An Investigation of Compensation Networks for Three-coil Wireless Power Transfer

Wireless power transfer (WPT) can power loads over large air gaps with relatively high efficiency, offering an innovative and convenient charging way. Especially, three-coil WPT shows the superiority, namely, the extended transmission distance with high efficiency. However, compensation networks in three-coil WPT still necessitate investigation. In this paper, three compensation topologies including S-S-S, S-S-P and N -S-S are investigated. Some important characteristics including load-independent constant voltage (CV), load-independent constant current (CC) and zero voltage switching (ZVS) are concluded and compared among different topologies. Detailed design procedures of compensation networks based on three-coil couplers are demonstrated. The fundamental analysis, coil design, compensation topologies and experimental verification are all presented and discussed in this paper.