drift region resistance, which is a significant resistive component in high-voltage power devices. Due to low on-state resistance combined with its inherently low switching loss, SiC MOSFET is an excellent candidate for high power converter design. With its lower power loss and operation capability at higher switching frequency, power converters based on SiC MOSFETs can offer much improved efficiency and compact size compared to those using Si IGBTs. In this paper, we report switching performance of a new 1.7kV, 50A SiC MOSFET; designed and developed by Cree, Inc. Hard-switching losses of the SiC MOSFETs with different circuit parameters and operating conditions are measured and compared with the 1.7kV, 50A Si IGBTs, using the same test setup. Switching performance of the 1.7kV SiC MOSFET and 1.7kV SiC Schottky diode connected in series are also evaluated under a zero current switching (ZCS) condition and important findings are reported.}, booktitle={2014 International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014}, author={Hazra, S. and De, A. and Bhattacharya, Subhashish and Cheng, L. and Palmour, J. and Schupbach, M. and Hull, B. and Allen, S.}, year={2014}, pages={3447–3454} }
 @inproceedings{vechalapu_kadavelugu_bhattacharya_2014, title={High voltage dual active bridge with series connected high voltage silicon carbide (SiC) devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934326083&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953674}, abstractNote={Using 6.5 kV Silicon (Si) IGBTs, high voltage high power DC to DC converters are realized either by multi-level converters or series connected devices based two level converters or modular multi-level converter using series connected devices two level converter as building blocks. The introduction of high voltage SiC devices (10 kV to 20 kV) reduces the component count significantly while improving the efficiency and power density of the converter. To explore further, this paper investigates the state of the art high voltage (>10 kV) SiC devices for high voltage dual active bridge (DAB) with series connected devices for high power applications. Experimental results for static and dynamic voltage balancing of 15 kV, 20 A SiC IGBT devices are given to validate the feasibility of series connection and also the experimental characterization of 10kV SiC MOSFET and 15 kV SiC IGBT with RC snubber are reported. By using energy loss data from the experimental characterization, HV side switching loss of a 1 MVA 16 kV/2 kV DAB topology has been evaluated for two independent cases with 10 kV, 10 A SiC MOSFET and 15 kV, 20 A SiC IGBT on the HV side of the converter, while using 1.7 kV Si IGBTs on LV side of the converter.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Vechalapu, K. and Kadavelugu, A.K. and Bhattacharya, S.}, year={2014}, pages={2057–2064} }
 @article{babaei_fardanesh_bhattacharya_2014, title={High-Power VSC-Based Simultaneous Positive- and Negative-Sequence Voltage Regulator}, volume={29}, ISSN={["1937-4208"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84907481310&partnerID=MN8TOARS}, DOI={10.1109/tpwrd.2014.2325773}, abstractNote={A voltage-source converter-based static synchronous compensator (STATCOM) is used in transmission and distribution systems for the purpose of voltage regulation and reactive power compensation. In the transmission level, angle-controlled STATCOMs are of primary interest due to their high efficiency and excellent waveform quality. There is a considerable number of angle-controlled STATCOMs installed in the different utilities in the U.S. Despite the high efficiency and good voltage quality, this type of STATCOM shows poor performance under ac system faults. They are usually tripped under severe unbalanced condition and system faults to protect the switches from huge negative-sequence current flow. This paper provides a solution to improve the transmission-level STATCOM performance under power system faults. The proposed solution is based on adding a single-phase inverter in series with the converter dc bus. One specific controller is designed which provides the capability of simultaneously controlling positive- and negative-sequence voltages. The results are supported by detailed simulation studies on the New York Power Authority STATCOM model using PSCAD/EMTDC.}, number={5}, journal={IEEE TRANSACTIONS ON POWER DELIVERY}, author={Babaei, Saman and Fardanesh, Bruce and Bhattacharya, Subhashish}, year={2014}, month={Oct}, pages={2124–2135} }
 @inproceedings{babaei_kashani_bhattacharya_2014, title={Instantaneous fault current limiter for PWM-controlled Voltage Source Converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900430903&partnerID=MN8TOARS}, DOI={10.1109/apec.2014.6803622}, abstractNote={The PWM-controlled Voltage Source Converters (VSCs) are commonly used in industrial and utility applications. In spite of superior features of fast voltage regulation and stable DC-link voltage, PWM-controlled VSCs have the major drawback of being sensitive to the grid disturbances especially the unbalanced conditions and system faults. Unbalanced input voltage generates large negative sequence current flow into the converter which results in oscillations with twice the line frequency on the DC-link voltage. This negative sequence current flow might damage the semiconductor switches. Beside the negative sequence voltage, the input voltage distorted with other harmonics also causes converter performance deterioration by producing harmonics on the DC-link voltage. This paper presents an alternative solution to improve the PWM-controlled VSC performance under unbalanced conditions and system faults and also under distorted input voltage condition caused by other harmonics rather than the negative sequence voltage. This solution is based on direct calculation of the negative sequence (or other harmonics) reference voltage without using any current regulator. This elimination of the current regulator makes the proposed controller very fast and robust. The effectiveness of this solution has been validated by simulation and Hardware-In-the-Loop test.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Babaei, S. and Kashani, M.G. and Bhattacharya, Subhashish}, year={2014}, pages={2286–2292} }
 @inproceedings{chattopadhyay_bhattacharya_foureaux_silva_braz cardoso_de paula_pires_cortizio_moraes_de s. brito_2014, title={Low voltage PV power integration into medium voltage grid using high voltage SiC devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906678377&partnerID=MN8TOARS}, DOI={10.1109/IPEC.2014.6870149}, abstractNote={High voltage high power semiconductor devices are being used for grid integration of renewable energy sources. 1200V, 100A SiC Mosfets, 10 kV SiC Mosfets and 10kV SiC JBS Diodes have proven to be beneficial for high voltage application. High Voltage SiC devices enable high switching frequency operation thus reducing size of passive elements. Scope of this paper focuses on an alternative approach for 0.9 MW PV power plant, which is currently being constructed in Brazil. Use of high power SiC devices for PV power plant for integration into 13.8 kV grid provides higher efficiency, reduction in size and volume.}, booktitle={2014 International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014}, author={Chattopadhyay, R. and Bhattacharya, S. and Foureaux, N.C. and Silva, S.M. and Braz Cardoso, F. and De Paula, H. and Pires, I.A. and Cortizio, P.C. and Moraes, L. and De S. Brito, J.A.}, year={2014}, pages={3225–3232} }
 @inproceedings{chattopadhyay_bhattacharya_foureaux_silva_cardoso_paula_pires_cortizio_moraes_brito_2014, title={Low voltage PV power integration into medium voltage grid using high voltage SiC devices}, booktitle={2014 international power electronics conference (ipec-hiroshima 2014 - ecce-asia)}, author={Chattopadhyay, R. and Bhattacharya, S. and Foureaux, N. C. and Silva, S. M. and Cardoso, F. B. and Paula, H. and Pires, I. A. and Cortizio, P. C. and Moraes, L. and Brito, J. A. D.}, year={2014}, pages={3225–3232} }
 @article{yousefpoor_parkhideh_azidehak_bhattacharya_fardanesh_2014, title={Modular transformer converter-based convertible static transmission controller for transmission grid management}, volume={29}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906235071&partnerID=MN8TOARS}, DOI={10.1109/TPEL.2014.2302014}, abstractNote={This paper investigates the concept of convertible static transmission controller (CSTC) using modular transformer converter (MTC) as the building block. The MTC is a bidirectional back-to-back ac/ac power conversion unit and the CSTC is a versatile transmission controller asset for dynamic power flow control and contingency management of the transmission grid. The proposed CSTC with new functions has several advantages compared to existing flexible ac transmission system controllers. System modularity for manufacturers and utilities/system operators using standard high power electronic systems is one of the advantages of this structure. In this paper, algebraic models of the CSTC are derived in two different operation modes (series-shunt and shunt-shunt connecting configurations). The proposed algebraic models are used to define the reference values for the CSTC converters based on the desired operating points for the meshed power system, the power transformers in particular. The dynamic performance of the CSTC with the proposed control structures and algebraic models will be investigated based on the PSCAD simulation. To prove the CSTC as a transmission asset and to verify the control structure and algorithm, ultrahigh fidelity controller hardware-in-the-loop testing has been conducted and comparative results will be presented. Finally, lab-scale experimental results are reported on the dynamic performance of the MTC-based CSTC.}, number={12}, journal={IEEE Transactions on Power Electronics}, author={Yousefpoor, N. and Parkhideh, B. and Azidehak, A. and Bhattacharya, S. and Fardanesh, B.}, year={2014}, pages={6293–6306} }
 @inproceedings{roy_de_bhattacharya_2014, title={Multi-port solid state transformer for inter-grid power flow control}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906689584&partnerID=MN8TOARS}, DOI={10.1109/ipec.2014.6870158}, abstractNote={This paper discusses about a multi-port solid state transformer (SST) which can be used as an inter-grid power flow controller. The objective of the converter is to integrate renewable energy sources with the existing grid along with controlled power flow between the grids. As an example, this paper describes a three terminal isolated SST with an integrated battery bank connected to it. The energy extracted from the renewable energy sources can be stored in the battery bank or can be directly fed to the utility grid. A suitable converter structure is chosen to activate bidirectional power flow between the energy sources. The extracted energy can also be used to supply the local demand. A laboratory prototype of the converter has been built and the functionality of the converter is validated with detailed experimental results.}, booktitle={2014 International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014}, author={Roy, S. and De, A. and Bhattacharya, Subhashish}, year={2014}, pages={3286–3291} }
 @inproceedings{yousefpoor_kim_bhattacharya_2014, title={Multi-terminal DC grid control under loss of terminal station}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934343815&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953470}, abstractNote={In this paper, the operation of Voltage Source Converter (VSC) based multi-terminal DC (MTDC) transmission system is evaluated under loss of converter station. From the control point of view, i) Master/Slave control method, and ii) droop control method are explored to control the multi-terminal DC grid. This paper compares different control methods for MTDC control under normal and loss of any terminal station. Also, a droop control structure with dead-band controller is proposed for MTDC grid control. The dynamic performance of a four-terminal DC grid is further investigated in PSCAD/EMTDC environment. Simulation results are presented and compared to demonstrate the superior performance of the proposed control method during loss of a converter station.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Yousefpoor, N. and Kim, S. and Bhattacharya, S.}, year={2014}, pages={744–749} }
 @inproceedings{hazra_bhattacharya_2014, title={Operation of Doubly Fed Induction Generator in ocean wave energy conversion system by stator phase sequence switching}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934343865&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953734}, abstractNote={This paper presents operation of a Doubly Fed Induction Generator (DFIG) to extract oscillatory power from ocean wave energy converter (WEC). DFIG has the advantage of generating power at both sub-synchronous and super-synchronous speed with only slip power to be handled by power converter at rotor side. At super-synchronous speed the rotor generates slip power along with the stator to take the net power generation above the generator power rating. Due to power generation capability above its rating, DFIG is a good candidate for WEC system. However, to operate DFIG in an oscillatory system where direction of rotor speed keeps changing it requires controlled supply from stator side as well. In this paper, a rotor side control method is proposed to operate the DFIG in oscillatory system with a low cost stator phase sequence switching circuit to adapt to the change of direction of the rotor speed. A suitable control scheme is proposed to control the machine flux during start up and speed reversal to eliminate current inrush at the stator side. The DFIG current is controlled in vector control method with control axes orientated along stator flux axis. The current controllers are designed to control the rotor side currents to produce power and to regulate machine flux in accordance with the wave energy converter dynamics. The system is modeled and simulated in MATLAB-Simulink platform to validate the proposed scheme. All the corresponding results are presented and discussed.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Hazra, S. and Bhattacharya, S.}, year={2014}, pages={2503–2510} }
 @inproceedings{madhusoodhanan_tripathi_patel_mainali_kadavelugu_hazra_bhattacharya_hatua_2014, title={Solid State Transformer and MV grid tie applications enabled by 15 kV SiC IGBTs and 10 kV SiC MOSFETs based multilevel converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906706613&partnerID=MN8TOARS}, DOI={10.1109/ipec.2014.6869800}, abstractNote={Recently, medium voltage SiC devices have been developed which can be used for grid tie applications at medium voltage. Two such devices - 15 kV SiC IGBT and 10 kV SiC MOSFET have opened up the possibility of looking into different converter topologies for medium voltage distribution grid interface. These can be used in medium voltage drives, active filter applications or as the active front end converter for Solid State Transformers (SST). Transformer-less Intelligent Power Substation (TIPS) is one such application for these devices. TIPS is proposed as a 3-phase SST interconnecting 13.8 kV distribution grid with 480 V utility grid. The Front End Converter (FEC) of TIPS is made up of 15 kV SiC IGBTs. This paper focuses on the advantages, design considerations and challenges associated with the operation of converters using these devices keeping TIPS as the topology of reference.}, booktitle={2014 International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014}, author={Madhusoodhanan, S. and Tripathi, A. and Patel, D. and Mainali, K. and Kadavelugu, A. and Hazra, S. and Bhattacharya, Subhashish and Hatua, K.}, year={2014}, pages={1626–1633} }
 @inproceedings{madhusoodhanan_tripathi_patel_mainali_bhattacharya_2014, title={Stability analysis of the high voltage DC link between the FEC and DC-DC Stage of a Transformer-less Intelligent Power Substation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84930259311&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953904}, abstractNote={The advent of medium voltage blocking SiC devices has resulted in the development of 3-phase Solid State Transformers (SSTs) to inter-connect the 13.8 kV distribution grid with the 480 V utility grid. One such 3-phase SST is the Transformerless Intelligent Power Substation (TIPS). TIPS is tied with the 13.8 kV grid through an ac-dc Front End Converter (FEC) stage. The isolation stage is a dc-dc Dual Active Bridge (DAB) converter. The FEC and DAB High Voltage (HV) side converter are composed of 15 kV SiC IGBTs. The dc bus at the interface between the FEC and DAB stages is rated for 22 kV. The stability of this dc link is of great concern. The closed loop input and output impedances of these stages affect the stability of the system depending on the direction of power flow. This in-turn depends on the adopted control strategies, dc bus capacitance and also on the operating conditions such as dc bus voltage, grid voltage and power levels. This paper does a thorough analysis of the stability of the TIPS HV dc link which could be extended to other similar systems.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Madhusoodhanan, S. and Tripathi, A. and Patel, D. and Mainali, K. and Bhattacharya, S.}, year={2014}, pages={3702–3709} }
 @inproceedings{rocha_de jesus cardoso filho_moghaddam_gould_bhattacharya_2014, title={Thermal stress and high temperature effects on power devices in a fault-resilient NPC IGCT-based converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900397925&partnerID=MN8TOARS}, DOI={10.1109/APEC.2014.6803659}, abstractNote={The integrated gate commutated thyristor (IGCT) and the press-pack power diodes are successfully applied in medium-voltage Neutral Point Clamped (NPC) converters in the power range from hundreds of kW to tenth of MW. Responsible for driving key processes in various industries, the requirements of reliability and high availability of these converters are absolutely relevant, since its repair or replacement may take too much time. Given the vital importance of such equipment for the electric drive systems, they are equipped with protection schemes which are usually reliable but not infallible. If the protection scheme of the converter does not work properly in a fault situation, serious damages may be expected in the power semiconductor devices. These catastrophic effects can be alleviated by a fault-resilient design of the converter's bus bars, limiting the damage pattern in the converter to their least complex parts. In this work the thermal behavior of the power semiconductors is investigated using finite element models in the COMSOL Multiphysics software. Simulations and experimental measurements are made to attest the effectiveness of the fault-resilient design.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Rocha, A.V. and De Jesus Cardoso Filho, B. and Moghaddam, G.K. and Gould, R.D. and Bhattacharya, S.}, year={2014}, pages={2526–2533} }
 @inproceedings{karimi-moghaddam_gould_bhattacharya_tremelling_2014, title={Thermomagnetic liquid cooling: A novel electric machine thermal management solution}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934343045&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953594}, abstractNote={This paper investigates application of temperature sensitive ferrofluids (TSFF) in the thermal management of electric machines as the cooling and dielectric media for end winding section of these systems. The goal is to exploit the thermal and magnetic characteristics of TSMFs such that not only the fluid will circulate over the end winding of an electric machine, but also existing thermal and magnetic fields (magnetic leakage field) in this part of the machine will provide the energy needed for circulating the cooling fluid. The cooling mechanism will therefore require no additional moving mechanical parts, pumps, or sensors. This subject is investigated theoretically and numerically using finite difference method and COMSOL Multiphysics simulation software in this study.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Karimi-Moghaddam, G. and Gould, R.D. and Bhattacharya, S. and Tremelling, D.D.}, year={2014}, pages={1482–1489} }
 @inproceedings{de_bhattacharya_2014, title={Three-phase four-switch partial resonant soft switched rectifier}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934344105&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953511}, abstractNote={The paper investigates a soft-switching partial-resonant link AC/DC converter. The proposed converter uses 4 active switches and overcomes the various shortcomings of conventional resonant AC Link schemes such as the need for a four-quadrant ac switch. The switching operations occur at zero voltage instants thus lowering the losses. The input current is harmonic free. It can perform buck and boost operations. As the converter requires less number of active switches and operates at high switching frequency, it offers both improved performance and considerable reduction of volume, weight and cost. A prototype converter system has been built and tested. The loss data from a prior characterization study has been used to compare the efficiency of the converter for different combinations of devices. It has been shown that the combination of SiC-MOSFET and Si-PiN Diode would lead to a better more efficient converter. The converter has also been compared with the state of the art available solutions. The various advantages in terms of switch reduction and eventual reduction of switching and conduction losses have been tabulated. The topology is expected to offer compact, fast, efficient and inexpensive solution to the present AC/DC power conversion requirements.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={De, A. and Bhattacharya, S.}, year={2014}, pages={1022–1028} }
 @inproceedings{sepahvand_madhusoodhanan_corzine_bhattacharya_ferdowsi_2014, title={Topology selection for medium-voltage three-phase SiC solid-state transformer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84946687199&partnerID=MN8TOARS}, DOI={10.1109/ICRERA.2014.7016432}, abstractNote={The first stage in the structure of a three-phase solid state transformer (SST) is a medium voltage active rectifier. Due to its relatively high voltage operating conditions, this rectifier requires careful topology selection for empirical implementation. In this paper, different topologies of active rectifiers are studied as candidates for the first stage in SSTs. The selected topologies are narrowed down to three most suitable topologies. Three selected topologies are the current source buck rectifier, the diode-clamped rectifier, and the series active filter. For comparison purposes, loss analysis of these three rectifiers is carried out using simulations and experimental implementation. In this study, for the sake of practicality and simplicity, 10 kV Silicon Carbide (SiC) MOSFETs and diodes are utilized to reduce the number of components in the multilevel structure of the rectifiers. Other than loss analysis, a new technique for capacitor voltage regulation for the series active filter topology is also proposed and experimentally verified. Considering the loss data and other issues such as line current total harmonic distortion (THD), it is concluded that the series active filter topology is the most suitable one for this application.}, booktitle={3rd International Conference on Renewable Energy Research and Applications, ICRERA 2014}, author={Sepahvand, H. and Madhusoodhanan, S. and Corzine, K. and Bhattacharya, S. and Ferdowsi, M.}, year={2014}, pages={485–489} }
 @inproceedings{kadavelugu_bhattacharya_leslie_ryu_grider_hatua_2014, title={Understanding dv/dt of 15 kV SiC N-IGBT and its control using active gate driver}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934301057&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2014.6953698}, abstractNote={The ultrahigh voltage (> 12 kV) SiC IGBTs are promising power semiconductor devices for medium voltage power conversion due to feasibility of simple two-level topologies, reduced component count and extremely high efficiency. However, the current devices generate high dv/dt during switching transitions because of the deep punch-through design. This paper investigates the behavior of dv/dt during the two-slope (different slopes before and after punch-through) turn-on and turn-off voltage transitions of these devices, by varying the device current, temperature and field-stop buffer layer design. It is shown that the dv/dt can be minimized by increasing the gate resistance, by taking the turn-on transition as reference. However, it is found that the increase in gate resistance has very weak impact on dv/dt above the punch-through voltage, and also resulting in significantly increased switching energy loss. It is shown that this problem can be addressed by using a two-stage active gate driver, where the gate current is appropriately controlled to limit the dv/dt over punch-through voltage and to minimize the switching energy loss under the punch-through voltage. Experimental results on 15 kV SiC N-IGBTs with field-stop buffer layer thickness of 2 μm and 5 μm are presented up to 11 kV with a detailed discussion of the results.}, booktitle={2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014}, author={Kadavelugu, A. and Bhattacharya, S. and Leslie, S. and Ryu, S.-H. and Grider, D. and Hatua, K.}, year={2014}, pages={2213–2220} }
 @inproceedings{kashani_mobarrez_bhattacharya_2014, title={Variable interleaving technique for photovoltaic cascaded DC-DC converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84976537351&partnerID=MN8TOARS}, DOI={10.1109/IECON.2014.7049359}, abstractNote={This paper introduces a variable interleaving technique for photovoltaic cascaded DC-DC converters. A series rather than parallel connection of converters allows higher switch utilization and lower rating of components; however, they suffer from nonhomogeneous irradiations condition. Under partial shading conditions, the input power of all PV panel will not be the same and as a result the output voltage of each converter will not be identical. This causes system to operate in an asymmetric condition, in which, the conventional interleaving techniques are not capable of eliminating the DC link output voltage variations. In this work, an interleaving algorithm is reported on cascaded DC/DC converters under asymmetric condition to minimize the DC link output voltage variations. The effectiveness of this algorithm for cascaded DC-DC converters has been validated by simulation and Hardware-In-the-Loop tests.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Kashani, M.G. and Mobarrez, M. and Bhattacharya, S.}, year={2014}, pages={5612–5617} }
 @inproceedings{bhattacharya_2014, title={Wide-band Gap (WBG) WBG devices enabled MV power converters for utility applications - Opportunities and challenges}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84918556929&partnerID=MN8TOARS}, DOI={10.1109/WiPDA.2014.6964611}, abstractNote={Presents a collection slides covering the following topic:gate resistance SiC MOSFET switching effect; SiC MOSFET 3-phase voltage source converter;dual active bridge isolated DC-DC converter;DAB isolated DC-DC converter;coaxial winding transformer;SiC JFET module switching;SiC IGBT co-pack module;silicon carbide half-bridge module;SiC MOSFET 3-phase 2-level Inverter;transformerless intelligent power substation; HF transformer; 3-level 3-phase SiC IGBT inverter; three level NPC;neutral point clamped;3-phase AFE rectifier hardware;TIPS converter; gate driver isolation transformer;SiC MOSFET based drive;Marcy substation;convertible static compensator; CSC;smart grid;solid state fault current limiter;FACTS; flexible AC transmission system;VSC transmission application;line commutated converter;LCC;HVDC circuit breaker;}, booktitle={2nd IEEE Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2014}, author={Bhattacharya, S.}, year={2014} }
 @inproceedings{kadavelugu_bhattcharya_baliga_ryu_grider_palmour_2014, title={Zero voltage switching characterization of 12 kV SiC N-IGBTs}, DOI={10.1109/ispsd.2014.6856048}, abstractNote={This paper reports experimental zero voltage switching (ZVS) characteristics of the state-of-the-art 12 kV SiC N-IGBTs with 2 μm and 5 μm field-stop buffer layer thicknesses. Extensive results up to 7 kV and 150°C are presented for both IGBTs with and without an external snubber capacitor. The 12 kV SiC IGBTs have been found to have significantly larger magnitude of turn-off current bump in comparison to the results reported for the commercial (≤ 6.5 kV) Si IGBTs, because of deep punch-through design. The turn-off current shape is majorly influenced by slower voltage rise before the punch-through, followed by faster voltage rise after the punch-through voltage. In addition, the difference in current gain resulting from different buffer layer thicknesses has considerable effect on the overall switching behavior and energy loss of the two IGBTs. A detailed explanation of all these phenomena is presented along with the considerations for power converter design while employing the ZVS technique with these ultrahigh voltage IGBTs.}, booktitle={Proceedings of the international symposium on power semiconductor}, author={Kadavelugu, A. and Bhattcharya, S. and Baliga, B. J. and Ryu, S. H. and Grider, D. and Palmour, J.}, year={2014}, pages={350–353} }
 @inproceedings{patel_kadavelugu_madhusoodhanan_bhattacharya_hatua_leslie_ryu_grider_agarwal_2013, title={15 kV SiC IGBT based three-phase three-level modular-leg power converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891113691&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647132}, abstractNote={The 15kV /20A, 4H-SiC n-IGBT is the state-of-the-art high voltage power semiconductor device. The transformerless intelligent power substation (TIPS) [1] for 13.8kV grid interfacing is built using this device. It is proposed to use a three-phase, three-level, diode clamped topology as the front end converter (FEC) in TIPS. A modular-leg structure has been employed for FEC. In modular-leg structure, each phase-leg will have its own DC-link capacitors and a low inductance bus-bar. However, modular-leg structure adds complexity in DC bus over-load protection, which is studied in this paper. Experimental results of modular-leg converter at 3kV DC link voltage and scale down prototype of AC switch for DC bus fault protection are presented.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Patel, D.C. and Kadavelugu, A. and Madhusoodhanan, S. and Bhattacharya, Subhashish and Hatua, K. and Leslie, S. and Ryu, S.-H. and Grider, D. and Agarwal, A.}, year={2013}, pages={3291–3298} }
 @inproceedings{babaei_parkhideh_bhattacharya_fardanesh_2013, title={A control method for angle-controlled STATCOMs under system faults}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893199035&partnerID=MN8TOARS}, DOI={10.1109/pesmg.2013.6672943}, abstractNote={Voltage-Sourced Converter (VSC) based Synchronous Static Compensator (STATCOM) is used for voltage regulation in transmission and distribution systems. Comparing with PWM STATCOMs, angle-controlled STATCOMs are fired once with the line frequency to lower the system losses. In recent years, angle-controlled STATCOMs have been deployed by utility owners for the purpose of voltage regulation, voltage stability improvement and increasing operational functionality. Despite the superior feature on voltage waveform quality and efficiency, the practical angle-controlled STATCOMs suffer from the over-current (and trips) and possible saturation of the interfacing transformers caused by negative sequence current during unbalanced conditions and faults. This paper specifically proposes a control structure to improve the angle-controlled STATCOMs performance under unbalanced conditions and faults. The main improvement is to decrease the negative sequence current and DC-link voltage oscillations substantially under power line faults through the control and not the component design. PSCAD/EMTDC and Real Time Digital Simulation (RTDS) results verify the validity of the proposed control structure under fault conditions.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Babaei, S. and Parkhideh, B. and Bhattacharya, Subhashish and Fardanesh, B.}, year={2013} }
 @inproceedings{babaei_bhattacharya_2013, title={A control structure for line-frequency-switched STATCOMs under system faults}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891087871&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647037}, abstractNote={Voltage-Sourced Converter (VSC) based Static Synchronous Compensator (STATCOM) is used for voltage regulation in transmission and distribution systems. Comparing with PWM STATCOMs, Angle-controlled STATCOMs are fired at line frequency to lower the system losses. In recent years, angle-controlled STATCOMs have been deployed by utility owners for the purpose of voltage regulation, voltage stability improvement and increasing operational functionality. Despite the superior feature on voltage waveform quality and efficiency, the practical angle-controlled STATCOMs suffer from the over-current (and trips) and possible saturation of the interfacing transformers caused by negative sequence current during unbalanced conditions and system faults. This paper specifically proposes a control structure to improve the angle-controlled STATCOMs performance under unbalanced conditions and system faults. The main improvement is to decrease the negative sequence current and DC-link voltage oscillations substantially under power line faults through the control and not the components design. PSCAD/EMTDC and experimental results verify the validity of the proposed control structure under unbalanced conditions and system faults.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Babaei, S. and Bhattacharya, Subhashish}, year={2013}, pages={2605–2612} }
 @inproceedings{chen_lee_cheng_teodorescu_blaabjerg_bhattacharya_2013, title={A flexible low-voltage ride-through operation for the distributed generation converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84880729315&partnerID=MN8TOARS}, DOI={10.1109/PEDS.2013.6527230}, abstractNote={With more and more distributed energy resources (DERs) are installed in the utility grid, the utility requires the DER generation system to remain grid-connected and injects reactive and active power to support grid voltage during voltage sags. In this paper, a positive- and negative-sequence current injection method is proposed to meet the low-voltage ride through (LVRT) requirement. The proposed method predefined a current constraint to avoid the overcurrent during the LVRT operation and adjust the positive-sequence reactive current to reduce the DC-bus voltage ripple. Comparisons of the proposed method and other LVRT techniques are also presented.}, booktitle={Proceedings of the International Conference on Power Electronics and Drive Systems}, author={Chen, H.-C. and Lee, C.-T. and Cheng, P.-T. and Teodorescu, R. and Blaabjerg, F. and Bhattacharya, S.}, year={2013}, pages={1354–1359} }
 @inproceedings{mirzaee_bhattacharya_bala_2013, title={A multi-loop control system for series DC active filter in a medium-voltage DC amplifier}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891093183&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647403}, abstractNote={In order to cope with increasing power demand onboard future combatant ships, US navy has embarked on medium-voltage dc as the next generation integrated power system. A viable dc power supply system solution for such ships is based on the mature technology of multi-pulse thyristor bridge front-end rectifiers. Due to the intrinsic ripple characteristic associated with thyristor commutations in such front-ends, a high bandwidth series dc active filter can be used to smooth out the dc-bus. In this paper, we propose a new multi-loop feedback and feed-forward control system for the series dc active filter in order to meet the stringent dc-bus ripple attenuation and disturbance rejection requirements. Analysis and simulations results show promise of multi-loop control scheme. Experimental results of the 12kVA/400Vdc laboratory test-bed with feed-forward control are provided.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Mirzaee, H. and Bhattacharya, Subhashish and Bala, S.}, year={2013}, pages={5193–5198} }
 @inproceedings{dutta_roy_bhattacharya_2013, title={A multi-terminal DC to DC converter topology with power accumulation from renewable energy sources with unregulated DC voltages}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84879384693&partnerID=MN8TOARS}, DOI={10.1109/apec.2013.6520440}, abstractNote={The following paper details out a converter topology which can act as an accumulator of power from different renewable energy sources (RES). Due to the intermittent nature of power availability from RES the DC buses are assumed unregulated. The proposed topology decouples individual voltage sources and reduces unwanted circulation of reactive power between the busses due to mismatch in voltage levels, and at the same time accumulates the power and produces a regulated DC output. The magnetic design of the transformer core has been shown and the topology has been verified with hardware experimental results.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Dutta, S. and Roy, S. and Bhattacharya, Subhashish}, year={2013}, pages={1124–1130} }
 @inproceedings{karimi-moghaddam_gould_bhattacharya_2013, title={A non-dimensional analysis to characterize thermomagnetic convection of a temperature sensitive magnetic fluid in a flow loop}, volume={8 B}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84903451690&partnerID=MN8TOARS}, DOI={10.1115/imece2013-66313}, abstractNote={This paper presents results from theoretical and numerical studies of a single-phase, temperature sensitive magnetic fluid operating under steady-state laminar flow conditions in a partially heated thermomagnetic circulation loop under the influence of an external magnetic field (created by a solenoid). A one-dimensional theoretical model has been developed using scaling arguments to characterize thermomagnetic circulation in this loop in terms of the geometric length scales, magnetic fluid properties, and strength of the imposed magnetic field. In parallel to this theoretical analysis, supporting numerical simulations using COMSOL Multiphysics simulation software have been undertaken to obtain data for use in this 1D model. A correlation for the non-dimensional heat transfer (Nusselt number) as a function of the appropriate magnetic Rayleigh number and a correlation for the mass flow rate based on the system’s properties are developed.}, booktitle={ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)}, author={Karimi-Moghaddam, G. and Gould, R.D. and Bhattacharya, Subhashish}, year={2013} }
 @inproceedings{hazra_bhattacharya_chakraborty_2013, title={A novel control principle for a high frequency transformer based multiport converter for integration of renewable energy sources}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893563302&partnerID=MN8TOARS}, DOI={10.1109/iecon.2013.6700467}, abstractNote={This paper presents a novel approach to control power flow inside a high frequency transformer based multiport DC-DC converter. A multiport converter can interface a number of power sources and sinks with control of power flow among them. In a renewable energy sources (RES) integration scheme, the multiport converter operates like an accumulator where it collects power from each RES and dispatches it to the load port. Typically, power flow between any two ports happens through the leakage inductance of the transformer by imposing a required phase shift between fundamental component of two square wave voltages, impressed at the ports. However, each port is connected with the other ports by some inductance and hence the power flow from a particular source port to load port is not decoupled and can not be controlled independently. This paper proposes decoupling of source ports by eliminating the load port leakage inductance with a negative inductance, emulated by voltage injection in series with leakage inductance. A three port transformer based system is simulated to validate the principle. A scaled prototype of the three port transformer is designed and the effect of load port leakage inductance is analyzed through experiment.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Hazra, S. and Bhattacharya, Subhashish and Chakraborty, C.}, year={2013}, pages={7984–7989} }
 @inproceedings{fregosi_bhattacharya_2013, title={A novel method for control of distributed storage devices in distribution: Ripple voltage injection with frequency droop}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893185579&partnerID=MN8TOARS}, DOI={10.1109/pesmg.2013.6672278}, abstractNote={Ripple voltage injection has been used to control distributed loads to implement demand response. In this paper, we propose a novel technique to improve ripple control by utilizing frequency droop to control the power flow of distributed storage devices. Droop enables an arbitrary number of distributed devices to communicate bi-directionally to achieve power sharing. The response time of such a system is defined by the control and does not change as the number of storage devices increases. By controlling distributed storage through ripple control, communication systems on the grid are freed to perform other functions. The proposed control technique is explained and design and simulation are presented for the application of controlling electric vehicle chargers on a distribution feeder for frequency support.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Fregosi, D. and Bhattacharya, Subhashish}, year={2013} }
 @inproceedings{juvekar_brandmeyer_compton_liu_bhattacharya_2013, title={A reliable photovoltaic integrated UPS system with modified maximum power point tracking (MPPT) algorithm}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891135659&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2013.6647306}, abstractNote={This paper presents a new approach to integrate a fluctuating renewable power source like PV array into a conventional UPS by only modifying existing UPS firmware without needing any additional power converter. The paper also presents PV-UPS integrated system simulation developed using MATLAB/SIMULINK and hardware testing results for a 550kVA UPS interfaced with 30kW of solar panels. Proposed solution is modular, scalable, can work together with existing conventional UPSs on site or even upgrade them to interface PV power and still be as reliable as a conventional UPS. The proposed solution will allow utilities to do peak shaving and will help customers to reduce energy bills and extend battery time while providing same excellent power quality as conventional UPS. Unlike PV inverters which are forced to go offline during utility outage, proposed system shall continue to support critical loads during outages which is especially important for areas where utility interruptions are common.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, publisher={IEEE}, author={Juvekar, S. and Brandmeyer, J. and Compton, B. and Liu, Y. and Bhattacharya, S.}, year={2013}, pages={4526–4531} }
