@article{wang_huang_guo_yu_yu_huang_2018, title={Soft-Switched Modulation Techniques for an Isolated Bidirectional DC-AC}, volume={33}, ISSN={["1941-0107"]}, DOI={10.1109/tpel.2017.2661965}, abstractNote={Two carrier-based unipolar-sinusoidal pulse width modulation (SPWM)-oriented modulation techniques for an isolated bidirectional dc–ac converter are proposed, compared, and validated in this paper. The dc–ac converter is composed of a full-bridge (FB) inverter cascaded with a cycloconverter through a high-frequency transformer. Both modulation techniques proposed in this paper can realize zero-voltage switching (ZVS) for the FB inverter and zero-current switching or ZVS for the cycloconverter in all load range, and are able to suppress the voltage spikes introduced by the transformer leakage inductance as well. In order to increase the converter efficiency and power density, we propose to utilize SiC MOSFETs for the converter. The first modulation technique enables the utilization of Si-SiC hybrid switches with no synchronous rectification (SR), for the purpose of lowering the converter cost. The second modulation technique requires all switches to be SiC MOSFETs, but with SR, which increases the converter efficiency. A 400-V dc to 240-V ac 1.2-kW prototype has been developed to validate the effectiveness and performance of the proposed carrier-based unipolar-SPWM-oriented modulation techniques.}, number={1}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Wang, Mengqi and Huang, Qingyun and Guo, Suxuan and Yu, Xiaohang and Yu, Wensong and Huang, Alex Q.}, year={2018}, month={Jan}, pages={137–150} }
 @article{wang_guo_huang_yu_huang_2017, title={An Isolated Bidirectional Single-Stage DC-AC Converter Using Wide-Band-Gap Devices With a Novel Carrier-Based Unipolar Modulation Technique Under Synchronous Rectification}, volume={32}, ISSN={["1941-0107"]}, DOI={10.1109/tpel.2016.2564360}, abstractNote={A novel carrier-based unipolar-sinusoidal pulse width modulation (SPWM)-oriented modulation technique with synchronous rectification for isolated bidirectional single-stage high-frequency-ac link dc-ac converters using SiC MOSFET is presented in this paper. The dc-ac converter is composed of a full-bridge (FB) inverter cascaded with a cycloconverter through a high-frequency transformer. A carrier-based unipolar-SPWM-oriented modulation technique with synchronous rectification is proposed to realize zero-voltage-switching (ZVS) for the FB inverter and zero-current or zero-voltage-switching (ZVS/ZCS) for the cycloconverter in all load ranges, and to suppress the voltage spikes introduced by the transformer leakage inductance as well. In order to increase the switching frequency, efficiency, and power density, this paper proposes to utilize SiC MOSFETs for the converter. Synchronous rectification is implemented to further increase the converter efficiency. With the novel modulation technique, there are two switches in the cycloconverter that are continuously on at each interval, which eliminates on-fourth of the switching loss. A simulation model and a 400 VDC-240 VAC, 1.2=kW prototype have been developed to validate the effectiveness and performance of the proposed unipolar soft-switching modulation technique and SiC converter.}, number={3}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Wang, Mengqi and Guo, Suxuan and Huang, Qingyun and Yu, Wensong and Huang, Alex Q.}, year={2017}, month={Mar}, pages={1832–1843} }
 @inproceedings{guo_liu_yu_zhang_huang_2016, title={Analysis and loss comparison of megahertz high voltage isolated dc/dc converters utilizing integrated sic mosfet module}, DOI={10.1109/wipda.2016.7799955}, abstractNote={Silicon Carbide (SiC) MOSFETs are being increasingly utilized in medium and high power electronics converters (>1 kW) because of the significantly lower switching and conduction losses when compared with conventional power switches such as the Si IGBT. SiC MOSFET based converters operating at high frequency can achieve high efficiency and high power density at the same time. Minimum switching loss can be achieved in the SiC MOSFET with carefully designed gate driving condition and DC link layout, such as the integrated SiC MOSFET module discussed in this paper. Multi-megahertz switching frequency could be realized by the proposed SiC MOSFET module with proper soft switching topology. This paper analyzes three isolated DC/DC converters, namely the asymmetrical half bridge converter, phase shift full bridge converter, and LLC resonant converter. The loss model of the SiC MOSFET is developed and utilized in the analysis. Comparisons are carried out from the device loss and soft switching requirement point of view. The LLC resonant converter is deemed more suitable for multi-megahertz application. A 4.5 kW 1.2 MHz LLC resonant converter prototype is developed and it demonstrates a peak efficiency of 97% at 4 kW.