A Three‐Phase Wireless Power Transfer System Based on Parity‐Time Symmetry Principle

ABSTRACT Wireless power transfer (WPT) technology has been widely studied and applied due to its ability to transfer energy without physical contact. Compared to single‐phase WPT systems, three‐phase WPT systems offer advantages in power density and magnetic field distribution. However, changes in the distance between coupling coils can alter transmission power. The parity‐time (PT) symmetry principle has been proven to enable stable power transmission in single‐phase WPT systems. To enhance power transmission stability in three‐phase WPT systems, this paper proposes a three‐phase WPT system based on the PT symmetry principle. Two major challenges must be addressed for three‐phase systems to operate in PT symmetric state: the design of circuit structures and parameter conditions that satisfy the PT symmetry and the complex circuit equations due to interphase mutual inductance. Firstly, a theoretical analysis is conducted to establish the conditions required for the three‐phase WPT system to operate in a PT symmetric state. The circuit equations are then simplified based on the characteristics of three‐phase symmetric systems. Following that, the transmission characteristics of the system are obtained using circuit theory. Finally, an experimental prototype is designed and built to validate the feasibility and effectiveness of the proposed three‐phase PT‐based WPT system.