Comprehensive Analysis of Side-Placed Metamaterials in Wireless Power Transfer System

In this article, we propose the side-placed negative-permeability metamaterial (NPM) and zero-permeability metamaterial (ZPM) in the wireless power transfer (WPT) system to simultaneously enhance the level of efficiency and meet the electromagnetic field (EMF) safety regulations. A theoretical analysis, simulation, and experiment are conducted to verify the feasibility of the proposed system model. Based on the principle of magneto-inductive waves (MIWs) and the shielding theory, the transmission characteristics of the WPT system without and with two NPM slabs, two ZPM slabs, and the combination of NPM and ZPM slabs are analyzed. The results demonstrate that the ZPM slabs and the combination of NPM and ZPM slabs have a high efficiency improvement when the transfer distance is located under 40 cm and exceeds 40 cm, respectively. Both methods can control the EMF leakage. Moreover, the side-placed metamaterial exhibits tolerance to the misalignment of the coil. Finally, comparative studies on the ZPM slab and aluminum are carried out. The experimental and simulation results show that the ZPM slab performs better than aluminum.