 @inproceedings{de_roy_bhattacharya_2013, title={Bidirectional soft-switched AC/AC high frequency link converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891133946&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647430}, abstractNote={This paper investigates a soft-switching partial-resonant link AC/AC converter. The proposed converter uses 12 unidirectional switches and overcomes the various shortcomings of conventional AC Link schemes. The switching operations occur at zero voltage instants thus lowering the switching losses. The input and output current is harmonic free and the controller also allows setting of desired power factor. It can perform buck and boost operations and has bi-directional power flow capability. As the converter operates at high switching frequency, it offers both improved performance and considerable reduction of volume, weight and cost. Detailed simulation results are presented and prototype converter system has been built and tested.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={De, A. and Roy, S. and Bhattacharya, Subhashish}, year={2013}, pages={5377–5384} }
 @inproceedings{de_roy_bhattacharya_divan_2013, title={Characterization and performance comparison of reverse blocking SiC and Si based switch}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893572618&partnerID=MN8TOARS}, DOI={10.1109/wipda.2013.6695567}, abstractNote={In this paper a custom made Reverse Voltage Blocking 1200V SiC switch or “current switch” (1200V SiC MOSFET in series with a 1200V SiC JBS diode) is compared with various other combinations of Reverse Voltage Blocking switches (with 1200V Si-IGBT, SiC MOSFET and Si-PIN diodes and SiC JBS diodes). The devices are tested under Reverse Voltage Commutation, Switch Overlap (turn on at non-zero current but zero voltage) and Hard Switching conditions. Test circuits have been constructed and tested at different dc voltage levels with various combinations of devices. The custom made current switch results show remarkable reduction of loss owing to reduced leakage inductance of the package. A new form of switching characteristic has been noticed and presented in this paper. The main motivation of the paper is to make a fair judgment on device selection for current stiff based hard and soft switching topologies.}, booktitle={1st IEEE Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2013 - Proceedings}, author={De, A. and Roy, S. and Bhattacharya, Subhashish and Divan, D.M.}, year={2013}, pages={80–83} }
 @inproceedings{kadavelugu_bhattacharya_ryu_brunt_grider_agarwal_leslie_2013, title={Characterization of 15 kV SiC n-IGBT and its application considerations for high power converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891115267&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647027}, abstractNote={The 4H-SiC n-IGBT is a promising power semiconductor device for medium voltage power conversion. Currently, Cree has successfully built 15 kV n-IGBTs. These IGBTs are pivotal for the smart grid power conversion systems and medium voltage drives. The need for complex multi-level topologies or series connected devices can be eliminated, while achieving reduced power loss, by using the SiC IGBT. In this paper, characteristics of the 15 kV n-IGBT have been reported for the first time. The turn-on and turn-off transitions of the 15 kV, 20 A IGBT have been experimentally evaluated up to 11 kV. This is highest switching characterization voltage ever reported on a single power semiconductor device. The paper includes static characteristics up to 25 A (forward) and 12 kV (blocking). The dependency of the power loss with voltage, current and temperature are provided. In addition, the basic converter design considerations using this ultrahigh voltage IGBT for high power conversion applications are presented. Also, a comparative evaluation is reported with an IGBT with thicker field-stop buffer layer as a means to show flexibility in choosing the IGBT design parameters based on the power converter frequency and power rating specification. Finally, power loss comparison of the IGBTs and MOSFET is provided to consummate the results for a complete reference.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Kadavelugu, A. and Bhattacharya, Subhashish and Ryu, S.-H. and Brunt, E. Van and Grider, D. and Agarwal, A. and Leslie, S.}, year={2013}, pages={2528–2535} }
 @inproceedings{tripathi_mainali_patel_bhattacharya_hatua_2013, title={Closed loop D-Q control of high-voltage high-power three-phase dual active bridge converter in presence of real transformer parasitic parameters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891099254&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647446}, abstractNote={Three-phase Dual Active Bridge (DAB) Y : Y/Δ composite topology offers advantage of nearly sinusoidal converter-currents without pulse-width modulation, which can be utilized for D-Q mode control implementation. D-Q control is smooth and regulates power-factor of DAB which ensures zero voltage switching (ZVS) operation of the DAB converter at wide-range loading conditions. A practical DAB high-frequency transformer has certain limitations like small leakage-inductance, limited magnetizing-inductance and unwanted parasitic-capacitance's which distort the primary-side currents at the rated high-voltage because primary inter-turn capacitance is high in per-unit for a real 100kW transformerdesign. This problem can be solved by using secondary currents and estimated magnetizing current to emulate primary-currents for D-Q control. Parasitic are introduced in the LV TIPS set-up by adding lumped elements to emulate real HV-transformer with objective to test the controls in worst case scenario. This paper proposes the solutions for some of the practical implementation problems of the control algorithm for the DAB.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Tripathi, A.K. and Mainali, K. and Patel, D. and Bhattacharya, Subhashish and Hatua, K.}, year={2013}, pages={5488–5495} }
 @inproceedings{madhusoodhanan_cho_kadavelugu_bhattacharya_grider_ryu_agarwal_leslie_2013, title={Comparative evaluation of SiC devices for PWM buck rectifier based active front end converter for MV grid interface}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891099153&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647097}, abstractNote={In this paper a new method for implementation of a 3-phase medium voltage rectifier is presented for Active Front End grid interface applications. A current source based PWM buck rectifier with Silicon Carbide (SiC) devices, different from the traditional GTO based current source rectifier, is used to grid tie with 3-phase, 4.16 kV grid. The power level considered is 100 kVA. Simplicity of construction, very high efficiency, better input line current control and small volume are the main advantages of this system. Due to low switching losses compared with traditional GTOs, PWM operation of the rectifier at higher switching frequencies is possible. A detailed simulation shows the validity of the proposed method. Efficiency comparison of the PWM Buck rectifier with 10 kV/10 A SiC MOSFET and 15 kV/20 A SiC IGBT as the active devices is also presented. Low voltage hardware prototype based high frequency switching validation is also carried out.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Madhusoodhanan, S. and Cho, Y. and Kadavelugu, A. and Bhattacharya, Subhashish and Grider, D. and Ryu, S.-H. and Agarwal, A. and Leslie, S.}, year={2013}, pages={3034–3041} }
 @inproceedings{yousefpoor_azidehak_bhattacharya_parkhideh_2013, title={Control of Active Mobile Substations under system faults}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891048215&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2013.6646948}, abstractNote={While conventional mobile substations are used to bypass the whole substation in case of loss or maintenance of power transformers, Active Mobile Substations (AMS) can be used both in normal conditions as a power router and in contingencies as a recovery transformer. The AMS is a mobile substation with integrated power electronics. By controlling its throughput power, it can be connected across different transformers of the grid. This paper explores transmission-level active mobile substations that provide back-up in case of power transformer failure or forced reduced operation scenarios in addition to power flow control for seasonal renewable energy transmission. The AMS must be designed to operate satisfactorily under typical fault and unbalanced conditions. In this paper, component design considerations in development of the AMS under unbalanced operating condition will be provided, and a new control strategy is proposed to control AMS under unbalanced operating conditions when component design is not sufficient to prevent overcurrent and trips. Detailed PSCAD simulation for the proposed control scheme is performed and results are presented. Experimental results are also shown to verify the proposed control method under unbalanced operating conditions.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Yousefpoor, N. and Azidehak, A. and Bhattacharya, Subhashish and Parkhideh, B.}, year={2013}, pages={1962–1969} }
 @inproceedings{madhusoodhanan_bhattacharya_hatua_2013, title={Control technique for 15 kV SiC IGBT based active front end converter of a 13.8 kV grid tied 100 kVA transformerless intelligent power substation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891067107&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647331}, abstractNote={This paper discusses the control technique adopted for a 3-Level Neutral Point Clamped (3L-NPC) converter, which is the rectifier stage of a 100 kVA solid state transformer known as the Transformerless Intelligent Power Substation (TIPS) interfacing with 13.8 kV grid. Due to high voltage (13.8 kV) and low power (100 kVA) specification for the rectifier, the control technique needs to be specially designed to control very low magnitude of line current (4.184 A r.m.s). Due to dead time in the converter and harmonic voltage present in the grid, the rectifier current is rich in lower order harmonics (6m±1). Moreover due to very high grid voltage, limiting starting inrush current within the converter current rating is a serious issue. A unified control technique is discussed to mitigate the above mentioned problems. Also the proposed control technique addresses the grid voltage unbalance and d.c bus mid-point voltage unbalance issue faced by the rectifier stage of TIPS. Simulation and SiC IGBT prototype experimental results verify the proposed techniques.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Madhusoodhanan, S. and Bhattacharya, Subhashish and Hatua, K.}, year={2013}, pages={4697–4704} }
 @inproceedings{babaei_bhattacharya_2013, title={DC-side series active power filter for STATCOM performance under system faults}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891093461&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647405}, abstractNote={Voltage-Sourced Converter (VSC) based Static Synchronous Compensator (STATCOM) is used in transmission and distribution systems for the purpose of voltage regulation and reactive power compensation. In the transmission level, angle-controlled STATCOMs are of primary interest due to their high efficiency and excellent waveform quality. This type of the STATCOM is fired at line frequency to lower the switching losses. There are considerable numbers of angle-controlled STATCOMs installed in the different utilities in the United States. Despite the high efficiency and good voltage quality, this type of the STATCOM is showing poor performance under AC-system faults. They are usually tripped under severe unbalanced condition and system faults to protect the switches from huge negative sequence current flow. This paper provides a solution to improve the transmission level STATCOM performance under power system faults. Proposed solution is based on adding a single phase inverter in series with converter DC-bus. This single phase inverter generates controllable oscillations with twice the line frequency on the DC-link voltage which will be reflected as negative sequence voltage at VSC output terminals. Generated negative sequence voltage limits the fault negative sequence current flow on the STATCOM tie line. Based on the proposed Solution one specific controller is designed which provides the capability of simultaneous controlling of the both positive and negative sequence voltages. The results are supported by detailed simulation studies on the New York Power Authority (NYPA) STATCOM model using the PSCAD/EMTDC.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Babaei, S. and Bhattacharya, Subhashish}, year={2013}, pages={5207–5214} }
 @inproceedings{hazra_madhusoodhanan_bhattacharya_moghaddam_hatua_2013, title={Design considerations and performance evaluation of 1200 V, 100 a SiC MOSFET based converter for high power density application}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891136369&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2013.6647272}, abstractNote={Silicon Carbide (SiC) MOSFET is capable of achieving better efficiency, power density and reliability of power converters due to its low on-state resistance, high temperature operation capability and lower switching losses compared to silicon (Si) IGBT. Operation of power converters at higher switching frequency using SiC devices allows reduction in filter size and hence improves the power to weight ratio of the converter. This paper presents switching characterization of 1200 V, 100 A SiC MOSFET module and compares efficiency of a Two Level Voltage Source Converter (2L-VSC) using SiC MOSFETs and Si IGBTs. Also, various design considerations of the 1200 V, 100 A SiC MOSFET based 2L-VSC including gate drive design, bus bar packaging and thermal management have been elaborated. The designed and developed 2L-VSC is operated to supply 35 kVA load at 20 kHz switching frequency with DC bus voltage at 800 V and the experimental results are presented.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Hazra, S. and Madhusoodhanan, S. and Bhattacharya, Subhashish and Moghaddam, G.K. and Hatua, K.}, year={2013}, pages={4278–4285} }
 @inproceedings{baliga_hazra_singh_roy_bhattacharya_paulakonis_notani_2013, title={Device characterization and performance of 1200V/45A SiC JFET module}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891141152&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6646711}, abstractNote={This paper evaluates the hard-switching performance of a novel cascode configuration of a 1200V/45A SiC JFET module. The device is first characterized and then switched up to 600V through double pulse testing. The capacitive effects of the device are analyzed and account for a significant current spike during turn-on. The switching behavior due to the gate drive circuitintroduction of varied gate resistances is discussed and analyzed. The switching behavior allows for the extraction of rise time, fall time, dV/dt, di/dt, and the switching losses - Eon and Eoff - while applying these varying gate resistances. The gate drive circuit is discussed and the hardware and test setup are shown and presented.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Baliga, V. and Hazra, S. and Singh, S. and Roy, S. and Bhattacharya, Subhashish and Paulakonis, J. and Notani, S.}, year={2013}, pages={273–278} }
 @article{babaei_parkhideh_chandorkar_fardanesh_bhattacharya_2014, title={Dual Angle Control for Line-Frequency-Switched Static Synchronous Compensators Under System Faults}, volume={29}, ISSN={["1941-0107"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893954434&partnerID=MN8TOARS}, DOI={10.1109/tpel.2013.2273799}, abstractNote={Voltage-sourced converter (VSC)-based static synchronous compensators (STATCOMs) are used for voltage regulation in transmission and distribution systems. Unlike PWM-controlled STATCOMs, angle-controlled STATCOMs are switched at line frequency to limit the system losses. In recent years, angle-controlled STATCOMs have been deployed by utilities for the purpose of transmission system voltage regulation, voltage stability improvement, and increasing operational functionality. Despite the superior feature on voltage waveform quality and efficiency, the practical angle-controlled STATCOMs suffer from the over-current (and trips) and possible saturation of the interfacing transformers caused by negative sequence current during unbalanced conditions and faults in the utility. This paper specifically proposes a control structure to improve the angle-controlled STATCOMs performance under unbalanced conditions and faults. The main improvement is a substantial decrease in the negative sequence current and dc-link voltage oscillations under power system faults by the proposed control. This eliminates the need to redesign the STACOM power components to operate under fault current and dc-link voltage oscillations. The proposed control structure is designed based on adding appropriate oscillations to the conventional angle-controller output that is the control angle by which the VSC voltage vector leads/lags the line voltage vector. Since this control structure uses two angles for controlling the VSC output voltage, it is called dual angle control (DAC). PSCAD/EMTDC and experimental results verify the validity of the proposed control structure under unbalanced system conditions and faults. The experiments were conducted on a transient network analyzer, a unique hardware-based flexible ac transmission system simulator which was designed to study system faults and transients for a 2 × 100 MVA STATCOM field installation.}, number={6}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Babaei, Saman and Parkhideh, Babak and Chandorkar, Mukul C. and Fardanesh, Bruce and Bhattacharya, Subhashish}, year={2014}, month={Jun}, pages={2723–2736} }
 @inproceedings{white_battacharya_2013, title={Electric arc furnace compensation using LaGrange minimization}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891091177&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2013.6646987}, abstractNote={Electric Arc Furnaces (EAFs) are generally moderated by ancillary compensation to remove the time-varying reactive component from the utility load; the compensation strategy is fundamentally based upon an application of the Clarke transformation which does not use the zero component; as a result, the highly unbalanced EAF currents have a component that remains uncompensated. The present work uses LaGrange minimization to determine inactive currents that are then used to direct a Static Compensator (STATCOM). Where there is significant unbalance, the technique results in reduced line currents and improvements to the magnitude and stability of power delivered to the arc. The real power delivered by the STATCOM under the LaGrange technique is zero; where there is no line imbalance the results are identical to those produced by use of the Clarke transformation. The LaGrange scheme is compared directly to the Clarke transformation-based compensation scheme by the use of a PSCad model.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={White, L.W. and Battacharya, S.}, year={2013}, pages={2253–2256} }
 @inproceedings{kadavelugu_bhattacharya_ryu_grider_agarwal_leslie_2013, title={Evaluation of 15 kV SiC N-IGBT and P-IGBT for complementary inverter topology with zero dv/dt stress on gate drivers}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891060348&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647026}, abstractNote={The complementary inverter topology with N-channel and P-channel switching devices is a known method of eliminating dv/dt stress on the gate drivers. In the Silicon (Si) based applications, this advantage did not gain wide attention due to inherent inefficiency of the P-type devices, and the matured technology to handle the dv/dt stress levels produced by these devices with highest blocking voltage rating of 6.5 kV. On the other hand, the ultrahigh voltage (> 12 kV) SiC devices generate high dv/dt due to their high speed switching. This requires meticulous design of the gate drivers for reliable operation of high power converters. As an easy alternative, the option of using a complementary inverter has been explored in this paper. Both N-channel and P-channel IGBTs with blocking capability of 15 kV have been investigated for the complementary structure. The N-IGBT is found to be more efficient than the P-IGBT, based on the experimental switching characterization results at 6 kV and 5 A. The results of the 3 kV half-bridge complementary inverter prototype are also presented. The option of trade-off of P-IGBT field-stop buffer layer parameters (thickness, doping concentration and lifetime) for better switching characteristics can provide the use of complementary topologies a promising alternative for high power conversion.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Kadavelugu, A. and Bhattacharya, Subhashish and Ryu, S.-H. and Grider, D. and Agarwal, A. and Leslie, S.}, year={2013}, pages={2522–2527} }
 @inproceedings{yousefpoor_azidehak_bhattacharya_parkhideh_2013, title={Experimental validation of modular transformer converter based convertible static transmission controller for transmission grid management}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891109040&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647036}, abstractNote={For power flow control with specific attention to renewable energy resources based transmission in a meshed network, less complex coordinated control can be obtained with the proposed Convertible Static Transmission Controller (CSTC) concept which is connected across the substation power transformer and can be reconfigured to the required modes of operation. Convertible Static Transmission Controller (CSTC) is a versatile transmission controller which can perform several functions including power flow control for renewable resources transmission and transformer back-up for disaster management or life extension purposes. Different connecting configuration options (shunt-shunt, series-shunt, and series-series) can be obtained in the proposed transmission controller. In this paper, the control structure of CSTC in different modes of operation is presented, and dynamic performance of the CSTC based on the proposed control structures is further investigated in three different connecting configurations in PSCAD/EMTDC environment. Lab-scale experimental results are also presented to evaluate the performance of CSTC in three different modes of operation.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Yousefpoor, N. and Azidehak, A. and Bhattacharya, Subhashish and Parkhideh, B.}, year={2013}, pages={2597–2604} }
 @inproceedings{dutta_bhattacharya_2013, title={Integration of multi-terminal DC to DC hub architecture with solid state transformer for renewable energy integration}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891084431&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2013.6647345}, abstractNote={In this paper an alternate to the DC to DC stage of a single phase solid state transformer is proposed comprising of a Multi limb core (MLC) transformer. Further two important operation conditions of a single phase solid state transformer (SST) with cascaded series connected converter topology is studied: soft startup from auxiliary DC source to avoid any inrush current on the DC capacitors and the control interaction between the cascaded converters under severe voltage sag. The voltage balance in the cascaded structure under extreme voltage sag is the primary concern and a solution is proposed.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Dutta, S. and Bhattacharya, S.R.S.}, year={2013}, pages={4793–4800} }
 @inproceedings{karimi-moghaddam_gould_bhattacharya_2013, title={Investigation of enhancement in pool boiling heat transfer of a binary temperature sensitive magnetic fluid}, volume={8 B}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84903487625&partnerID=MN8TOARS}, DOI={10.1115/imece2013-66308}, abstractNote={In this paper, the performance of pool boiling heat transfer using a binary temperature sensitive magnetic fluid in the presence of a non-uniform magnetic field is investigated numerically. By using a binary magnetic fluid, enhanced boiling heat transfer is obtained by thermomagnetic convection without deterioration of properties of the fluid. This work is aimed at gaining a qualitative understanding the magnetic field effects on boiling heat transfer enhancement of magnetic fluids. In order to accomplish this, the boiling process and the effects of position of the external magnetic field on flow pattern and heat transfer are investigated in a 2D rectangular domain using COMSOL Multiphysics simulation software. Finally, the boiling curves for a binary temperature sensitive magnetic fluid and its base fluid (without magnetic particles) are compared for various applied heat flux magnitudes.}, booktitle={ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)}, author={Karimi-Moghaddam, G. and Gould, R.D. and Bhattacharya, Subhashish}, year={2013} }
 @inproceedings{watterson_white_bhattacharya_widener_bosworth_vodyakho_steurer_neumayr_edrington_2013, title={Operation and design considerations of FID at distribution voltages}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84879360229&partnerID=MN8TOARS}, DOI={10.1109/apec.2013.6520601}, abstractNote={This paper addresses the theory, construction, and testing of a novel prototype Solid State Fault Isolation Device (SSFID) that serves as an enabling technology for the multi-university, National Science Foundation funded Future Renewable Electrical Energy Distribution and Management (FREEDM) initiative. This initiative focuses on performing the fundamental research and devising breakthrough technologies to aid in the conversion of today's conventional grid to a more flexible and effective Power Electronics Distribution System (PEDS). The SSFID, the device on which this paper focuses, provides high speed (micro-seconds) sectionalizing and re-closing abilities that will support the use and function of other components of the FREEDM system that are being designed and tested by the other universities involved in the initiative. Its functional parameters and requirements are discussed and a prototype design, as well as its testing results, is presented.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Watterson, J. and White, L. and Bhattacharya, Subhashish and Widener, C. and Bosworth, M. and Vodyakho, O. and Steurer, M. and Neumayr, D. and Edrington, C.}, year={2013}, pages={2206–2211} }
 @inproceedings{babaei_bhattacharya_2013, title={Oscillatory angle control scheme for PWM static synchronous compensators under unbalanced conditions and system faults}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891134988&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2013.6646949}, abstractNote={Grid connected Voltage Source Converters (VSCs) are the heart of many applications with power quality concerns due to their reactive power controllability. Among the widely used grid-connected applications of the VSCs, the Static Synchronous Compensators (STATCOMs) are commonly used for compensating the voltage quality problems that come from voltage sag and swell. In spite of superior feature of fast voltage regulation and reactive power support functionality, VSC-based STATCOMs have the major drawback of being sensitive to the grid disturbances, especially the unbalanced condition and faults. Moreover, when the STATCOMs are used in the Distributed Generation (DG) applications or reactive power support of the sensitive industrial load, the unbalanced condition becomes even more intolerable. Protection system usually trips due to over current or highly distorted current caused by negative sequence current flow under unbalanced conditions and system faults. This paper propose an alternative control structure to keep the VSC-based STATCOM online during the unbalanced condition and system faults by limiting the negative sequence current. This eliminates the need to redesign/overdesign of the STACOM power components and over rating of the semiconductor switches to operate under fault current. Converter MVA rating reduction will decrease the cost significantly. Proposed controller performance has been verified by simulation and Hardware-In-the-Loop test.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Babaei, S. and Bhattacharya, Subhashish}, year={2013}, pages={1970–1977} }
 @inproceedings{carr_wang_bhattacharya_hatua_madhusoodhanan_2013, title={Overloading and overvoltage evaluation of a Transformerless Intelligent Power Substation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893191278&partnerID=MN8TOARS}, DOI={10.1109/PESMG.2013.6672840}, abstractNote={The Transformerless Intelligent Power Substation (TIPS) has been proposed as a replacement for the traditional distribution transformer in future power grids due to its improved voltage and power quality regulation capabilities. This system provides several benefits, but the use of power electronic devices imposes limitations on the TIPS's overloading and temporary overvoltage withstand capabilities. The overloading limits and the behavior of the TIPS under the temporary overvoltage impulse are examined in this paper, laying the groundwork to develop methods to mitigate these limitations.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Carr, J. and Wang, Z. and Bhattacharya, S. and Hatua, K. and Madhusoodhanan, S.}, year={2013} }
 @inproceedings{de_roy_bhattacharya_divan_2013, title={Performance analysis and characterization of current switch under reverse voltage commutation, overlap voltage bump and zero current switching}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84879373029&partnerID=MN8TOARS}, DOI={10.1109/apec.2013.6520636}, abstractNote={Diode reverse recovery is notorious for increasing switching losses in current stiff converters. A lot of effort has been made over the years to mitigate the reverse recovery losses. However, there exists ways to use this feature to achieve zero voltage transition in the same converter thereby, mitigating the loss incurred as compared to hard switched turn off. An attempt has been made in this paper to demonstrate the behavior of several devices working under Reverse voltage commutation, hard switched and zero current turn off condition. Test Circuits have been constructed and tested at various voltage levels with various combinations of devices. A new form of switching characteristic has been noticed and presented in this paper. The main motivation of the paper is to make a fair judgment on device selection for various soft-switch based topologies.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={De, A. and Roy, S. and Bhattacharya, Subhashish and Divan, D.M.}, year={2013}, pages={2429–2435} }
 @inproceedings{narwal_kim_yousefpoor_bhattacharya_2013, title={Performance evaluation and control of modular multilevel converter under system fault conditions}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893562203&partnerID=MN8TOARS}, DOI={10.1109/IECON.2013.6700171}, abstractNote={For industrial applications requiring medium and high-power supplies modular multilevel converter (MMC) based voltage source converters (VSC) offer advantages over traditional VSCs. These include achievement of higher voltage levels with utilization of lower voltage power semiconductor devices. The control structure of MMC for fault operating condition is proposed in this paper, and dynamic performance of the MMC based on the proposed control structures is further investigated in PSCAD/EMTDC environment. Real Time Digital Simulator (RTDS) results are also presented to verify the controller performance under normal and fault operating conditions.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Narwal, A. and Kim, S. and Yousefpoor, N. and Bhattacharya, S.}, year={2013}, pages={6299–6304} }
 @inproceedings{mirzaee_beddingfield_bhattacharya_parkhideh_2013, title={Performance investigation of hybrid converter systems for mobile mining applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891046405&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6646788}, abstractNote={To supply the AC high power drive systems, several Active Front-Ends (AFEs) with DC choppers are currently used to ensure reliable operation and an acceptable harmonic current spectrum. Recently, integration of the energy storage system with the mining equipment as an example of large mobile multimotor applications has received industry attention, especially for peak load shaving and energy management of the mines. Currently, the regenerative energy is often burnt into the choppers. The industry is motivated to capture this regenerative energy since it can be as high as 60% of the motoring power, as high as 3MJ in every operation cycle and 24 MW peak power. Hybrid approach for the front-end converter system has shown a technology path to deploy on-board energy storage without sacrificing the efficiency and reliability of the entire system. This paper addresses the dynamic performance analysis of such systems through detailed simulation and laboratory scale experiments.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Mirzaee, H. and Beddingfield, R. and Bhattacharya, Subhashish and Parkhideh, B.}, year={2013}, pages={825–831} }
 @inproceedings{yu_wu_bhattacharya_2013, title={Power dispatch strategy in microgrid integrated with solid state transformer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893156032&partnerID=MN8TOARS}, DOI={10.1109/PESMG.2013.6672265}, abstractNote={The Future Renewable Electric Energy Delivery and Management (FREEDM) System smoothly integrate and manage a variety of controllable loads, DRER (distributed renewable energy resource) and DESD (distributed energy storage device) through the revolutionary solid state transformer (SST). The distributed grid intelligence integrated with the SST facilitates the optimal power dispatch for a residential distribution system. This paper presents a mathematical formulation to determine the optimal power dispatch strategy in order to minimize the operational cost as well as the emission pollution. In this paper, a multi-objective immune particle swarm optimization (MIPSO) based computational intelligence approach is adopted to find the Pareto solution. Several numerical simulation studies demonstrate the effectiveness and accuracy of the proposed power dispatch strategy in a residential distribution system. More analysis indicates that the fitting degree between load profile and output of renewable energy generators (such as PV cells) is an identifier, which would be applied as a reference to make power exchange schedule between micro grid and utility grid.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Yu, J. and Wu, Z. and Bhattacharya, S.}, year={2013} }
 @inproceedings{baek_roy_bhattacharya_kim_2013, title={Power flow analysis for 3-port 3-phase dual active bridge dc/dc converter and design validation using high frequency planar transformer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891090658&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6646727}, abstractNote={In this paper, an inductor-integrated three-winding shell-type planar transformer is designed and analyzed for three-port dual-active bridge (DAB) dc/dc converters in wye wye-delta connection. The steady-state operation principle of the proposed topology has been studied and design parameters of the isolation transformer are analytically determined. The proposed geometry and design method for the ac-link transformer allows us to integrate a large number of bulky inductors required for three phase DAB operation to the transformer without additional connections and unanticipated parasitic effects. It also considerably simplifies the equivalent leakage inductance circuit model and power flow analysis. This configuration is suitable for high power and high step up/down ratio dc/dc converter applications which requires series and/or parallel combination of converters. The experimental and FEM simulation results from prototypes are presented and it validates the theoretical considerations and feasibility of the proposed approach for isolated dc/dc converter applications such as solid-state transformer (SST).}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Baek, S. and Roy, S. and Bhattacharya, Subhashish and Kim, S.}, year={2013}, pages={388–395} }
 @inproceedings{dutta_bhattacharya_2013, title={Predictive current mode control of single phase dual active bridge DC to DC converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891133680&partnerID=MN8TOARS}, DOI={10.1109/ecce.2013.6647451}, abstractNote={In this digest a review of various current control strategies in a bidirectional isolated DC to DC converter is shown. Average current control, peak current control and predictive current control is proposed for the single phase topology. A comparison between the controllers is shown with simulation results and experimental verification.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Dutta, S. and Bhattacharya, Subhashish}, year={2013}, pages={5526–5533} }
 @inproceedings{madhusoodhanan_patel_bhattacharya_carr_wang_2013, title={Protection of a transformerless intelligent power substation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84899427434&partnerID=MN8TOARS}, DOI={10.1109/pedg.2013.6785610}, abstractNote={The Transformerless Intelligent Power Substation (TIPS) is being developed as an alternative to the conventional line frequency transformers at the 13.8 kV distribution grid - 480 V utility grid interface. The Front End Converter (FEC) of TIPS is composed of newly developed 15 kV/20 A Silicon Carbide (SiC) IGBTs and series connected 10 kV/10 A SiC Junction Barrier Schottky (JBS) diodes. The low device current ratings open up a big challenge in the protection of these devices in the event of faults on the a.c side or on the d.c bus as well as during high surge voltage on the line. This paper covers a detailed study of the various components of the fault protection system in terms of their breaking time, breaking current and fault coordination. The evaluation is also done with respect to different fault types like 3-phase to ground fault and single phase to ground fault at various points of the system. The effect of fault on passive elements is also considered.}, booktitle={2013 4th IEEE International Symposium on Power Electronics for Distributed Generation Systems, PEDG 2013 - Conference Proceedings}, author={Madhusoodhanan, S. and Patel, D. and Bhattacharya, Subhashish and Carr, J.A. and Wang, Z.}, year={2013} }
 @inproceedings{yousefpoor_azidehak_bhattacharya_parkhideh_celanovic_genic_2013, title={Real-time Hardware-in-the-Loop simulation of convertible static transmission controller for transmission grid management}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84889049526&partnerID=MN8TOARS}, DOI={10.1109/compel.2013.6626403}, abstractNote={We propose a Convertible Static Transmission Controller (CSTC) concept that enables coordinated power flow control with emphasis on large penetration of renewable energy resources based transmission in a meshed network. CSTS can be connected across the substation power transformer and reconfigured for different modes of operation to perform as a versatile transmission controller with several functions including: power flow control for transmission of renewable resources, and as a transformer back-up for disaster management and/or life extension purposes. Different connecting configuration options, i.e. shunt-shunt, series-shunt, and series-series can be obtained. In this paper, we demonstrated the viability of the proposed concept using Typhoon HIL400 ultra-high fidelity Hardware-in-the-Loop (HIL) system in three different modes of operation. HIL simulations are used to verify the validity of the proposed control architecture for CSTC operation during both normal and unbalanced power system conditions for different connecting configurations.}, booktitle={2013 IEEE 14th Workshop on Control and Modeling for Power Electronics, COMPEL 2013}, author={Yousefpoor, N. and Azidehak, A. and Bhattacharya, Subhashish and Parkhideh, B. and Celanovic, I. and Genic, A.}, year={2013} }
 @inproceedings{kashani_babaei_bhattacharya_2013, title={SVC and STATCOM application in Electric Arc Furnace efficiency improvement}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84899437744&partnerID=MN8TOARS}, DOI={10.1109/pedg.2013.6785641}, abstractNote={Electric Arc Furnaces (EAF) are high power industrial loads which cause power quality problems at all voltage levels due to their unbalanced and nonlinear characteristics. The rapid, stochastic large swings in real and reactive power required by the arc furnace causes voltage drops, rapid voltage variation and distortion across the ac supply network. These voltage drops and fluctuations not only have negative impact on the power system quality and other loads, but also have an effect on the arc furnace operation, power output and efficiency. Hence, some sort of reactive compensation is required to limit the voltage disturbances injected by arc furnace into the electric power system. In this paper, an accurate electric arc furnace model, whose parameters have been set according to a 80 MVA actual arc furnace, is studied. A Static VAR Compensator (SVC) is simulated in PSCad and Real Time Digital Simulation (RTDS)/RSCAD platform for the purpose of comparison of voltage regulation at EAF bus. It is shown that the SVC mitigates the reactive power fluctuations in addition to providing the fundamental reactive power, and regulates the Point of Common Coupling (PCC) bus voltage precisely during the arc furnace operation. To verify the PSCad simulation results and make a comparison, a real time simulation study based on Real Time Digital Simulation (RTDS)/RSCAD platform has been performed in this case. On the other hand, a 80 MVA static synchronous compensator (STATCOM) is simulated in PSCad. It is illustrated that the SVC is inherently limited in its ability to respond rapidly to the fluctuating arc furnace load. It is found that the transient performance of the EAF voltage in case which equipped with the STATCOM is better than the case equipped with SVC. It is also demonstrated that although the voltage regulation by the SVC compensates a portion of the reactive power fluctuation, it is completely unable to supply any portion of the fluctuating real power drawn by the arc furnace, while the STATCOM can supply those components of active and reactive power fluctuation. The STATCOM will not normally have a source of real power connected to its DC terminals. It is therefore unable to supply sustained real power or real power fluctuations. With suitable choice of DC capacitor, however, it is capable of supplying in large part the fluctuating real power requirement of the furnace.}, booktitle={2013 4th IEEE International Symposium on Power Electronics for Distributed Generation Systems, PEDG 2013 - Conference Proceedings}, author={Kashani, M.G. and Babaei, S. and Bhattacharya, Subhashish}, year={2013} }
