Efficiency Optimization of WPTS Based on Variable Angle Phase Shift Control for EV charging

Without extra dc-dc converters, variable angle phase shift control (VAPSC) strategy is commonly used in a wireless power transfer system (WPTS) to achieve the required output and ZVS operation of converters simultaneously. However, the power losses of the WPTS with VAPSC have not been analyzed when the WPTS operates in the optimal power angle range (OPAR). In this paper, the power losses of the SS-type WPTS have been analyzed in detail. Moreover, based on VAPSC, a double-loop control strategy (DLCS) with a dynamic efficiency optimization method is proposed. Finally, a 500-W WPTS prototype is built to verify the rationality of the proposed control strategy. It can achieve a very high overall transfer efficiency in the whole charging process and the maximum transfer efficiency can reach 95.2% with k = 0.2 under the rated transfer power.