A Phase Angle Self-Synchronization Topology for Parallel Operations of Multi-Inverters in High Frequency AC Distribution

Abstract

—High frequency ac (HFAC) power distribution system (PDS) has been known as the effective alternative of dc power distribution system (DC PDS) because of its excellent advantages such as high power density, high efficiency, fast dynamic response and fewer conversion stages. Multiple HFAC inverters are operated in parallel to satisfy the source side requirements like high power grade, safety margin and reliability. In order to eliminate circulation current caused by the amplitude and phase differences among the inverters, the amplitude and phase of individual inverter are required to be synchronous. However, parallel controls become extremely complicated as amplitude and phase are coupled together in full-bridge inverter with traditional phase-shift modulation. In this paper, a controllable half-bridge LCLC resonant inverter and dual-PWM modulation are presented with phase angle self-synchronization. Control strategy is given for voltage adjusting and phase-amplitude decoupling. Besides, the resonant network normalization parameters and control angle is summarized to ensure soft-switching. The simulation model and experimental prototype are implemented with the output frequency of 25 kHz. The experiment results and theoretical analysis agree well to verify the features of the proposed inverter.

Keywords:

• high frequency AC (HFAC)
• resonant inverter in parallel
• LCLC resonant tank
• soft switching

ACKNOWLEDGMENTS

The authors would also like to thank anonymous reviewers for their valuable comments and suggestions.

Additional information

Funding

The authors gratefully acknowledge the financial support of National Natural Science Foundation of China (No. 61573155), Guangdong Natural Science Foundation (No. 2016A030313508), and Guangdong Science and Technology Planning Project (No. 2016A010102007, No. 2016B090918028).

Notes on contributors

Junfeng Liu

Junfeng Liu received the M.S. degree in control engineering from the South China University of Technology, Guangzhou, China, in 2005, and the Ph.D. degree from the Hong Kong Polytechnic University, Kowloon, Hong Kong, in 2013. From 2005 to 2008, he was a development engineer of Guangdong Nortel Network, Guangzhou, China. In 2014, he joined the South China University of Technology, Guangzhou, where he was an Associated Professor at School of Automation Science and Engineering. His research interests include power electronics applications, nonlinear control, high frequency power distribution system, and motion control system.

Xuesheng Li

Xuesheng Li was born in Henan, China, in 1991. He received his B.S. degree in Electrical Engineering and Automation from the Henan Polytechnic University, Jiaozuo, China, in 2013, and the M. S. degree in Electrical Engineering and Automation from South China University of Technology, Guangzhou, China, in 2016. He is working in the China Southern Power Grid. His current research interests include resonant converters, high frequency power distribution systems, and renewable energy generation.

Zehui Yu

Zehui Yu was born in Shanwei, China, in 1994. He received his B.S. degree from Southwest Jiaotong University, Chengdu, China, in 2017. He is currently working toward his M.S. degree in Power Electronic at South China University of Technology, Guangzhou, China. His research interests include modeling and control of power electronics converters and high-frequency dc/dc conversion.

Jun Zeng

Jun Zeng received her Ph.D. degree in control theory and control engineering from the South China University of Technology, Guangzhou, China in 2007. She is an professor in the Electric Power College of the South China University of Technology, Guangzhou, China. Her current research interests include power electronics applications, energy management and intelligence control in distributed generation and integration of renewable energy to smart grid.