 @inproceedings{yousefpoor_kim_bhattacharya_parkhideh_2013, title={Supervisory control of convertible static transmission controller in shunt-shunt mode of operation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893579665&partnerID=MN8TOARS}, DOI={10.1109/iecon.2013.6699322}, abstractNote={The Convertible static transmission controller is a versatile device which can be installed across a transmission transformer to extend the life time of existing transformers by partially bypassing and conditioning the substation throughput power. The proposed technology can provide several integration options with multiple operational modes. From the supervisory control point of view, a control algorithm is required to set the reference values of active and reactive power flow of CSTC converters based on the desired operating points for transformer active and reactive power. In this paper, the algebraic model of CSTC in shunt-shunt mode of operation is derived. Algebraic model of CSTC is used for steady state and transient stability analysis. Algebraic model will present the behavior of transformer power flow with respect to various operating points of CSTC converters. The P-Q transformer operating range can be obtained based on the proposed algebraic model. Dynamic performance of the CSTC system is also investigated in PSCAD/EMTDC environment. Simulation results will be presented to verify the proposed algebraic model of CSTC in shunt-shunt mode of operation based on steady state results.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Yousefpoor, N. and Kim, S. and Bhattacharya, Subhashish and Parkhideh, B.}, year={2013}, pages={1314–1319} }
 @article{parkhideh_mirzaee_bhattacharya_2013, title={Supplementary Energy Storage and Hybrid Front-End Converters for High-Power Mobile Mining Equipment}, volume={49}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84880876687&partnerID=MN8TOARS}, DOI={10.1109/tia.2013.2257637}, abstractNote={To supply the high-power ac-drive systems of the mining equipment, several active front ends with dc choppers are used to ensure reliable operation and an acceptable harmonic current spectrum. Recently, the integration of the energy storage system with the mining equipment has received industry attention, particularly for peak load shaving and smarter energy management of the mines. Currently, the regenerative energy is often burned into the choppers and is not fed back to the grid. The industry is motivated to capture this regenerative energy since it can be as high as 60% of the motoring power, as high as 3 MJ in every operation cycle, and as high as 24-MW peak power. Therefore, there is a possibility of large cost reductions and component rating reduction. In this paper, we investigate the operation of the current state-of-the-art front-end converter systems for multimotor applications. In particular, we propose power conversion configurations and methodology to determine the suitable energy storage technology for the development of the multimotor mobile mining equipment that has encouraging incentives for both the manufacturers and the mine operators.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Parkhideh, Babak and Mirzaee, Hesam and Bhattacharya, Subhashish}, year={2013}, pages={1863–1872} }
 @inproceedings{carr_wang_bhattacharya_patel_2013, title={Transient overvoltage rating and BIL of the transformerless intelligent power substation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893178752&partnerID=MN8TOARS}, DOI={10.1109/PESMG.2013.6672424}, abstractNote={The overvoltage impulse protection of the transformerless intelligent power substation (TIPS) is explored in this paper. Two failure mechanisms, excess current causing thermal failure of the devices and excess component to ground voltage causing failure of the insulation, are considered. A variety of grounding, protection, and filter circuits were analyzed. It was found that the current and voltage do not exceed the limits of safety if the midpoint of the TIPS DC bus capacitor bank is grounded. A recommended protection scheme was proposed based on these results, consisting of a MOV at the input to the TIPS to divert surge currents and a reactive connection to ground to limit the device currents without resulting in a large voltage between the midpoint and ground. A large voltage was found to fall across the input filter, which should be designed with sufficient BIL to withstand this voltage.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Carr, J. and Wang, Z. and Bhattacharya, S. and Patel, D.}, year={2013} }
 @inproceedings{ryu_capell_jonas_lemma_o’loughlin_clayton_van brunt_lam_richmond_burk_et al._2013, title={Ultra high voltage IGBTs in 4H-SiC}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893540558&partnerID=MN8TOARS}, DOI={10.1109/WiPDA.2013.6695557}, abstractNote={A 1 cm × 1 cm 4H-SiC N-IGBT exhibited a blocking voltage of 20.7 kV with a leakage current of 140 μA, which represents the highest blocking voltage reported from an MOS semiconductor power switching device to date. The device showed a VF of 6.4 V at an IC of 20 A, and a differential Ron,sp of 28 mΩ-cm2. Temperature insensitive on-state characteristics were demonstrated. Switching measurements with a supply voltage of 8 kV were performed, and a turn-off time of 720 ns and a turn-off loss of 5.4 mJ were measured at 25°C, for a 8.4 mm × 8.4 mm device with 140 μm drift layer and 5 μm Field Stop buffer layer. It was demonstrated that the charge injection from the backside can be controlled by varying the thickness of the Field-Stop buffer layer. A 55 kW, 1.7 kV to 7 kV boost converter operating at 5 kHz was demonstrated using the 4H-SiC N-IGBT, and an efficiency value of 97.8% was reported.}, booktitle={1st IEEE Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2013 - Proceedings}, author={Ryu, S. and Capell, C. and Jonas, C. and Lemma, Y. and O’Loughlin, M. and Clayton, J. and Van Brunt, E. and Lam, K. and Richmond, J. and Burk, A. and et al.}, year={2013}, pages={36–39} }
 @inproceedings{javanbakht_mohagheghi_parkhideh_dutta_chattopadhyay_bhattacharya_2013, title={Vehicle-to-grid scheme based on inductive power transfer for advanced distribution automation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84891073969&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2013.6647127}, abstractNote={The latest technological advances in battery and converter technology, along with government mandates on energy independence and resilience, are expected to pave the way for higher deployment of plug-in electric vehicles (PEV) in the transportation fleet. These vehicles, when equipped with bidirectional energy transfer capabilities, can function as mobile energy resources and can be utilized in a Vehicle-to-Grid (V2G) scheme in order to temporarily inject energy back into the power grid, thereby functioning as energy storage systems. The forecasted increase in the number of these dispersed vehicles can potentially turn them into a significant energy resource that can be used by the utilities for ancillary services or even for long-term integration with the power system. The notion of energy injection through V2G schemes has been conceptually investigated in the literature for charging stations or single residential charging devices. In all these case studies, the vehicle needs to be parked, and a connection be established by the driver, for the duration of the battery charge or discharge. This paper looks into V2G through the employment of contactless means for energy transfer, namely inductive power transfer (IPT). IPT adds flexibility to V2G schemes by allowing energy exchange with vehicles in motion or when the driver is not physically present to establish a connection. The performance of IPT for bidirectional power flow has been shown through simulation as well as experimental results. Also, statistical analysis are provided that demonstrate the large scale integration of these vehicles into the grid.}, booktitle={2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013}, author={Javanbakht, P. and Mohagheghi, S. and Parkhideh, B. and Dutta, S. and Chattopadhyay, R. and Bhattacharya, S.}, year={2013}, pages={3250–3257} }
 @inproceedings{dutta_roy_bhattacharya_2013, title={integration of multi-terminal dc to dc hub architecture with solid state transformer for renewable energy integration}, booktitle={2013 ieee energy conversion congress and exposition (ecce)}, author={Dutta, S. and Roy, S. and Bhattacharya, S.}, year={2013}, pages={4793–4800} }
 @inproceedings{tripathi_hatua_bhattacharya_2012, title={A comparative study of three-phase dual active bridge topologies and their suitability for D-Q mode control}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870924513&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2012.6342605}, abstractNote={A comparative evaluation of three different three-phase Dual Active Bridge (DAB) topologies with a 15-kV Si-IGBT based three-level converter at the high-voltage side and 1200-V SiC-MOSFET based converters in three different arrangements at the low-voltage side are compared. The proposed DABs are an integral part of a solid state transformer which connects a 13.8-kV distribution grid and a 480-V utility grid. The three-level converters connected at the high-voltage side in each topology with 30° zero-enforcing and proposed arrangements at low-voltage side of the high frequency-link transformer help to reduce dominant harmonic currents. Thus harmonic-free currents in the high frequency link transformer are achieved without pulse-width modulation which can be utilized for D-Q Mode smooth-control.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Tripathi, A.K. and Hatua, K. and Bhattacharya, S.}, year={2012}, pages={1719–1724} }
 @inproceedings{juvekar_compton_bhattacharya_2012, title={A fast acting DC solid state fault isolation device (FID) with Si and SiC devices for MVDC distribution system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870869018&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2012.6342566}, abstractNote={This paper presents a low voltage (400V) hardware prototype of a fast acting medium voltage DC circuit breaker. Simulation results obtained using PLECS software and hardware testing results are also presented for the same prototype. The prototype serves as a proof of concept showing implementation of firmware logic capable of interrupting DC fault current within 4.042 micro-seconds from the instant an overcurrent condition occurs. The authors propose that the same concept can be extended to medium voltage DC level and present a performance comparison of real 6.5kV silicon (Si) and 10kV silicon carbide (SiC) devices as solid state fault isolation devices (SSFID) in a medium voltage DC (MVDC) distribution system using SPICE simulations. The MVDC SSFID described in this paper finds an application in MVDC distribution system described by Next Generation Integrated Power System (NGIPS) roadmap [1] proposed by Electric Ship Office (ESO) of Office of Naval Research (ONR). Other applications include large scale grid connected solar and wind farm at MVDC level.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, publisher={IEEE}, author={Juvekar, S. and Compton, B. and Bhattacharya, S.}, year={2012}, pages={2005–2010} }
 @inproceedings{dutta_bhattacharya_chandorkar_2012, title={A novel predictive phase shift controller for bidirectional isolated dc to dc converter for high power applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870872317&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342791}, abstractNote={In this paper a novel predictive algorithm has been proposed for bi-directional dc-dc converters with high frequency transformer isolation. The converter is a dual active bridge converter. The proposed algorithm is a faster alternative to the classical PI based phase shift controller. This mode of control can remove dc bias in the isolation transformer within several switching cycles hence preventing transformer saturation. Aspects of the proposed algorithm have been implemented on a hardware test bed and verified.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Dutta, S. and Bhattacharya, Subhashish and Chandorkar, M.}, year={2012}, pages={418–423} }
 @inproceedings{white_bhattacharya_2012, title={A single phase PSCad electric arc furnace model}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84872908679&partnerID=MN8TOARS}, DOI={10.1109/IECON.2012.6389532}, abstractNote={Electric Arc Furnaces (EAFs) are among the larger loads imposed upon the electrical grid. The size of these loads, when combined with the stochastic nature of the electric arc, and the poor reaction of the grid to such loads, makes the EAF worthy of study in general and modeling in particular. The present work develops a model of an EAF that is designed as a custom component for use with the PSCad modeling software but can be used equally well in real-time simulation systems. The model is single-phase, allowing multiple instances to be connected in any configuration so that unbalanced situations can be easily simulated. The model is completely documented so that it can be duplicated with no additional information.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={White, L.W. and Bhattacharya, S.}, year={2012}, pages={5352–5356} }
 @inproceedings{tripathi_hatua_mirzaee_bhattacharya_2012, title={A three-phase three winding topology for dual active bridge and its D-Q mode control}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84860132779&partnerID=MN8TOARS}, DOI={10.1109/apec.2012.6165998}, abstractNote={A new Dual Active Bridge (DAB) topology is proposed with a 15-kV SiC-IGBT based three-level inverter at the high-voltage side and 1200-V SiC-MOSFET based paralleled two-level inverter at the low-voltage side. The proposed DAB is an integral part of a solid state transformer which connects a 13.8-kV distribution grid and a 480-V utility grid. The three-level inverter connected at the high-voltage side and a pair of two-level inverters connected at the low-voltage sides (in Y/Δ) of the high frequency link transformer help to reduce dominant harmonic currents. Thus harmonic-free currents in the high frequency link transformer are achieved without pulse-width modulation. A simple control is proposed and validated with simulation results.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Tripathi, A.K. and Hatua, K. and Mirzaee, H. and Bhattacharya, Subhashish}, year={2012}, pages={1368–1372} }
 @inproceedings{baek_bhattacharya_cougo_ortiz_2012, title={Accurate equivalent circuit modeling of a medium-voltage and high-frequency coaxial winding DC-link transformer for solid state transformer applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870918183&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342645}, abstractNote={The 12kV-400V dc-dc stage of a distribution level solid state transformers (SST) has been under research and development. Development of a 15kV SiC Mosfet allows a single stage of the dc-dc converter to operate at medium voltage at an operating frequency of over 20kHz. Nonetheless, the high rising and falling time during pulse switching in the dual active bridge operation is another significant obstacle to realize this technology. In order to understand and predict the frequency response with pulse switching and consider common-mode response via circuit analysis accurately, lumped-element equivalent circuit model has been developed for broadband coaxial winding transformer (CWT) with analytic expressions. The simple lumped-element equivalent circuit introduced in this paper has been verified by measurement results from a prototype for a medium-voltage (MV) and high frequency (HF) coaxial winding power transformer up to the frequency where the length of the coaxial body is a quarter of a wavelength and further study up to 30MHz has been described.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Baek, S.S. and Bhattacharya, Subhashish and Cougo, B. and Ortiz, G.}, year={2012}, pages={1439–1446} }
 @inproceedings{yousefpoor_parkhideh_bhattacharya_2012, title={An approach to regulating Dual Series Static Compensator (DSSC)}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870923153&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342176}, abstractNote={For power flow control with specific attention to renewable energy resources based transmission in a meshed network, less complex coordinated control can be obtained with the proposed convertible static transmission controller (CSTC) concept which is connected across the substation power transformer and can be reconfigured to the required modes of operation. Dual Series Static Compensator (DSSC) mode or series-series mode available in the CSTC provides superior performance in terms of operating characteristics compared to conventional power flow controllers. In this paper, detailed steady-state and dynamic performance of DSSC will be investigated, and the control structure of DSSC will be proposed to control active and reactive power independently. This paper specifically explores the challenges of the proposed control method. In particular, the proposed control structure is based on line current PLL. The dynamic performance of DSSC is further investigated in PSCAD/EMTDC environment.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Yousefpoor, N. and Parkhideh, B. and Bhattacharya, Subhashish}, year={2012}, pages={4732–4737} }
 @inproceedings{babaei_parkhideh_bhattacharya_2012, title={Analysis of 48-pulse based STATCOM and UPFC performance under balanced and fault conditions}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84872923067&partnerID=MN8TOARS}, DOI={10.1109/IECON.2012.6388598}, abstractNote={Convertible Static Compensator (CSC) which is a versatile Flexible AC Transmission System (FACTS) technology has been installed on Marcy 345 kV substation and increases power transfer capability, operational functionality, and power flow controllability of the New York Power Authority (NYPA) transmission system. This paper presents a comprehensive description of CSC inverter 48-pulse wave construction along with introduction of control strategy deployed in CSC when it is operating as a STATCOM and UPFC. STATCOM and UPFC steady state and dynamic operation PSCAD simulation results under different testing conditions including unbalanced condition and faults are presented. This paper also provides comprehensive analysis of the STATCOM response to negative sequence and harmonic voltage components on the transmission line during fault conditions. The amounts of DC-link capacitance that lead to maximum and minimum of fundamental negative sequence current on the tie line and 120 Hz oscillation on the DC-link voltage are calculated. Simulation results of STATCOM performance with different DC-link capacitance during fault condition will be shown. At the end of the paper, one exiting problem regarding to UPFC operation of NYPA CSC has been addressed and illustrated with precise simulation results.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Babaei, S. and Parkhideh, B. and Bhattacharya, S.}, year={2012}, pages={1211–1216} }
 @inproceedings{zhang_wang_bhattacharya_2012, title={Architecture of solid state transformer-based energy router and models of energy traffic}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84860849112&partnerID=MN8TOARS}, DOI={10.1109/ISGT.2012.6175637}, abstractNote={Recently, a large number of renewable energy resources and DC loads spur the research spotlight of the future power grid, which is also referred to as Energy Internet. In order to achieve such a fundamental innovation to the novel energy paradigm, many devices are to be designed, manufactured, and evaluated. In this paper, we describe the solid state transformer-based energy router in which incoming energy traffic can be converted and routed to an outgoing energy traffic. In particular, we focus on the architecture design of such a router and models of energy storage devices, generators, and loads, for Energy Local Area Network (ELAN). The proposed energy router features plug-and-play Multiple-Input Multiple-Output (MIMO), and customized operating system, that providing a system level modeling for the optimal design and performance analysis of energy routers.}, booktitle={2012 IEEE PES Innovative Smart Grid Technologies, ISGT 2012}, author={Zhang, J. and Wang, W. and Bhattacharya, S.}, year={2012} }
 @inproceedings{kadavelugu_wang_bhattacharya_huang_2012, title={Auxiliary power supply for Solid State Transformers}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870892973&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342647}, abstractNote={In contrast to traditional 60 Hz transformer, solid state transformer (SST) offers power flow control, integration of renewables and maintaining grid stability in high renewable penetration scenario. Like a typical power converter, SST requires low voltage (24 V dc) power for its control and sensing circuits. In running condition, this power is derived from its low voltage dc bus at 400 V. But it is challenging to derive it during start-up, because the only source available during start-up is the distribution grid at 7.2 kV, 60 Hz. Due to high input voltage (7.2 kV, 60 Hz), deriving a control supply of about 150 W, even for just start-up duration of about 200 ms, presents a novel power electronics problem. In this paper, two solutions have been proposed to address this issue, by taking a 20 kVA, 6.5 kV Si IGBT and 15 kV SiC MOSFET based SSTs as the reference converters. The first solution is generic and is based on storing the required start-up energy in a dc capacitance. This is based on developing a cost-effective high voltage switch using low voltage IGBTs with self-driven functionality. The second solution, applicable only to SST topologies with high voltage ac capacitive filter, is to tap the energy from the capacitor itself. The fundamental constraints considered for both the solutions are practical feasibility at high voltage (7.2 kV ac or over 10 kV dc), power loss, size, weight and cost-effectiveness. Experimental validation of extracting continuous power for the IGBT gate driver ICs from the snubber is presented with 200 V input. And, the results of the auxiliary power derivation from the filter capacitor are shown with 5.7 kV ac input.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Kadavelugu, A. and Wang, G. and Bhattacharya, Subhashish and Huang, A.}, year={2012}, pages={1426–1432} }
 @inproceedings{parks_dutta_ramachandram_hatua_bhattacharya_2012, title={Black start control of a solid state transformer for emergency power restoration}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870862926&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342824}, abstractNote={This paper demonstrates the black start capabilities of a single phase 20kVA solid state transformer (SST), specifically for microgrid power restoration during islanding. SST's have many benefits including better management of renewable energy resources and more intelligent control than the classical transformer which acts only as a passive device. An additional benefit of the SST that is demonstrated in this paper is the ability to use these renewable energy resources directly connected to the SST to restore microgrid load power during an islanding event. During the black start procedure the SST can switch the control operation of its three cascaded power converter stages, AC/DC rectifier, Dual Active Bridge, and DC/AC inverter, in order to restore the microgrid load. The benefits of using the SST for black start restoration are also discussed and compared with other traditional methods.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Parks, N. and Dutta, S. and Ramachandram, V. and Hatua, K. and Bhattacharya, Subhashish}, year={2012}, pages={188–195} }
 @inproceedings{madhusoodhanan_hatua_bhattacharya_leslie_ryu_das_agarwal_grider_2012, title={Comparison study of 12kV n-type SiC IGBT with 10kV SiC MOSFET and 6.5kV Si IGBT based on 3L-NPC VSC applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870947926&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342807}, abstractNote={Silicon Carbide (SiC) devices and modules have been developed with high blocking voltages for Medium Voltage power electronics applications. Silicon devices do not exhibit higher blocking voltage capability due to its relatively low band gap energy compared to SiC counterparts. For the first time, 12kV SiC IGBTs have been fabricated. These devices exhibit excellent switching and static characteristics. A Three-level Neutral Point Clamped Voltage Source Converter (3L-NPC VSC) has been simulated with newly developed SiC IGBTs. This 3L-NPC Converter is used as a 7.2kV grid interface for the solid state transformer and STATCOM operation. Also a comparative study is carried out with 3L-NPC VSC simulated with 10kV SiC MOSFET and 6.5kV Silicon IGBT device data.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Madhusoodhanan, S. and Hatua, K. and Bhattacharya, Subhashish and Leslie, S. and Ryu, S.-H. and Das, M. and Agarwal, A. and Grider, D.}, year={2012}, pages={310–317} }
 @inproceedings{yousefpoor_parkhideh_babaei_bhattacharya_2012, title={Control of cascaded multi-level STATCOM using line voltage total harmonic distortion minimization technique}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870890532&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342596}, abstractNote={In this paper, a new switching strategy is proposed for a multi-level STATCOM system. An efficient approach in reducing the harmonic contents of the inverter's output voltage is total harmonic distortion (THD) minimization. In multilevel inverters with fundamental frequency switching strategy (each switch turning on and off once per output cycle), the switching angles can be selected such that the output THD is minimized. In three phase multilevel inverters, the optimization algorithm is commonly applied to the phase voltage of the inverter. This results in the minimum THD in phase voltage, but not necessarily in the line to line minimum THD. In this paper, THD minimization process is directly applied to the line to line voltage of the inverter, and a new control strategy of multilevel STATCOM is proposed. The proposed method will be implemented, in RTDS and the closed loop operation of multi-level STATCOM will be explored.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Yousefpoor, N. and Parkhideh, B. and Babaei, S. and Bhattacharya, Subhashish}, year={2012}, pages={1782–1787} }
 @inproceedings{babaei_parkhideh_fardanesh_bhattacharya_2012, title={Convertible static compensator (CSC) performance under system fault}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870604089&partnerID=MN8TOARS}, DOI={10.1109/pesgm.2012.6345705}, abstractNote={Convertible Static Compensator (CSC) which is a versatile FACTS technology has been installed on Marcy 345 kV substation and increases power transfer capability, operational functionality, and power flow controllability of the New York Power Authority (NYPA) transmission system. This paper presents a detailed description of CSC inverter operation and PSCAD simulation results of the CSC when it is operating as a STATCOM. The STATCOM steady state and dynamic operation simulation results under different conditions including unbalanced condition and faults is discussed. For fault condition analysis, attention is focused to Double L-G (LLG) fault at three different locations, one very close and two others electrically far from STATCOM terminals. This paper also demonstrates the effectiveness of the emergency PWM (EPWM) strategy a solution for limiting the poles current and preventing STATCOM over current tripping during fault conditions.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Babaei, S. and Parkhideh, B. and Fardanesh, B. and Bhattacharya, Subhashish}, year={2012} }
 @inproceedings{parkhideh_yousefpoor_babaei_bhattacharya_2012, title={Design considerations in development of Active Mobile Substations}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870944060&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342767}, abstractNote={While conventional mobile substations are used to bypass the whole substation in case of loss or maintenance of power transformers, Active Mobile Substations (AMS) can be used in normal conditions as a power router and contingencies as a recovery transformer. The AMS is a mobile substation with integrated power electronics and by controlling its throughput power can be connected across different transformers of the grid. The AMS is expected to be at least 20MVA with 230kV and 69kV outputs. This paper proposes transmission-level active mobile substations that provide back-up in case of power transformer failure or forced reduced operation scenarios in addition to power flow control for seasonal renewable energy transmission. These functions altogether have been aggregated not only because of the technical merits but also to address the economic concerns regarding the cost of the power electronics for transmission applications. In this paper, design considerations in development of the AMS will be provided in terms of power electronics building blocks, converter system control and its effects, and required supervisory control. Throughout the paper, theoretical analyses and relevant results are presented.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Parkhideh, B. and Yousefpoor, N. and Babaei, S. and Bhattacharya, Subhashish}, year={2012}, pages={595–602} }
 @inproceedings{boillat_roy_tripathi_bhattacharya_2012, title={Design considerations of a three phase dual active bridge based on reactive power flow}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870919073&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2012.6342790}, abstractNote={This paper discusses about the reactive power flow calculation in a dual-active-bridge (DAB) following the CP (conservative power) and PQ (instantaneous reactive power) theories. Based on the results from reactive power calculation, the optimal virtual turns ratio is determined so as to draw equal reactive power from the primary and secondary sides of the DAB-transformer. The equal sharing of the reactive power makes the DAB system more efficient. This paper also discusses about the computation of active and reactive power flow based on experimental data. As an example, a three winding transformer is selected for the experimentation and the better turns ratio is pointed out which can provide better efficiency.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Boillat, D. and Roy, S. and Tripathi, A. and Bhattacharya, S.}, year={2012}, pages={424–430} }
 @inproceedings{mirzaee_bhattachary_bala_2012, title={Design issues in a medium-voltage DC amplifier with a multi-pulse thyristor bridge front-end}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870881833&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342766}, abstractNote={In this paper the design issues of a medium-voltage DC amplifier with a multi-pulse thyristor bridge front-end are presented. A medium voltage dc amplifier is needed in de-risking new technologies coming onboard future electric ships. Based on the required system dynamic specifications, an initial design reveals the problems with a multi-pulse thyristor front-end, and then provides a novel solution to meet the requirements, are presented. The proposed system solution is validated through both simulation and experimental results.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Mirzaee, H. and Bhattachary, S. and Bala, S.}, year={2012}, pages={603–609} }
 @inproceedings{dutta_parkhideh_bhattacharya_moghaddam_gould_2012, title={Development of a predictive observer thermal model for power semiconductor devices for overload monitoring in high power high frequency converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84860126119&partnerID=MN8TOARS}, DOI={10.1109/apec.2012.6166144}, abstractNote={In this paper a predictive observer model for power semiconductor devices is developed and integrated in the digital controller. The Model is simulated in Mat lab Simulink and tested with a power converter in hardware for the accuracy of modeling.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Dutta, S. and Parkhideh, B. and Bhattacharya, Subhashish and Moghaddam, G.K. and Gould, R.}, year={2012}, pages={2305–2310} }
 @inproceedings{de_roy_bhattacharya_2012, title={Efficiency Comparison of AC-Link and TIPS (SST) Topologies based on accurate device models}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870894365&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342282}, abstractNote={In this paper, a comparative study on AC-Link™ Topology and a conventional solid state transformer (TIPS) has been shown. Alongside, as a building block, a comparative device level design study has been shown for 6.5kV Si-IGBT/SiC JBS diode, 6.5kV Si-IGBT/Si-PiN Diode and 10kV SiC-MOSFET/SiC-JBS Diode for a zero voltage/current transition and hard switched condition for medium voltage application. It is shown that soft switching yields a considerable reduction of losses for all devices. A low voltage hardware device test prototype has been built and tested. The main motive of the paper is to make a fair judgment on the two topologies with accurate device testing. This is further extended to the maximum attainable frequency analysis, corresponding efficiency comparison, frequency transfer capability and various other topology based comparisons.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={De, A. and Roy, S. and Bhattacharya, Subhashish}, year={2012}, pages={3862–3868} }
 @inproceedings{kumar_green_de_roy_bhattacharya_2012, title={Field Programmable Analog Array (FPAA) based Shunt Active Filter controller}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870904185&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342708}, abstractNote={The presence of multiple harmonics in the power line due to various non-linear loads like adjustable speed drives, computers, fax machine, PLC's, etc. requires high frequency switching of an active filter inverter so as to reduce the harmonic content at the point of common coupling (PCC) to be typically lower than 5% as specified by IEEE 519 harmonic standards. In this paper, the Field Programmable Analog Array (FPAA) based analog controller has been used to implement a Synchronous Reference Frame (SRF) controller algorithm for harmonic current extraction for Shunt Active Filter controller and the results are compared with the conventional digital implementation on Field Programmable Gate Array (FPGA). The FPAA based analog controller implementation proves to be faster than the digital FPGA implementation and can be a potential to replace analog controllers used for active filters.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Kumar, M. and Green, E. and De, A. and Roy, S. and Bhattacharya, Subhashish}, year={2012}, pages={1011–1016} }
 @inproceedings{shah_juneja_bhattacharya_dean_2012, title={High frequency GaN device-enabled CubeSat EPS with real-time scheduling}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870948186&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342522}, abstractNote={This paper describes the hardware and software architectures and experimental results of a flexible and scalable electric power system (EPS) for CubeSat applications. The EPS has the three flexible battery charging modules (FBCM) to charge the battery and the four flexible digital point of load (FDPOL) converters to drive loads. It uses the maximum power point tracking (MPPT) algorithm to maximize output power from the solar arrays along with the battery state of health and state of charge determination algorithms to determine the health of the Li-ion batteries. This paper also evaluates converter performance with GaN devices driven at high frequencies in order to reduce the size of the filter components and provide better control of the converters. Analysis of a sample load's transients and its voltage regulation, using a real-time operating system (RTOS), is also discussed briefly in this paper.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Shah, M. and Juneja, A. and Bhattacharya, Subhashish and Dean, A.G.}, year={2012}, pages={2934–2941} }
 @inproceedings{ryu_capell_cheng_jonas_gupta_donofrio_clayton_o’loughlin_burk_grider_et al._2012, title={High performance, ultra high voltage 4H-SiC IGBTs}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870861131&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2012.6342311}, abstractNote={We present our latest developments in ultra high voltage 4H-SiC IGBTs. A 4H-SiC P-IGBT, with a chip size of 6.7 mm × 6.7 mm and an active area of 0.16 cm2 exhibited a record high blocking voltage of 15 kV, while showing a room temperature differential specific on-resistance of 24 mΩ-cm2 with a gate bias of -20 V. A 4H-SiC N-IGBT with the same area showed a blocking voltage of 12.5 kV, and demonstrated a room temperature differential specific on-resistance of 5.3 mΩ-cm2 with a gate bias of 20 V. Buffer layer design, which includes controlling the doping concentration and the thickness of the field-stop buffer layers, was used to control the charge injection from the backside. Effects on buffer layer design on static characteristics and switching behavior are reported.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Ryu, S.-H. and Capell, C. and Cheng, L. and Jonas, C. and Gupta, A. and Donofrio, M. and Clayton, J. and O’Loughlin, M. and Burk, A. and Grider, D. and et al.}, year={2012}, pages={3603–3608} }
 @inproceedings{parkhideh_mirzaee_bhattacharya_2012, title={Hybrid front end converters for large multi-motor applications integrated with energy storage}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84860116590&partnerID=MN8TOARS}, DOI={10.1109/apec.2012.6165881}, abstractNote={To supply the AC drive systems several Active Front Ends (AFE) with DC choppers are used to insure a reliable and acceptable harmonic current spectrum operation. Recently, energy storage system integration with the mining equipment has received industry attention, especially for peak load shaving and smarter energy management of the mine. Currently, the regenerative energy is often burnt into the choppers and is not fed back to the grid. The industry is motivated to capture this regenerative power since it can be as high as 60% of the motoring power and as high as 24 MW. Therefore, there is a possibility of large cost reduction and component downsizing. However, present status of development seems not to be very promising mainly because energy storage systems, (such as ultracapacitors) are still considered as an add-on part to existing products. In this paper, we investigate the operation of the current state-of-the-art front end converter systems for multi-motor applications. In particular, we propose power conversion configurations and methodology to determine the suitable energy storage technology for development of the multi-motor mobile mining equipment that has encouraging incentives for both the manufacturer and the mine operator.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Parkhideh, B. and Mirzaee, H. and Bhattacharya, Subhashish}, year={2012}, pages={607–614} }
 @inproceedings{mohagheghi_parkhideh_bhattacharya_2012, title={Inductive power transfer for electric vehicles: Potential benefits for the distribution grid}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84860788026&partnerID=MN8TOARS}, DOI={10.1109/IEVC.2012.6183266}, abstractNote={It is believed that the latest advances in battery and converter technology, along with government mandates on energy independence and resilience, will pave the way for higher deployment of electric vehicles in the transportation fleet. These vehicles, when equipped with bidirectional energy transfer capabilities, can function as mobile energy resources and be utilized in a vehicle-to-grid (V2G) scheme to temporarily inject energy back into the power grid. The forecasted increase in the number of these vehicles can turn them into a considerable energy resource to be used by the utilities as ancillary services or even for long-term integration with the grid. The energy injection into the power system by electric vehicles has been investigated in the literature for charging stations or single residential charging devices. The need for the vehicle to be stationary during the transfer, and the possible drive and/or change in the driving route in order to go the station are some of the hurdles that may lead to inconvenience and hence lower V2G participation by the vehicle drivers. Moreover, the need for an electrical connection between the vehicle and the station makes implementing remote supervisory control schemes difficult, if not impractical. However, with the advent of inductive charging systems for contactless transfer of energy, new horizons have been opened for seamless integration of these resources of energy into the distribution grid. This paper focuses on the applications of inductive power transfer systems for V2G purposes in the modern distribution grid. It will be shown here that such a scheme could potentially allow for supervisory control and management of the mobile energy resources with the ultimate goal of improving the reliability and security of the power grid without the need for capacity expansion.}, booktitle={2012 IEEE International Electric Vehicle Conference, IEVC 2012}, author={Mohagheghi, S. and Parkhideh, B. and Bhattacharya, S.}, year={2012} }
