Design and Optimization of High Misalignment Edge-Enhanced Stepped Coil Structure for Dynamic Wireless Power Transfer System

Abstract

In order to address the issue of mutual inductance variation in dynamic wireless power transfer systems for electric vehicles, which leads to significant fluctuations in system output, an edge-enhanced stepped coil structure is proposed to improve the system's anti-offset performance. Firstly, a model of the edge-enhanced stepped coil structure has been constructed, and the characteristics of mutual inductance variation for this structure have been analyzed. Secondly, a method for calculating mutual inductance in a stepped coil structure is proposed based on the Biot-Saval law. Then, based on the proposed method for calculating mutual inductance in stepped coils, the parameters of the edge-enhanced stepped coil structure are optimized according to the principle of minimizing fluctuations in mutual inductance. Additionally, a magnetic core structure that aligns with the coil's characteristics is designed to enhance both mutual inductance and the coil's resistance to offset performance. Finally, a 500 W experimental prototype has been constructed. The experimental results show that the mutual inductance fluctuation rate of the edge-enhanced stepped coil does not exceed 5% when the Y-axis direction is offset by 50% (362 mm) of the outer diameter of the transmitter coil. The transmission efficiency of the system is as high as 93.92%, and the fluctuation rate of the output current is less than 5%.