Design of new metamaterial with negative permeability for efficient wireless power transfer

Abstract

SummaryTo solve the problem that the efficiency of a wireless power transfer system decreases with increasing transmission distance, metamaterial (MTM) has offered an effective solution. In this paper, a novel compact MTM with negative permeability is designed to improve the transfer efficiency of wireless power transfer at the operating frequency of 13.56 MHz. By placing the MTM slab at different positions between coils, the transmission coefficient of the wireless power transfer system with one MTM slab is calculated. Also, the impact of transmission distance is studied. Based on the two‐port network method, the transfer efficiency of wireless power transfer is respectively calculated for the system with one MTM slab and with two MTM slabs. The results demonstrate that transfer efficiency at the transmission distance of 150, 200, and 250 mm are, respectively, 82.4%, 67.8%, and 47.3% when one MTM slab is introduced. For the system with two MTM slabs, the corresponding transfer efficiency is 84.9%, 77.3%, and 66.1% separately. Compared with the system without MTM, it is found that there is a large improvement in transfer efficiency especially when two MTM slabs are positioned between coils at the transmission distance of 250 mm. The magnetic field distribution of the system with one or two MTM slabs introduced is investigated. The results show that magnetic coupling between coils is strengthened, which is favorable for transfer efficiency enhancement.