 @inproceedings{karimi-moghaddam_gould_bhattacharya_2012, title={Numerical investigation of electronic liquid cooling based on the thermomagnetic effect}, volume={7}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84887279923&partnerID=MN8TOARS}, DOI={10.1115/IMECE2012-87764}, abstractNote={Liquid cooling for thermal management has been widely applied in high power electronic systems. Use of pumps may often introduce reliability and mechanical limitations such as vibration of moving parts, noise problems, leakage problems, and considerable power consumption. This paper presents a theoretical design of circulating a liquid coolant using magnetic and thermal fields which surround high power electronic systems by means of thermomagnetic effects of temperature sensitive magnetic fluids. Numerical simulation models of the heat transfer process from a magnetic liquid contained in a closed flow loop in the presence of an external magnetic field have been developed. These models include the coupling of three fundamental phenomena, i.e. magnetic, thermal, and fluid dynamic features. In this cooling device, the thermomagnetic convection is generated by a non-uniform magnetic field from a solenoid, which is placed close to the fluid loop. The device cooling load is calculated in the region near the solenoid. No energy is needed, other than the heat load (i.e. waste heat from actual electrical device), to drive the cooling system, and as such, the device can be considered completely self-powered. In effect, the heat added to the ferrofluid in the presence of a magnetic field is converted into useful flow work. In this numerical study, the effects of different factors such as input heat load, magnetic field strength and magnetic distribution (based on solenoid dimensions and the applied electrical current) along the loop, on the performance of the cooling system are analyzed and discussed. Finally, the variation of the local Nusselt number along the heated and cooled regions of the flow loop are calculated and compared with laminar entry length analytical solutions.}, number={PARTS A, B, C, D}, booktitle={ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)}, author={Karimi-Moghaddam, G. and Gould, R.D. and Bhattacharya, S.}, year={2012}, pages={1441–1447} }
 @inproceedings{hazra_bhattacharya_uppalapati_bird_2012, title={Ocean energy power take-off using oscillating paddle}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870926635&partnerID=MN8TOARS}, DOI={10.1109/ecce.2012.6342793}, abstractNote={This paper presents an ocean energy power take-off system using paddle like wave energy converter (WEC), magnetic gear and efficient power converter architecture. As the WEC oscillates at a low speed of about 5-25 rpm, the direct drive generator is not an efficient design. To increase the generator speed a cost effective flux focusing magnetic gear is proposed. Power converter architecture is discussed and integration of energy storage in the system to smooth the power output is elaborated. Super-capacitor is chosen as energy storage for its better oscillatory power absorbing capability than battery. WEC is emulated in hardware using motor generator set-up and energy storage integration in the system is demonstrated.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Hazra, S. and Bhattacharya, Subhashish and Uppalapati, K.K. and Bird, J.}, year={2012}, pages={407–413} }
 @inproceedings{practical operation range improvement of voltage-sourced converter based statcom_2012, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84860158421&partnerID=MN8TOARS}, DOI={10.1109/APEC.2012.6165822}, abstractNote={Voltage-Sourced Converter (VSC) based STATCOM is used for voltage regulation in transmission and distribution systems. In order to lower the STATCOM losses and total system loss, switching devices in “angle controlled” STATCOM are fired once with the line frequency (50/60 Hz). Despite the superior features on voltage waveform quality and efficiency, the practical angle controlled STATCOMs suffer from the over current and possible saturation of the interfacing transformers caused by negative sequence generated by system faults and disturbances. In this paper, the current control scheme and Instantaneous Phase-Locked Loop (IPLL) for an “angle controlled” STATCOM are presented. From power electronic point of view, IPLL prevents over-current in the VSC under system faults and bus voltage distortions. The current control can further improve STATCOM operation with higher percentages of negative sequence voltage. In addition to improved system performance under fault, the system can be installed with regular transformers, not custom-designed or over-rated transformers. RTDS (Real Time Digital Simulator) results verify the applicability of the proposed IPLL based control methods.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, year={2012}, pages={211–217} }
 @inproceedings{practical operation range improvement of voltage-sourced converter based statcom_2012, booktitle={2012 twenty-seventh annual ieee applied power electronics conference and exposition (apec)}, year={2012}, pages={211–217} }
 @inproceedings{hazra_bhattacharya_2012, title={Short time power smoothing of a low power wave energy system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84872982349&partnerID=MN8TOARS}, DOI={10.1109/iecon.2012.6389128}, abstractNote={This paper presents smoothing of oscillatory power generated by a wave energy converter (WEC) from sea wave. WEC oscillates in sea wave and an electrical generator connected to it generates oscillatory power of typical period of oscillation of 6 to 10 seconds. This power can not be directly fed to a load or grid and hence an energy storage device is required to filter out the oscillation. Super-capacitor (SC) is a better choice over battery as an energy storage device due to its low maintenance requirement and better power capacity. A WEC is emulated in hardware using induction motor (IM) and a permanent magnet synchronous machine (PMSM) is used as the generator. Power generation from WEC is controlled by controlling PMSM current. Power flow to and from SC is controlled to smooth the power output. The overall control system is implemented in hardware and smoothing of the oscillatory power using SC is demonstrated.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Hazra, S. and Bhattacharya, Subhashish}, year={2012}, pages={5846–5851} }
 @inbook{bayram_michailidis_devetsikiotis_granelli_bhattacharya_2012, title={Smart vehicles in the smart grid: Challenges, trends, and application to the design of charging stations}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84957378317&partnerID=MN8TOARS}, DOI={10.1007/978-1-4614-1605-6}, booktitle={Control and Optimization Methods for Electric Smart Grids}, author={Bayram, I.S. and Michailidis, G. and Devetsikiotis, M. and Granelli, F. and Bhattacharya, S.}, year={2012}, pages={133–145} }
 @inproceedings{wang_xu_hatua_madhusoodhanan_bhattacharya_2012, title={Solid state transformer specification via feeder modeling and simulation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870598630&partnerID=MN8TOARS}, DOI={10.1109/PESGM.2012.6345403}, abstractNote={This paper discusses the design specification method of a 1MVA, 13.8kV/480V solid state transformer (SST, also called a Transformerless Intelligent Power Substation - TIPS). A simplified IEEE 34 bus test feeder was used in the study and a dynamic model of the TIPS was developed and incorporated into the feeder model. Feeder circuit stability issues when TIPS connects at a weak system point were observed and mitigation method studied. The overloading capability of TIPS and the overvoltage protection requirements of TIPS were also investigated.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Wang, Z. and Xu, J. and Hatua, K. and Madhusoodhanan, S. and Bhattacharya, S.}, year={2012} }
 @inproceedings{karimi-moghaddam_gould_madhusoodhanan_hatua_bhattacharya_leslie_ryu_das_agarwal_grider_2012, title={Thermal design considerations for 12kV SiC n-IGBT based 3L NPC converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870903069&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2012.6342445}, abstractNote={Transformer less Intelligent Power Substation (TIPS) is a solid state replacement for the conventional bulky distribution transformers used for 13.8kV and 480V grid interconnectivity. A 100kVA 3L NPC converter is being built using 12kV SiC n-IGBT for the high voltage grid interface. In this paper, detailed thermal behavior of this converter is studied for optimum thermal design. The thermal profile at the die level at different power factor of operation is studied. This study helps the optimum component placement in the converter. Also it shows that the operating modes of the converter play a key role in optimum thermal design.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012}, author={Karimi-Moghaddam, G. and Gould, R.D. and Madhusoodhanan, S. and Hatua, K. and Bhattacharya, S. and Leslie, S. and Ryu, S.-H. and Das, M. and Agarwal, A. and Grider, D.}, year={2012}, pages={2180–2186} }
 @inproceedings{parkhideh_yousefpoor_fardanesh_bhattacharya_2012, title={Vector analysis and performance evaluation of Modular Transformer Converter (MTC) based Convertible Static Transmission Controller}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870580518&partnerID=MN8TOARS}, DOI={10.1109/pesgm.2012.6344967}, abstractNote={Modular Transformer Converter (MTC) is the building block to realize a versatile and transportable transmission controller which can perform several functions including power flow control for renewable resources transmission and transformer back-up for disaster management or life extension purposes. This structure has several advantages in comparison with conventional FACTS controllers. Modularity for manufacturers and utilities using standard high power electronic systems is one of the advantages of this structure. Different connecting configuration options (shunt-shunt, series-shunt, and series-series) can be obtained in the transmission controller with the MTC structures. These features allow them to be deployed dispersedly or aggregated to meet power, voltage, VAR and other power systems contingency requirements. In this paper, vector analysis of each mode to determine the operating characteristics of the proposed transmission controller is presented and compared to conventional FACTS controllers. The dynamic performance of the MTC system is further investigated in three different connecting configurations in PSCAD/EMTDC environment.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Parkhideh, B. and Yousefpoor, N. and Fardanesh, B. and Bhattacharya, Subhashish}, year={2012} }
 @article{parkhideh_bhattacharya_2013, title={Vector-Controlled Voltage-Source-Converter-Based Transmission Under Grid Disturbances}, volume={28}, ISSN={["1941-0107"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84867080235&partnerID=MN8TOARS}, DOI={10.1109/tpel.2012.2204071}, abstractNote={Voltage-source converter (VSC)-based transmission systems have attractive potential features in terms of power flow control and stability of the network. Although relatively low switching frequency operation of high-power converters (9-15 times the line frequency) is desirable, it makes them sensitive to power network imbalances when they may be needed the most. This paper specifically proposes a control structure to improve the performance of high-power vector-controlled back-to-back VSC systems for conventional and emerging utility applications. The main improvement is to suppress the possible dc-link voltage fluctuations under power line faults and unbalanced conditions. The proposed controller structure is designed based on regulating the converter system's states locally in dq synchronous reference frame without sequence components extraction or resonant notch compensator. RTDS results verify the validity of the proposed control architecture during normal and unbalanced power system conditions.}, number={2}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Parkhideh, Babak and Bhattacharya, Subhashish}, year={2013}, month={Feb}, pages={661–672} }
 @article{zhao_wang_bhattacharya_huang_2013, title={Voltage and Power Balance Control for a Cascaded H-Bridge Converter-Based Solid-State Transformer}, volume={28}, ISSN={["1941-0107"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84878813627&partnerID=MN8TOARS}, DOI={10.1109/tpel.2012.2216549}, abstractNote={The solid-state transformer (SST) is an interface device between ac distribution grids and dc distribution systems. The SST consists of a cascaded multilevel ac/dc rectifier stage, a dual active bridge (DAB) converter stage with high-frequency transformers to provide a regulated 400-V dc distribution, and an optional dc/ac stage that can be connected to the 400-V dc bus to provide residential 120/240 V $_{\rm ac}$. However, due to dc-link voltage and power unbalance in the cascaded modules, the unbalanced dc-link voltages and power increase the stress of the semiconductor devices and cause overvoltage or overcurrent issues. This paper proposes a new voltage and power balance control for the cascaded H-Bridge converter-based SST. Based on the single-phase dq model, a novel voltage and the power control strategy is proposed to balance the rectifier capacitor voltages and the real power through parallel DAB modules. Furthermore, the intrinsic power constraints of the cascaded H-Bridge voltage balance control are derived and analyzed. With the proposed control methods, the dc-link voltage and the real power through each module can be balanced. The SST switching model simulation and the prototype experiments are presented to verify the performance of the proposed voltage and power balance controller.}, number={4}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Zhao, Tiefu and Wang, Gangyao and Bhattacharya, Subharshish and Huang, Alex Q.}, year={2013}, month={Apr}, pages={1523–1532} }
 @inproceedings{mirzaee_bhattacharya_bala_2011, title={A high power medium-voltage DC amplifier system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855161389&partnerID=MN8TOARS}, DOI={10.1109/ecce.2011.6064319}, abstractNote={In this paper the concept of a medium-voltage dc amplifier system is proposed. The dc amplifier system must provide a medium-voltage dc bus with the possibility of superposing a high bandwidth time-varying signal and should be capable of producing voltage excursions at a high slew-rate. This is intended to facilitate the development of new technologies, i.e. new high power non-linear loads based on power electronics, in all electric ships as part of the newly proposed MVDC ship power system. This paper sets forth the set of parameters and specifications of the medium-voltage dc amplifier system and proposes a specific circuit topology to achieve the required characteristics. Simulation results verify the feasibility and demonstrate highly dynamic performance of the proposed system configuration.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Mirzaee, H. and Bhattacharya, Subhashish and Bala, S.}, year={2011}, pages={4043–4050} }
 @inproceedings{basu_chakraborty_bhattacharya_2011, title={A static synchronous compensator (STATCOM) using parallel inverters operating at different switching frequencies}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84856540120&partnerID=MN8TOARS}, DOI={10.1109/IECON.2011.6119987}, abstractNote={Performance of a static synchronous compensator (STATCOM) is presented in this paper. A low frequency and a high frequency inverter are used for this purpose. The low frequency inverter operates in square wave mode in the limiting case, when the STATCOM operates like a static VAR compensator (SVC). Minimum numbers of switchings per cycle in the square wave inverter (SWI) make the switching losses low. However, it will inject huge amount of harmonics to the point of common coupling (PCC). The 2nd inverter that operates at a higher frequency is used to compensate for the harmonics. Therefore, the combination of the SWI and the high frequency inverter (HFI) is proposed in this paper for VAR compensation. The HFI is connected through a passive L-C filter. Such hybrid configuration has the advantage of operating the HFI at a lower voltage level. As the HFI is only compensating the harmonics generated by the SWI, the power rating of the inverter is less. Performance of the proposed topology is verified by MATLAB/SIMULINK and also confirmed by prototype experimentation.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Basu, T.S. and Chakraborty, C. and Bhattacharya, S.}, year={2011}, pages={4122–4127} }
 @inproceedings{parkhideh_bhattacharya_2011, title={A unified Modular Transformer Converter (MTC) system with advanced angle control structure}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855220376&partnerID=MN8TOARS}, DOI={10.1109/ecce.2011.6064276}, abstractNote={A unified Modular Transformer Converter (MTC) system is proposed that is transportable and can be installed in existing transmission substations to provide power flow control, back-up, and fault current limiter functions. The multifunctional characteristic of the proposed system is obtained by inserting the device across the substation transformer. The MTC system can be realized with standard drive converters and regular transformers through advanced angle control. The proposed controller structure enables the line frequency switching operation of the converter system while maintaining a superior harmonic spectrum.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Parkhideh, B. and Bhattacharya, Subhashish}, year={2011}, pages={3736–3743} }
 @article{li_huang_liang_bhattacharya_2012, title={Analysis and Design of Active NPC (ANPC) Inverters for Fault-Tolerant Operation of High-Power Electrical Drives}, volume={27}, ISSN={["1941-0107"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84855387046&partnerID=MN8TOARS}, DOI={10.1109/tpel.2011.2143430}, abstractNote={Compared with neutral-point-clamped (NPC) inverters, active NPC (ANPC) inverters enable a substantially increased output power and an improved performance at zero speed for high-power electrical drives. This paper analyzes the operation of three-level (3L) ANPC inverters under device failure conditions, and proposes the fault-tolerant strategies to enable continuous operating of the inverters and drive systems under single and multiple device open- and short-failure conditions. Therefore, the reliability and robustness of the electrical drives are greatly improved. Moreover, the proposed solution adds no additional components to standard 3L-ANPC inverters; thus, the cost for robust operation of drives is lower. Simulation and experiment results are provided for verification. Furthermore, a comprehensive comparison for the reliability function of 3L-ANPC and 3L-NPC inverters is presented. The results show that 3L-ANPC inverters have higher reliability than 3L-NPC inverters when a derating is allowed for the drive system under fault-tolerant operation. If a derated operation is not allowed, the two inverters have similar reliability for device open failure, while 3L-NPC inverters have higher reliability than 3L-ANPC inverters for device short failure.}, number={2}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Li, Jun and Huang, Alex Q. and Liang, Zhigang and Bhattacharya, Subhashish}, year={2012}, month={Feb} }
 @inproceedings{baek_bhattacharya_2011, title={Analytical modeling of a medium-voltage and high-frequency resonant coaxial-type power transformer for a solid state transformer application}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855185904&partnerID=MN8TOARS}, DOI={10.1109/ecce.2011.6064014}, abstractNote={This paper introduces a unique medium-voltage and high-frequency resonant coaxial-type power transformer (RCT) for a power-distribution level Solid State Transformer (SST) application [1]. The dc-dc stage of the SST application requires a compact high performance resonant transformer that operates under high electric stress and frequency. The RCT discussed in this work brings the virtues of the coaxial-type transformer, which has been use in radio frequency applications, to medium-voltage power conversion applications. The high frequency parasitic effects, which are negligible at 60Hz, become a significant concern in a SST operating above kHz range. Hence, the parasitics of the transformer need to be accurately predicted and controlled for quality power control and safety. The RCT not only minimizes the parasitics of the transformer but also integrates a resonant tank comprised of a series inductance and shunt capacitance by utilizing the stray magnetic and electric flux within the transformer. The limited space in compact size is efficiently used and materials can be optimized. The unique analytic design method of an RCT is introduced and the equivalent circuit model is developed in this paper. The specific design is based on the high performance transformer for a dual-active bridge (DAB) converter, which is one of the most popular topologies in bidirectional power conversion, in the dc-dc stage of the SST application being developed at the FREEDM System Center and its concept is verified with FEM analysis and experiments.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Baek, S. and Bhattacharya, Subhashish}, year={2011}, pages={1873–1880} }
 @inproceedings{baek_dutta_bhattacharya_2011, title={Characterization of a three-phase dual active bridge DC/DC converter in wye-delta connection for a high frequency and high power applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855226034&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2011.6064339}, abstractNote={In this paper, high-frequency (HF) three-phase dual active bridge (DAB) dc/dc converter in wye-delta connection is characterized and the optimal condition in efficiency and size of the practical application is investigated. The proposed topology has many advantages, such as linear operation and wide range of full ZVS operation region which have been the major restrictions of the existing single-phase DAB applications. This new approach is applied to a 10kW DAB dc/dc converter prototype with multiple outputs to mitigate the switching losses using newly introduced 1200V SiC MOSFET and 1200V JBS Diodes.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Baek, S. and Dutta, S. and Bhattacharya, S.}, year={2011}, pages={4183–4188} }
 @inproceedings{mirzaee_parkhideh_bhattacharya_2011, title={Design and control of Series DC Active Filter (SDAF) for shipboard Medium-Voltage DC power system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79958289408&partnerID=MN8TOARS}, DOI={10.1109/ESTS.2011.5770914}, abstractNote={Shipboard power system (SPS) can have either ac or dc distribution systems, or a combination of both ac and dc distribution systems. However, the Navy has identified Medium-Voltage DC (MVDC) as a long-term solution for electric power distribution to meet the high power density requirements in future shipboard power systems. Thyristor bridges are a viable front-end converter topology due to its mature technology, high efficiency, and high current capacity. In such medium-voltage dc systems providing a highly stabilized low-ripple dc-bus is crucial for the reliable operation of entire system. In this paper, a 7.5kV Medium-Voltage DC (MVDC) system based on a twelve-pulse thyristor-bridge configuration is proposed. The system incorporates a Series DC Active Filter (SDAF) to smooth out DC link ripples and improves overall system damping. Detailed design, system components and control, and simulation results for the series DC active filter system are presented in the paper.}, booktitle={2011 IEEE Electric Ship Technologies Symposium, ESTS 2011}, author={Mirzaee, H. and Parkhideh, B. and Bhattacharya, S.}, year={2011}, pages={452–458} }
 @inproceedings{wang_baek_elliott_kadavelugu_wang_she_dutta_liu_zhao_yao_et al._2011, title={Design and hardware implementation of Gen-1 silicon based solid state transformer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79955785263&partnerID=MN8TOARS}, DOI={10.1109/apec.2011.5744766}, abstractNote={This paper presents the design and hardware implementation and testing of 20kVA Gen-1 silicon based solid state transformer (SST), the high input voltage and high voltage isolation requirement are two major concerns for the SST design. So a 6.5kV 25A dual IGBT module has been customized packaged specially for this high voltage low current application, and an optically coupled high voltage sensor and IGBT gate driver has been designed in order to fulfill the high voltage isolation requirement. This paper also discusses the auxiliary power supply structure and thermal management for the SST power stage.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Wang, G. and Baek, S. and Elliott, J. and Kadavelugu, A. and Wang, F. and She, X. and Dutta, S. and Liu, Y. and Zhao, T. and Yao, W. and et al.}, year={2011}, pages={1344–1349} }
 @inproceedings{mirzaee_bhattacharya_ryu_agarwal_2011, title={Design comparison of 6.5 kV Si-IGBT, 6.5kV SiC JBS diode, and 10 kV SiC MOSFETs in megawatt converters for shipboard power system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79958277253&partnerID=MN8TOARS}, DOI={10.1109/ESTS.2011.5770876}, abstractNote={In this paper a comparative design study has been shown with 6.5kV Si-IGBT/Si-P IN diode, 6.5kV Si-IGBT/SiC-JBS diode, and 10kV SiC-M OSFET/SiC-JBS diode in an act ive front-end (AFE) converter for medium-voltage shipboard application. Megawatt converters based on the aforementioned technologies are being designed and compared at tw o different switching frequencies. In this regard, accurate circuit models for 5-10A die for each (a) silicon 6.5kV IGBT, (b) 6.5kV Si-IGBT incorporating a 6.5kV SiC-JB S Diode, and (c) 10kV SiC MOSFET with 10kV SiC JBS Diode, are paralleled to ma ke a 100A switch and used as conv erter switching devices in SPICE circuit simulation to perform the comparative analysis. Switching waveforms, characteristics, switching power and energy loss measurements are follo wed by an efficiency comparison of a 1MW converter with 7.5kVdc at 1kH z and 5kH z switching frequencies. It is shown that 6.5kV Si-IGBT/SiC-JBS diode, with its high efficiency performance up to 5kHz, is a strong candidate for MW ran ge converters. The 10kV SiC-MOSFET/SiC-JBS diode is an option for h igher switching frequency MW converters.}, booktitle={2011 IEEE Electric Ship Technologies Symposium, ESTS 2011}, author={Mirzaee, H. and Bhattacharya, S. and Ryu, S.-H. and Agarwal, A.}, year={2011}, pages={248–253} }
 @inproceedings{mirzaee_de_tripathi_bhattacharya_2011, title={Design comparison of high power medium-voltage converters based on 6.5kV Si-IGBT/Si-PiN diode, 6.5kV Si-IGBT/SiC-JBS diode, and 10kV SiC MOSFET/SiC-JBS diode}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855217441&partnerID=MN8TOARS}, DOI={10.1109/ecce.2011.6064090}, abstractNote={In this paper a comparative design study of high power medium-voltage three-level NPC converter with 6.5kV Si-IGBT/Si-PIN diode, 6.5kV Si-IGBT/SiC-JBS diode, and 10kV SiC-MOSFET/SiC-JBS diode is presented. Power module circuit models including packaging parasitic inductances are created based on accurate device die SPICE circuit models for each (a) 6.5kV Si-IGBT/PiN diode; (b) 6.5kV Si-IGBT/SiC-JBS diode; and (c) 10kV SiC-MOSFET/SiC-JBS diode. Switching waveforms, characteristics, switching power and energy loss measurements of power modules including symmetric/asymmetric parasitic inductances are followed by SPICE circuit simulation and efficiency comparison of a 1MW 3L-NPC converter at 1kHz, 5kHz, and 10kHz switching frequencies. It is shown that 6.5kV Si-IGBT incorporating an anti-parallel SiC-JBS diode, with its high efficiency performance up to 5kHz, is a strong candidate for MW range converters. The 10kV SiC-MOSFET/SiC-JBS diode remains an option for higher switching frequency high power converters.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Mirzaee, H. and De, A. and Tripathi, A. and Bhattacharya, Subhashish}, year={2011}, pages={2421–2428} }
 @inproceedings{steurer_vodyakho_langston_bhattacharya_mirzaee_2011, title={Development of a model-based specification of a medium voltage DC amplifier for DC shipboard system studies}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84871295772&partnerID=MN8TOARS}, booktitle={Proceedings of the 2011 - Grand Challenges in Modeling and Simulation Conference, GCMS 2011}, author={Steurer, M. and Vodyakho, O. and Langston, J. and Bhattacharya, S. and Mirzaee, H.}, year={2011}, pages={116–123} }
 @inproceedings{vodyakho_widener_steurer_neumayr_edrington_bhattacharya_mirzaee_2011, title={Development of solid-state fault isolation devices for future power electronics-based distribution systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79955768189&partnerID=MN8TOARS}, DOI={10.1109/APEC.2011.5744584}, abstractNote={This paper addresses the timely issues of modeling, and defining selection criteria for, a solidstate fault isolation device (FID) intended for use in power electronics-based distribution systems (PEDS). The paper subsequently derives the FID parameters in the PEDS envisioned under a new multi-university Engineering Research Center funded by the US National Science Foundation. When conventional circuit breakers are used in distribution systems, they have relatively long clearing times, causing feeder voltages to be reduced for a significant amount of time. Although acceptable in convention systems, this relatively long clearing time would cause significantly long, complete voltage collapses in a PEDS. Sensitive loads such as computers would fail even if the voltage returns within a few seconds. However, if a semiconductor circuit breaker were to be used instead of the conventional system, it would be able to switch fast enough to keep the time of voltage disturbances within acceptable limits. This paper discusses the management of the overvoltage resulting from very fast circuit breaker operation through the use of passive clamping devices and di/dt control during turn-off. The paper includes experimental results at medium voltage from a developed hardware prototype. In addition, a validated simulation model of a medium voltage FID was developed for future studies. Simulation results are presented.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Vodyakho, O. and Widener, C. and Steurer, M. and Neumayr, D. and Edrington, C. and Bhattacharya, S. and Mirzaee, H.}, year={2011}, pages={113–118} }
 @inproceedings{fregosi_bhattacharya_atcitty_2011, title={Empirical battery model characterizing a utility-scale carbon-enhanced VRLA battery}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855168395&partnerID=MN8TOARS}, DOI={10.1109/ecce.2011.6064248}, abstractNote={In this paper, the electrical characteristics of a carbon enhanced valve-regulated lead-acid (VRLA) battery from East Penn Manufacturing are investigated and a dynamic model is developed for use in electrical simulations. The electrochemical processes that cause specific dynamic behaviors have been investigated. These processes are explained and a non-linear electric model, which captures the results of some of these electrochemical dynamics, is presented. The method to determine model parameters using experimental data is shown. To verify the battery model, both a pulsed current profile and an arbitrary current profile were applied to the battery and to the battery model and the voltage responses of the two were compared.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Fregosi, D. and Bhattacharya, Subhashish and Atcitty, S.}, year={2011}, pages={3541–3548} }
 @inproceedings{parkhideh_mirzaee_beddingfield_bhattacharya_2011, title={Enabling energy storage integration in high power multi-motor applications with active filter solutions}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-82955193204&partnerID=MN8TOARS}, DOI={10.1109/IAS.2011.6074394}, abstractNote={AC drive systems have gained popularity in multi-motor applications including mining industry because the production rate of mines increases by almost 20% compared to DC drive systems. Typically, to supply the AC drive systems several Active Front Ends (AFE) with DC choppers are used to insure a reliable and acceptable harmonic current spectrum operation. Recently, energy storage system integration with the mining equipment has received industry attention, especially for peak load shaving and smarter energy management of the mine. The energy storage system is intended to capture the regenerative energy and reuse it for the motoring operation of the drive. Currently, the regenerative energy is often burnt into the choppers and is not fed back to the grid‥ The industry is motivated to capture this regenerative power since it can be as high as 60% of the motoring power and as high as 24 MW. Therefore, there is a possibility of large cost reduction and component downsizing. However, present status of development seems not to be very promising mainly because energy storage systems, (such as ultracapacitors) are still considered as an add-on part to existing products. In this paper, we propose power conversion configurations, yet robust and reliable for development of the multi-motor mobile mining equipment that has encouraging incentives for both the manufacturer and the mine operator.}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Parkhideh, B. and Mirzaee, H. and Beddingfield, R. and Bhattacharya, S.}, year={2011} }
 @inproceedings{xu_zhang_wang_juneja_bhattacharya_2011, title={Energy router: Architectures and functionalities toward energy internet}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84862965618&partnerID=MN8TOARS}, DOI={10.1109/SmartGridComm.2011.6102340}, abstractNote={The next-generation electric power system, known as the smart grid, will incorporate a large number of renewable energy resources that fundamentally change the energy management paradigm. In order to manage efficiently the energy supply and demand in the power grid, energy routers are required which adjust dynamically the energy distribution in the grid, which is so called the Energy Internet. We discuss in this paper the functional expectations on the energy router design and present our preliminary research results on the energy router architectural construction and communication performance. This paper documents our work-in-progress on the design and implementation of energy router, a critical equipment to enable intelligent energy management in the smart grid.}, booktitle={2011 IEEE International Conference on Smart Grid Communications, SmartGridComm 2011}, author={Xu, Y. and Zhang, J. and Wang, W. and Juneja, A. and Bhattacharya, S.}, year={2011}, pages={31–36} }
 @inproceedings{notani_bhattacharya_2011, title={Flexible electrical power system controller design and battery integration for 1U to 12U CubeSats}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855199741&partnerID=MN8TOARS}, DOI={10.1109/ecce.2011.6064262}, abstractNote={The paper presents the power distribution system architecture, hardware and software design and specifications of the electrical power system (EPS) for CubeSats. The sources of power in these CubeSats are solar panels on each of their six faces. The maximum power point tracking (MPPT) techniques are used to maximize the output of power from these solar panels. The EPS also has two Li-ion batteries mounted on it, the capacity of the batteries depend on the size and configuration of the CubeSat. The EPS has three flexible battery charging modules (FBCM) to charge the battery and seven independent flexible digital point of load (FDPOL) converters to drive the loads. The digital control is provided by TI TMS320F28335 DSP which runs the MPPT algorithms, takes feedback from the loads, runs the battery State of Health (SOH) and State of Charge (SOC) determination algorithms and determines state of health of the EPS.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Notani, S. and Bhattacharya, Subhashish}, year={2011}, pages={3633–3640} }
 @inproceedings{kadavelugu_baek_dutta_bhattacharya_das_agarwal_scofield_2011, title={High-frequency design considerations of dual active bridge 1200 V SiC MOSFET DC-DC converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79955786991&partnerID=MN8TOARS}, DOI={10.1109/apec.2011.5744614}, abstractNote={Silicon carbide (SiC) is more favorable than Silicon (Si) to build high voltage devices due its wider band-gap and higher critical field strength. Especially, the SiC MOSFETs are finding their niche in 1 kV range, which is currently dominated by Si IGBTs. This paper aims at demonstrating high power and high frequency operation of the SiC MOSFETs, as a means to evaluate the feasibility of using SiC MOSFETs for high power density applications. The sample devices chosen for this study are 1200 V, 20 A, SiC MOSFETs co-packed with 10 A JBS diodes — manufactured by the CREE Inc. A dual active bridge (DAB) converter has been built to validate the suitability of SiC devices for high power density converters. The design details of the DAB hardware, and the high frequency transformer used for interfacing both the bridges are given. Experimental results on the DAB at 100 kHz switching frequency are presented. Finally, the device switching waveforms up to 1 MHz are given.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Kadavelugu, A. and Baek, S. and Dutta, S. and Bhattacharya, Subhashish and Das, M. and Agarwal, A. and Scofield, J.}, year={2011}, pages={314–320} }
 @inproceedings{instantaneous phase-locked loop for performance improvement of power system with statcom under single-line to ground fault_2011, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855184463&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2011.6064278}, abstractNote={Voltage-Sourced Converter (VSC) based STATCOM is used for voltage regulation in transmission and distribution systems. STATCOMs often tripped and shut down during power system faults such as Single-Line to Ground (SLG) fault, mainly due to over current protection when the voltage support is needed the most. For “angle-controlled” STATCOM, there are generally two possible control methods to improve the STATCOM performance. One is implementing separate conventional PLLs (Phase-Locked Loop) and multiple controllers for positive and negative sequences, and another is implementing single PLL, which is able to provide information of both positive and negative sequences, with a single controller. In this paper, the required PLL signal to improve the STATCOM performance under power system fault will be introduced without the need for sequence extraction control blocks. The proposed synchronization method is called Instantaneous PLL (or IPLL). As a result, over-currents (and trips) in the VSC during faults is prevented, and the STATCOM provides voltage support and required reactive power. The detailed analysis of the proposed IPLL signal effect on a 100 MVA angle-controlled STATCOM is presented.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, year={2011}, pages={3750–3757} }
 @inproceedings{instantaneous phase-locked loop for performance improvement of power system with statcom under single-line to ground fault_2011, booktitle={2011 IEEE Energy Conversion Congress and Exposition (ECCE)}, year={2011}, pages={3750–3757} }
 @inproceedings{karimi-moghaddam_rende_gould_bhattacharya_2012, title={Investigation of high performance heat sink characteristics in forced convection cooling of power electronic systems}, DOI={10.1115/imece2011-64318}, abstractNote={This study presents the experimental performance of a high fin density heat sink for semiconductor power modules — such as IGBTs. As a case study a commercially available extruded heat sink has been chosen. By analyzing the steady-state maximum temperatures as well as various geometric orientations, Nusselt number correlations were found experimentally, which can be used to predict the performance of the heat sink. It was found that the experimental Nusselt number correlations can predict the performance of the heat sink to within a 10%. Furthermore, steady-state maximum temperature results showed that for low fan speeds (2 m/s–3 m/s), the device junction temperatures achieved a value no higher than 80°C, which is well below the junction temperature limit for 125°C for silicon power semiconductor devices. Furthermore, it was shown that for two heat sinks in series forced convection tests, gap spacing between the devices has a minimal effect on the overall performance. Also, a numerical simulation study using COMSOL Multiphysics simulation software to study flow and temperature fields has been conducted. These modeling results the thermal behavior of heat sink are validated by experimental measurements.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2011, vol 11}, author={Karimi-Moghaddam, G. and Rende, C. and Gould, R. D. and Bhattacharya, S.}, year={2012}, pages={815–821} }
 @inproceedings{karimi-moghaddam_rende_gould_bhattacharya_2011, title={Investigation of high performance heat sink characteristics in forced convection cooling of power electronic systems}, volume={11}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84869163236&partnerID=MN8TOARS}, booktitle={ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011}, author={Karimi-Moghaddam, G. and Rende, C. and Gould, R.D. and Bhattacharya, S.}, year={2011}, pages={815–821} }
 @inproceedings{bayram_michailidis_devetsikiotis_bhattacharya_chakrabortty_granelli_2011, title={Local energy storage sizing in plug-in hybrid electric vehicle charging stations under blocking probability constraints}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84855855281&partnerID=MN8TOARS}, DOI={10.1109/SmartGridComm.2011.6102396}, abstractNote={Plug-in hybrid electric vehicles (PHEV) are becoming gradually more attractive than internal combustion engine vehicles, even though the current electrical grid is not potentially able to support the required power demand increase to introduce charging stations. Acknowledging that design and development of charging stations has crucial importance, this paper introduces a candidate PHEV charging station architecture, along with a quantitative stochastic model, that allows us to analyze the performance of the system by using arguments from queuing theory and economics. A relevant component of the proposed architecture is the capability of the charging stations to store excess power obtained from the grid. The goal is to design a general architecture which will be able to sustain grid stability, while providing a required level of quality of service; and to describe a general methodology to analyze the performance of such stations with respect to the traffic characteristics, energy storage size, pricing and cost parameters. Our results indicate that significant gains in net cost/profit and useful insights can be made with the right choice of storage size. Such considerations are crucial in this early stage of designing the smart grid and charging stations of the future.}, booktitle={2011 IEEE International Conference on Smart Grid Communications, SmartGridComm 2011}, author={Bayram, I.S. and Michailidis, G. and Devetsikiotis, M. and Bhattacharya, S. and Chakrabortty, A. and Granelli, F.}, year={2011}, pages={78–83} }
 @inproceedings{dutta_moghaddam_bhattacharya_gould_2012, title={Novel power electronics overload and temperature rise and time interval prediction based on dynamic thermal modeling}, DOI={10.1115/imece2011-64048}, abstractNote={In this digest an overload predicting algorithm is proposed based on the converter operating point and the thermal model of a 6.5 KV Silicon IGBT module. This algorithm can predict both the overload and the time interval for overload and hence can be used for thermal cycle performance evaluation for converters.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2011, vol 11}, author={Dutta, S. and Moghaddam, G. K. and Bhattacharya, S. and Gould, R.}, year={2012}, pages={809–813} }
