Improving the Transfer Efficiency of a Wireless Energy Transfer System Using Multiple Coils

Abstract

This study is to suggest using multiple transmission coils to improve the energy transfer efficiency of a wireless energy transfer (WET) system which aims to power electronic appliances such mobile phones, labtops, iPads, etc, without using cables. The original WET system consists of a large room-size transmission coil transferring energy wirelessly to a small receiver coil built insider an electronic appliance. The newly proposed system is to replace the single transmission coil with 3 orthogonally aligned transmission coils. The aim is to create a multi-oriented magnetic field so that energy transfer efficiency will be relatively more stable when the receiver coil changes in orientation. Our simulation results show that at some worse-situation orientations of the receiver coil, the increase in transfer efficiency is many folds, from 0.4% in the worse situation to a 2.75% after using the multiple-transmission-coil method. This, to some extent, safeguards the wireless charging process from a large power drop to a much smaller power drop during possible random motions of the receiver. But, on the other hand, the improvements obtained from the proposed system in the normal high-efficiency situations are not very significant.