}, booktitle={2016 IEEE 4th Workshop on Wide Bandgap Power Devices and Applications (wipda)}, author={Guo, S. X. and Liu, P. K. and Yu, R. Y. and Zhang, L. Q. and Huang, A. Q.}, year={2016}, pages={291–296} }
 @inproceedings{guo_zhang_lei_li_yu_huang_2016, title={Design and application of a 1200V ultra-fast integrated silicon carbide MOSFET module}, DOI={10.1109/apec.2016.7468151}, abstractNote={With the commercial introduction of wide bandgap power devices such as Silicon Carbide (SiC) and Gallium Nitride (GaN) in the last few years, the high power and high frequency power electronics applications have gained more attention. The fast switching speed and high temperature features of SiC MOSFET break the limit of the traditional silicon MOSFET. However, the EMI problem under high dI/dt and dV/dt is an unneglectable problem. The overshoot and oscillation on drain-source voltage and gating signal could cause breakdown of the switches. This paper proposes a 1200V integrated SiC MOSFET module. With the ultra-fast gate driver integrated with the SiC MOSFET, the parasitic inductance and capacitance could be reduced dramatically, which accordingly suppress the EMI problem caused by the parasitic parameters. Thus zero gate resistance could be adopted in the module to further increase the switching speed. The switching performance of the integrated SiC module is shown better than the discrete package device. The switching loss of the SiC MOSFET module is measured by the inverter level measurement and composition method. Zero switching loss could be achieved when the drain current is lower than a critical value. The module has been tested at 1.5MHz and 3.38MHz switching frequency to prove its high speed capability. For isolated topology applications, the impact of high frequency on the power density and efficiency is discussed in this paper.}, booktitle={Apec 2016 31st annual ieee applied power electronics conference and exposition}, author={Guo, S. X. and Zhang, L. Q. and Lei, Y. and Li, X. and Yu, Wensong and Huang, A. Q.}, year={2016}, pages={2063–2070} }
 @inproceedings{liu_zhang_huang_guo_lei_2016, title={High bandwidth current sensing of sic mosfet with a si current mirror}, DOI={10.1109/wipda.2016.7799937}, abstractNote={SiC Intelligent Power Module (IPM) with high bandwidth integrated current sensors is a future trend to improve the device protection capability and chip utilization. In this work, an integrated current sensing scheme for Silicon Carbide (SiC) MOSFET power module using a Si MOSFET current mirror is proposed, analyzed and tested. The use of Si MOSFET not only lowers the overall cost, but compensates the temperature variation as well. The influence of device mismatching on sensing accuracy are discussed. Optimal selection and trade-off of sensing resistor value are calculated. Discrete device circuit and conceptual DBC-based module are tested to verify the scheme's feasibility and performance. The results show good steady state accuracy and high bandwidth performance.}, booktitle={2016 IEEE 4th Workshop on Wide Bandgap Power Devices and Applications (wipda)}, author={Liu, P. K. and Zhang, L. Q. and Huang, A. Q. and Guo, S. X. and Lei, Y.}, year={2016}, pages={200–203} }