 @inproceedings{dutta_moghaddam_bhattacharya_gould_2011, title={Novel power electronics overload and temperature rise and time interval prediction based on dynamic thermal modeling}, volume={11}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84869185147&partnerID=MN8TOARS}, booktitle={ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011}, author={Dutta, S. and Moghaddam, G.K. and Bhattacharya, S. and Gould, R.}, year={2011}, pages={809–813} }
 @article{bhattacharya_chakraborty_bhattacharya_2012, title={Parallel-connected shunt hybrid active power filters operating at different switching frequencies for improved performance}, volume={59}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84862999144&partnerID=MN8TOARS}, DOI={10.1109/TIE.2011.2173893}, abstractNote={This paper proposes a combination of low- and high-frequency hybrid active power filter (APF) to operate in parallel for better performance. The individual hybrid APF is a series combination of L-C filter with the corresponding voltage source inverter. The dc links of both the inverters are connected in parallel, and the voltage of the dc link is maintained by the low-frequency inverter (LFI). The low- and high-frequency inverters eliminate lower order and higher order harmonics, respectively. In addition, it is possible to design the LFI such that it can also compensate the reactive power of the load. The individual L-C filter of the hybrid topology is designed to take care of specific order of harmonics that are predominant in the load. A combination of feedforward and feedback controller is designed for the proposed conditioner. The performances of the proposed topology and the controller are first examined by MATLAB/SIMULINK-based simulation. An experimental prototype is also designed to confirm the usefulness of the proposed system.}, number={11}, journal={IEEE Transactions on Industrial Electronics}, author={Bhattacharya, A. and Chakraborty, C. and Bhattacharya, S.}, year={2012}, pages={4007–4019} }
 @inproceedings{she_lukic_huang_bhattacharya_baran_2011, title={Performance evaluation of solid state transformer based microgrid in FREEDM systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79955771308&partnerID=MN8TOARS}, DOI={10.1109/apec.2011.5744594}, abstractNote={A new concept of solid state transformer based microgrid system is presented in this paper. By utilizing 400V DC bus generated from Gen-I solid state transformer proposed by FREEDM systems center, integration issues of DC microgrid and solid state transformer are analyzed. Zonal DC microgrid concept is applied to this novel system with the consideration of burden minimization to the existing AC grid. The future grid architecture is described by using this solid state transformer based integrated microgrid system.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={She, X. and Lukic, Srdjan and Huang, A.Q. and Bhattacharya, Subhashish and Baran, M.}, year={2011}, pages={182–188} }
 @inproceedings{zhao_she_bhattacharya_wang_wang_huang_2011, title={Power synchronization control for capacitor minimization in Solid State Transformers (SST)}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855183853&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2011.6064147}, abstractNote={The Solid State Transformer (SST) has been researched and designed to interface with the distribution system. The SST consists of a multilevel AC/DC rectifier stage, a bidirectional DC/DC converter stage and a DC/AC inverter stage. However, in all of the previous designs, large capacitors are required to limit the DC bus voltage ripple within the allowable range and stabilize the multistage system. The large capacitors, especially at high voltage level, result in a large size and volume, as well as significant component cost. This paper proposes a feed-forward power ripple control and an inverter power synchronization control method to reduce the required DC filter capacitance and the 120Hz voltage ripple for high voltage and low voltage DC buses. The switching model simulations illustrate the DC bus capacitance can be greatly reduced comparing to the conventional designed value and meet the same voltage ripple requirements. The SST prototype experiments also validate the proposed power synchronization controller.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Zhao, T. and She, X. and Bhattacharya, S. and Wang, G. and Wang, F. and Huang, A.}, year={2011}, pages={2812–2818} }
 @inproceedings{bhattacharya_babaei_2011, title={Series connected IGCT based three-level neutral point clamped voltage source inverter pole for high power converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855177074&partnerID=MN8TOARS}, DOI={10.1109/ecce.2011.6064349}, abstractNote={This paper reports design and experimental verification of series connected 4.5kV, 4kA IGCT based high power three-level Neutral Point Clamped (NPC) inverter pole. A simplified EMTDC model of a three level NPC inverter pole for different switching transitions based on experimental results is presented which is used for designing of RC snubber circuit for the IGCT switches. Dynamic voltage sharing issues and advantages of series connected 4.5kV, 4kA IGCT for high power 12 MVA three-level NPC inverter pole are investigated. Experimental results are presented for two three level NPC inverter poles operated as H-bridge with three series connected 4.5kV, 4kA IGCT per switch.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Bhattacharya, Subhashish and Babaei, S.}, year={2011}, pages={4248–4255} }
 @article{vodyakho_steurer_neumayr_edrington_karady_bhattacharya_2011, title={Solid-state fault isolation devices: application to future power electronics-based distribution systems}, volume={5}, ISSN={["1751-8679"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79960520892&partnerID=MN8TOARS}, DOI={10.1049/iet-epa.2010.0258}, abstractNote={This study addresses the timely issues of modelling, and defining selection criteria for, a solid-state fault isolation device (FID) intended for use in power electronics-based distribution systems (PEDS). This work subsequently derives the FID parameters by mapping the characteristics of a conventional medium-voltage distribution system onto that of the PEDS envisioned under a new multi-university Engineering Research Centre. When conventional circuit breakers are used in distribution systems, they have a relatively long clearing time, causing the voltage to collapse for a significant time. A semiconductor circuit breaker, however, is expected to be able to switch fast enough to keep a voltage disturbance within acceptable limits. The main focus of this study is to address the operational issues of the interaction between the power electronic converters and the solid-state FID. The utilisation of rate of current decrease (di/dt) control during turn-off in conjunction with passive clamping devices to manage the overvoltage that results from very fast circuit breaker operation is introduced. In contrast to a simple conventional RC-snubber circuit, the proposed overvoltage management avoids high leakage current, which is the undesirable drawback of RC-snubber circuits. The presented prototype is experimentally verified with low and medium-voltage test circuits.}, number={6}, journal={IET ELECTRIC POWER APPLICATIONS}, author={Vodyakho, O. and Steurer, M. and Neumayr, D. and Edrington, C. S. and Karady, G. and Bhattacharya, S.}, year={2011}, month={Jul}, pages={521–528} }
 @inproceedings{parkhideh_bhattacharya_2011, title={Towards smart transmission substations with modular transformer converter systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-82855164131&partnerID=MN8TOARS}, DOI={10.1109/pes.2011.6039586}, abstractNote={This paper provides the background and introduces the concept of Modular Transformer Converter (MTC) system as a power flow controller for transmission substations. The MTC based power flow controller is desired also to provide back-up function due to aging and failure of transmission transformers. Several different connection configurations for the MTC based power flow controller are proposed and compared. The proposed MTC solution offers controllable and increased power flow margins as well as improved system performance under line faults and system disturbances. The proposed MTC solution is aimed at being scalable, transportable, efficient, and to increase reliability for transmission systems.}, booktitle={IEEE Power and Energy Society General Meeting}, author={Parkhideh, B. and Bhattacharya, Subhashish}, year={2011} }
 @inproceedings{hatua_dutta_tripathi_baek_karimi_bhattacharya_2011, title={Transformer less intelligent power substation design with 15kV SiC IGBT for grid interconnection}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855226026&partnerID=MN8TOARS}, DOI={10.1109/ecce.2011.6064346}, abstractNote={Basic power topology for a Solid State Transformer (SST) with new 15kV SiC IGBT devices is discussed. It is difficult to build high efficient, light weight, magnetically isolated solid state transformer for high voltage (13.8 kV) grid connectivity with existing Si 6.5kV rated IGBTs and diodes. Existing state of the art high voltage (6.5kV), high speed power devices (IGBT) cause considerable amount of loss (switching and conduction loss). With the advent of SiC devices these limitations are largely mitigated and this provides the motivation for new power topologies. The targeted efficiency of the proposed SST is 98%.Simulation results for a 1 MVA proposed SST topology is presented.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Hatua, K. and Dutta, S. and Tripathi, A. and Baek, S. and Karimi, G. and Bhattacharya, Subhashish}, year={2011}, pages={4225–4232} }
 @inproceedings{kadavelugu_baliga_bhattacharya_das_agarwal_2011, title={Zero voltage switching performance of 1200V SiC MOSFET, 1200V silicon IGBT and 900V CoolMOS MOSFET}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81855177139&partnerID=MN8TOARS}, DOI={10.1109/ecce.2011.6064006}, abstractNote={This paper evaluates zero voltage switching (ZVS) performance of 1200 V SiC MOSFET with respect to 1200 V silicon IGBTs (PT and FST) and 900 V CoolMOS MOSFET. The converter topology chosen for the study is a dual active bridge (DAB) dc-dc converter. Typically, in a high power DAB converter, ZVS is achieved through LC resonance of leakage inductance of the high frequency transformer and external capacitance across the drain and source (or collector and emitter for IGBTs) terminals. However, the SiC MOSFET offers a completely new set of parameters for ZVS when compared to its Silicon counterparts. In this paper, it is shown that a high power converter is possible with ZVS turn-on as well as low-loss turn-off using SiC MOSFETs, with out adding any external capacitance. The unique features of the SiC MOSFET that helps in achieving this are its CDS value, the variation of CDS with drain voltage, and low current turn-off time. The corresponding parameters of the silicon IGBTs and CoolMOS devices are presented to show the uniqueness of the SiC MOSFET. Simulation results corresponding to a 6 kW, 100 kHz DAB converter are presented with the SiC MOSFET as well as the silicon IGBTs and CoolMOS to provide a comparative ZVS performance.}, booktitle={IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings}, author={Kadavelugu, A. and Baliga, V. and Bhattacharya, Subhashish and Das, M. and Agarwal, A.}, year={2011}, pages={1819–1826} }
 @article{white_bhattacharya_2010, title={A Discrete MatlabSimulink Flickermeter Model for Power Quality Studies}, volume={59}, ISSN={["1557-9662"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-76849100178&partnerID=MN8TOARS}, DOI={10.1109/tim.2009.2023121}, abstractNote={A discrete model of the IEC 61000-4-15 flickermeter is developed for use with the Matlab-Simulink simulation software package. The discrete model is a faithful reproduction of a flickermeter defined by the IEC Standard; it duplicates the functional blocks described by the standard and operates in the same way as the standardized instrument to assure complete fidelity of results. The model is intended to be used within larger simulations that contain discrete model blocks, either alone or in combination with the Simulink SimPowerSystems blockset, to provide direct quantification of flicker. The model is fully developed, and all model parameters are provided for use with 60-Hz systems. A discrete calibrator is described that duplicates the test waveforms described by the IEC Standard.}, number={3}, journal={IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT}, author={White, Leonard W. and Bhattacharya, Subhashish}, year={2010}, month={Mar}, pages={527–533} }
 @article{li_bhattacharya_huang_2011, title={A New Nine-Level Active NPC (ANPC) Converter for Grid Connection of Large Wind Turbines for Distributed Generation}, volume={26}, ISSN={["1941-0107"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79957505632&partnerID=MN8TOARS}, DOI={10.1109/tpel.2010.2093154}, abstractNote={Wind power is one of the most promising emerging renewable energy technologies for distributed generation (DG). In this paper, a new nine-level active neutral-point-clamped (9L ANPC) converter is proposed for the grid connection of large wind turbines (WTs) to improve the waveform quality of the converter output voltage and current. Therefore, the bulky passive grid filters can be reduced or even removed. The topology, operating principles, control schemes, and main features, as well as semiconductor device selection of the proposed converter are presented in detail. The floating capacitor voltage control based on redundant switching states and capacitor prioritization is detailed. A comparison between the new topology and other existing 9L topologies is presented to illustrate the characteristics and performance of the new converter. The proposed 9L ANPC converter is studied in the case of the grid connection of a 6-MW WT without using passive grid filters in DG systems. Simulation and experiment results are presented to validate the proposed converter topology and control schemes. The proper operation and the compliance to the harmonic limit standards of the filterless grid-connected WT system are verified by simulation results.}, number={3}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Li, Jun and Bhattacharya, Subhashish and Huang, Alex Q.}, year={2011}, month={Mar}, pages={961–972} }
 @inproceedings{mirzaee_dutta_bhattacharya_2010, title={A medium-voltage DC (MVDC) with series active injection for shipboard power system applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650154309&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5618184}, abstractNote={Modern electric ships utilize a medium-voltage zonal dc distribution system to meet the ever increasing power demand while keeping the power density as low as possible. Power electronics building blocks (PEBBs) composed of different DC/AC and DC/DC converters are used to convert the main DC bus voltage to appropriate dc and ac voltage levels suited for the loads in such a system. Due to the fact that most of these power electronic converters present a constant power load (CPL) with negative incremental impedance at the input terminal, the interaction of these converters under different system configurations with the main AC-DC rectifier of the MVDC system might induce voltage oscillations on the main DC-bus. In this paper, a novel method of series active injection on the dc-side is proposed to smooth out disturbances on the main DC-bus. This has resulted in much smoother DC-bus voltage enabling the system to use less amount of passive storage elements on dc-side which is very beneficial to ship's limited onboard space. The simulation results presented verify the operation and functionality of the proposed system.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Mirzaee, H. and Dutta, S. and Bhattacharya, S.}, year={2010}, pages={2865–2870} }
 @inproceedings{li_zhou_liang_bhattacharya_huang_2010, title={A simplified space vector based current controller for any general N-level converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650165482&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5618277}, abstractNote={This paper proposes a simplified current controller for any general N-level converter based on space vector (SV) theory. Through the presented mapping technique between the subhexagon of the N-level converter and the hexagon of the two-level converter, the proper output voltage vector of the N-level converter can be identified to suppress harmonic current content in steady state and attain fast current response in transient state. Meanwhile, the redundant switching states of the voltage vectors can be used to reduce or balance the device power losses, and regulate floating capacitor voltages. The controller complexity is greatly reduced due to the use of very simple lookup tables, thus it can be easily extended to any general N-level converter. The proposed scheme is explained for a five-level active NPC converter and the simulation results are presented to prove its correctness.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Li, J. and Zhou, X. and Liang, Z. and Bhattacharya, S. and Huang, A.Q.}, year={2010}, pages={2156–2163} }
 @inproceedings{ramamurthy_notani_bhattacharya_2010, title={Advanced lithium ion battery modeling and power stage integration technique}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650151456&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5618249}, abstractNote={This paper focuses on the system modeling aspect of energy storage, power conversion and digital power control involved in non-renewable power systems. Lithium based batteries, the energy storage devices were modeled at different state of charges (SOC) using Electro chemical Impedance Spectroscopy (EIS). EIS based impedance measurements were fitted to a standard electrochemical battery model. The AC impedance model of the battery was integrated to the power supply control loop. The battery impedance changes with SOC of the battery and its effect on the control loop was observed. Based on the battery impedance based control loop performance, a dynamic compensation technique was proposed to optimally stabilize different control loops in the battery charging cycle. The system model and design aspects were verified using a synchronous buck based charging system.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Ramamurthy, A. and Notani, S. and Bhattacharya, S.}, year={2010}, pages={1485–1492} }
 @inproceedings{chen_huang_bhattacharya_2010, title={Analysis of static voltage balance of series connected self-power emitter turn-off thyristors}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650136965&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5618426}, abstractNote={Self-power emitter turn-off thyristor (SPETO) is a high power switching device which could provide power for its gate driver during operation. Self-power function is a major benefit, whereas it brings an issue of large power loss on parallel resistors when two or more SPETOs are in series connection and static voltage balance between them is expected. In this paper, the root reason causing large power loss on parallel resistors is analyzed; a solution that could greatly reduce the power loss is proposed and verified by experimental results.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Chen, Q. and Huang, A. and Bhattacharya, S.}, year={2010}, pages={4547–4550} }
 @article{li_huang_bhattacharya_jing_2010, title={Application of Active NPC Converter on Generator Side for MW Direct-driven Wind Turbine}, ISSN={["1048-2334"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77952213746&partnerID=MN8TOARS}, DOI={10.1109/apec.2010.5433381}, abstractNote={3L-NPC topology is usually used in MW wind turbine (WT) systems with full-scale converter configuration. However, due to its drawback of unequal device loss distribution, the converter rated power, and thus the WT unit capacity is limited. Moreover, in cased of device failure in generator converter, in order to protect the WT system, the converter has to shut down to disconnect the WT. This paper presents the application of active NPC (ANPC) converter on generator side. Loss-balancing schemes are discussed, and thermal performance of NPC and ANPC generator converters are compared. Also, the control scheme of generator converter under single device failure condition is proposed to maintain the WT in service and continue to provide real power, which brings benefits in the reliable and economic aspects to the WT system. Simulation results are provided to validate the proposed control methods.}, journal={2010 TWENTY-FIFTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC)}, author={Li, Jun and Huang, Alex Q. and Bhattacharya, Subhashish and Jing, Wei}, year={2010}, pages={1010–1017} }
 @inproceedings{wang_wang_bhattacharya_huang_2010, title={Comparison of 10-kV SiC power devices in solid-state transformer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650148187&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5617759}, abstractNote={The characteristics and losses of 10-kV SiC MOSFETs, p-IGBTs and emitter turn-off thyristors (ETOs) were compared using the experimental measurements, PSPICE simulations and numerical simulations. Using the extracted loss information and method of loss calculation in the AC/DC rectifier and DC/DC converter, the frequency capability of these 10-kV SiC power devices in a 20 kVA solid-state transformer (SST) was investigated and compared in the same total power loss density of 300 W/cm2 and junction temperature of 125 °C. The comparison shows that 10-kV SiC MOSFETs have the highest switching frequency capability amongst the discussed 10-kV SiC device types in the AC/DC rectifier stage and DC/DC converter stage of the SST.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Wang, J. and Wang, G. and Bhattacharya, S. and Huang, A.Q.}, year={2010}, pages={3284–3289} }
 @inproceedings{wang_huang_wang_zhao_bhattacharya_huang_2010, title={Comparisons of 6.5kV 25A Si IGBT and 10-kV SiC MOSFET in solid-state transformer application}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650117900&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5618069}, abstractNote={A 6.5kV 25A dual IGBT module is customized and packaged specially for high voltage low current application like solid state transformer and its characteristics and losses have been tested under the low current operation and compared with 10kV SiC MOSFET. Based on the test results, the switching losses under different frequencies in a 20kVA Solid-State Transformer (SST) has been calculated for both devices. The result shows 10kV SiC MOSFET has 7–10 times higher switching frequency capability than 6.5kV Si IGBT in the SST application.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Wang, G. and Huang, X. and Wang, J. and Zhao, T. and Bhattacharya, S. and Huang, A.Q.}, year={2010}, pages={100–104} }
 @article{bhattacharya_zhao_wang_dutta_baek_du_parkhideh_zhou_huang_2010, title={Design and Development of Generation-I Silicon based Solid State Transformer}, ISSN={["1048-2334"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77952195486&partnerID=MN8TOARS}, DOI={10.1109/apec.2010.5433455}, abstractNote={The Solid State Transformer (SST) is one of the key elements proposed in the National Science Foundation (NSF) Generation-III Engineering Research Center (ERC) “Future Renewable Electric Energy Delivery and Management” (FREEDM) Systems Center. The SST is used to enable active management of distributed renewable energy resources, energy storage devices and loads. In this paper, the Generation-I SST single-phase 20kVA, based on 6.5kV Si-IGBT is proposed for interface with 12kV distribution system voltage. The SST system design parameters, overall system efficiency, high frequency transformer design, dual active bridge converter, auxiliary power supply and gate drives are investigated. Design considerations and experimental results of the prototype SST are reported.}, journal={2010 TWENTY-FIFTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC)}, author={Bhattacharya, Subhashish and Zhao, Tiefu and Wang, Gangyao and Dutta, Sumit and Baek, Seunghun and Du, Yu and Parkhideh, Babak and Zhou, Xiaohu and Huang, Alex Q.}, year={2010}, pages={1666–1673} }
 @inproceedings{leung_baek_dutta_bhattacharya_2010, title={Design considerations of high voltage and high frequency three phase transformer for Solid State Transformer Application}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650099327&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5618234}, abstractNote={The three-phase Solid State Transformer (SST) is one of the key elements in the Future Renewable Electric Energy Delivery and Management (FREEDM) System. The SST consists of an input rectifier, Dual Active Bridge (DAB) bidirectional dc-dc converter and followed by an inverter for ac voltage output. The DAB converter is a bidirectional dc-dc converter using high frequency transformers to step up or down the voltages at high frequency for a reduction in size while maintaining high efficiency and reliability. The single phase high-frequency high-voltage transformer for two-level DAB has been reported by the authors [2]. In this paper, high frequency three-phase transformer for multi-level (3-level) and multi-phase (three-phase) DAB is designed for three-phase multilevel SST. There are two proposed topologies and for each topology the high voltage and high frequency transformer is designed at 3 kHz and 20 kHz. The proposed transformer designs for electromagnetic, thermal and mechanical analysis are validated with the simulation of Finite Element Analysis software.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Leung, C.-K. and Baek, S. and Dutta, S. and Bhattacharya, S.}, year={2010}, pages={1551–1558} }
 @inproceedings{baek_du_wang_bhattacharya_2010, title={Design considerations of high voltage and high frequency transformer for solid state transformer application}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78751474139&partnerID=MN8TOARS}, DOI={10.1109/IECON.2010.5674991}, abstractNote={This paper presents overall design considerations of the high-voltage and high-frequency (HV-HF) transformer in dc/dc converter stages of solid state transformer (SST). SST is a new concept of an interface for direct connection between the distribution line and local customers which can be considered as another generation source as well from the local smart-grid point of view. Therefore, the size and weight reduction are the main objectives of this system. Therefore, increasing operating frequency to minimize the bulky magnetic elements and solid insulation become necessary. Especially, the inductance of transformer plays a crucial role in Dual-Active Bridge (DAB) converter to determine the power transfer, therefore, the inductance optimization depending on winding structures is investigated and a high voltage insulation is carefully designed to support 15kV in this paper. A comprehensive electromagnetic analysis is conducted to validate the proposed design by finite element analysis (FEA) and experimental result with 2kVA scale-down transformer is analyzed first and, finally, 3 versions of 7kVA HV-HF transformer are built and tested for SST application.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Baek, S. and Du, Y. and Wang, G. and Bhattacharya, Subhashish}, year={2010}, pages={421–426} }
 @inproceedings{fregosi_white_green_watterson_bhattacharya_2010, title={Digital Flickermeter design and implementation based on IEC standard}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650128886&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5618422}, abstractNote={The present work describes the design and implementation of a IEC 61000-4-15 digital Flickermeter on a National Instruments CompactRIO Controller; the Flickermeter is configured for use on 120 VAC, 60 Hz systems. The IEC Flickermeter Standard defines an instrument that quantifies human perception of the magnitude and frequency of voltage change supplied to a gas-filled filament lamp with a single ‘perceived flicker’ value. A physical instrument for use in measuring the level of flicker that might appear in real-world scenarios is described. The instrument is a faithful reproduction of the Flickermeter defined by the IEC Standard. The Flickermeter has been validated by importing calibration points through a file stored in the processor's memory. Additionally, a physical calibrator with the necessary accuracy was implemented on a separate CompactRIO Controller, allowing validation through the use of a physical signal. The digital Flickermeter, as tested, is in full compliance with the IEC 61000-4-15 Standard meeting mandated error rates at all test points.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Fregosi, D. and White, L.W. and Green, E. and Watterson, J. and Bhattacharya, S.}, year={2010}, pages={4521–4526} }
 @article{teleke_bhattacharya_baran_2010, title={Enhanced Control of Voltage Source Converters for DC Shipboard Power Systems}, volume={122}, ISSN={["1559-3584"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650143229&partnerID=MN8TOARS}, DOI={10.1111/j.1559-3584.2010.00239.x}, abstractNote={In this paper, an enhanced control scheme for a pulse-width-modulated (PWM) voltage source con- verter (VSC) is proposed for a DC zonal sbipboard power system (SPS). First, the main design parameters of VSC such as switching frequency and DC-link capacitance are investigated and optimized for the SPS application. Then, the nonideal operating conditions such as sudden load change, sudden supply voltage change, and unbalanced supply voltage are considered. To address these issues, the VSC control strategy has been enhanced by (i) adopting a different PWM strategy that changes the carrier frequency under nonideal operating conditions, (ii) adding a negative-sequence controller, and (iii) implementing an instantaneous phase locked loop (PLL). The results show that the proposed controller shows indeed a satisfactory performance for this specific application and it can also operate at unity displacement power factor under nonideal conditions.}, number={1}, journal={NAVAL ENGINEERS JOURNAL}, author={Teleke, Sercan and Bhattacharya, Subhashish and Baran, Mesut}, year={2010}, pages={81–91} }
 @inproceedings{du_baek_bhattacharya_huang_2010, title={High-voltage high-frequency transformer design for a 7.2kV to 120V/240V 20kVA solid state transformer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78751558902&partnerID=MN8TOARS}, DOI={10.1109/iecon.2010.5674828}, abstractNote={Solid state transformer (SST) exhibits good features such as high power density, small volume and weight, controlled power factor, voltage sag ride through, etc. compared with traditional line frequency transformer. The 7.2kV AC to 120V/240V AC 20kVA solid state transformer is a key component of the future renewable electric energy delivery and management (FREEDM) systems as the interface between the 7.2kV distribution grid and the low voltage residential micro-grid. Three cascaded 6.7kVA high-voltage high-frequency transformers operating at 3kHz are employed to convert voltage from 3800V high voltage DC link of each cascaded stage to 400V low voltage DC link. The transformer is required to withstand at least 15kV high frequency voltage insulation continuously. Transformer magnetic core materials were reviewed and compared. Winding layout alternatives for leakage, magnetizing inductance and insulation were compared. An insulation strategy based on split core and separate winding structure with inserted insulation layer between the C cores was proposed. One 6.7kVA high voltage high frequency transformer prototype was built and the test results were reported.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Du, Y. and Baek, S. and Bhattacharya, Subhashish and Huang, A.Q.}, year={2010}, pages={493–498} }
 @inproceedings{stefanski_qin_chowdhury_kimball_bhattacharya_2010, title={Identifying techniques, topologies and features for maximizing the efficiency of a distribution grid with solid state power devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650040405&partnerID=MN8TOARS}, DOI={10.1109/NAPS.2010.5618966}, abstractNote={The FREEDM grid utilizes solid state transformers (SST) and solid state fault interruption devices (FID) which may lead to unfavorable operating losses as compared to a conventional grid. Various SST topologies and switching techniques are identified for minimizing losses and a performance evaluation is made to determine the efficiency of the FREEDM distribution network to improve the overall efficiency. Losses include conductors, SSTs, FIDs, and conventional distribution transformers tested under various loading levels. Compared to a conventional distribution network, the FREEDM grid has a slight reduction in losses. By choosing the proper distribution line configuration, conductor type, switching devices and switching techniques, the power losses on the system may be minimized further.}, booktitle={North American Power Symposium 2010, NAPS 2010}, author={Stefanski, K. and Qin, H. and Chowdhury, B.H. and Kimball, J.W. and Bhattacharya, S.}, year={2010} }
 @inproceedings{vodyakho_steurer_edrington_karady_bhattacharya_2010, title={Instantiation of solid state fault isolation devices for future power electronic based distribution systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78649617239&partnerID=MN8TOARS}, DOI={10.1109/PES.2010.5590129}, abstractNote={This paper addresses the timely issues of modeling of, and defining selection criteria for, a solid state fault isolation device (FID) to be used in power electronic based distribution systems (PEDS). Circuit interruption requirements and FID location in power electronics based distribution system are discussed in this paper. The paper subsequently derives the FID parameters by mapping the characteristics of a conventional medium-voltage distribution system onto that of the PEDS envisioned under a new multi-university Engineering Research Center funded by the National Science Foundation. A design of a high frequency solid state transformer (SST) is presented and evaluated. An average-value simulation model of a SST, as the interface of the PEDS to the legacy system, is used to derive key parameters of the FID. The simulation and experimental results validated the feasibility of the proposed FID topology. Finally, the conceptual Power Hardware-in-the-Loop simulation setup for testing the FID under various system conditions is presented.}, booktitle={IEEE PES General Meeting, PES 2010}, author={Vodyakho, O. and Steurer, M. and Edrington, C. and Karady, G. and Bhattacharya, S.}, year={2010} }
 @inproceedings{white_lukic_bhattacharya_2010, title={Investigations into the minimization of electrical costs for traction-type elevators}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650153772&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5618473}, abstractNote={This work examines the real-time utilization of energy in an operating elevator drive system with a goal, not of improving efficiency per se, but rather of reducing the cost paid by the system owner for the operation of the equipment. Several load-leveling and peak-shaving schemes using ultracapacitors are reviewed, including (1) off-peak energy storage for on-peak use, (2) energy storage to reduce the utility demand cost, (3) energy storage to reduce inrush peaks, and (4) energy storage to redirect regenerated energy. Each of these schemes is developed to demonstrate technical acceptability and then evaluated with respect to cost effectiveness.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={White, L.W. and Lukic, S.M. and Bhattacharya, S.}, year={2010}, pages={4285–4292} }
 @inproceedings{du_wang_wang_bhattacharya_huang_2010, title={Modeling of the impact of diode junction capacitance on high voltage high frequency rectifiers based on 10kV SiC JBS diodes}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650087880&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5618065}, abstractNote={There is strong industrial need to boost the power density of the high voltage generators, for example, in medical radiology applications. 10kV SiC JBS diode is potential candidate to be employed in the high voltage high frequency rectifier in future high voltage generator applications. However, the impact of the relatively large diode junction capacitance of SiC JBS diode cannot be neglected at high frequency and high voltage conditions. An electric circuit model is proposed to describe this effect for full bridge and half bridge high voltage diode rectifiers based on mathematical derivations. The effect of junction capacitance is to decrease the output voltage and to increase the ratio of capacitive reactive power in the circuit, which can be represented by an equivalent shunt capacitor with input source and ideal diode rectifier. The model is validated by simulation results, and can be used for the further design of the high voltage generators.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Du, Y. and Wang, G. and Wang, J. and Bhattacharya, S. and Huang, A.Q.}, year={2010}, pages={105–111} }
 @inproceedings{zhou_liu_bhattacharya_huang_2010, title={New inductor current feedback control with active harmonics injection for inverter stage of solid state transformer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78751540900&partnerID=MN8TOARS}, DOI={10.1109/iecon.2010.5675216}, abstractNote={Solid state transformer (SST) is considered the key unit for power processing and conversion in the future distributed renewable energy network. The role of SST is to enable the active management of distributed energy resources, energy storage devices and different type of loads in a distribution grid. Inverter stage of SST supplies sinusoidal voltage to the users. In this paper an improved inductor current control based on active harmonics injection is proposed to overcome the drawback of inferior performance of conventional inductor current feedback control for the nonlinear loads. The inductor current overshoot during the load transient is investigated by using both capacitor current feedback control and inductor current feedback control. The inductor current feedback control has the capability to limit current overshoot even with a smaller inductor, which shows the potential to further reduce the size and weight of the passive components.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Zhou, X. and Liu, Y. and Bhattacharya, Subhashish and Huang, A.}, year={2010}, pages={593–598} }
 @article{teleke_baran_bhattacharya_huang_2010, title={Optimal Control of Battery Energy Storage for Wind Farm Dispatching}, volume={25}, ISSN={["1558-0059"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77956056892&partnerID=MN8TOARS}, DOI={10.1109/tec.2010.2041550}, abstractNote={Integrating a battery energy storage system (BESS) with a large wind farm can make a wind farm more dispatchable. This paper focuses on development of a control strategy for optimal use of the BESS for this purpose. The paper considers an open-loop optimal control scheme to incorporate the operating constraints of the BESS, such as state of charge limits, charge/discharge current limits, and lifetime. The goal of the control is to have the BESS to provide as much smoothing as possible, so that the wind farm can be dispatched on an hourly basis based on the forecasted wind conditions. The effectiveness of this control strategy has been tested by using an actual wind farm data. Furthermore, a real-time implementation strategy using model predictive control is also proposed. Finally, it is shown that the control strategy is very important in improving the BESS performance for this application.}, number={3}, journal={IEEE TRANSACTIONS ON ENERGY CONVERSION}, author={Teleke, Sercan and Baran, Mesut E. and Bhattacharya, Subhashish and Huang, Alex Q.}, year={2010}, month={Sep}, pages={787–794} }
 @article{ramamurthy_bhattacharya_thompson_day_2010, title={Optimal Phase Changing Frequency Determination for Multiphase Voltage Regulator Modules}, ISSN={["1048-2334"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77952193155&partnerID=MN8TOARS}, DOI={10.1109/apec.2010.5433342}, abstractNote={Modern processers have the capability of indicating the power state of the processor to the Voltage Regulator (VR) PWM controller so that it can change its operating state to maximize efficiency at light loads and to flatten out its efficiency curve for idle power reduction. The CPU worst case assert and de-assert frequency can be very high for the PWM controller and for the VR to follow. Thus for the VR to take advantage of the low power state signal from the CPU, the signal has to be passed through an analog/digital low-pass filter. The optimum frequency for this filter design is determined in this paper. This filtered frequency with which the VR drops its phases optimizes the overall efficiency of the system. The experimental results are given for a four-phase VRM. It is also shown in this paper that the transient efficiency is as vital as the steady state efficiency considering the load profile of modern CPUs.}, journal={2010 TWENTY-FIFTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC)}, author={Ramamurthy, Anand and Bhattacharya, Subhashish and Thompson, Chris and Day, Jon}, year={2010}, pages={1243–1247} }
 @inproceedings{pantic_bhattacharya_lukic_2010, title={Optimal resonant tank design considerations for primary track compensation in inductive power transfer systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650149637&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5618093}, abstractNote={In this paper, design of a primary resonant tank for resonant converters compensation in an Inductive Power Transfer (IPT) system is analyzed and some criteria for selecting its reactive components are established. The optimization goal is to maximize the transferred power, while limiting the number of compensation components to no more than two reactive components. Additionally, VA limits of the inverter are taken into consideration. Current track requirements are relaxed and instead of constant track current, small track load dependency is allowed, which is acceptable in practice. The theoretical investigations and calculations, as well as simulations for two important practical cases considered are presented in the paper. It is shown that LC compensation structure allows maximum delivered power, but not for the case when the impedances of compensation elements are the same as it would be expected. Additionally, the impact of converter ratings and allowed load dependent track current variation on the optimal design are investigated through the set of numerical simulations.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Pantic, Z. and Bhattacharya, S. and Lukic, S.}, year={2010}, pages={1602–1609} }
