@inproceedings{huang_yu_huang_yu_2017, title={Adaptive zero-voltage-switching control and hybrid current control for high efficiency GaN-based MHz totem-pole PFC rectifier}, DOI={10.1109/apec.2017.7930937}, abstractNote={This paper presents an adaptive Zero-Voltage-Switching control (ZVS) method and a hybrid current control strategy for the GaN-based MHz Totem-pole PFC rectifier. This novel ZVS control achieves the minimum ZVS time margin and maximum switching frequency clamping by adaptively controlling the synchronous rectifier (SR) turn off current. This adaptive SR turn off current control is a unified control strategy based on a proposed unified analytical converter model. The analytical model and the control strategy are applicable for full-range of input voltage and full-range of load for ZVS Totem-pole PFC. In addition, a dual-loop current control strategy is also proposed in this paper. This dual-loop current controller uses the outer average current control loop to directly regulates the inductor average current. The inner current control loop combines the peak current controller and the time based SR turn off current controller. The proposed SR turn off current control for ZVS is adaptively controlled by this time based controller. To verify the proposed ZVS control method and the hybrid current controller, a 1.5kW GaN-based MHz Totem-pole PFC prototype is demonstrated with full-range ZVS, 99% peak efficiency and high quality AC current.}, booktitle={2017 thirty second annual ieee applied power electronics conference and exposition (apec)}, author={Huang, Q. Y. and Yu, R. Y. and Huang, A. Q. and Yu, Wensong}, year={2017}, pages={1763–1770} }
 @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{wang_huang_yu_huang_2016, title={High-frequency AC distributed power delivery system}, DOI={10.1109/apec.2016.7468394}, abstractNote={A novel high-frequency-AC (HFAC) distributed power delivery system is presented in this paper. The target applications of the proposed system are the aerial and ground transportation, and renewable energy systems. Unlike traditional line-frequency-AC (LFAC) or DC distributed power delivery system, the bus frequency of the proposed system can be set at tens or hundreds of kilo-Hertz, so as the power transmission frequency. As a result, 50 or 60 Hz transformers will be eliminated from the system. DC arcing flash will not exist as well with the utilization of HFAC bus. In this paper, single-stage isolated bi-directional power electronics interfaces are developed which enables distributed AC and DC sources or loads to access the main HFAC bus. Soft-switching is also realized for all the semiconductor devices in the power electronics interface. Distributed control architecture is developed so that each source or load can operate independently. Simulation results are provided to validate the distributed control architecture. A scaled-down hardware demonstration, with the bus specification of 54 kHz and 400 VAC, is presented to validate the proposed architecture of the HFAC distributed power delivery system.}, booktitle={Apec 2016 31st annual ieee applied power electronics conference and exposition}, author={Wang, M. Q. and Huang, Q. Y. and Yu, Wensong and Huang, A. Q.}, year={2016}, pages={3648–3654} }
 @inproceedings{huang_yu_huang_2016, title={Independent DC link voltage control of cascaded multilevel PV inverter}, DOI={10.1109/apec.2016.7468249}, abstractNote={For the independent DC link voltage control of the single phase cascaded multilevel PV inverter, this paper proposes an improved control strategy that consists only one total voltage loop and n feed-forward-based weighting factors. Actually, the multiple modulation signals have predictable ratios with each other because the series connection of the outputs of the H-bridges. Utilizing this feature, this proposed control strategy directly generates the weighting factors by the DC link input powers and voltage references which are independent with the output of the voltage feedback loop. The voltage feedback loop controls the sum of the DC link voltages while the feed-forward signals force the ratio between DC link voltages to be equal to the ratio between the references at steady state. Compared with the previous control strategies that contain at least n voltage controllers, the proposed control structure is much simplified. Besides, the small signal modeling and controller design of the inner current and outer voltage loop are also included in this paper. In addition, the adaptive gain is proposed to keep the loop gain unchanged even at the situation of weak irradiation. This control strategy is verified by the simulated and experimental results with accurate DC link control and more than 99.5% MPPT efficiency for each H-bridge even at severe irradiation mismatch conditions.}, booktitle={Apec 2016 31st annual ieee applied power electronics conference and exposition}, author={Huang, Q. Y. and Yu, Wensong and Huang, A. Q.}, year={2016}, pages={2727–2734} }