 @inproceedings{guo_zhang_lei_li_xue_yu_huang_2015, title={3.38 Mhz operation of 1.2kV SiC MOSFET with integrated ultra-fast gate drive}, DOI={10.1109/wipda.2015.7369298}, abstractNote={With the commercialization of wide bandgap power devices such as SiC MOSFETs and JBS diodes, power electronics converters used in the harsh environments such as hybrid electric vehicles and aerospace attract more and more attentions. The low loss, high temperature and fast switching capabilities are utilized in the converters to improve the power density and efficiency. However, the EMI problem caused by the fast switching is a major constrain for improving switching frequency. For this reason, an integrated SiC module with 1.2kV MOSFET and ultra-fast gate drive circuits is proposed and developed. Two 1.2kV SiC MOSFETs bare dies and two high current gate driver chips are integrated in a compact integrated module package to reduce the parasitic inductance. 0Ω gate resistor therefore can be used in this module to improve the device at maximum speed. Noise free operation of the tested module is verified even under extremely high dV/dt and dI/dt conditions. The ultra-low turn-off loss of the module is being demonstrated. Finally, the integrated module is demonstrated in two megahertz converters: an 800W 1.5MHz synchronous boost converter and a 3.38MHz half bridge inverter. The era for high voltage-megahertz switching has arrived.}, booktitle={WiPDA 2015 3rd IEEE Workshop on Wide Bandgap Power Devices and Applications}, author={Guo, S. X. and Zhang, L. Q. and Lei, Y. and Li, X. and Xue, F. and Yu, Wensong and Huang, A. Q.}, year={2015}, pages={390–395} }
 @inproceedings{xue_yu_guo_yu_huang_2015, title={Loss analysis of GaN Devices in an isolated bidirectional DC-DC converter}, DOI={10.1109/wipda.2015.7369261}, abstractNote={GaN devices have emerged as a possible replacement for silicon devices in various power conversion applications and as an enabler of new applications not previously possible. This paper presents a 600V Gallium-Nitride (GaN) device based isolated bidirectional DC-DC converter applied in battery energy storage systems. Apart from the features of low turn-off loss, low output capacitance and low drain-source on-state resistance, the most salient one in our bidirectional DC-DC converter application is the ultra-fast freewheeling "body diode" that GaN devices have when compared with Si devices. To distinguish the above mentioned performances of GaN from those of the comparable Si devices, a figure of merit for power devices operating in synchronous rectifying mode is proposed. The converter's operating principle is analyzed in steady state. Switching losses of high voltage and low voltage side switches are simulated based on detailed PSpice models. The converter's safe operation area is extended by using GaN device is explained by calculating the loss in hard switching mode. A thermal simulation is conducted to predict its temperature. Experimental results are presented for a 1 kW, 380-to-12 V prototype DC-DC converter, which demonstrate the validity of the analysis and simulation.}, booktitle={WiPDA 2015 3rd IEEE Workshop on Wide Bandgap Power Devices and Applications}, author={Xue, F. and Yu, R. Y. and Guo, S. X. and Yu, Wensong and Huang, A. Q.}, year={2015}, pages={201–205} }
 @inproceedings{guo_huang_2014, title={Control and analysis of the high efficiency split phase PWM inverter}, DOI={10.1109/apec.2014.6803641}, abstractNote={The traditional power switch phase leg is widely used in the power electronic devices. However, the short through of the phase leg is always a problem for reliability, efficiency, higher switching frequency. Besides, both of power device turn-on/turn-off time and the reverse recovery time of poor performance body diodes will limit the switching frequency and power conversion efficiency. This paper proposes a new split phase PWM inverter which could split the MOSFET based phase legs by coupled inductor to prevent the short through and disable poor performance body diode. The extended Schottky diodes could be adopted to eliminate reverse recovery loss. By using the traditional bipolar or unipolar PWM control schemes, the circulating current which is caused by the feature of inductors will exist in the circuit and will increase power loss. An advanced unipolar PWM control strategy is proposed in this paper to minimize circulation current and to improve power conversion efficiency. Simulation is done to verify the better performance of split phase PWM inverter and the proposed advanced unipolar PWM control strategy.}, booktitle={2014 twenty-ninth annual ieee applied power electronics conference and exposition (apec)}, author={Guo, S. X. and Huang, A. Q.}, year={2014}, pages={2415–2420} }