@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} }
 @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} }
 @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{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{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)}, author={Acharya, Sayan and Hazra, S. and Vechalapu, K. and Bhattacharya, S.}, year={2017}, pages={3329–3336} }
 @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{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{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{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_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{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} }
 @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}, number={7}, journal={IEEE Transactions on Power Electronics}, author={Hazra, S. and De, A. K. and Cheng, L. and Palmour, J. and Schupbach, M. and Hull, B. A. and Allen, S. and Bhattacharya, S.}, year={2016}, pages={4742–4754} }
 @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{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{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{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} }
 @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{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{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{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{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{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{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{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}, booktitle={2013 ieee energy conversion congress and exposition (ecce)}, author={Hazra, S. and Madhusoodhanan, S. and Bhattacharya, S. 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} }
 @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{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} }