@inproceedings{gao_husain_wang_huang_2015, title={Solid-state transformer interfaced PMSG wind energy conversion system}, DOI={10.1109/apec.2015.7104517}, abstractNote={The solid-state transformer (SST) has been regarded as an emerging technology where emphasis is mainly on the design of the device. To explore its system integration opportunities, this paper proposes and demonstrates a SST interfaced permanent magnet synchronous generator (PMSG) wind energy conversion system. The system integration issues along with wind turbine level control methods have been presented and simulated for power management. Moreover, the lab hardware prototype has been set up, which consists of an induction motor based wind turbine emulator (WTE), PMSG, pulse-width modulation (PWM) rectifier, SST, and resistive load bank. Experiments have been carried out to validate the proposed system and control strategy.}, booktitle={2015 thirtieth annual ieee applied power electronics conference and exposition (apec 2015)}, author={Gao, R. and Husain, I. and Wang, F. and Huang, A. Q.}, year={2015}, pages={1310–1317} }
 @inproceedings{wang_huang_wang_song_ni_ryu_grider_schupbach_palmour_2015, title={Static and dynamic performance characterization and comparison of 15 kV SiC MOSFET and 15 kV SiC n-IGBTs}, DOI={10.1109/ispsd.2015.7123431}, abstractNote={This paper presents the static and dynamic performance of 15 kV SiC IGBTs with 2 um and 5 um field-stop buffer layer thicknesses respectively and compares them with 15 kV SiC MOSFET in term of loss and switching capability. Their switching energy for different gate resistors and temperature have been reported and compared. A 5 kHz 10.5 kW 8 kV boost converter has been built and tested using these three devices respectively. The MOSFET based boost converter has the highest efficiency 99.39% which is the highest reported efficiency for a high voltage SiC device based converter. PLECS loss models can be developed for these devices based on the characterization data to simplify the simulation of a variety circuits or applications which potentially utilize these devices.}, booktitle={Proceedings of the international symposium on power semiconductor}, author={Wang, G. Y. and Huang, A. Q. and Wang, F. and Song, X. Q. and Ni, X. J. and Ryu, S. H. and Grider, D. and Schupbach, M. and Palmour, J.}, year={2015}, pages={229–232} }
 @inproceedings{wang_wang_huang_yu_ni_2014, title={A 3.6kV high performance solid state transformer based on 13kV SiC MOSFET}, DOI={10.1109/pedg.2014.6878693}, abstractNote={This paper presents the development of a distribution network solid state transformer (SST) based on high voltage (13kV) SiC MOSFET and JBS diode. This distribution SST is composed with a medium voltage ac/dc rectifier, medium voltage medium frequency dc/dc converter and a low voltage inverter. It's able to be interfaced to 3.6kV distribution grid and output both a 400V dc and 240/120V ac. This paper presents the characterization of the high voltage SiC MOSFET devices, and the design of rectifier and dc/dc converter. The test results of its grid-connected operation including pre-charge, start up, regeneration, etc. are included to show the functionalities of the designed SST prototype.}, booktitle={Ieee international symposium on power electronics for distributed}, author={Wang, F. and Wang, G. Y. and Huang, A. and Yu, Wensong and Ni, X. J.}, year={2014} }
 @inproceedings{wang_huang_2014, title={A novel single stage AC/DC converter for fast charging applications with unity power factor}, DOI={10.1109/apec.2014.6803559}, abstractNote={This paper introduces a single phase AC/DC converter with unity power factor input at grid side. The proposed topology consists of a diode bridge followed by an asymmetrical DAB circuit working in boost mode. The DAB is utilized to regulate both DC output voltage and averaged input current. With single-side PWM modulation, the DAB can possess advantages such as lower RMS currents and larger soft switching range. Zero cycling current can also be achieved to reduce power losses. Simulation and some experimental test have been carried out to verify the effectiveness of proposed converter.}, booktitle={2014 twenty-ninth annual ieee applied power electronics conference and exposition (apec)}, author={Wang, F. and Huang, A.}, year={2014}, pages={1860–1865} }
 @article{she_yu_wang_huang_2014, title={Design and Demonstration of a 3.6-kV-120-V/10-kVA Solid-State Transformer for Smart Grid Application}, volume={29}, ISSN={["1941-0107"]}, DOI={10.1109/tpel.2013.2293471}, abstractNote={Solid-state transformer (SST) has been regarded as one of the most important emerging technologies for traction system and smart grid application. This paper presents the system design and performance demonstration of a high-voltage SST lab prototype that works as the active grid interface in smart grid architecture. Specifically, the designs of the key components of the system, including both power stage and controller platform, are presented. In addition, the advanced control system is developed to achieve high-performance operation. Furthermore, integration issues of SST with dc microgrid are presented. Lastly, tests under different scenarios are conducted to verify the following advanced features of the presented SST technology: 1) VAR compensation; 2) voltage regulation; 3) source voltage sag operation; and 4) microgrid integration.}, number={8}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={She, Xu and Yu, Xunwei and Wang, Fei and Huang, Alex Q.}, year={2014}, month={Aug}, pages={3982–3996} }
