Research on Porous Compensated Active Metal Magnetic Shielding Structure of Wireless Power Transfer System for Electric Vehicles

ABSTRACT

In wireless power transfer (WPT) systems for electric vehicles, a major challenge in current research is how to reduce magnetic leakage while maintaining high transmission efficiency and minimizing the use of magnetic shielding materials. To address this, this paper proposes a porous‐compensated active metal magnetic shielding structure. This structure ensures magnetic leakage safety while significantly reducing the use of magnetic shielding materials, and introduces anti‐series active shielding coils to reduce the leakage magnetic field in the target area. First, this paper adopts a rectangular coil magnetic field calculation method based on vector magnetic potential. This method is used to analyze magnetic leakage at the system's target surface, providing a theoretical basis for magnetic leakage optimization. Second, a magnetic shielding structure is proposed, with a detailed analysis of its operating principle and derivation of its circuit model. Then, an optimization method is proposed based on the magnetic leakage distribution at the target surface to minimize the volume of shielding material while ensuring magnetic leakage safety. Finally, based on the optimized coil and magnetic shielding material parameters, a WPT system featuring a porous‐compensated active metal magnetic shielding structure was developed. Simulation and experimental validation demonstrated the effectiveness of the proposed magnetic shielding structure and method. The results show that at an output power of 4 kW, while maintaining leakage flux safety, the design saves 32.7% of core material and 28.7% of aluminum plate material compared with solid‐core and solid‐aluminum plate configurations of the same size, respectively. Furthermore, the leakage flux in the target area before and after offset is below 27 T, and the transmission efficiency exceeds 94%.