 @inproceedings{wang_huang_yu_huang_2015, title={An Isolated Bi-directional high-frequency-AC link DC-AC converter using hybrid SiC switches with carrier-based unipolar modulation technique}, DOI={10.1109/ifeec.2015.7361625}, abstractNote={A novel isolated bi-directional soft-switched high-frequency-AC (HFAC) link DC-AC converter using SiC MOSFET and IGBT hybrid switches 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. In order to increase the converter efficiency, and to push the transformer frequency to 50-100 kHz, SiC MOSFETs are preferable devices compared to the traditional IGBTs or SCRs. A unipolar-SPWM-oriented modulation technique is proposed to realize zero-voltage-switching (ZVS) for FB and zero-current-switching (ZCS) for cycloconverter, and to suppress the voltage spikes introduced by the transformer leakage inductance as well. With the novel modulation technique, half of the AC switches in the cycloconverter work under transformer frequency and the rest work at line frequency (60 Hz). Therefore a SiC-IGBT hybrid switch structure is proposed for the cycloconverter. Simulation model and a 400 VDC to 240 VAC, 3 kW prototype have been developed to validate the effectiveness and performance of the proposed unipolar soft-switching modulation technique and the hybrid switch structure.}, booktitle={2015 IEEE 2nd International Future Energy Electronics Conference (IFEEC)}, author={Wang, M. Q. and Huang, Q. Y. and Yu, Wensong and Huang, A. Q.}, year={2015} }
 @inproceedings{wang_huang_yu_huang_2015, title={An isolated bi-directional soft-switched DC-AC converter using wide-band-gap devices with novel carrier-based unipolar modulation technique under synchronous rectification}, DOI={10.1109/apec.2015.7104672}, abstractNote={A novel carrier-based unipolar-SPWM-oriented modulation technique with synchronous rectification for isolated bi-directional soft-switched high-frequency-AC (HFAC) link DC-AC converter 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. In order to increase the efficiency and power density, we proposed to utilize SiC MOSFETs for the converter. A carrier-based unipolar-SPWM-oriented modulation technique is proposed to realize zero-voltage-switching (ZVS) for FB and zero-current or zero-voltage-switching (ZVS/ZCS) for cycloconverter in all load range, and to suppress the voltage spikes introduced by the transformer leakage inductance as well. Synchronous rectification is implemented to further increase the converter efficiency. With the novel modulation technique, 1/4 of the AC switches in the cycloconverter are always on which eliminates 1/4 of the switching loss. Simulation model and a 400 VDC to 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.}, booktitle={2015 thirtieth annual ieee applied power electronics conference and exposition (apec 2015)}, author={Wang, M. Q. and Huang, Q. Y. and Yu, Wensong and Huang, A. Q.}, year={2015}, pages={2317–2324} }
 @inproceedings{huang_wang_yu_huang_2015, title={Power-weighting-based multiple input and multiple output control strategy for single-phase PV cascaded H-bridge multilevel grid-connected inverter}, DOI={10.1109/apec.2015.7104646}, abstractNote={This paper presents a power-weighting-based multiple input and multiple output control strategy and performance improvements schemes for single-phase PV cascaded H-bridge multilevel grid-connected inverter. The truly individual MPPT block for each H-bridge converter realizes independent MPPT, and the sum of each voltage reference provides the system voltage reference for the voltage loop. And the sum of each PV voltage is the system voltage feedback. The output of the voltage controller delivers the peak value of the sinusoidal current reference. The output of this central current controller is assigned directly according to the PV power weighting factors to create the coordinated control signals for PWM generation of each H-bridge respectively. This approach makes the control structure for this cascaded multilevel inverter have only one central dual loop controller, and the PWM generation will be decoupled from the voltage controllers. This feature is similar with the single H-bridge inverter's dual loop control. Furthermore, to improve the dynamic response of the voltage loops, a sample and hold block at double line frequency is included in each voltage loop. Therefore, the voltage loop bandwidth will increase to 25~30Hz and the MPPT speed will be much faster as well. Besides, the power-based duty-ratio feed-forward technique is proposed to improve the current loop performance. Finally, simulated and experimental results are provided to verify the performance of the proposed control approaches.}, booktitle={2015 thirtieth annual ieee applied power electronics conference and exposition (apec 2015)}, author={Huang, Q. Y. and Wang, M. Q. and Yu, Wensong and Huang, A. Q.}, year={2015}, pages={2148–2153} }