 @inproceedings{wang_wang_magai_lei_huang_das_2013, title={Performance comparison of 1200V 100A SiC MOSFET and 1200V 100A silicon IGBT}, DOI={10.1109/ecce.2013.6647124}, abstractNote={This paper presents the characteristics of the first commercial 1200V 100A SiC MOSFET module and compares it with state-of-the-art silicon IGBT with the same rating. The results show that the 1200V SiC MOSFET has faster switching speed and much lower loss compared with silicon IGBT. Moreover, the silicon IGBT switching loss will increase significantly for higher operation temperature, while the SiC MOSFET switching loss is almost the same for different temperature. A loss model has been implemented in PLECs in order to simulation the losses. An 11kW singlephase inverter prototype with 600V dc bus and 380Vac output voltage has been built for evaluating and comparing the SiC MOSFET and Si IGBT performance. The test results match with the simulation very well and show that with 40 kHz switching frequency the inverter efficiency can be increased to 98.5% from 96.5% if replacing the Si IGBT with the SiC MOSFET module.}, booktitle={2013 ieee energy conversion congress and exposition (ecce)}, author={Wang, G. Y. and Wang, F. and Magai, G. and Lei, Y. and Huang, A. and Das, M.}, year={2013}, pages={3230–3234} }
 @article{she_huang_wang_burgos_2013, title={Wind Energy System With Integrated Functions of Active Power Transfer, Reactive Power Compensation, and Voltage Conversion}, volume={60}, ISSN={["1557-9948"]}, DOI={10.1109/tie.2012.2216245}, abstractNote={As the power of wind energy system increases, the control of their active and reactive power becomes increasingly more important from a system standpoint given that these are typical frequency and voltage control parameters. In this paper, a family of wind energy systems with integrated functions of active power transfer, reactive power compensation, and voltage conversion is proposed. The proposed wind energy systems using solid-state transformer (SST) can effectively suppress the voltage fluctuation caused by the transient nature of wind energy without additional reactive power compensator and, as such, may enable the large penetration of wind farm (WF) into the power grid. To this end, a simulation study for WF driven by squirrel-cage induction generators is presented to verify the effectiveness of the proposed system. In addition, a modular-type high-voltage and high-power three-phase SST topology is presented for the proposed system, and its basic building block, which is a single-phase SST, is analyzed. The functions of SST in the presented wind energy system are verified in a single-phase laboratory prototype with scaled-down experiments. Lastly, cost issue of the proposed technology is analyzed with comparison to the traditional one.}, number={10}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={She, Xu and Huang, Alex Q. and Wang, Fei and Burgos, Rolando}, year={2013}, month={Oct}, pages={4512–4524} }
 @inproceedings{wang_lu_wang_huang_2012, title={Development of distributed grid intelligence platform for solid state transformer}, DOI={10.1109/smartgridcomm.2012.6486031}, abstractNote={This paper introduces the development of a platform intended as a distributed controller for grid intelligence (DGI) system at FREEDM Systems Center. This platform serves as both a hard real-time local converter controller and a communication node for distributed deployment of energy management schemes. One of the converter devices it controls is the solid state transformer (SST), one of the key elements to interface renewable energy sources into distribution system in FREEDM Center. Both the hardware design and software structure for SST control are presented in this paper. For the communication part, the Distributed Network Protocol (DNP) 3.0 is adopted to congregate multiple SSTs to balance local generation and demands in a coordinated manner. Experiment results are presented to show that this distributed platform has good performance.}, booktitle={2012 IEEE Third International Conference on Smart Grid Communications (SmartGridComm)}, author={Wang, F. and Lu, X. and Wang, Wenye and Huang, A.}, year={2012}, pages={481–485} }
 @inproceedings{wang_huang_wang_she_burgos_2012, title={Feed-forward control of solid state transformer}, DOI={10.1109/apec.2012.6165964}, abstractNote={The solid state transformer (SST) can be viewed as an energy router for electricity in an analogous way to what network routers are for information. The SST impact on the system can be hence paramount, especially in terms of stability since it is essentially an active closed-loop regulated power converter. Within the SST itself however, with its different ac-dc, dc-dc and dc-ac stages, stability is also crucial, as it is well understood that for cascaded converter systems the interaction between stages is the cause of instability from a small-signal perspective. This paper represents an initial quest into the SST stability study, exploring two feed-forward control schemes for the ac-dc and dc-dc converter stages. Simulation and experimental results with a 7.2 kV ac 400 V dc, 20 kW laboratory prototype are presented for validation purposes.}, booktitle={2012 twenty-seventh annual ieee applied power electronics conference and exposition (apec)}, author={Wang, F. and Huang, A. and Wang, G. Y. and She, X. and Burgos, R.}, year={2012}, pages={1153–1158} }
 @inproceedings{wang_she_wang_huang_burgos_2012, title={Parallel operation of solid state transformer}, booktitle={2012 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Wang, F. and She, X. and Wang, G. Y. and Huang, A. and Burgos, R.}, year={2012}, pages={1433–1438} }
