A Fixed-Frequency Single-Stage Wireless Motor Driver Utilizing a Modified Class-E Resonant Topology with a Controlled Variable Inductor and Stepped-Core Tx/Rx Couplers

This paper presents a single-stage wireless motor driver (WMD) based on a modified Class-E resonant topology for DC motor control. An active clamping circuit and a high-order harmonic suppression circuit are implemented to enhance switch reliability and optimize power transfer efficiency. Additionally, a variable inductor module, along with a stepped-core transmitter (Tx)/receiver (Rx) coupler set, is integrated into the resonant tank to enable fixed-frequency switching while maintaining high efficiency during coil misalignment. The paper covers system descriptions, circuit operating modes, steady-state analysis, and the design process of the magnetic components. A 180-W power rating WMD prototype was constructed to validate the theoretical analysis. The resonant tank demonstrated an efficiency improvement of up to 4.79%, and the system achieved a maximum efficiency of 89.72%, offering practical validation of the proposed concepts. © 2025 IEEE.