A Phase-Shift Soft-Switching Control Strategy for Dual Active Wireless Power Transfer System

In recent years, wireless power transfer (WPT) technology has developed rapidly. In order to control power transmission and optimize efficiency, a large number of control methods have been proposed. Due to the unique inherent characteristics of the WPT system, the various control methods are faced to three challenges. First, transmission efficiency is significantly affected by the change in output power. Secondly, the severe hard switching loss of the high frequency converters cannot be ignored. Finally, high-speed wireless communication is required between the primary and secondary sides of the WPT system. In this paper, a fixed-frequency phase-shift control strategy is proposed for dual active WPT system in order to realize the soft-switching of the converters in the full load range without high-speed wireless communication. At the same time, the dependency of efficiency on load is greatly reduced, which results in significant efficiency improvements over a wide range of output power. In addition, synchronous rectification and bi-directional energy transfer can be implemented because of the dual active structure.