 @inproceedings{yu_wang_huang_2012, title={Power management strategy for plug and play DC microgrid}, DOI={10.1109/isgteurope.2012.6465882}, abstractNote={DC microgrid is getting more and more attention as an effective and efficient solution to integrate different kinds of renewable energy storage and energy resources with DC loads. A typical DC microgrid envisioned for future DC powered residential homes is investigated in this paper, including distributed power management strategy design, plug and play function implementation, communication ports to monitor the system performance. In this power management strategy, each module in the system is in the distributed control and can be plugged and unplugged into the system without affecting the system performance. Furthermore, the communication ports guarantee all modules information can be sent to the control center to monitor the whole system information.}, booktitle={2012 3rd ieee pes innovative smart grid technologies europe (isgt europe)}, author={Yu, X. W. and Wang, F. and Huang, A. Q.}, year={2012} }
 @inproceedings{she_burgos_wang_wang_huang_2012, title={Review of solid state transformer in the distribution system: From components to field application}, DOI={10.1109/ecce.2012.6342269}, abstractNote={The emergence of high power converters makes the modern power grid more active than it was before. One of the research directions in this area is the solid state transformer, which aims at replacing the traditional 50/60 Hz power transformer by means of high frequency isolated AC/AC solid state conversion techniques. This paper presents a systematical technology review essential for the development of solid state transformer in the distribution system, especially focusing on the following four areas: high voltage and high frequency power devices, high power and high frequency transformers, AC/AC converter topologies, and applications of solid state transformer in the distribution system. For each category, the state-of-art technologies are reviewed and possible research directions are presented. It is concluded that the solid state transformer is an emerging technology for the modernization of the future smart grid.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={She, X. and Burgos, R. and Wang, G. Y. and Wang, F. and Huang, A. Q.}, year={2012}, pages={4077–4084} }
 @inproceedings{she_wang_burgos_huang_2012, title={Solid state transformer interfaced wind energy system with integrated active power transfer, reactive power compensation and voltage conversion functions}, DOI={10.1109/ecce.2012.6342508}, abstractNote={As the power of wind energy system increases, the control of their active and reactive power becomes increasingly more important from a system standpoint given that these are typical frequency and voltage control parameters. In this paper a family of wind energy systems with integrated active power transfer, reactive power compensation and voltage-conversion functionality is proposed. The proposed wind energy systems using solid state transformer (SST) can effectively suppress the voltage fluctuation caused by the transient nature of wind energy without additional reactive power compensator and as such may enable the large penetration of wind farm (WF) into the distribution system. To this end, a simulation study for WF driven by squirrel-cage induction generators is presented to verify the effectiveness of the proposed system. In addition, a modular type high voltage and high power three-phase SST topology is presented for the proposed system, and its basic building block, which is a single-phase SST, is analyzed. The function of SST in the presented wind energy system is verified in a single-phase laboratory prototype with scaled down experiments.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={She, X. and Wang, F. and Burgos, R. and Huang, A. Q.}, year={2012}, pages={3140–3147} }
 @inproceedings{she_huang_wang_zhao_wang_yao_2011, title={A new voltage-balancing controller in cascaded multilevel converters}, DOI={10.1109/ecce.2011.6063766}, abstractNote={Voltage-balancing controller in cascaded multilevel converters has been discussed extensively in previous literatures where several effective methods have been proposed. The coupling effect between a voltage-balancing controller and the original system controller is however not addressed comprehensively. This paper proposes a new voltage-balancing controller for single-phase cascaded multilevel converters in a d-q coordinate. The theoretical finding shows that the proposed method can effectively eliminate the coupling between two controllers in both steady and dynamic state. Simulation and experimental results validate the proposed method.}, booktitle={2011 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={She, X. and Huang, A. Q. and Wang, G. Y. and Zhao, T. F. and Wang, F. and Yao, W. X.}, year={2011}, pages={177–184} }
 @inproceedings{wang_she_wang_kadavelugu_zhao_huang_yao_2011, title={Comparisons of different control strategies for 20kVA solid state transformer}, DOI={10.1109/ecce.2011.6064196}, abstractNote={This paper presents and compares different control strategies for 20kVA silicon IGBT based solid state transformer (SST). The SST has a cascaded seven level rectifier stage, three output parallel Dual Active Bridge (DAB) DC/DC stage and an inverter stage. The voltage of the three high voltage capacitors must be balanced for the safe operation of the IGBTs, however, the mismatch of power devices parameters and variance of high frequency transformer leakage inductance of the DAB stage will cause voltage unbalance for these capacitors as well as the power unbalance of the three output parallel DAB stages. This paper analyzed these effects and discussed the limitations and merits for several different control strategies. The newly proposed control strategy for the SST has been determined as the most suitable strategy in terms of performance and simplicity. Simulation and experiment results are presented to validate the analysis.}, booktitle={2011 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Wang, G. Y. and She, X. and Wang, F. and Kadavelugu, A. and Zhao, T. F. and Huang, A. and Yao, W. X.}, year={2011}, pages={3173–3178} }
 @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} }