Research on combined shielding layer and transmission efficiency of wireless charging system for EVs

Abstract

The ferrite core plays an essential role in coupling enhancement and magnetic shielding for the wireless power transfer (WPT) of electric vehicles (EVs). However, with the charging power level rises, the single-layer ferrite acts as an electromagnetic shielding device for the system. Its working effect during the charging process is not in meeting the shielding requirements. In this paper, a composite shield consisting of ferrite and ultra-thin silicon steel (UTSS) is proposed, taking advantage of the excellent electromagnetic properties as well as the mechanical properties of UTSS. A numerical model was developed to compare and analyse the static parameters of the coil, the transmission efficiency of the system and the shielding effect when different shielding layers are added. Verification of the feasibility and advantages of composite shields. The final shield was fabricated and an experimental platform was built to verify it. Numerical calculations and experimental results show that the transmission efficiency of the composite shield can reach 92.25%, an improvement of 7.96% compared to the unshielded case. The structure also significantly suppresses electromagnetic field leakage, the maximum value of the field differs by 88.41% compared to unshielded.