 @inproceedings{mcbryde_kadavelugu_compton_bhattacharya_das_agarwal_2010, title={Performance comparison of 1200V silicon and SiC devices for UPS application}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78751483327&partnerID=MN8TOARS}, DOI={10.1109/IECON.2010.5675125}, abstractNote={In this paper, a comparative study of 1200V Silicon IGBTs with Silicon Carbide (SiC) MOSFETs is presented for a 6kVA single-phase 230V online Uninterruptible Power Supply (UPS) system. The UPS is first tested with the 1200V silicon IGBT/Diode devices (2 parallel 34A IGBT/diode) and then the inverter devices are replaced by next generation SiC 1200V MOSFET/Diode devices (2 parallel 20A MOSFET/10A Diode co-packs). The UPS efficiency is compared with two different sets of devices, at different loading and gate driving conditions. SiC MOSFETs significantly improve the efficiency of the UPS at light load conditions. The experimental results are presented at 20kHz switching frequency.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={McBryde, J. and Kadavelugu, A. and Compton, B. and Bhattacharya, S. and Das, M. and Agarwal, A.}, year={2010}, pages={2657–2662} }
 @article{teleke_baran_bhattacharya_huang_2010, title={Rule-based control of battery energy storage for dispatching intermittent renewable sources}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77957007183&partnerID=MN8TOARS}, DOI={10.1109/TSTE.2010.2061880}, abstractNote={Integrating a battery energy storage system (BESS) with a solar photovoltaic (PV) system or a wind farm can make these intermittent renewable energy sources more dispatchable. This paper focuses on the development of a control strategy for optimal use of the BESS for this purpose. The paper considers a rule-based control scheme, which is the solution of the optimal control problem defined, to incorporate the operating constraints of the BESS, such as state of charge limits, charge/discharge current limits, and lifetime. The goal of the control is to have the BESS provide as much smoothing as possible so that the renewable resource can be dispatched on an hourly basis based on the forecasted solar/wind conditions. The effectiveness of this control strategy has been tested by using an actual PV system and wind farm data and it is shown that the BESS can indeed help to cope with variability in wind's and solar's generation.}, number={3}, journal={IEEE Transactions on Sustainable Energy}, author={Teleke, S. and Baran, M.E. and Bhattacharya, S. and Huang, A.Q.}, year={2010}, pages={117–124} }
 @inproceedings{bhattacharya_mirzaee_2010, title={Series active filter control and implementation for utility interface of multiple adjustable speed drives}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78751534269&partnerID=MN8TOARS}, DOI={10.1109/IECON.2010.5675126}, abstractNote={The control of Series Active Filter (SAF) to meet IEEE 519 standard for harmonic voltage source front-end based multiple adjustable speed motor drives, is reported in this paper. The series active filter design, control, implementation and issues in the practical application for utility interface of multiple three-phase six-pulse diode rectifier with dc side capacitor fed 480V, 150kW motor drives are investigated. The simulation and experimental results validate series active filter performance for utility interface of multiple ASDs under practical utility conditions.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Bhattacharya, S. and Mirzaee, H.}, year={2010}, pages={2663–2668} }
 @inproceedings{zhou_li_liang_huang_bhattacharya_2010, title={The issue of plug-in hybrid electric vehicles' grid integration and its control solution}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650135071&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2010.5617710}, abstractNote={In this paper, a bi-directional battery charger is applied as an interface between plug-in hybrid electric vehicles and the grid. The major issue of using power electronics interface for grid integration of PHEVs is high frequency resonance. This resonance is caused by a high order filter, which is composed of the charger's LC filter and the grid impedance. An active damping method is proposed to mitigate the resonance. The modeling and controller design are presented. The damping performance to both the converter output harmonics and the grid harmonics are analyzed. The proposed controller can effectively reduce the high frequency resonance on the grid current. The proposed method is verified by the simulation and experiment.}, booktitle={2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings}, author={Zhou, X. and Li, J. and Liang, Z. and Huang, A. and Bhattacharya, S.}, year={2010}, pages={3596–3603} }
 @inproceedings{teleke_baran_bhattacharya_huang_2010, title={Validation of battery energy storage control for wind farm dispatching}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78649570830&partnerID=MN8TOARS}, DOI={10.1109/PES.2010.5589640}, abstractNote={Integrating a Battery Energy Storage System (BESS) with a large wind farm can smooth out the intermittent power from the wind farm. This paper focuses on the experimental validation of the proposed control strategy for the BESS. The paper considers a rule based control scheme, which is the solution of the optimal control problem defined, to incorporate the operating constraints of the BESS, such as state of charge limits, charge/discharge current limits and lifetime. The goal of the control is to have the BESS provide as much smoothing as possible so that the wind farm can be dispatched on an hourly basis based on the forecasted wind conditions. The effectiveness of this control strategy has been tested by using an actual wind farm data and it is shown that optimal dispatching is achieved with the proposed method. Finally, the method is verified with an experiment and the details of the implementation are explained.}, booktitle={IEEE PES General Meeting, PES 2010}, author={Teleke, S. and Baran, M.E. and Bhattacharya, S. and Huang, A.}, year={2010} }
 @article{zhao_wang_zeng_dutta_bhattacharya_huang_2010, title={Voltage and Power Balance Control for a Cascaded Multilevel Solid State Transformer}, ISSN={["1048-2334"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77952178838&partnerID=MN8TOARS}, DOI={10.1109/apec.2010.5433584}, abstractNote={In this paper, a 20kVA Solid State Transformer (SST) based on 6.5kV IGBT is proposed for interface with 7.2kV distribution system voltage. The proposed SST consists of a cascaded multilevel AC/DC rectifier stage, a Dual Active Bridge (DAB) converter stage with high frequency transformers and a DC/AC inverter stage. Based on the single phase d-q vector control, a novel control strategy is proposed to balance the rectifier capacitor voltages and the real power through the DAB parallel modules. Furthermore, the power constraints of the voltage balance control are analyzed. The SST switching model simulation demonstrates the effectiveness of the proposed voltage and power balance controller. A 3kW SST scale-down prototype is implemented. The experiment results verify the single phase d-q vector controller for the SST cascaded multilevel rectifier.}, journal={2010 TWENTY-FIFTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC)}, author={Zhao, Tiefu and Wang, Gangyao and Zeng, Jie and Dutta, Sumit and Bhattacharya, Subhashish and Huang, Alex Q.}, year={2010}, pages={761–767} }
 @inproceedings{bhattacharya_chakraborty_bhattacharya_2009, title={A reduced switch transformer-less dual hybrid active power filter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77951562152&partnerID=MN8TOARS}, DOI={10.1109/IECON.2009.5414783}, abstractNote={This paper proposes transformer-less dual hybrid topologies suitable for rectifier type load. Performance of the reduced switch version of the network is highlighted. It consists of two inverters, one operates at a lower frequency (typically around 550 Hz) and the other operates at higher frequency (around 20 kHz). Less number of switches is used to improve reliability and reduce cost. The low frequency inverter is in series with a passive filter to optimally eliminate 5 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> and 7 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> harmonics, whereas the high frequency inverter is connected to a passive filter to optimally eliminate 11 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> and 13 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> harmonics in addition to the other harmonics of the load and any additional harmonics generated by the low frequency inverter. The usefulness of the proposed topology is confirmed by simulation and prototype experimentation in the laboratory.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Bhattacharya, A. and Chakraborty, C. and Bhattacharya, S.}, year={2009}, pages={88–93} }
 @inproceedings{parkhideh_bhattacharya_2009, title={Active power transfer capability of shunt family of FACTS devices based on angle control}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72449168801&partnerID=MN8TOARS}, DOI={10.1109/ECCE.2009.5316127}, abstractNote={The shunt FACTS devices like STATCOM are well adopted based on angle control structure. This control scheme allows a much better converter output voltage and line switching frequency (50/60 Hz). This paper will discuss the feasibility of enhancement in the operation region of these devices to accommodate the active power transfer. The concept will use general linear feedback method with single input (angle) two output system which has unique design limitations.}, booktitle={2009 IEEE Energy Conversion Congress and Exposition, ECCE 2009}, author={Parkhideh, B. and Bhattacharya, Subhashish}, year={2009}, pages={2711–2718} }
 @inproceedings{zhao_zeng_bhattacharya_baran_huang_2009, title={An average model of solid state transformer for dynamic system simulation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-71849090346&partnerID=MN8TOARS}, DOI={10.1109/pes.2009.5275542}, abstractNote={The Solid State Transformer (SST) is one of the key elements proposed in the National Science Foundation (NSF) Generation-III Engineering Research Center (ERC) “Future Renewable Electric Energy Delivery and Management” (FREEDM) Systems Center established in 2008. The SST is used to enable active management of distributed renewable energy resources, energy storage devices and loads. In this paper, a 20kVA solid state transformer based on 6.5kV IGBT is proposed for interface with 12kV distribution system voltage. The average model and control scheme of SST including AC/DC rectifier, Dual Active Bridge (DAB) converter and DC/AC inverter are developed to enable dynamic system level simulation. The developed average model is verified by comparing with the detailed switching model simulation. The dynamic system level SST simulation verifies the proposed controller and the corresponding average model illustrates the functionalities and advantages of the SST in FREEDM system.}, booktitle={2009 IEEE Power and Energy Society General Meeting, PES '09}, author={Zhao, T. and Zeng, J. and Bhattacharya, Subhashish and Baran, M.E. and Huang, A.Q.}, year={2009}, pages={1516–1523} }
 @inproceedings{li_liu_bhattacharya_huang_2009, title={An optimum PWM strategy for 5-level active NPC (ANPC) converter based on real-time solution for THD minimization}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72449155137&partnerID=MN8TOARS}, DOI={10.1109/ecce.2009.5316229}, abstractNote={The recently introduced active NPC (ANPC) converter is becoming an attractive topology of multilevel converter family. This paper presents the analysis of the 5-level ANPC converter with an optimum PWM strategy to achieve the minimized total harmonic distortion (THD) for high power or high frequency applications. Instead of relying on the conventional look-up table based on off-line calculated solutions, the switching angles of the optimum PWM are calculated through a real-time algorithm, which is time-efficient and therefore easy to implement in real-time by digital processors. The control scheme of balancing the floating capacitors voltages is also proposed. Simulation results verify the performance of the proposed strategies.}, booktitle={2009 IEEE Energy Conversion Congress and Exposition, ECCE 2009}, author={Li, J. and Liu, Y. and Bhattacharya, Subhashish and Huang, A.Q.}, year={2009}, pages={1976–1982} }
 @inproceedings{bhattacharya_teshnizi_parkhideh_2009, title={An universal active power filter controller system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72849145530&partnerID=MN8TOARS}, DOI={10.1109/IAS.2009.5324847}, abstractNote={An universal active power filter controller system is proposed that adapts itself to both harmonic current source type loads as well as harmonic voltage source type loads is presented in this paper. The system level harmonic filtering application issues of a multiple and clustered harmonic producing load site, such as at an industrial load site or at a distribution substation, are addressed. Harmonic filtering solution for such sites is especially complicated because the overall site load characteristics can change from a harmonic current source type to a harmonic voltage source type load, depending on the operating point of the various individual loads. The proposed Hybrid Series Active Filter (HSAF) solution provides harmonic filtering for harmonic current source type load characteristics, and degrades controllably to a 'pure' Series Active Filter (SAF) to provide harmonic filtering for harmonic voltage source type load characteristics. Both the HSAF and SAF are controlled by Synchronous Reference Frame (SRF) controller. Field test results validate the adaptability and effectiveness of the proposed HSAF/SAF system for a 480V, 750kVA multiple and clustered load site. Index Terms— Hybrid Series Active Filter (HSAF), Series Active Filter (SAF), Harmonic Filtering, Synchronous Reference Frame (SRF) controller, clustered harmonic loads}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Bhattacharya, S. and Teshnizi, H.M. and Parkhideh, B.}, year={2009} }
 @inproceedings{wang_du_bhattacharya_huang_2009, title={Characterization, modeling of 10-kV SiC JBS diodes and their application prospect in X-ray generators}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72449197461&partnerID=MN8TOARS}, DOI={10.1109/ecce.2009.5315963}, abstractNote={The 10-kV Silicon Carbide (SiC) Junction Barrier Schottky (JBS) diodes are currently being developed by a number of organizations in the United States with the aim to enable their applications in high voltage power conversions. The aim of this paper is to characterize and model the 10-kV SiC JBS diode so that their prospect and benefits in power electronic systems can be provided. Using the SPICE model of the 10-kV 5A SiC JBS diode, the advantages of 10-kV SiC JBS diodes in the application of X-ray generators were shown by PSPICE simulations for the first time. The simulation results predict that the 10-kV SiC JBS diodes based high voltage rectifiers in X-ray generators can greatly reduce the number of series diodes required and power loss than compared to the 1-kV silicon ultra fast recovery diodes based rectifiers.}, booktitle={2009 IEEE Energy Conversion Congress and Exposition, ECCE 2009}, author={Wang, J. and Du, Y. and Bhattacharya, Subhashish and Huang, A.Q.}, year={2009}, pages={1488–1493} }
 @article{teleke_baran_huang_bhattacharya_anderson_2009, title={Control Strategies for Battery Energy Storage for Wind Farm Dispatching}, volume={24}, ISSN={["1558-0059"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70049103778&partnerID=MN8TOARS}, DOI={10.1109/TEC.2009.2016000}, abstractNote={Integrating a battery energy storage system (BESS) with a large wind farm can smooth out the intermittent power from the wind farm. This paper focuses on development of a control strategy for optimal use of the BESS for this purpose. The paper considers a conventional feedback-based control scheme with revisions to incorporate the operating constraints of the BESS, such as state of charge limits, charge/discharge rate, and lifetime. The goal of the control is to have the BESS provide as much smoothing as possible so that the wind farm can be dispatched on an hourly basis based on the forecasted wind conditions. The effectiveness of this control strategy has been tested by using an actual wind farm data. Finally, it is shown that the control strategy is very important in determining the proper BESS size needed for this application.}, number={3}, journal={IEEE TRANSACTIONS ON ENERGY CONVERSION}, author={Teleke, Sercan and Baran, Mesut E. and Huang, Alex Q. and Bhattacharya, Subhashish and Anderson, Loren}, year={2009}, month={Sep}, pages={725–732} }
 @inproceedings{dawley_bhattacharya_2009, title={Control of multi-level three-phase dual current source inverters for high power industrial applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72849140213&partnerID=MN8TOARS}, DOI={10.1109/IAS.2009.5324884}, abstractNote={A novel switching control strategy for multi-level (three-level) three-phase dual current source inverters for high power drives applications is reported. The important issue of dc current sharing between the dual inverters is implemented by a simple Space Vector based PWM scheme for both current source inverters. A second alternative scheme to achieve dc link current sharing using a simple flux-based control is also proposed and implemented by regular sine-triangle PWM scheme. The operation of dual current source inverters is validated under both normal supply voltages, load transients and supply side faults or voltage sags. Detailed simulation results are presented to validate the operation of the dual current source inverter for high power drives applications.}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Dawley, R. and Bhattacharya, S.}, year={2009} }
 @inproceedings{liu_p._g._c._huang_langston_steurer_litzenberger_anderson_adapa_et al._2009, title={Controller hardware-in-the-loop validation for a0 10 MVA ETO-based STATCOM for wind farm application}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72449158355&partnerID=MN8TOARS}, DOI={10.1109/ecce.2009.5316033}, abstractNote={This paper reports experimental validation of a Static Synchronous Compensation (STATCOM) by controller hardware-in-the-loop (CHIL) testing with a real-time digital simulator (RTDS). The controller is designed and developed for a 10 MVA STATCOM for voltage regulation at the PCC of a 50 MW wind farm connected to a 69kV utility grid. Emitter Turn-off (ETO) thyristors are switching devices in the multilevel inverter. The STATCOM controller was developed for a cascade multilevel inverter and has been validated on a laboratory test-bench. The CHIL testing of the controller is done with detailed scaled model of the 50 MW wind farm and 69kV utility system. The experimental results from the RTDS for both steady state and dynamic changes in the STATCOM output validate the STATCOM controller design and performance.}, booktitle={2009 IEEE Energy Conversion Congress and Exposition, ECCE 2009}, author={Liu, Y. and P., Liang Z. and G., Song Z. and C., Bhattacharya W. and Huang, S. and Langston, A. and Steurer, J. and Litzenberger, M. and Anderson, W. and Adapa, L. and et al.}, year={2009}, pages={1398–1403} }
 @inproceedings{liu_huang_bhattacharya_2009, title={Dead-band controller for balancing individual dc capacitor voltages in cascade multilevel inverter based STATCOM}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-65949109712&partnerID=MN8TOARS}, DOI={10.1109/APEC.2009.4802734}, abstractNote={This paper presents a dead-band controller for balancing individual dc capacitor voltages in a three-phase cascade multilevel inverter based static synchronous compensator (STATCOM). The design of the feed-back control is based on the detailed small-signal model. The proposed dead-band controller can stabilizes the phase shift of H-bridge voltages, and then reduces the risk of unnecessary switching of power semiconductors. The controller can balance individual dc capacitor voltages when H-bridges run with different switching patterns and have parameter variations. Moreover, it is shown that the controller can work well in all operation regions. Experimental results verify the performance of the controller.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Liu, Y. and Huang, A.Q. and Bhattacharya, S.}, year={2009}, pages={683–688} }
 @inproceedings{zhou_lukic_bhattacharya_huang_2009, title={Design and control of grid-connected converter in bi-directional battery charger for plug-in hybrid electric vehicle application}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72149131445&partnerID=MN8TOARS}, DOI={10.1109/vppc.2009.5289691}, abstractNote={A new bi-directional power converter for Plug-in Hybrid Electric Vehicles (PHEV) is proposed based on a typical household circuitry configuration. This converter can achieve three major functions: battery charger mode, vehicle to grid mode (V2G) and vehicle to home mode (V2H), which are the main topics of integration of PHEVs with the grid. The detailed converter design is presented. An improved AC/DC controller is proposed in order to achieve low input current harmonics for the charger mode. The Proportional resonant+harmonics selective compensation method is utilized for the V2G mode, and capacitor current feedback and proportional resonant control methods are adopted for the V2H mode. Compared with conventional PI controllers, the proposed controllers greatly enhance the grid-connected converter's performance in the aspects of low harmonics output and robustness against background noise.}, booktitle={5th IEEE Vehicle Power and Propulsion Conference, VPPC '09}, author={Zhou, X. and Lukic, Srdjan and Bhattacharya, Subhashish and Huang, A.}, year={2009}, pages={1716–1721} }
 @inproceedings{vodyakho_steurer_edrington_karady_chowdhury_bhattacharya_2009, title={Design of a solid state fault isolation device for implementation in power electronics based distribution systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77954763843&partnerID=MN8TOARS}, DOI={10.1109/NAPS.2009.5484023}, abstractNote={This paper addresses the timely issues of modeling of, and defining selection criteria for, a solid state fault isolation device (SSFID) to be used in power electronic based distribution systems. The paper derives the SSFID parameters by mapping the characteristics of a conventional medium-voltage distribution system onto that of the power electronic based Future Renewable Electric Energy Delivery and Management (FREEDM) system envisioned under a new multi-university Engineering Research Center funded by the National Science Foundation. Major drawbacks of all SSFID solutions presented so far are material costs and on-state losses. Power semiconductor devices are briefly compared considering the requirements of a solid state switch integrated into a 15 kV class medium voltage grid. A design of a high frequency Solid State Transformer (SST) is presented and evaluated. The simulation results verify the functionality and feasibility of SST. Utilizing an average-value simulation model of a SST, as the interface of the power electronics based distribution system to the legacy system, is used to derive key parameters of the SSFID. Circuit interruption requirements and SSFID location in power electronics based distribution system are discussed in this paper. The simulation and experimental results in low voltage single phase system validated the feasibility of the proposed SSFID topology. Finally, the conceptual Power Hardware-in-the-Loop setup for SSFID testing is presented and discussed in this paper.}, booktitle={41st North American Power Symposium, NAPS 2009}, author={Vodyakho, O. and Steurer, M. and Edrington, C. and Karady, G. and Chowdhury, B. and Bhattacharya, S.}, year={2009} }
 @inproceedings{li_huang_bhattacharya_lukic_2009, title={ETO Light multilevel converters for large electric vehicle and hybrid electric vehicle drives}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72149086393&partnerID=MN8TOARS}, DOI={10.1109/vppc.2009.5289513}, abstractNote={multilevel converters are very popular for high power AC drives to meet the power demands for large electric/hybrid electric vehicles. Emitter Turn-off (ETO) thyristor is one of the present state-of-the-art high power semiconductor devices. The newest version of ETO (Gen-4 ETO) is more intelligent and reliable. Packed with advanced features as well as superior performance, ETO device and ETO-based power converters are very attractive for large electric drives. This paper presents the ETO Light neutral-point-clamped (NPC) converter design and thermal analysis. The modular digital controller architecture for this converter is proposed in order to improve the system reliability and increase its expansion flexibility. As a solution to further increase the converter output power, the ETO Light active NPC (ANPC) converter is presented, and moreover its fault tolerant capability is discussed.}, booktitle={5th IEEE Vehicle Power and Propulsion Conference, VPPC '09}, author={Li, J. and Huang, A. and Bhattacharya, Subhashish and Lukic, Srdjan}, year={2009}, pages={1455–1460} }
 @inproceedings{song_zhou_liang_bhattacharya_huang_2009, title={Modeling and control design of distributed power flow controller based-on per-phase control}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72449137681&partnerID=MN8TOARS}, DOI={10.1109/ecce.2009.5316307}, abstractNote={The distributed power flow controller (DPFC) based-on Emitter Turn-Off (ETO) light converter is one newly proposed solid state power electronics technology based Flexible AC Transmission System (FACTS) devices which is effective to control the active power flow through the transmission lines. This modular DPFC has low cost, high reliability and makes it possible to have the transformerless connection to the existing power grid. In this paper, the development and analysis of modeling techniques and feedback schemes based on per phase control of DPFC are proposed. The simulation results and experimental results show the consistency of the propose model and the feasibility of the feedback control design for the DPFC per-phase operation.}, booktitle={2009 IEEE Energy Conversion Congress and Exposition, ECCE 2009}, author={Song, W. and Zhou, X. and Liang, Z. and Bhattacharya, Subhashish and Huang, A.Q.}, year={2009}, pages={3262–3267} }
 @inproceedings{zhou_wang_lukic_bhattacharya_huang_2009, title={Multi-function bi-directional battery charger for plug-in hybrid electric vehicle application}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72449142726&partnerID=MN8TOARS}, DOI={10.1109/ecce.2009.5316226}, abstractNote={A new multi-function bi-directional battery charger for plug-in hybrid electric vehicles (PHEV) is proposed based on the power circuitry configuration of an American house. This bi-directional charger can achieve three functions including battery charging, vehicle to grid (V2G) and vehicle to home (V2H), all of which are the major research areas of PHEV's integration with the power grid. The integration infrastructure and practical design issues are analyzed. The multiple control loop designs are presented for the three operation modes. Simulation and experimental results verify the functions and performance of the proposed charger. With the capability of achieving multiple functions, the bi-directional charger will contribute and enhance grid related research of PHEVs.}, booktitle={2009 IEEE Energy Conversion Congress and Exposition, ECCE 2009}, author={Zhou, X. and Wang, G. and Lukic, Srdjan and Bhattacharya, Subhashish and Huang, A.}, year={2009}, pages={3930–3936} }
 @inproceedings{li_bhattacharya_lukic_huang_2009, title={Multilevel active NPC converter for filterless grid-connection for large wind turbines}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77951560597&partnerID=MN8TOARS}, DOI={10.1109/IECON.2009.5414863}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Li, J. and Bhattacharya, S. and Lukic, S. and Huang, A.Q.}, year={2009}, pages={4583–4588} }
 @inproceedings{parkhideh_bhattacharya_2009, title={Resilient operation of voltage-sourced BTB HVDC systems under power system disturbances}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-71849110994&partnerID=MN8TOARS}, DOI={10.1109/PES.2009.5275672}, abstractNote={The penetration factor of Back-to-Back (BTB) Voltage-Sourced Converter (VSC) based HVDC system, will be high enough and promising if they do not only make the overall system more vulnerable but also maintain the desired function in any circumstances like fault conditions. This paper proposes two different control structures which yield to suppress the DC link voltage oscillations of these interface components in case of power systems disturbances. The shortcomings of previous methods are highlighted which is mainly due to the relatively low switching frequency operation of these high power devices. The comprehensive analytical design procedure will be presented for both controllers and performance of them are verified and evaluated through simulation.}, booktitle={2009 IEEE Power and Energy Society General Meeting, PES '09}, author={Parkhideh, B. and Bhattacharya, Subhashish}, year={2009}, pages={2443–2449} }
 @article{bhattacharya_chakraborty_bhattacharya_2009, title={Shunt Compensation}, volume={3}, ISSN={["1941-0115"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70350129956&partnerID=MN8TOARS}, DOI={10.1109/MIE.2009.933881}, abstractNote={This article has surveyed some of the most important techniques used to generate the reference current for the shunt-type APF (active power filter). The GA-based approach is discussed in detail. Zero-crossing detection of one of the source voltages is sufficient, and the PLL may be removed. An ANN-based PI controller is added for faster buildup of the voltage across the capacitor. Faster control of the capacitor-voltage reduces the size of the capacitor and also improves the bandwidth of the controller. The proposed technique is simulated (in Simulink) and is also experimentally confirmed by developing a dSPACE1104-based prototype. With the availability of low-cost and high-speed processors, such computationally extensive methods are expected to be popular in the future.}, number={3}, journal={IEEE INDUSTRIAL ELECTRONICS MAGAZINE}, author={Bhattacharya, Avik and Chakraborty, Chandan and Bhattacharya, Subhashish}, year={2009}, month={Sep}, pages={38–49} }
 @article{liu_huang_song_bhattacharya_tan_2009, title={Small-Signal Model-Based Control Strategy for Balancing Individual DC Capacitor Voltages in Cascade Multilevel Inverter-Based STATCOM}, volume={56}, ISSN={["1557-9948"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-67649366309&partnerID=MN8TOARS}, DOI={10.1109/TIE.2009.2017101}, abstractNote={This paper presents a new feedback control strategy for balancing individual DC capacitor voltages in a three-phase cascade multilevel inverter-based static synchronous compensator. The design of the control strategy is based on the detailed small-signal model. The key part of the proposed controller is a compensator to cancel the variation parts in the model. The controller can balance individual DC capacitor voltages when H-bridges run with different switching patterns and have parameter variations. It has two advantages: 1) the controller can work well in all operation modes (the capacitive mode, the inductive mode, and the standby mode) and 2) the impact of the individual DC voltage controller on the voltage quality is small. Simulation results and experimental results verify the performance of the controller.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Liu, Yu and Huang, Alex Q. and Song, Wenchao and Bhattacharya, Subhashish and Tan, Guojun}, year={2009}, month={Jun}, pages={2259–2269} }
 @inproceedings{testing of a controller for an eto-based statcom through controller hardware-in-the-loop simulation_2009, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-71849103332&partnerID=MN8TOARS}, DOI={10.1109/PES.2009.5275210}, abstractNote={The testing of a controller for a proposed 10 MVA STATCOM through hardware-in-the-loop experimentation is described in this paper. The electrical environment into which the STATCOM is to be inserted, including a significant portion of the utility network and a nearby wind farm are simulated using a large-scale digital real time electromagnetic transients simulator. The STATCOM controller is interfaced to the simulation, providing firing pulses to the simulated STATCOM and receiving feedback of system voltages and currents. Notional wind speed data is used to simulate realistic behavior of the wind farm. This paper presents preliminary results of the ongoing testing of the controller under the most realistic system conditions.}, booktitle={2009 IEEE Power and Energy Society General Meeting, PES '09}, year={2009} }
 @inproceedings{li_huang_bhattacharya_guojun_2009, title={Three-Level active neutral-point-clamped (ANPC) converter with fault tolerant ability}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-65949090075&partnerID=MN8TOARS}, DOI={10.1109/APEC.2009.4802759}, abstractNote={Compared with traditional three-level neutral-point-clamped converter, the recently proposed three-level active neutral-point-clamped (ANPC) converter can overcome the unequal loss distribution among semiconductor devices, and therefore result in increased output power or switching frequency. In industrial applications, fault tolerance of power electronics converters is very important considering system availability, safety and reliability. This paper presents the fault tolerant ability of three-level ANPC converter. Control schemes are proposed to keep the neutral-point voltage balanced and get stable and continuous output under single device fault for both open-circuit fault and short-circuit fault cases. Simulation results show the effectiveness of the fault tolerant ability of the three-level ANPC inverter under the presented control strategies, which are promising to carry on further experimental validation.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Li, J. and Huang, A.Q. and Bhattacharya, S. and Guojun, T.}, year={2009}, pages={840–845} }
 @article{mancilla-david_bhattacharya_venkataramanan_2008, title={A comparative evaluation of series power-flow controllers using dc- and ac-link converters}, volume={23}, ISSN={["1937-4208"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-42249083188&partnerID=MN8TOARS}, DOI={10.1109/TPWRD.2008.917702}, abstractNote={This paper presents a comparative evaluation of direct AC-AC converters and multipulse voltage source DC-AC converters for providing series compensation of transmission systems. This paper provides a detailed discussion of power circuit design issues related to various performance considerations for both approaches. A benchmark case study is used to demonstrate the operation and performance of both designs in terms of steady-state and dynamic performance indices. It is shown through detailed computer simulations that both approaches are competitive with respect to each other in terms of their functional performance.}, number={2}, journal={IEEE TRANSACTIONS ON POWER DELIVERY}, author={Mancilla-David, Fernando and Bhattacharya, Subhashish and Venkataramanan, Giri}, year={2008}, month={Apr}, pages={985–996} }
 @inproceedings{parkhideh_bhattacharya_2008, title={A practical approach to controlling the back-to-back voltage source converter system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-63149102009&partnerID=MN8TOARS}, DOI={10.1109/IECON.2008.4758006}, abstractNote={This paper presents a new approach for the modeling and dynamic control of the back-to-back systems which are based on voltage source converters. The state-space average method is used to derive the non-linear model of the system. Through a non-linear transformation and power balance fact a linear model for the system is developed. It is shown that DC link of the system can be regulated only from the supplier side and not from both sides which is adopted to the new market structure in the liberalized power systems and the mathematical approach is given. The decoupled controller is designed based on the state feedback method and the proposed model is validated through the comparison of the average and switching model simulations. The system performance is studied under different normal and fault cases.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Parkhideh, B. and Bhattacharya, S.}, year={2008}, pages={514–519} }
 @inproceedings{mazumdar_bhattacharya_2008, title={Application of online trained Echo State Networks for harmonic compliance issues}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-52349092282&partnerID=MN8TOARS}, DOI={10.1109/PESC.2008.4592582}, abstractNote={Complexities with existing algorithms have thus far limited supervised training techniques for Recurrent Neural Networks (RNN) from widespread use. Echo State Networks (ESN) present a newer approach to training RNNs. However for certain applications, it is mandatory to learn and adjust the ESN parameters online, i.e. during the actual task that the ESN is supposed to perform. Certain properties of ESNs make online learning unsuitable. This paper proposes a modified version of the standard ESN wherein the output weights are trained online, as against computing it. The new algorithm is applied to determine the true harmonic current injection of a nonlinear load in a power distribution network. Experimental results presented in this paper confirm that attempting to predict the Total Harmonic Distortion (THD) of a load by simply measuring the load's current may not be accurate and the results of the new algorithm are validated with actual system measurements. The method of predicting the true harmonic injection of a nonlinear load is referred to as load modeling [1] and is applicable for both single and three phase loads.}, booktitle={PESC Record - IEEE Annual Power Electronics Specialists Conference}, author={Mazumdar, J. and Bhattacharya, S.}, year={2008}, pages={4016–4021} }
 @article{liu_bhattacharya_song_huang_2008, title={Control Strategy for Cascade Multilevel Inverter based STATCOM with Optimal Combination Modulation}, ISBN={["978-1-4244-1667-7"]}, ISSN={["0275-9306"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-52349084808&partnerID=MN8TOARS}, DOI={10.1109/pesc.2008.4592734}, abstractNote={Static synchronous compensation (STATCOM) is a flexible AC transmission system (FACTS) device connected in shunt to the network for generating or absorbing reactive power. The STATCOM is used to regulate voltage, control power factor and stabilize power flow. The transformerless STATCOM is attractive due to low cost and power losses. Cascaded multilevel inverters are viable topologies for the transformerless STATCOM since each power semiconductor device only sustains low voltage. To meet IEEE 519 standard and keep low switching frequency, an optimal combination modulation strategy is used, which leads to some challenges in designing the controller, such as extra switching and the balancing of individual dc capacitor voltages. In this paper, the design of the controller is specified. Simulation results and experimental results are shown to verify the performance of the proposed control strategy.}, journal={2008 IEEE POWER ELECTRONICS SPECIALISTS CONFERENCE, VOLS 1-10}, author={Liu, Yu and Bhattacharya, Subhashish and Song, Wenchao and Huang, Alex Q.}, year={2008}, pages={4812–4818} }
 @inproceedings{control reconfiguration of vsc based statcom for de-icer application_2008, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-52349102824&partnerID=MN8TOARS}, DOI={10.1109/PES.2008.4596930}, abstractNote={Icing of power transmission lines during winter storms can cause serious power outages. There are some viable methods to solve this problem. Ice on power transmission lines can be melted effectively by passing dc currents through the transmission conductors. STATCOM equipment can provide a novel, cost-effective solution, by connecting via its dc terminals to a source or sink of electric power. In a conventional application, STATCOM can be used to provide fast reactive power for voltage support and power oscillation damping. The same equipment, with a simple control reconfiguration, by changing Iq reference under Iq regulation, giving fixed angle for angle control to keep charging DC capacitors and changing DC voltage according the demanded DC current through transmission conductors, can perform the ice melting function when it is needed. Simulation results for a 48-pulse VSC based ±150 MVA STATCOM validate the control reconfiguration of VSC based STATCOM for De-icer application.}, booktitle={IEEE Power and Energy Society 2008 General Meeting: Conversion and Delivery of Electrical Energy in the 21st Century, PES}, year={2008} }
 @inproceedings{liu_huang_tan_bhattacharya_2008, title={Control strategy improving fault ride-through capability of cascade multilevel inverter based STATCOM}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-57949085657&partnerID=MN8TOARS}, DOI={10.1109/08IAS.2008.283}, abstractNote={A 10 MVA synchronous static compensation (STATCOM) is being designed for the wind farm owned by the Seawest and connected to the Bonneville power administration (BPA) network in U. S. The five-level cascade multilevel inverter based STATCOM will be used to mitigate the voltage fluctuation. The fault ride through is regarded as the main challenge not only to the wind-turbine, but also to the STATCOM. The common control strategy for the fault ride through is to limit the currents within the rating values. With this strategy, however, we find out big over currents that will trig the over current protections during transient processes. We also find out the over voltages on DC capacitors that will trip the system. In the paper, we propose the improved control strategy for boosting the fault ride through capability. By degrading the power rating during faults, the big over current is avoided. Moreover, by lowering the reference of DC capacitor voltages, the DC capacitors are safe during faults. Simulation results are given to verify the proposed control strategy.}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Liu, Y. and Huang, A.Q. and Tan, G. and Bhattacharya, S.}, year={2008} }
