Digital Phase Synchronization and Wireless Communication in a Bidirectional S-S-Compensated Wireless Power Transfer System for Electric Vehicles

A bidirectional wireless power transfer (BD-WPT) system with phase-shift pulse-width modulation (PWM) control is proposed for electric vehicle applications, incorporating a wireless communication method for data exchange between the primary and pickup-side converters. The system enables bidirectional power flow while ensuring stable and efficient power regulation. Digital clock frequency synchronization between the DSP processors on both sides is achieved via a wireless transceiver, eliminating the need for analog synchronization circuits and maintaining smooth power transfer. Power regulation is controlled by adjusting the phase shift on both sides using a digital PI controller and phase-shift PWM control. The operating principle of the BD-WPT system and the series–series (SS) compensation topology are investigated, and the optimal PI controller parameters are derived using Bode plot analysis of the system’s transfer function. A 2 kW SS-compensated BD-WPT prototype with constant power control is developed and experimentally validated. To evaluate power regulation performance, the system is tested under coil misalignment in the x-axis direction while maintaining a constant 2 kW DC output. Experimental results confirm the effectiveness and robustness of the proposed closed-loop control scheme, achieving an overall system efficiency of 94.86% at 2 kW output power.