Magnetic Field Leakage Reduction and Efficiency Enhancement of Wireless Power Transfer by Using Side-Positioned Coil Array

A side-positioned coil array printed on a PCB slab effectively suppressing the magnetic field leakage of a magnetic resonant wireless power transfer (WPT) system while preserving good transfer efficiency is presented in this paper. Based on a basic two-coil WPT system working at 6.78 MHz, a slab with four coils printed on both sides is proposed and fabricated. The effect of the slab on the magnetic field shielding and power transfer efficiency is investigated through physical experiment, when the slab is placed at the side of the WPT system. The magnetic fields around the WPT with and without the slab are measured by a magnetic probe under the control of a 3D scanning system. The measured results show that the proposed coil array reduces the magnetic field leakage by an average of 6.42 dB without degrading the transfer efficiency, instead it improves the efficiency of the WPT system at an average of about 27%.