 @inproceedings{godbole_bhattacharya_2008, title={Design and development of a flexible multi-purpose controller hardware system for power electronics and other industrial applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-57949088640&partnerID=MN8TOARS}, DOI={10.1109/08IAS.2008.160}, abstractNote={This paper proposes the concept of a universal controller hardware system for power electronics applications. With the presence of generic interfaces and communication schemes, this system can be used in various other control scenarios. A prototype hardware system incorporating a high performance floating point digital signal processor (DSP) and a powerful field programmable gate array (FPGA) has been built to demonstrate the concept of real-time hardware simulation. Prior to being deployed for control of a complete power electronics system, an intermediate step that would yield more information pertaining to system timing is the hardware simulation enabled by such a board. Extracting maximum throughput from this system with a few innovative schemes has been another goal of this project. In order to achieve this objective, the embedded peripherals of the Texas Instruments C6000 series DSP have been programmed to facilitate a higher degree of parallelism. The core of this paper deals with the different sub-systems that comprise the real-time controller (RTC) board, and their interaction with one another. One of the novel schemes proposed in this paper involves the on-board communication between the DSP and several analog-to-digital converter (ADC) chips using the multi-channel audio serial port (McASP) peripheral. The efficacy of this concept is made possible by a robust software architecture, enabled by the enhanced direct memory access (EDMA) peripheral. In addition to the DSP peripheral activity, significant processing capability is offered by the Cyclone II series FPGA. The option of universal connectivity is provided over either Ethernet or USB. The FPGA also provides a platform for developing a complete system with an embedded 32-bit processor. The RTC board prototype can be used for power electronics applications with the addition of certain interface boards, which can be readily developed.}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Godbole, R. and Bhattacharya, S.}, year={2008} }
 @inproceedings{han_huang_bhattacharya_white_ingram_atcitty_wong_2008, title={Design of an ultra-capacitor energy storage system (UESS) for power quality improvement of electric arc furnaces}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-57949095776&partnerID=MN8TOARS}, DOI={10.1109/08IAS.2008.336}, abstractNote={Electrical arc furnace (EAF), acting as a fast varying real power and reactive power sink, not only induces the power quality pollution back to utility, but also prevent the effective production of metal industry. In this paper, a methodology of designing an energy storage system (ESS) for EAFs is presented. Based on the field data-based study of a typical EAF, the power, energy, and speed requirement of ESS are quantitatively evaluated. Based on the requirement, an ultra-capacitor energy storage system (UESS) is deemed as the suitable type of ESS for the EAF application. The design of UESS is described, and the preliminary experimental results are given.}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Han, C. and Huang, A.Q. and Bhattacharya, S. and White, L.W. and Ingram, M. and Atcitty, S. and Wong, W.}, year={2008} }
 @article{baran_teleke_huang_bhattacharya_anderson_atcitty_2008, title={Dispatching of wind farms using battery energy storage}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-82855166814&partnerID=MN8TOARS}, DOI={10.1504/IJPElec.2008.022348}, abstractNote={In this paper, a STATCOM interfaced battery energy storage system (BESS) is considered for smoothing intermittent power output of a large wind farm so that it can be dispatched. The main advantage of the system is that it can inject both real power (by charging/discharging the BESS) and the reactive power to the system. The paper investigates the main design issues related to BESS – the control method for BESS, BESS size and its performance requirements. Simulations based on an actual wind farm data show that the output of the wind farm can be smoothed with BESS to facilitate dispatching of the wind farm.}, number={2}, journal={International Journal of Power Electronics}, author={Baran, M. and Teleke, S. and Huang, A. and Bhattacharya, S. and Anderson, L. and Atcitty, S.}, year={2008}, pages={164–175} }
 @inproceedings{song_huang_bhattacharya_2008, title={Distributed power flow controller design based-on ETO-light converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-49249122205&partnerID=MN8TOARS}, DOI={10.1109/APEC.2008.4522985}, abstractNote={Static synchronous series compensator (SSSC) is one of the solid state power electronics technology based flexible AC transmission system (FACTS) devices which is effective to control the active power flow across the transmission lines by altering or changing the characteristic impedance of power line. However its widespread application is still limited by high costs, low reliability and long build cycle. In this paper, a new ETO light converter based series compensating distributed power flow controller (DPFC) is introduced. The proposed single phase modular power flow controller system combines modular converter, modular heat-pipe and modular digital interface designs to achieve modular single phase control. It has intelligent functions such as the self-power and self-protection. Its interfaces are fully optical fibers and simple for connection. The modular DPFC makes it possible to have the transformerless connection to the existing power grid. These specific designs reduce the cost and increase the reliability greatly and introduce significant benefits to the power system. The proposed power flow controller system is verified by a single-phase power transmission system.}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Song, W. and Huang, A.Q. and Bhattacharya, S.}, year={2008}, pages={1893–1897} }
 @inproceedings{liu_doss_song_chen_mundkur_zhao_huang_bhattacharya_2008, title={ETO light multilevel inverter for STATCOM}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-63149086190&partnerID=MN8TOARS}, DOI={10.1109/IECON.2008.4758480}, abstractNote={This paper presents a 10 MVA multilevel inverter for the application of static synchronous compensator (STATCOM). Emitter turn-off (ETO) thyristors are used as active switching devices in the inverter. The cascade multilevel inverter is based on ETO light H-bridge building block (HBBB). The technology innovations of ETO simplify the HBBB construction. Air-cooled heat pipes also decrease the cost and increase the reliability. Large turn-off SOA and self-power of ETO, modular design and multi-layer protection fatherly enhance the reliability. The optimal combination modulation strategy is used to optimize the tradeoff between switching frequencies and harmonic constraints. Finally, the paper presents the complete control strategy, including the new control for balancing individual dc capacitor voltages, and multi-layer protection as well. Experimental results are given to verify the performance.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Liu, Y. and Doss, S. and Song, W. and Chen, Q. and Mundkur, S.S. and Zhao, T. and Huang, A.Q. and Bhattacharya, S.}, year={2008}, pages={3246–3251} }
 @inproceedings{song_bhattacharya_huang_2008, title={Fault-tolerant transformerless power flow controller based-on ETO light converter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-57949112415&partnerID=MN8TOARS}, DOI={10.1109/08IAS.2008.294}, abstractNote={Static synchronous series compensator (SSSC) is one of the solid state flexible AC transmission system (FACTS) devices which is effective to control the active power flow across the transmission lines by altering or changing the characteristic impedance of the power line. However its widespread application is still limited by higher cost, series protection requirements, and low reliability. Attention is drawn to the issues of fault-tolerance and distributed design of the SSSC to achieve high reliability and lower cost. In this paper, a new 1-2 MVA modular ETO Light converter with low cost and high power density is introduced. Combined with modular air-cooled heat-pipe, modular digital interface, this modular converter has self-sensor, self-power and self-protection functions. The high voltage/current rating and control power self-generation enable the transformerless connection. Two fault-tolerant power flow controllers based on ETO Light converter are proposed. The SSSC operating principle and control strategies are introduced and discussed. The proposed protection scheme and SSSC controller operation is validated by simulation results. Full scale hardware demonstration is underway and experimental results will be presented in the final paper. Some experimental test results of ETO Light converter are also presented.}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Song, W. and Bhattacharya, S. and Huang, A.Q.}, year={2008} }
 @inproceedings{parkhideh_zeng_baek_bhattacharya_baran_huang_2008, title={Improved wind farm's power availability by Battery Energy Storage Systems: Modeling and control}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-63149199450&partnerID=MN8TOARS}, DOI={10.1109/IECON.2008.4758053}, abstractNote={This paper presents the study on the integration of battery energy storage system (BESS) to STATCOM for smoothing out the intermittent output power of a wind farm. Lead-acid battery type is considered as the energy storage system for availability and comparably simpler management system. Reviewed several modeling approaches indicating their advantages and drawbacks; particularly, appropriate for high power applicationspsila time-frames, current-based third order model is developed. The experimental tests are conducted to identify the parameters and consequently, to construct the battery model. The performance of the proposed system is analyzed by introducing the state-of-charge (SOC) controller implemented for this type of battery integrated to a proposed 10 MVA STATCOM for a 50 MW wind farm.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Parkhideh, B. and Zeng, J. and Baek, S. and Bhattacharya, S. and Baran, M. and Huang, A.Q.}, year={2008}, pages={784–789} }
 @inproceedings{improving distribution system performance with integrated statcom and supercapacitor energy storage system_2008, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-52349090430&partnerID=MN8TOARS}, DOI={10.1109/PESC.2008.4592129}, abstractNote={The STATCOM (synchronous static compensator) based on voltage source converter (VSC) is used for voltage regulation in transmission and distribution systems. However, strict requirements of STATCOM losses and total system loss penalty preclude the use of high frequency PWM (pulse-width modulation) for VSC based STATCOM applications. This constraint of implementing VSC without PWM results in VSC DC voltage dip, over-currents and trips of the STATCOM during and after system disturbances and faults, when its VAR support functionality is most required. In this paper, the integration and control of energy storage systems (ESSs), such as supercapacitor (ultracapacitor - UCAP) into a D-STATCOM (Distribution system STATCOM) is developed to mitigate such problems, enhance power quality and improve distribution system reliability. This paper develops the control concepts to charge/discharge the UCAP by the D-STATCOM, and validate the performance of an integrated D-STATCOM/UCAP system for improving distribution system performance under all types of system related disturbances and system faults - such as single-line to ground fault (SLG), line-line fault and 3-phase system faults. Simulation results of a 125 kVA D-STATCOM validate that integrated the D-STATCOM with 600 V, 1.0 Farad UCAP is suited for distribution system voltage regulation and voltage sag mitigation. In case of a system fault, UCAP based energy storage will aid to keep the D-STATCOM DC voltage constant and avoid over-current and trips of the VSC based D-STATCOM.}, booktitle={PESC Record - IEEE Annual Power Electronics Specialists Conference}, year={2008}, pages={1390–1395} }
 @inproceedings{improving distribution system performance with integrated statcom and supercapacitor energy storage system_2008, booktitle={2008 IEEE Power Electronics Specialists Conference}, year={2008}, pages={1390–1395} }
 @article{parkhideh_bhattacharya_han_2008, title={Integration of Supercapacitor with STATCOM for Electric Arc Furnace Flicker Mitigation}, ISBN={["978-1-4244-1667-7"]}, ISSN={["0275-9306"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-52349083343&partnerID=MN8TOARS}, DOI={10.1109/pesc.2008.4592275}, abstractNote={The STATCOM based on voltage source converter is used for voltage regulation in transmission and distribution systems. In this paper, the integration and control of energy storage systems such as supercapacitor into a distribution system STATCOM (D-STATCOM) with voltage controller is developed to enhance power quality and improve distribution system reliability. This paper develops the control concepts to charge/discharge the supercapacitor by the D-STATCOM, and validates the performance for an integrated D-STATCOM/supercapacitor system for improving distribution system performance. The potential performance improvements are verified by simulation results for rapidly varying arc-furnace loads for voltage flicker mitigation, by supplying fluctuating real power by the D-STATCOM/supercapacitor system.}, journal={2008 IEEE POWER ELECTRONICS SPECIALISTS CONFERENCE, VOLS 1-10}, author={Parkhideh, Babak and Bhattacharya, Subhashish and Han, Chong}, year={2008}, pages={2242-+} }
 @inproceedings{parkhideh_bhattacharya_mazumdar_koellner_2008, title={Modeling and control of large shovel converter systems integrated with supercapacitor}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-57949086822&partnerID=MN8TOARS}, DOI={10.1109/08IAS.2008.157}, abstractNote={In this paper, detailed modeling and control of the active front end (AFE) of AC drive mining applications specifically the shovel systems are presented. Through a nonlinear transformation and power balance fact, a linear model of the converter is developed which makes the controller independent of the operating points. Due to the low switching frequency operation of the shovel converter systems and issues regarding the rating and thermal management of the system, deploying DC chopper and crowbar circuits as a protective measure is unavoidable. As an alternative, supercapacitor is proposed not only to improve the controller performance but also to recover the regenerative energy instead of dissipating into the chopper circuits.}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Parkhideh, B. and Bhattacharya, S. and Mazumdar, J. and Koellner, W.}, year={2008} }
 @inproceedings{zhao_bhattacharya_huang_2008, title={Operation of series and shunt converters with 48-pulse series connected three-level NPC converter for UPFC}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-63149095639&partnerID=MN8TOARS}, DOI={10.1109/IECON.2008.4758488}, abstractNote={The 48-pulse series connected 3-level neutral point clamped (NPC) converter approach has been used in unified power flow controller (UPFC) application due to its near sinusoidal voltage quality. This paper investigates the control and operation of series and shunt converters with 48-pulse voltage source converters (VSC) for UPFC application. A novel controller for series converter is designed based on the ldquoangle controlldquo of the 48-pulse voltage source converter. The complete simulation model of shunt and series converters for UPFC application is implemented in Matlab/Simulink. The practical real and reactive power operation boundary of UPFC in a 3-bus power system is specifically investigated. The performance of UPFC connected to the 500-kV grid with the proposed controller is evaluated. The simulation results validate the proposed control scheme under both steady state and dynamic operating conditions.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Zhao, T. and Bhattacharya, S. and Huang, A.Q.}, year={2008}, pages={3296–3301} }
 @inproceedings{ramamurthy_bhattacharya_2008, title={Optimized digital maximum power point tracker implementation for satellites}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-57949092729&partnerID=MN8TOARS}, DOI={10.1109/INTLEC.2008.4664126}, abstractNote={Maximum Power Point Tracking MPPT for solar panels is critical for space applications where power saving gets the first priority with the availability of limited resources. Of the available methods for MPPT, the Perturb and Observe (P&O) method is accurate and simple to implement. In the MPPT design choosing the sampling time and duty cycle step size is important which determines its predictable operation during rapidly varying irradiance conditions. The paper talks about the state of the art design of MPPT converters with a digital closed loop control. A modular software programming algorithm was used which supports a ldquoPlug and Playrdquo feature. The detailed implementation of a MPPT converter for 10W solar panel using Texas Instruments TMS320F2808 Digital Signal Controller is shown in this paper.}, booktitle={INTELEC, International Telecommunications Energy Conference (Proceedings)}, author={Ramamurthy, A. and Bhattacharya, S.}, year={2008} }
 @article{chakraborty_dalapati_bhattacharya_2009, title={Performance Evaluation of Controlled-Capacitor-Charging-Type Inverters}, volume={56}, ISSN={["0278-0046"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85008048049&partnerID=MN8TOARS}, DOI={10.1109/tie.2008.2008765}, abstractNote={This paper presents the performance of capacitor-charging-type inverters. Both single- and three-phase inverters are considered. A simple technique to design the L -C elements of such an inverter is introduced. The switching devices are operated in the discontinuous conduction mode to reduce the size of the inductor and also for better dynamic performance. The inverter is simulated in PSPICE. An experimental prototype is produced to verify the results from simulation. Experimentations have been conducted for single-phase and three-phase systems. The inverter is found to operate satisfactorily for various types of load including unbalanced load.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Chakraborty, Chandan and Dalapati, Suvarun and Bhattacharya, Subhashish}, year={2009}, month={Jan}, pages={12–19} }
 @inproceedings{li_bhattacharya_huang_2008, title={Performance comparison of a new current regulator for 3-level NPC inverter for sinusoidal and non-sinusoidal current tracking applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-63149098424&partnerID=MN8TOARS}, DOI={10.1109/IECON.2008.4758069}, abstractNote={In this paper, a new current regulator is applied for a 3-level NPC inverter to achieve both current regulation and neutral-point voltage balance. The performance of the proposed current regulator is validated for both sinusoidal current tracking, such as for a 3-level NPC inverter based motor drive application, and also for non-sinusoidal current tracking, such as for active filter application. Performance comparison and current regulator design considerations are addressed for sinusoidal and non-sinusoidal current tracking applications. Detailed simulation results are presented for performance validation of the new current regulator for both cases and the RMS current error is used as a performance index for comparison.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Li, J. and Bhattacharya, S. and Huang, A.}, year={2008}, pages={879–884} }
 @inproceedings{performance improved during system fault of angle controlled statcom by current control_2008, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-52349093106&partnerID=MN8TOARS}, DOI={10.1109/PES.2008.4596928}, abstractNote={Voltage source converter (VSC) based STATCOM (synchronous static compensator) is used for voltage regulation in transmission and distribution systems. Over-currents and trips of the STATCOM during and after system faults or bus voltage harmonic distortions may occur in STATCOM without PWM control. Selecting proper DC capacitor (Cdc) may keep negative-sequence and harmonic currents low, and as a result, prevent over-currents within the STATCOM. However, the capacitor value depends on the type of voltage distortion. In this paper, we propose and develop a current control strategy for an ldquoangle controlledrdquo STATCOM, to prevent over-currents (and trips) in the VSC during and after system faults and bus voltage distortions. Simulation results are presented for a 48-pulse VSC based plusmn100 MVAR STATCOM connected to a 2-bus power system. Simulation results validate the current control strategy to prevent VSC over-currents and to supply required reactive power under system fault.}, booktitle={IEEE Power and Energy Society 2008 General Meeting: Conversion and Delivery of Electrical Energy in the 21st Century, PES}, year={2008} }
 @inproceedings{statcom control with instantaneous phase-locked loop for performance improvement under single-line to ground fault_2008, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-63149183180&partnerID=MN8TOARS}, DOI={10.1109/IECON.2008.4758085}, abstractNote={The STATCOM (Synchronous Static Compensator) based on VSC (Voltage Source Converter) is used for voltage regulation in transmission and distribution systems. The STATCOM can rapidly generate or absorb dynamic reactive power during system faults for voltage regulation. Strict requirements of STATCOM loss and total system loss penalty preclude the use of PWM (Pulse-Width Modulation) for STATCOM applications. The commonly- implemented PLL (Phase-locked Loop) in the system, which is based on positive-sequence bus voltage, can not response to dynamical changing of negative-sequence bus voltage due to system faults. These constraints result in over-currents and trips of the STATCOM during system faults. In this paper, we propose and develop an ldquoInstantaneous PLLrdquo to prevent over-currents (and trips) in the VSC during single-line to ground system faults, and to ensure that the STATCOM supplies required reactive power.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, year={2008}, pages={971–976} }
 @article{han_huang_baran_bhattacharya_litzenberger_anderson_johnson_edris_2008, title={STATCOM impact study on the integration of a large wind farm into a weak loop power system}, volume={23}, ISSN={["1558-0059"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-40849120152&partnerID=MN8TOARS}, DOI={10.1109/TEC.2006.888031}, abstractNote={Recently, renewable wind energy is enjoying a rapid growth globally to become an important green electricity source to replace polluting and exhausting fossil fuel. However, with wind being an uncontrollable resource and the nature of distributed wind induction generators, integrating a large-scale wind-farm into a power system poses challenges, particularly in a weak power system. In the paper, the impact of STATCOM to facilitate the integration of a large wind farm into a weak power system is studied. First, an actual weak power system with two nearby large wind farms is introduced. Based on the field SCADA data analysis, the power quality issues are highlighted and a centralized STATCOM is proposed to solve them, particularly the short-term (seconds to minutes) voltage fluctuations. Second, a model of the system, wind farm and STATCOM for steady-state and dynamic impact study is presented, and the model is validated by comparing with the actual field data. Using simulated PV and QV curves, voltage control and stability issues are analyzed, and the size and location of STATCOM are assessed. Finally, a STATCOM control strategy for voltage fluctuation suppression is presented and dynamic simulations verify the performance of proposed STATCOM and its control strategy}, number={1}, journal={IEEE TRANSACTIONS ON ENERGY CONVERSION}, author={Han, Chong and Huang, Alex Q. and Baran, Mesut E. and Bhattacharya, Subliashish and Litzenberger, Wayne and Anderson, Loren and Johnson, Anders L. and Edris, Abdel-Aty}, year={2008}, month={Mar}, pages={226–233} }
 @inproceedings{baran_teleke_huang_bhattacharya_anderson_atcitty_2008, title={STATCOM with energy storage for smoothing intermittent wind farm power}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-52349104245&partnerID=MN8TOARS}, DOI={10.1109/PES.2008.4596546}, abstractNote={In this paper, STATCOM with battery energy storage system (BESS) is proposed for smoothing intermittent power output of a large wind farm. The main advantage of the system is that it can inject both real power (by charging/discharging the BESS) and the reactive power to the system. Simulations based on an actual wind farm data indicate that indeed with the proposed control strategy the power output of the wind farm can be smoothed to facilitate 1/2 h dispatching of the wind farm. Also, the reactive power compensation provided by the STATCOM helps to smooth out the fast voltage variations at the interconnecting bus.}, booktitle={IEEE Power and Energy Society 2008 General Meeting: Conversion and Delivery of Electrical Energy in the 21st Century, PES}, author={Baran, M.E. and Teleke, S. and Huang, A. and Bhattacharya, S. and Anderson, L. and Atcitty, S.}, year={2008} }
 @inproceedings{parkhideh_bhattacharya_mazumdar_koellner_2008, title={Utilization of supplementary energy storage systems in high power mining converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-57949096290&partnerID=MN8TOARS}, DOI={10.1109/08IAS.2008.340}, abstractNote={This paper proposes the utilization of ultracapacitor as additional energy storage device in high power AC mining converters. A critical requirement for these converters is to be able to maintain a robust DC link under all operating conditions. However, due to lower switching frequencies of the IGBT devices, the bandwidth of the controllers is limited. As a result, during regenerative periods, the DC link voltage may have a tendency to increase. Protective devices like choppers and crowbars are added to the system. Integration of the ultracapacitor system to the converter can aid the recovery and storage of the regenerative energy and reutilize that energy for meeting the systems power demand. This will improve the overall performance of the system and reduce the dependence on the chopper and crowbar circuits. Implementation of this system translates to power quality improvement of the main grid.}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Parkhideh, B. and Bhattacharya, S. and Mazumdar, J. and Koellner, W.}, year={2008} }
 @inproceedings{teleke_bhattacharya_baran_2007, title={A novel PWM voltage source converter for a DC zonal Shipboard Power System}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-49949110057&partnerID=MN8TOARS}, DOI={10.1109/IECON.2007.4460171}, abstractNote={In this paper, mathematical modeling and control of a PWM VSC converter is developed for a DC zonal shipboard power system (SPS) application. After selecting suitable controller parameters, a new PWM strategy is utilized by changing the carrier frequency under non ideal operating conditions. Moreover, the effect of different design parameters such as triangular wave PWM carrier frequency and DC link capacitance are observed and using the simulation results, the DC link capacitance size and PWM carrier wave frequencies are optimized for the SPS application. Non ideal operating conditions such as sudden load change, sudden supply voltage change and unbalanced supply voltage are simulated to verify the VSC performance utilizing this new PWM strategy. From the results, it is observed that the VSC can indeed show a satisfactory performance for this specific application and it can also operate under unity power factor under these non ideal conditions.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Teleke, S. and Bhattacharya, S. and Baran, M.E.}, year={2007}, pages={1536–1541} }
 @inproceedings{huang_bhattacharya_baran_chen_han_2007, title={Active power management of electric power system using emerging power electronics technology}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-42549152727&partnerID=MN8TOARS}, DOI={10.1109/PES.2007.386146}, abstractNote={Operation of today's very large scale and interconnected electric power systems depends critically on the devices that facilitate management of power flow on the grid. These devices can be based on passive components such as capacitor and inductor, or rely on the solid state power electronics technology to achieve much faster control bandwidth. Widely known as FACTS (Flexible AC Transmission system) devices, these power electronics controllers can regulate voltage and improve stability, hence increasing power flow capability, or they can be used to directly control the power flow, or they can be used to separate regional grid from each other to reduce the interactions between these grids. More advanced applications include the incorporation of energy storage to shape the peak power requirement and to smooth the power output of large wind farms. While the benefit of an actively managed power grid is well understood, widespread use of power electronics controllers in electric power grid is still limited. The main reason behind this is the higher cost and perceived lower reliability. In this paper, the authors will discuss emerging power electronics controllers that are under development at Semiconductor Power Electronics Center of NC State University, and explain how these developments will facilitate wider and broader applications.}, booktitle={2007 IEEE Power Engineering Society General Meeting, PES}, author={Huang, A.Q. and Bhattacharya, S. and Baran, M. and Chen, B. and Han, C.}, year={2007} }
 @inproceedings{current control of angle controlled statcom_2007, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-50249158114&partnerID=MN8TOARS}, DOI={10.1109/NAPS.2007.4402329}, abstractNote={Voltage source converter (VSC) based STATCOM (synchronous static compensator) is used for voltage regulation in transmission and distribution systems. Over-currents and trips of the STATCOM during and after system faults or harmonic distortions may occur in STATCOM without PWM control. Selecting proper DC capacitor (Cdc) may keep negative-sequence current and harmonics low, and as a result, prevent over-currents within the STATCOM. However, the capacitor value depends on the type of distortion. In this paper, we propose and develop a current control strategy based on angle control, to prevent over-currents (and trips) in the VSC during and after system faults and harmonic distortions, and to ensure the STATCOM with small Cdc to supply required reactive power. Simulation results are presented for a 48-pulse VSC based plusmn100 MVAR STATCOM connected to a 2-bus power system. Simulation results validate the current control strategy to prevent VSC over-currents and to supply required reactive power under system fault and harmonic distortions.}, booktitle={2007 39th North American Power Symposium, NAPS}, year={2007}, pages={322–328} }
 @inproceedings{magnetic saturation in transformers used for a 48-pulse voltage-source converter based statcom under line to a line system faults_2007, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-48349092461&partnerID=MN8TOARS}, DOI={10.1109/PESC.2007.4342397}, abstractNote={The STATCOM (Synchronous Static Compensator) based on voltage source converter (VSC) is used to supply dynamic VARs required during power system faults for voltage support. However, magnetic saturation of transformers used in VSC topology result in over-current and trips of the STATCOM during system faults, when dynamic VARs and voltage support are required the most. In this paper, we propose and develop an "emergency PWM" strategy to prevent over-currents in VSC and transformer magnetic saturation for line-to-line system faults. A plusmn 100 MVAR STATCOM with a 48-pulse VSC based on 3-level Neutral Point Clamped (NPC) topology and four series connected transformers with realistic saturation (B-H) characteristics are considered. Simulation results are presented for a 48-pulse VSC based plusmn 100 MVAR STATCOM connected to a 2-bus power system to validate the "emergency PWM" strategy to prevent VSC over-current and transformer saturation and supply reactive power under line-to-line system faults. A practical issue of impact of slightly different saturation (B-H) characteristics of the four series transformers, on VSC performance is shown by simulation results for line-to-line fault.}, booktitle={PESC Record - IEEE Annual Power Electronics Specialists Conference}, year={2007}, pages={2450–2456} }
 @inproceedings{hon_cheng_bhattacharya_lin_2007, title={Modeling and control of three-pliase active front-end converters}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-49949085107&partnerID=MN8TOARS}, DOI={10.1109/IECON.2007.4460280}, abstractNote={Insulated Gate Bipolar Transistor based active front-end converters are widely utilized by industries thanks to the advantages of bi-directional power flow, unity power factor, low harmonic distortion of the line current, and smaller filter size. In this paper, the model and control of the active front- end converter system are presented and the operation principles are analyzed. Detailed discussions on controller designs aiming at enhancing the disturbance rejection capability and robustness are presented, and the performance is validated by experimental results.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Hon, C.-C. and Cheng, P.-T. and Bhattacharya, S. and Lin, J.}, year={2007}, pages={1449–1454} }
 @inproceedings{baran_teleke_bhattacharya_2007, title={Overcurrent protection in DC zonal shipboard power systems using solid state protection devices}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34548848247&partnerID=MN8TOARS}, DOI={10.1109/ESTS.2007.372089}, abstractNote={In this paper, potential solutions to address the protection challenges in DC Shipboard Power Systems (SPSs) have been investigated. Two different options have been considered. The first option involves the use of Solid-State Circuit Breakers (SSCBs) for fault current limiting and interruption. Simulations on a prototype DC SPS have been performed to assess the performance of a SSCB. It is shown that the SSCB can interrupt the fault current very fast, within 20 milliseconds. The second option considered involves the use of Voltage Source Converter (VSC) themselves to act like crowbars. The simulations on the prototype system have been performed to assess the feasibility and effectiveness of this approach. It is shown that this is an effective method provided that VSC switches are properly chosen for it.}, booktitle={IEEE Electric Ship Technologies Symposium, ESTS 2007}, author={Baran, M.E. and Teleke, S. and Bhattacharya, S.}, year={2007}, pages={221–224} }
 @inproceedings{statcom control and operation with series connected transformer based 48-pulse vsc_2007, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-49949112136&partnerID=MN8TOARS}, DOI={10.1109/IECON.2007.4460359}, abstractNote={Static synchronous compensator (STATCOM) is a static compensator used to regulate voltage by reactive power injection, and to improve dynamic stability of power system. In this paper, the STATCOM control and operation for a 48-pulse VSC topology implemented with series connected transformers is reported. Two different control modes - voltage control and VAR control - for the STATCOM are investigated for a single STATCOM and dual STATCOM connected to a transmission bus. The two +100 MVAR (STATCOM) based on a full model comprising 48-pulse Gate Turn-off (GTO) thyristor based VSC is modeled. The control scheme for the STATCOM is fully validated by detailed simulations for a 2-bus power system. The VSC topology issues on the STATCOM control and performance are presented}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, year={2007}, pages={1714–1719} }
 @inproceedings{han_huang_baran_bhattacharya_litzenberger_anderson_johnson_edris_2007, title={STATCOM impact study on the integration of a large wind farm into a weak loop power system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-42549122030&partnerID=MN8TOARS}, DOI={10.1109/PES.2007.385765}, abstractNote={Recently, renewable wind energy is enjoying a rapid growth globally to become an important green electricity source to replace polluting and exhausting fossil fuel. However, with wind being an uncontrollable resource and the nature of distributed wind induction generators, integrating a large-scale wind-farm into a power system poses challenges, particularly in a weak power system. In the paper, the impact of static synchronous compensator (STATCOM) to facilitate the integration of a large wind farm (WF) into a weak power system is studied. First, an actual weak power system with two nearby large WFs is introduced. Based on the field SCADA data analysis, the power quality issues are highlighted and a centralized STATCOM is proposed to solve them, particularly the short-term (seconds to minutes) voltage fluctuations. Second, a model of the system, WF, and STATCOM for steady state and dynamic impact study is presented, and the model is validated by comparing with the actual field data. Using simulated PV and QV curves, voltage control and stability issues are analyzed, and the size and location of STATCOM are assessed. Finally, a STATCOM control strategy for voltage fluctuation suppression is presented and dynamic simulations verify the performance of proposed STATCOM and its control strategy.}, booktitle={2007 IEEE Power Engineering Society General Meeting, PES}, author={Han, C. and Huang, A. and Baran, M. and Bhattacharya, S. and Litzenberger, W. and Anderson, L. and Johnson, A. and Edris, A.-A.}, year={2007} }
 @inproceedings{statcom operation strategy under power system faults_2007, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-42549150053&partnerID=MN8TOARS}, DOI={10.1109/PES.2007.386184}, abstractNote={The STATCOM (synchronous static compensator) operation can be adversely affected due to voltage source converter (VSC) over-currents and trips, during power system faults when its dynamic VAR support functionality is most required strict requirements of STATCOM losses and total system loss penalty preclude the use of PWM (pulse-width modulation) for VSC based STATCOM applications. This constraint of implementing VSC without PWM functionality, results in over- currents and trips of the STATCOM during and after system faults. In this paper, we propose an "emergency PWM" strategy to prevent over-currents (and trips) in the VSC during and after system faults, with slightly different B-H characteristics (due to manufacturing tolerances) for series connected transformers. Simulation results are presented for a 48-pulse VSC based plusmn100 MVAr STATCOM connected to a 2-bus power system. Simulation results validate the "emergency PWM" strategy to prevent VSC over-currents and to supply reactive power under all power system faults - single-line to ground, line-line and three-phase system faults.}, booktitle={2007 IEEE Power Engineering Society General Meeting, PES}, year={2007} }
 @inproceedings{statcom operation strategy with saturable transformer under three-phase power system faults_2007, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-49949091002&partnerID=MN8TOARS}, DOI={10.1109/IECON.2007.4460311}, abstractNote={The STATCOM (synchronous static compensator) based on voltage source converter (VSC) is used for voltage regulation in transmission and distribution systems. The STATCOM can rapidly supply dynamic VARs required during system faults for voltage support. The "emergency PWM" strategy developed in this paper can prevent over- current and transformer saturation in the VSC during and after three-phase power system faults, and also meet the strict requirements of STATCOM losses and total system loss penalty. Simulation results are presented for a 48-pulse VSC based plusmn100 MVAR STATCOM connected to a 2-bus power system to validate the "emergency PWM" strategy to prevent VSC over-current and transformer saturation and to supply required reactive power under a three-phase system faults. The proposed "emergency PWM" strategy is explained in terms of positive and negative sequence voltage for the system bus and STATCOM voltage.}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, year={2007}, pages={1720–1725} }
 @inproceedings{statcom operation under single line-ground system faults with magnetic saturation in series connected transformers based 48-pulse voltage-source converter_2007, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-51049083112&partnerID=MN8TOARS}, DOI={10.1109/EPE.2007.4417687}, abstractNote={In this paper, we investigate an "emergency PWM" method to prevent over-currents in VSC based STATCOM and control transformer magnetic saturation under single line-ground (SLG) power system faults. The 100 MVA 48-pulse VSC topology is based on four series connected transformers on the primary side and each transformer secondary is connected to a 3 Phi, 3-level Neutral Point Connected (NPC) VSC, with a common dc bus. A practical issue of impact of slightly different saturation (B-H) characteristics of series connected transformers, on VSC performance is investigated for SLG faults in the power system. The detailed simulation results for a 48-pulse GTO thyristor based VSC +100 MVA STATCOM connected to a 2-bus power system under SLG system faults validate that the proposed "emergency PWM" enables STATCOM operation under transformer saturation without over-currents in the GTO devices. The proposed "emergency PWM" strategy prevents STATCOM tripping under SLG power system faults.}, booktitle={2007 European Conference on Power Electronics and Applications, EPE}, year={2007} }
 @inproceedings{statcom operation with saturable transformer under single line to ground power system faults_2007, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34748857348&partnerID=MN8TOARS}, DOI={10.1109/PCCON.2007.373085}, abstractNote={The STATCOM (synchronous static compensator) based on voltage source converter (VSC) is used for voltage regulation in transmission and distribution systems. The STATCOM can rapidly supply dynamic VARs required during system faults for voltage support. The "emergency PWM" strategy developed in this paper can prevent over-current and transformer saturation in the VSC during and after single line to ground system faults, and also meet the strict requirements of STATCOM losses and total system loss penalty. Simulation results are presented for a 48-pulse VSC based plusmn140 MVAR STATCOM connected to a 2-bus power system to validate the "emergency PWM" strategy to prevent VSC over-current and transformer saturation and to supply required reactive power under a single-line to ground (SLG) system faults. The proposed "emergency PWM" strategy is explained in terms of positive and negative sequence voltage for the system bus voltage and STATCOM generated voltage.}, booktitle={Fourth Power Conversion Conference-NAGOYA, PCC-NAGOYA 2007 - Conference Proceedings}, year={2007}, pages={975–982} }
