Studies on the different assembles of magnetic shielding pieces in electromagnetic induction-type wireless charging system

In this paper, the different assembles of magnetic shielding piece made from ferrite were studied on a simple test platform. The distribution of the voltage could be significantly focused by the piece in transmitter and the coupling coefficient k was also improved. The piece in the receiver could help improve the voltage conversion efficiency η. The symmetrical mode (aa) (with basic pieces in both sides) were thought to be the optimal basic mode. It was found that the magnetic flux density in mode (aa) was significantly higher than that in mode (oo) (without basic piece). The deflection angle θ of the central magnetic field in mode (aa) was significantly reduced compared with that in mode (oo). Different additional pieces were attached on the base pieces, and four assemblies were designed to investigate the shape effect on the system. The effect of the peripheral addition was weaker than the central addition either in the transmitter or the receiver. The high value of the k and η for asymmetrical mode (db) (with central and peripheral additions in transmitter, and with central addition in receiver) suppressed many reported papers of wireless charging.