Metamaterial for wireless power transfer system at 13.56MHz with coil misalignment

Abstract

Power transfer efficiency (PTE) of wireless power transfer decreases sharply due to divergence of magnetic field when the distance between transmitter (Tx) and receiver (Rx) coils increases, especially with coil misalignment. However, electromagnetic (EM) metamaterial (MM) can manipulate the direction of EM fields due to its negative effective permeability. Metamaterials can mitigate the effects of low efficiency under coil misalignment. In this paper, an ultra-thin and extremely sub-wavelength magnetic MM is designed for a 13.56 MHz WPT system to enhance magnetic field and its PTE. Two coil situations of lateral or angular misalignment are both investigated with metamaterial. The simulation and experimental results indicate that the WPT efficiency decreases caused by misalignment and it can be significantlly enhanced by using metamaterials. Therefore, the metamaterial is an effective means to improve PTE of WPT under coil misalignment in a more practical environment.