 @inproceedings{a practical operation strategy for statcom under single line to ground faults in the power system_2006, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-81755177819&partnerID=MN8TOARS}, DOI={10.1109/PSCE.2006.296430}, abstractNote={The STATCOM (synchronous static compensator) based on voltage source converter (VSC) is used for voltage regulation in transmission and distribution systems. The STATCOM can rapidly supply dynamic VARs required during system faults for voltage support. Strict requirements of STATCOM losses and total system loss penalty preclude the use of PWM (pulse-width modulation) for VSC based STATCOM applications. This constraint of implementing VSC without PWM functionality, results in over-currents and trips of the STATCOM during and after system faults, when its VAR support functionality is most required. In this paper, we propose and develop an "emergency PWM" strategy to prevent over-currents (and trips) in the VSC during and after single line to ground system faults, and to ensure that the STATCOM supplies required reactive power. The operational results for a 48-pulse VSC based 150 MVAR STATCOM are presented to illustrate the problem during and after a system fault, and motivation for this work. Simulation results are presented for a 48-pulse VSC based 100 MVAR STATCOM connected to a 2-bus power system. Simulation results validate the "emergency PWM" strategy to prevent VSC over-currents and to supply required reactive power under a single line to ground system faults}, booktitle={2006 IEEE PES Power Systems Conference and Exposition, PSCE 2006 - Proceedings}, year={2006}, pages={877–883} }
 @inproceedings{liu_du_huang_bhattacharya_2006, title={An optimal combination modulation strategy for a seven-level cascade multilevel converter based STATCOM}, volume={4}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34948830620&partnerID=MN8TOARS}, DOI={10.1109/IAS.2006.256769}, abstractNote={This paper proposes an optimal modulation strategy for a static synchronous compensation (STATCOM) using a seven-level cascade multilevel converter without any filter. Cascade multilevel converters have been used in STATCOM application due to its ability to reduce harmonics and increase output power by increasing the level of output voltages for a given semiconductor device without device series connection. Challenges in high power application include relatively low switching frequency (few hundred hertz to 1 kHz) limited by the thermal handling capability of semiconductor switch, and the low harmonic requirement specified by IEEE 519 standard. With carrier based PWM, the STATCOM can generate lower current harmonic distortions at the expense of working at higher switching frequency. If step modulation strategy is used, the inverter works with lower switching frequency, but the STATCOM injects higher current harmonic distortions to power system, which generally leads to usage of extra filters. The proposed optimal combination modulation strategy works with low switching frequency and has low current harmonic distortions. The simulation results show that it can satisfy the device thermal requirements and IEEE 519 harmonic requirements simultaneously}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Liu, Y. and Du, Z. and Huang, A.Q. and Bhattacharya, S.}, year={2006}, pages={1732–1737} }
 @inproceedings{tewari_doss_chen_huang_bhattacharya_du_2006, title={Electro-thermal design of a heat pipe based high power voltage source converter using emitter turn-off thyristor}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34948867209&partnerID=MN8TOARS}, DOI={10.1109/IAS.2006.256615}, abstractNote={Flexible AC transmission system (FACTS) applications are gaining more popularity and have been given a great impetus by the development of multilevel converters for high power applications. In this paper, a high power modular voltage source converter (VSC) is developed based on the newly developed emitter turn-off thyristor (ETO). In order to achieve this modular functionality, heat pipes are used as the cooling system, replacing the traditional water based cooling method. Through the use of non-isolated heat pipes, we can avoid the electrical isolation issue of cooling system in high voltage FACTS application. The heat pipe also helps to increase the VSCs power density and reliability by reducing the amount of pipes used and reduction of components counts. The hardware configuration, thermal calculation as well as component selection and design are presented in this paper}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Tewari, K. and Doss, S.R. and Chen, B. and Huang, A.Q. and Bhattacharya, S. and Du, Z.}, year={2006}, pages={785–790} }
 @inproceedings{huang_chen_han_du_bhattacharya_baran_edris_ingram_atcitty_2006, title={Emitter turn-off (ETO) thyristor: An emerging power semiconductor switch with lower cost, improved reliability and scalability of facts controllers}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84876760579&partnerID=MN8TOARS}, booktitle={41st International Conference on Large High Voltage Electric Systems 2006, CIGRE 2006}, author={Huang, A.Q. and Chen, B. and Han, C. and Du, Z. and Bhattacharya, S. and Baran, M. and Edris, A.-A. and Ingram, M. and Atcitty, S.}, year={2006} }
 @inproceedings{du_chen_han_yang_song_bhattacharya_huang_2007, title={STATCOM ETO failure analysis}, volume={3}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-45149086060&partnerID=MN8TOARS}, DOI={10.1109/IPEMC.2006.297316}, booktitle={Conference Proceedings - IPEMC 2006: CES/IEEE 5th International Power Electronics and Motion Control Conference}, author={Du, Z. and Chen, B. and Han, C. and Yang, Z. and Song, W. and Bhattacharya, S. and Huang, A.Q.}, year={2007}, pages={1455–1458} }
 @inproceedings{han_huang_baran_bhattacharya_litzenberger_anderson_johnson_edris_2006, title={STATCOM impact study on the integration of a large wind farm into a weak loop power system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70049103818&partnerID=MN8TOARS}, DOI={10.1109/PSCE.2006.296488}, abstractNote={Summary form only given. Recently, renewable wind energy is enjoying a rapid growth globally to become an important green electricity source to replace polluting and exhausting fossil fuel. However, with wind being an uncontrollable resource and the nature of distributed wind induction generators, integrating a large-scale wind-farm into a power system poses challenges, particularly in a weak power system. In the paper, the impact of STATCOM to facilitate the integration of a large wind farm into a weak power system is studied. First, an actual weak power system with two nearby large wind farms is introduced. Based on the field SCADA data analysis, the power quality issues are highlighted and a centralized STATCOM is proposed to solve them, particularly the short-term (seconds to minutes) voltage fluctuations. Second, a model of the system, wind farm and STATCOM for steady-state and dynamic impact study is presented, and the model is validated by comparing with the actual field data. Using simulated PV and QV curves, voltage control and stability issues are analyzed, and the size and location of STATCOM are assessed. Finally, a STATCOM control strategy for voltage fluctuation suppression is presented and dynamic simulations verify the performance of proposed STATCOM and its control strategy.}, booktitle={2006 IEEE PES Power Systems Conference and Exposition, PSCE 2006 - Proceedings}, author={Han, C. and Huang, A.Q. and Baran, M. and Bhattacharya, S. and Litzenberger, W. and Anderson, L. and Johnson, A. and Edris, A.-A.}, year={2006}, pages={1266–1272} }
 @inproceedings{bhattacharya_2005, title={Series connected IGCT based high power three-level neutral point clamped voltage source inverter pole for FACTS applications}, volume={2005}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33847744335&partnerID=MN8TOARS}, DOI={10.1109/PESC.2005.1581955}, abstractNote={This paper reports requirements, issues and design considerations for high power three-level neutral point clamped (NPC) inverter pole. Dynamic voltage sharing issues, viability and advantages of series connected 4.5 kV, 4 kA IGCT for high power 12 MVA three-level NPC inverter pole are investigated. IGCT turn-off tests at high DC voltage and rated current are used for snubber design and inverter pole clamp design, and to verify simulation results. Experimental results are presented for a two 12 MVA three-level NPC inverter poles operated as H-bridge with three series connected 4.5 kV, 4 kA IGCT per switch}, booktitle={PESC Record - IEEE Annual Power Electronics Specialists Conference}, author={Bhattacharya, S.}, year={2005}, pages={2315–2321} }
 @inproceedings{dalapati_chakraborty_bhattacharya_2006, title={Single phase, full bridge, Controlled Capacitor Charging (CCC) type inverter}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-49249126128&partnerID=MN8TOARS}, DOI={10.1109/ICIT.2006.372277}, abstractNote={Controlled capacitor charging (CCC) is a new technique to synthesize sinusoidal voltage at the output from the unregulated DC at the input. The method is based on controlled charging/discharging of a capacitor to realize the desired voltage waveform. A capacitor (C) that is connected across the load is charged/discharged through an inductor (L) by applying high frequency pulses. Applied pulses could be of either positive or negative polarity depending on the error signal in the controller. The controller senses the output-voltage and the current through the inductor (L) to maintain Zero Current Switching (ZCS) at every turn-on, while keeping the output-voltage close to the reference waveform by a hysteresis algorithm. This paper presents the performance of the single-phase, full-bridge CCC Inverter. A simple procedure to design such inverter is also discussed. The proposed controller is simulated in PSPICE. Supporting results from experimental prototype confirm the usefulness of the proposed Inverter.}, booktitle={Proceedings of the IEEE International Conference on Industrial Technology}, author={Dalapati, S. and Chakraborty, C. and Bhattacharya, S.}, year={2006}, pages={265–270} }
 @inproceedings{tewari_chen_li_huang_bhattacharya_2005, title={Investigation of high temperature operation of the emitter turn-off thyristor}, volume={2005}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33749673997&partnerID=MN8TOARS}, DOI={10.1109/IECON.2005.1568978}, abstractNote={This paper investigates the emitter turn-off thyristor's (ETO's) high temperature operation from thermal stability point of view. The objective is to identify the electrical and thermal limitations to the high temperature application of the ETO. The loss characteristics of the ETO, including switching loss, conduction loss, and leakage loss are studied experimentally and analytically, at high junction temperature. A closed loop thermal system and stability criterion is developed and analyzed. At low junction temperature, the switching loss determines the thermal stability. At high junction temperature, the high leakage loss leads to thermal instability. From the developed thermal system, the maximum operating junction temperature for the ETO has been derived, under certain operating conditions. Steady state operating junction temperature of 160 Degrees Celsius is obtained for the ETO}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Tewari, K. and Chen, B. and Li, D. and Huang, A.Q. and Bhattacharya, S.}, year={2005}, pages={633–638} }
 @inproceedings{shperling_sun_bhattacharya_2005, title={Power flow control on 345 kV lines with the 200 MVA convertible static compensator}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-51549116892&partnerID=MN8TOARS}, DOI={10.1109/PTC.2005.4524832}, abstractNote={A 200 MVA, 345 kV system control FACTS device, consisting of two 100 MVA converters, two 100 MVA high voltage series transformers inserted in 345 kV transmission lines and a 200 MVA shunt transformer, was tested and utilized on a 345 kV network. This device, namely convertible static compensator (CSC), has four basic configurations: static synchronous compensator (STATCOM), static synchronous series compensator (SSSC), unified power flow controller (UPFC), and interline power flow controller (IPFC). The testing confirmed the device capability to operate in multiple configurations and its ability to control and regulate the power flows on two 345 kV transmission lines. The CSC test results confirmed its capability to regulate the substation bus voltage and line power flows under steady-state and dynamic conditions. The CSC flexibility allows to utilize it during normal as well as various emergency system conditions.}, booktitle={2005 IEEE Russia Power Tech, PowerTech}, author={Shperling, B. and Sun, J. and Bhattacharya, S.}, year={2005} }
 @inproceedings{chakraborty_dalapati_bhattacharya_2005, title={Variable frequency variable duty cycle operation of the Controlled Capacitor Charging (CCC) type inverter}, volume={2005}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33749681559&partnerID=MN8TOARS}, DOI={10.1109/IECON.2005.1568972}, abstractNote={The controlled capacitor charging (CCC) type inverter uses a simple L-C network, where the capacitor (C) that is connected across the load is charged through an inductor (L) connected in series with the load. The charging in such an inverter has to take place in a controlled manner to produce a desired sinusoidal waveform at the output. This paper presents a variable frequency variable duty cycle based charging technique to keep the output voltage within a hysteresis band, while achieving zero-current switching for every pulse at turn-on. The output voltage across the capacitor and the current through the inductor are fed back to the control circuit. An appropriate logic in the controller determines the width of each individual pulse, as well as the frequency of pulses. Extensive simulations in PSPICE have been carried out. A prototype inverter has been fabricated in the laboratory. Excellent correlation between the simulation and experimental results validated the proposed control technique}, booktitle={IECON Proceedings (Industrial Electronics Conference)}, author={Chakraborty, C. and Dalapati, S. and Bhattacharya, S.}, year={2005}, pages={598–603} }
 @inproceedings{sun_hopkins_shperling_fardanesh_graham_parisi_macdonald_bhattacharya_berkowitz_edris_2004, title={Operating characteristics of the convertible static compensator on the 345 kV network}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-20144388605&partnerID=MN8TOARS}, booktitle={2004 IEEE PES Power Systems Conference and Exposition}, author={Sun, J. and Hopkins, L. and Shperling, B. and Fardanesh, B. and Graham, M.R. and Parisi, M. and MacDonald, S. and Bhattacharya, S. and Berkowitz, S. and Edris, A.}, year={2004}, pages={732–737} }
 @article{cheng_huang_pan_bhattacharya_2003, title={Design and implementation of a series voltage sag compensator under practical utility conditions}, volume={39}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0038487357&partnerID=MN8TOARS}, DOI={10.1109/TIA.2003.811780}, abstractNote={Voltage sags have become one of the most important power quality concerns in recent years. According to survey results across the US, voltage sags and short-duration power outages account for 92% of power quality problems encountered by industrial customers. Voltage sags often cause undervoltage faults in various sensitive loads and subsequently interrupt the manufacturing processes. Such interruptions often inflict severe losses for industries. In Taiwan, ROC, most high-tech manufacturers use uninterruptible power supplies to avoid interruptions, but the cost effectiveness of such an approach remains unclear. As the utility grid continues to improve the reliability of electric power, the inverter-based voltage sag compensator has become a viable solution to prevent production interruptions resulting from voltage sags. The existing sag compensation systems accomplish a fast response within a small fraction of a fundamental cycle by tracking the line voltages closely, and switch on the compensator whenever the voltage waveforms deviate from the normal values. However, the utility voltages often contain transient spikes with amplitudes up to 200% resulting from switching of power-factor-correction capacitors, circuit breakers switchings, lightning strikes, and so on. Such transient disturbances may trigger the sag compensator into operation if its controller is very sensitive. The switching frequency of the sag compensator inverter is inadequate to compensate the narrow pulses of voltage spikes. Furthermore, the power semiconductor devices (like insulated gate bipolar transistors) of the inverter may also be damaged due to overvoltage by the surges. In this paper, a brief overview of power quality issues of a high-tech industry park in Taiwan is provided to validate the need for ride-through technologies. A synchronous-reference-frame-based controller for the inverter-based voltage sag compensator is also presented. A sag detection mechanism is included in the controller for correct and prompt identification of voltage sags. Disturbances like voltage spikes are attenuated to avoid any false triggering of the compensator. The overall system responds to voltage sags and restores the voltage back to balanced 1.0 pu for critical loads within one-eighth to one-fourth of a cycle, which meet the requirement of industry standards like the SEMI-F47 standard. Simulation and laboratory test results are presented to verify the functionality of the proposed system.}, number={3}, journal={IEEE Transactions on Industry Applications}, author={Cheng, P.-T. and Huang, C.-C. and Pan, C.-C. and Bhattacharya, S.}, year={2003}, pages={844–853} }
 @inproceedings{bhattacharya_divan_1995, title={Design and implementation of a hybrid series active filter system}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937436299&partnerID=MN8TOARS}, DOI={10.1109/PESC.1995.474811}, abstractNote={A hybrid series active filter system has been designed, built and installed at Beverly Pump Station in New England Electric Power Company utility for 765 kVA, 480 V adjustable speed drive load to comply with IEEE 519 recommended harmonic standards. The series active filter has a small rating-35 kVA which is 4% of the load kVA-and is controlled by a synchronous reference frame (SRF) based controller. The hybrid series active filter system is controlled to act as a "harmonic isolator" between the supply and load. This paper discusses the SRF controller implementation issues, design considerations of the series coupling transformer and protection issues of the small rating series active filter inverter. Operation of the series active filter under off-tuned passive filter conditions is investigated. The effectiveness of the series active filter to provide harmonic damping and the use of simpler and low cost passive filter structures such as power factor correction capacitors is demonstrated by laboratory experimental results. Field installation results demonstrate the practical and economic viability of hybrid series active filter systems for harmonic compensation of large nonlinear loads to comply with IEEE 519 recommended harmonic standards.<<ETX>>}, booktitle={PESC Record - IEEE Annual Power Electronics Specialists Conference}, author={Bhattacharya, S. and Divan, D.}, year={1995}, pages={189–195} }
 @inproceedings{cheng_huang_pan_bhattacharya_2002, title={Design and implementation of a series voltage sag compensator under practical utility conditions}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036078253&partnerID=MN8TOARS}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Cheng, P.-T. and Huang, C.-C. and Pan, C.-C. and Bhattacharya, S.}, year={2002}, pages={1061–1067} }
 @inproceedings{bhattacharya_resta_divan_novotny_lipo_1996, title={Experimental comparison of motor bearing currents with PWM hard and soft switched voltage source inverters}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029747469&partnerID=MN8TOARS}, DOI={10.1109/PESC.1996.548784}, abstractNote={This paper compares motor bearing currents due to PWM hard switched and soft switched inverters. The mechanisms for bearing currents are first identified using an approach based on direct excitation of the motor bearing with sinusoidal and square wave signals to characterize the bearings. It is shown that many of the motor models that have been proposed in the literature to explain bearing currents do not adequately explain the observed higher frequency effects. The paper also outlines some of the important phenomena which need to be considered for a more complete description of bearing currents. Finally, the paper compares the performance of hard and soft switched inverters with respect to bearing currents. Experimental results are provided for PWM hard switched and soft switched IGBT inverters which have exactly same power circuit layout, identical chassis and rating of 70 kW.}, booktitle={PESC Record - IEEE Annual Power Electronics Specialists Conference}, author={Bhattacharya, S. and Resta, L. and Divan, D.M. and Novotny, D.W. and Lipo, T.A.}, year={1996}, pages={1528–1534} }
 @article{cheng_bhattacharya_divan_2000, title={Operations of the dominant harmonic active filter (DHAF) under realistic utility conditions}, volume={4}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034515562&partnerID=MN8TOARS}, DOI={10.1109/28.936394}, abstractNote={This paper presents laboratory test results of the dominant harmonic active filter (DHAF) prototype. The DHAF system achieves harmonic isolation at the dominant harmonics using square-wave active filter inverters. The key advantages of the DHAF system are the low rating and low bandwidth requirements of the active filter inverter. Such characteristics allow cost-effective and viable applications of the DHAF system to mitigate harmonic problems for high-power nonlinear loads (10-100 MW and above). Several practical situations, including source-sink resonance, ambient harmonic interferences, and unbalanced grid voltages are applied to the DHAF prototype to validate its performance. The operation principles of the DHAF system and the synchronous-reference-frame-based controller are discussed to explain how harmonic isolation at the dominant harmonics is accomplished. A design example of the DHAF system for a 20 MVA rectifier load at an industrial site is also given to illustrate its application.}, journal={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Cheng, P.-T. and Bhattacharya, S. and Divan, D.}, year={2000}, pages={2135–2142} }
 @article{cheng_bhattacharya_divan_2000, title={Experimental vérification of dominant harmonic active filter for high-power applications}, volume={36}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0033890406&partnerID=MN8TOARS}, DOI={10.1109/28.833775}, abstractNote={A synchronous-reference-frame (SRF)-based controller for the dominant harmonic active filter (DHAF) system has already been proposed by the authors. The SRF controller is designed to achieve harmonic isolation at the dominant harmonic frequencies (such as at the 5th and/or 7th) between the supply and load. This allows implementation of the DHAF system by square-wave inverters switching at the 5th or 7th harmonic frequency. Compared to conventional active filter systems which require high-switching-frequency pulsewidth modulation inverters, the square-wave-inverter-based DHAF system provides a viable and cost-effective solution to achieve harmonic isolation for high-power nonlinear loads (10 MW and above) or cluster of nonlinear loads, to meet the IEEE 519 recommended harmonic standard. In this paper, a new feedforward command of the SRF controller is proposed which provides better dynamic performance. The improved feedforward command of the SRF controller can suppress any system resonances at the dominant harmonic frequencies and meet IEEE 519 harmonic current limits. Experimental results are presented to validate the effectiveness of the SRF controller and the DHAF system.}, number={2}, journal={IEEE Transactions on Industry Applications}, author={Cheng, P.-T. and Bhattacharya, S. and Divan, D.}, year={2000}, pages={567–577} }
 @article{cheng_bhattacharya_divan_1999, title={Application of dominant harmonic active filter system with 12 pulse nonlinear loads}, volume={14}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0033116513&partnerID=MN8TOARS}, DOI={10.1109/61.754112}, abstractNote={Harmonic filtering is required for 12 pulse rectifier-utility interface to meet IEEE 519 harmonic current limits. Passive filter techniques employ tuned L-C filters at dominant 11th and 13th harmonic frequencies. However, they also require 5th and 7th tuned filters to avoid series and parallel resonance conditions. State of the art active filtering solutions require high bandwidth and relatively large rating PWM inverters for harmonic filtering of 12 pulse rectifier loads. Thus existing passive and active harmonic filtering solutions are not cost-effective for high power 12 pulse rectifier loads. Dominant harmonic active filter (DHAF) based on square-wave inverters is proposed to cost-effectively meet IEEE 519 harmonic current limits for 12 pulse rectifier loads. The proposed DHAF system employs square-wave inverters switching at 5th and 7th harmonic frequencies, which are transformer coupled in series with 11th and 13th passive filters respectively. The square-wave inverters are controlled to provide 'harmonic isolation' between the supply and load at 5th and 7th harmonic frequencies. The square-wave inverters are rated 1%-2% of the load kVA rating. The proposed DHAF system eliminates the need for large kVAR rated and bulky 5th and 7th passive filters, delivers superior harmonic filtering performance, and provides cost-effective harmonic filtering solution. Simulation results are given to validate the 'harmonic isolation' feature at 5th and 7th harmonic frequencies, and also demonstrate harmonic filtering required to meet IEEE 519 harmonic current limits.}, number={2}, journal={IEEE Transactions on Power Delivery}, author={Cheng, P.-T. and Bhattacharya, S. and Divan, D.M.}, year={1999}, pages={642–647} }
 @article{bhattacharya_resta_divan_novotny_1999, title={Experimental comparison of motor bearing currents with PWM hard- and soft-switched voltage-source inverters}, volume={14}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032629348&partnerID=MN8TOARS}, DOI={10.1109/63.761699}, abstractNote={This paper compares motor bearing currents due to pulsewidth modulation (PWM) hard- and soft-switched inverters. The mechanisms for bearing currents are first identified using an approach based on direct small-signal excitation of the motor bearing with sinusoidal and square-wave signals to characterize the bearings. It is shown that many of the motor models that have been proposed in the literature to explain bearing currents do not adequately explain the observed higher frequency effects. The paper also outlines some of the important phenomena which need to be considered for a more complete description of bearing currents. Finally, the paper compares the performance of hard and soft-switched inverters with respect to bearing currents and shaft voltage. Experimental results are provided for PWM hard- and soft-switched insulated gate bipolar transistor (IGBT) inverters which have exactly the same power circuit layout, identical chassis, and rating of 70 kVA.}, number={3}, journal={IEEE Transactions on Power Electronics}, author={Bhattacharya, S. and Resta, L. and Divan, D.M. and Novotny, D.W.}, year={1999}, pages={552–562} }
 @article{cheng_bhattacharya_divan_1999, title={Line harmonics reduction in high-power systems using square-wave inverters-based dominant harmonic active filter}, volume={14}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0033097168&partnerID=MN8TOARS}, DOI={10.1109/63.750179}, abstractNote={This paper presents a dominant harmonic active filter (DHAF) scheme using small-rated square-wave inverters for supply line harmonic current reduction for high-power nonlinear loads in the range of 10 MW and above to meet IEEE 519 harmonic standard. The active filter inverters are connected in series with the fifth and seventh L-C tuned filters, respectively. A synchronous reference frame-based controller which achieves harmonic isolation for the dominant fifth and seventh harmonic load currents in the presence of supply voltage harmonic distortion is presented. Impact of mistuned passive filters on the operation and rating of the square-wave active filter inverters is examined. Simulation results validate the proposed harmonic isolation controller under mistuned fifth and seventh L-C tuned filter conditions and supply voltage harmonic distortion. The proposed scheme is general and applicable for high-power 6- or 12-pulse rectifier loads. The use of small-rated square-wave inverters (approximately 2% of load kilovoltampere rating) increases the cost effectiveness of the DHAF system for high-power applications.}, number={2}, journal={IEEE Transactions on Power Electronics}, author={Cheng, P.-T. and Bhattacharya, S. and Divan, D.D.}, year={1999}, pages={265–272} }
 @article{bhattacharya_frank_divan_banerjee_1998, title={Active filter system implementation}, volume={4}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032166308&partnerID=MN8TOARS}, DOI={10.1109/2943.715508}, abstractNote={Adjustable speed AC drives with low input current THD are becoming increasingly important in industry. This article has detailed the implementation of a parallel active filter, which is integrated within a 450 kW adjustable speed drive to provide an overall system which conforms to IEEE 519, and which provides significant benefits on a system level. The design of the active filter is seen to be driven by overall system specifications which include input current THD, efficiency, displacement power factor, a high level of integration with the load converter, and cost targets. Active filter operation and control has been analyzed at a detailed level, and fundamental issues relating to current regulator topology and operation, limits on compensation capability, DC bus control, switching frequency ripple suppression, etc., have all been addressed, and have all been shown to be very important in terms of helping the system meet its performance objectives. The overall drive system including the active filter, meets IEEE 519 by reducing the supply current THD from 26.8% without the active filter to 4.1% with the active filter operating. This is achieved in presence of supply voltage THD of 2.3% and filter terminal voltage V/sub f/ unbalance of 1.3% and, includes an ASD load induced subharmonic component at 33 Hz. Further, individual harmonic limits are met up to the 35th harmonic.}, number={5}, journal={IEEE Industry Applications Magazine}, author={Bhattacharya, S. and Frank, T.M. and Divan, D.M. and Banerjee, B.}, year={1998}, pages={47–63} }
 @article{cheng_bhattacharya_divan_1998, title={Control of square-wave inverters in high-power hybrid active filter systems}, volume={34}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032071720&partnerID=MN8TOARS}, DOI={10.1109/28.673715}, abstractNote={This paper presents a new control scheme for a hybrid parallel active filter (HPAF) system intended for high-power applications-up to 100 MW nonlinear loads-to meet IEEE 519 recommended harmonic standards. The active filter inverter is realized with small-rated (1%-2% of the load rating) square-wave inverters operating at the dominant harmonic frequencies. The proposed system achieves harmonic isolation at desired dominant harmonic frequencies, such as the fifth and seventh, even in the presence of supply voltage harmonic distortions. A novel method of active filter inverter DC-bus control, as proposed here, achieves power balancing by exchanging energy at the fundamental frequency and at the dominant harmonic frequency (such as the fifth). The proposed square-wave inverter-based HPAF system provides improved filtering characteristics as compared to the conventional passive filter and is expected to be cost effective for high-power nonlinear loads compared to the conventional passive filter or other active filtering solutions. The concept of harmonic isolation at dominant harmonic frequencies by square-wave inverters with the proposed control scheme is validated by simulation results.}, number={3}, journal={IEEE Transactions on Industry Applications}, author={Cheng, P.-T. and Bhattacharya, S. and Divan, D.M.}, year={1998}, pages={458–472} }
 @inproceedings{cheng_bhattacharya_divan_1998, title={Experimental verification of dominant harmonic active filter (D.H.A.F.) for high power applications}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032308520&partnerID=MN8TOARS}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Cheng, Po-Tai and Bhattacharya, Subhashish and Divan, Deepak}, year={1998}, pages={1400–1407} }
 @article{wallace_kutkut_bhattacharya_divan_novotny_1998, title={Inductor design for high-power applications with broad-spectrum excitation}, volume={13}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0031646395&partnerID=MN8TOARS}, DOI={10.1109/63.654976}, abstractNote={The design of high-power inductors for applications with broad current spectrum excitation is a challenging task. The resonant inductor of a resonant DC-link inverter (RDCLI) is one such example. The inductor current consists of a resonant current component, a DC component, which supplies the active power to the load and a modulation component, which depends on the modulation strategy. In addition, the frequency and amplitude of the dominant current components change with operating point. Conventional inductor designs for single-frequency excitation do not perform well in broad-spectrum applications. In order to improve these designs, the impact of broad current spectrums on winding design, core selection, power density, and thermal-handling capability must be investigated. In this paper, alternate inductor topologies, which better address the above issues, are proposed and investigated.}, number={1}, journal={IEEE Transactions on Power Electronics}, author={Wallace, I.T. and Kutkut, N.H. and Bhattacharya, S. and Divan, D.M. and Novotny, D.W.}, year={1998}, pages={202–208} }
 @article{bhattacharya_cheng_divan_1997, title={Hybrid solutions for improving passive filter performance in high power applications}, volume={33}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0031143192&partnerID=MN8TOARS}, DOI={10.1109/28.585864}, abstractNote={This paper presents a new control scheme for a parallel hybrid active filter system intended for harmonic compensation of large nonlinear loads up to 50 MVA, to meet IEEE 519 recommended harmonic standards. The active filter is small rated, 2%-3% of load kilovoltampere rating. The control scheme is based on the concept of synthesizing a dynamically variable inductance, and its usefulness is demonstrated for an active filtering application. A synchronous reference frame (SRF) controller implements the dynamically varying negative or positive inductance by generating active filter inverter voltage commands. This variable inductance controller parallel hybrid active filter system can selectively synthesize multiple "active inductances" at dominant harmonic frequencies without affecting passive filter impedances at all other frequencies. This controller also provides a "current limiting" function to prevent passive filter overloading under ambient harmonic loads and/or supply voltage distortions. Three implementation variations of a parallel hybrid active filter system are presented. This paper also proposes the use of power factor correction capacitors as low cost passive filters for a parallel hybrid active filter system, which are controlled to provide either single or multiple tuned harmonic sinks and to increase cost effectiveness for high power applications. Simulation results validate the proposed variable inductance controller operation for mistuned passive filters.}, number={3}, journal={IEEE Transactions on Industry Applications}, author={Bhattacharya, S. and Cheng, P.-T. and Divan, D.M.}, year={1997}, pages={732–747} }
 @inproceedings{bhattacharya_divan_1996, title={Active filter solutions for utility interface of industrial loads}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029711761&partnerID=MN8TOARS}, booktitle={Proceedings of the IEEE International Conference on Power Electronics, Drives & Energy Systems for Industrial Growth, PEDES}, author={Bhattacharya, Subhashish and Divan, Deepak}, year={1996}, pages={1078–1084} }
 @inproceedings{bhattacharya_cheng_divan_1996, title={Control of square-wave inverters in high power hybrid active filter systems}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0030421802&partnerID=MN8TOARS}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Bhattacharya, Subhashish and Cheng, Po-Tai and Divan, Deepak M.}, year={1996}, pages={1106–1113} }
 @inproceedings{veltman_bhattacharya_divan_1996, title={Flux based and predictive voltage based current regulators for motor drive applications}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029713799&partnerID=MN8TOARS}, booktitle={Proceedings of the IEEE International Conference on Power Electronics, Drives & Energy Systems for Industrial Growth, PEDES}, author={Veltman, Andre and Bhattacharya, Subhashish and Divan, Deepak M.}, year={1996}, pages={229–235} }
 @article{bhattacharya_veltman_divan_1996, title={Flux-based active filter controller}, volume={32}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0030149418&partnerID=MN8TOARS}, DOI={10.1109/28.502159}, abstractNote={This paper presents a synchronous frame flux-based control method for a parallel active filter application. The flux-based controller directly implements the inverter switchings in the synchronous reference frame by a hysteresis rule-based carrier-less pulse-width modulation (PWM) strategy to achieve high current bandwidth. This paper addresses the issues and impact on parallel active filtering requirements for utility interface of commonly used harmonic front-ends. The synchronous frame flux-based controller provides additional insights for harmonic current compensation requirements. Simulation results provide the validation of the flux-based active filter controller to meet IEEE Standard 519 recommended harmonic standards for large rated nonlinear loads under balanced and unbalanced supply conditions.}, number={3}, journal={IEEE Transactions on Industry Applications}, author={Bhattacharya, S. and Veltman, A. and Divan, D.M.}, year={1996}, pages={491–502} }
 @inproceedings{cheng_bhattacharya_divan_1996, title={Hybrid solutions for improving passive filter performance in high power applications}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029753957&partnerID=MN8TOARS}, booktitle={Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC}, author={Cheng, Po-Tai and Bhattacharya, Subhashish and Divan, Deepak M.}, year={1996}, pages={911–917} }
 @inproceedings{cheng_bhattacharya_divan_1996, title={Line harmonics reduction in high power systems using square - wave inverters}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029751677&partnerID=MN8TOARS}, booktitle={PESC Record - IEEE Annual Power Electronics Specialists Conference}, author={Cheng, Po-Tai and Bhattacharya, Subhashish and Divan, Deepak M.}, year={1996}, pages={1135–1141} }
 @inproceedings{bhattacharya_frank_divan_banerjee_1996, title={Parallel active filter system implementation and design issues for utility interface of adjustable speed drive systems}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0030386538&partnerID=MN8TOARS}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Bhattacharya, S. and Frank, T.M. and Divan, D.M. and Banerjee, B.}, year={1996}, pages={1032–1039} }
 @inproceedings{bhattacharya_divan_banerjee_1995, title={Active filter solutions for utility interface}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029546406&partnerID=MN8TOARS}, booktitle={IEEE International Symposium on Industrial Electronics}, author={Bhattacharya, S. and Divan, D.M. and Banerjee, B.}, year={1995}, pages={53–63} }
 @inproceedings{bhattacharya_veltman_divan_lorenz_1995, title={Flux based active filter controller}, volume={3}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029537055&partnerID=MN8TOARS}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Bhattacharya, S. and Veltman, A. and Divan, D.M. and Lorenz, R.D.}, year={1995}, pages={2483–2491} }
 @inproceedings{wallace_kutkut_bhattacharya_divan_novotny_1995, title={Inductor design for high power applications with broad spectrum excitation}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029191176&partnerID=MN8TOARS}, booktitle={PESC Record - IEEE Annual Power Electronics Specialists Conference}, author={Wallace, I.T. and Kutkut, N.H. and Bhattacharya, S. and Divan, D.M. and Novotny, D.W.}, year={1995}, pages={1057–1063} }
 @inproceedings{bhattacharya_holmes_divan_1995, title={Optimizing three phase current regulators for low inductance loads}, volume={3}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029528280&partnerID=MN8TOARS}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Bhattacharya, S. and Holmes, D.G. and Divan, D.M.}, year={1995}, pages={2357–2364} }
 @inproceedings{bhattacharya_divan_1995, title={Synchronous frame based controller implementation for a hybrid series active filter system}, volume={3}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029481792&partnerID=MN8TOARS}, booktitle={Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)}, author={Bhattacharya, Subhashish and Divan, Deepak}, year={1995}, pages={2531–2540} }
 @article{lefebvre_gole_reeve_pilottc_martins_bhattacharya_1995, title={Working Group on Dynamic Performance and Modeling of DC Systems and Power Electronics for Transmission Systems Report on test systems for ac/dc interaction studies}, volume={10}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0029386368&partnerID=MN8TOARS}, DOI={10.1109/61.473347}, abstractNote={This working group report presents DC benchmark models tailored to AC/DC interaction. This is to encourage comparisons of the performance of different control strategies or computational tools related to various AC/DC interaction phenomena and system dynamic performance (electromechanical oscillations, AC/DC recovery problems). >}, number={4}, journal={IEEE Transactions on Power Delivery}, author={Lefebvre, S. and Gole, A.M. and Reeve, J. and Pilottc, L. and Martins, N. and Bhattacharya, S.}, year={1995}, pages={2027–2034} }
 @article{warnock_sun_bhattacharya_1992, title={IIA-3 p<sup>+</sup> Polysilicon Emitters for Sub-0.5 µm High-Performance p-n-p}, volume={39}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0026953989&partnerID=MN8TOARS}, DOI={10.1109/16.163485}, abstractNote={Summary form only given. The authors describe the tradeoffs between E-B (emitter-base) junction depth, base width, and device characteristics for high-performance sub-0.5- mu m p-n-p designs. Near-ideal p-n-p transistors have been fabricated with emitter widths down to 0.25 mu m while maintaining an E-B junction depth close to 60 nm. Further improvements in emitter processing, e.g., poly thickness, interfacial oxygen level, emitter implant, and anneal conditions, will allow thinner base widths to be achieved at these small emitter dimensions for future quarter-micrometer complementary bipolar technologies. >}, number={11}, journal={IEEE Transactions on Electron Devices}, author={Warnock, J. and Sun, J.Y.C. and Bhattacharya, S.}, year={1992}, pages={2637–2638} }