A Dual-Sided Control Strategy Based on Mode Switching for Efficiency Optimization in Wireless Power Transfer System

Transfer efficiency of a wireless power transfer (WPT) system is tightly related to the load, which varies greatly in a wide range during the charging process. Generally speaking, dual-sided control strategies are commonly applied to overcome the load variation and improve system efficiency. However, the system may suffer from hard switching, high control complexity, and auxiliary dc/dc converters. In this article, a dual-sided control strategy based on mode switching is proposed to approach an optimal load impedance, zero-voltage switching of all mosfets in WPT system, and a required output. In this control strategy, the output voltage of the inverter is adjusted in a wide range by switching the operation mode of the inverter to approach the optimal load impedance. The output current/voltage is regulated by the active rectifier control. Besides, a novel phase-locked method is proposed for the semi-bridgeless active rectifier control, which is simpler compared with the traditional phase-locked method. Finally, a 500-W prototype is built to verify the theoretical analysis, and the peak system efficiency of 93.9% is gained with k = 0.23.

Automated summary

A dual-sided control strategy based on mode switching is proposed to approach an optimal load impedance and achieve the required output in this article. The control strategy adjusts the output voltage of the inverter by switching the operation mode of the inverter in a wide range to approach the optimal load impedance. Additionally, a novel phase-locked method is proposed for the semi-bridgeless active rectifier control, which is simpler compared with traditional methods.