CC–CV Wireless EV Charging With Power Balance Control in Primary- and Secondary-Side Converters

This paper presents the design, simulation, and experimental validation of a constant current–constant voltage (CC–CV) wireless electric vehicle (EV) charging system utilizing Power Balance Control (PBC) in both primary-side (PS) and secondary-side (SS) converter configurations. The system was tested using a step-resistance load and a typical 72 V, 50 Ah lithium-ion NMC battery to assess control precision, dynamic behavior, and charging efficiency of the system. Experimental results demonstrate that both PS and SS converters employing PBC successfully achieve stable CC–CV operation. The SS converter achieved a peak efficiency of 82%, outperforming 77% from the PS converter. Regarding transient performance, the PBC significantly enhanced settling times over the conventional proportional–integral (PI) controller. Specifically, the settling time was reduced from 600ms to 100ms in the PS converter and from 400ms to 20ms in the SS converter, with minimal voltage overshoot. Power loss analysis indicated that the highest losses occurred in CC mode, particularly in the inductive power transfer (IPT) coils and high-frequency inverters. The SS control effectively minimized these losses by dynamically adjusting its input resistance to match the optimal load resistance. Overall, the proposed PBC approach, especially in the SS converter, demonstrates efficiency, faster dynamic response, and robust power regulation for next-generation wireless EV charging systems.