Wireless Power Transfer System With High-Order Compensation Network Based on Parity-Time-Symmetric Principle and Relay Coil

The parity-time (PT) symmetric principle has been proved that it can improve the degree of freedom of the wireless power transfer (WPT) system with multiple repeaters, while maintaining constant transfer efficiency and transmission power. This article presents a novel three-coil WPT system with S/S/PS compensation network based on the PT symmetry principle to further expand the exact PT-symmetric region and increase the output power. First, the PS compensation network increases the order of the system. This problem has been solved by simplifying the PS compensation network to the S compensation network with equivalent circuit theory. Second, it is found that the proposed system has smaller critical coupling coefficient and is able to provide higher output power compared to traditional three-coil PT-symmetric system. Third, the capacitance distribution ratio can be designed to make the system adapt to different application scenarios. Finally, an experimental prototype 48 W is developed to verify the proposed system.