Electromagnetic radiation generated by the wireless power transfer (WPT) can be harmful to humans and environment. In order to satisfy the safety requirements, electromagnetic leakage to the nearby transmission channels should be controlled below a safe level. Except for the ferrite and metallic shielding materials, several researchers have put forward the zero-permeability metamaterial (ZP-MM). However, there have been few scientific studies with the application of ZP-MM in four-coil WPT systems. In this paper, we propose an optimized ZP-MM for shielding leaked magnetic field. Next, we setup a miniaturized WPT system loaded with ZP-MM at 13.56MHz. As a result, when ZP-MM is used, the transmission efficiency is reduced about 28.8% and the magnetic field magnitude of the receiver has been decreased about 72.7%, compared to free space. To better highlight the shielding effect, the aluminum plate is inserted in the middle of the Tx and Rx coils. The results show that the shielding effect of ZP-MM is better than aluminum plate. Obviously, the proposed ZP-MM has good performance in magnetic field shielding for WPT systems.

Wireless power transfer,zero-permeability metamaterial,magnetic field shielding,electromagnetic radiation