Soft Switching Based Design of Wireless In-Wheel Motor Drive System with Series/Capacitor-Parallel Compensation

Wireless in-wheel motor drive systems have been used to reduce the disconnection risk of power cables. A series/capacitor-parallel (S/CP) compensation topology is proposed for the system. Despite the structural similarity with the series/series-parallel (S/SP) compensation, the S/CP compensation adopts a different design concept to enhance the voltage gain flexibility. Soft switching is first considered in the design given its importance for resonant converters. Based on the derived soft switching boundaries, design points can be readily determined. Meanwhile, virtual parameters are introduced to eliminate the terminal effect on soft switching. Furthermore, noting the motor load’s substantial tolerance of bus voltage variations, an optimization design method is proposed. The proposed design method can facilitate soft switching, ensure bus voltage requirements, and maintain high efficiency over a broad range of loads and misalignments. Finally, a 600 W prototype is built to verify the theoretical analysis, and a maximum efficiency of 96.81% is achieved. © 2025 IEEE.