@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{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{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{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{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{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{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{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} }
 @article{acharya_she_tao_frangieh_todorovic_datta_2019, title={Active Gate Driver for SiC-MOSFET-Based PV Inverter With Enhanced Operating Range}, volume={55}, ISSN={["1939-9367"]}, url={https://doi.org/10.1109/TIA.2018.2878764}, DOI={10.1109/TIA.2018.2878764}, abstractNote={For photo-voltaic (PV) inverter applications, the grid code mandates reactive power support to the grid, and the amount of reactive power injection may be limited by the voltage overshoot during the switching transients. For SiC-MOSFET based PV inverters this problem is more pronounced since the voltage and current gradient during switching transitions are much higher than a Si-based power devices. During a gloomy day when the inverter has to operate at PV panel's open circuit voltage, it becomes harder to push higher currents through the device but also keeping the device within its SOA and low the switching loss at all operating conditions. Slowing down the switching transient could be a remedy but this also increases the converter switching loss. This paper demonstrates an application of dynamic gate resistance modulation technique to keep the SiC-device inside its safe operating area (SOA) while maintaining a low switching loss with minimum voltage and current overshoots. The proposed implementation is verified with hardware test results at high junction temperatures (up to 150°C).}, number={2}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Acharya, Sayan and She, Xu and Tao, Fengfeng and Frangieh, Tony and Todorovic, Maja Harfman and Datta, Rajib}, year={2019}, pages={1677–1689} }
 @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} }
 @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} }
 @article{acharya_she_todorovic_datta_mandrusiak_2019, title={Thermal Performance Evaluation of a 1.7-kV, 450-A SiC-MOSFET Based Modular Three-Phase Power Block With Wide Fundamental Frequency Operations}, volume={55}, ISSN={["1939-9367"]}, url={https://doi.org/10.1109/TIA.2018.2879028}, DOI={10.1109/TIA.2018.2879028}, abstractNote={To accelerate wide industry adoption of Silicon Carbide (SiC) based technology, a three-phase two-level inverter based power block is designed with the latest generation high performance 1.7 kV/450 A SiC-mosfet module from General Electric. The designed power block is expected to replace the currently standardized 1.7 kV/450 A Silicon (Si) insulated gate bipolar transistor (IGBT) based three-phase power block. Power converters face thermal challenges when subjected to very low fundamental frequency operations (below 10 Hz). This is particularly relevant in the wind power applications. At low operating fundamental frequencies, the junction temperature of the power device experiences high peak-to-peak ripple, which degrades the reliability of the power modules significantly. This paper presents the thermal performance of the designed power block and draws comparisons with a similar rated Si-IGBT module based power blocks, especially at low output fundamental frequency operations. Key performance indices, including power rating curves at different switching frequencies and power factors; temperature ripple at different fundamental frequencies, are examined. Simulation and experimental results are provided to validate the claims. The results indicate that the SiC-mosfet module based power block can be a promising replacement for the Si-IGBT based power block especially in applications where wide range of fundamental frequency operations are needed.}, number={2}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Acharya, Sayan and She, Xu and Todorovic, Maja Harfman and Datta, Rajib and Mandrusiak, Gary}, year={2019}, pages={1795–1806} }
 @inproceedings{anurag_acharya_prabowo_gohil_kassa_bhattacharya_2018, title={An accurate calorimetric 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={Thirty-third annual ieee applied power electronics conference and exposition (apec 2018)}, author={Anurag, A. and Acharya, Sayan and Prabowo, Y. and Gohil, G. and Kassa, H. and Bhattacharya, S.}, year={2018}, pages={1695–1700} }
 @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={Thirty-third annual ieee applied power electronics conference and exposition (apec 2018)}, author={Chattopadhyay, R. and Gohil, G. and Acharya, Sayan and Nair, V. and Bhattacharya, S.}, year={2018}, pages={1807–1814} }
 @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)}, 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} }
 @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}, author={Chavan, G. and Acharya, Sayan and Bhattacharya, S. and Inam, H.}, year={2017}, pages={1–7} }
 @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'17 ecce europe)}, author={Pinares, G. and Bongiorno, M. and Acharya, Sayan and Bhattacharya, S.}, year={2017}, pages={P1–P10} }
 @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{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}, author={Chattopadhyay, R. and Acharya, Sayan and Gohil, G. and Bhattacharya, S.}, year={2017}, pages={1–8} }
 @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={2016 ieee power and energy society general meeting (pesgm)}, author={Chavan, G. and Acharya, Sayan and Bhattacharya, S. and Das, D. and Inam, H.}, year={2016} }
 @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)}, author={Acharya, Sayan and Vechalapu, K. and Bhattacharya, S. and Yousefpoor, N.}, year={2015}, pages={3184–3191} }
 @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)}, author={Azidehak, A. and Chattopadhyay, R. and Acharya, Sayan and Tripathi, A. K. and Kashani, M. G. and Chavan, G. and Bhattacharya, S.}, year={2015}, pages={3400–3406} }
 @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)}, author={Acharya, Sayan and Bhattacharya, S. and Yousefpoor, N.}, year={2015}, pages={2287–2293} }
 @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)}, author={Acharya, Sayan and Azidehak, A. and Vechalapu, K. and Kashani, M. and Chavan, G. and Bhattacharya, S. and Yousefpoor, N.}, year={2015}, pages={5386–5393} }