Study on Composite Structure of Tian-Font Magnetic Shielding and Anti-Series Active Coils for Wireless Power Transfer System

Abstract

In the wireless power transfer (WPT) system of electric vehicles, conventional magnetic shielding techniques usually rely on a large number of magnetic cores and aluminum plates, posing a cost challenge. To address this issue, this paper proposes a composite structure of Tian-font magnetic shielding and antiseries active coils to minimize material use while maintaining safe magnetic leakage levels. First, a calculation method of the magnetic field is introduced to analyze magnetic leakage in the target region of the system, providing a theoretical basis for optimization. Secondly, a composite shielding structure is introduced, its working principle is analyzed in detail and its circuit model is derived. Subsequently, a method for optimizing coil parameters is presented, and the optimal coil and shielding material parameters are determined. Finally, a WPT system based on this structure is built and verified through simulation and experiment. Results show that under a transmission power of 4 kW, the maximum magnetic leakage in the target region before and after offset is lower than 27 μT and the transmission efficiency is more than 93%. Compared to the same size, non-gouged magnetic shield structure, it saves 36.78% of the magnetic core and 32.52% of the aluminum plate.