Variable Angle Phase Shift Control in Series-Series Type Wireless Power Transfer System

In this paper, first, to realize the constant current charging for EV's Battery and ZVS operation of all the switches in wireless power transfer system (WPTS) simultaneously, a novel variable angle phase shift control strategy (VAPSC) is proposed only by controlling the active rectifier (AR). Second, based on VAPSC, the ac equivalent impedance and the conditions for achieving ZVS are derived in detail. Third, according to the characteristics of constant current charging and the conditions for achieving ZVS, the optimal power angle range (OPAR) is obtained. Meanwhile, the control structure based on VAPSC is presented to make the system work accurately at any points of OPAR by adjusting the zero voltage switching angle (ZVSA). Finally, a 500W WPTS is built to verify the correctness of theoretical analysis and the effectiveness of VAPSC. The maximum transfer efficiency can achieve 94.5% with k = 0.2 near the maximum transfer power.