A PT-symmetric wireless power transfer system with dual-frequency switching capability

Abstract In this paper, a dual-frequency switchable wireless power transfer (WPT) system based on parity–time (PT) symmetry is proposed. For the transmitter, a high-efficiency switch-mode amplifier is employed as the negative impedance to provide the required gain. To realize dual-frequency operation, the magnetic coupling coil is designed as triple-tap structure which can be used to create two distinct series inductor-capacitor (LC) resonant branches by switch. At the receiver, two parallel inductor-capacitor-resistor (LCR) resonant circuits with corresponding dual operational frequency of transmitter are adopted to achieve stable energy reception. The transmission characteristics of the system under different frequency switching modes are analyzed theoretically and verified experimentally. The results demonstrate that, whether operating in the low- or high-frequency mode, the system can maintain the PT-symmetric state in the strong coupling regime, achieving robust and efficient WPT with system efficiency >80%. The proposed dual-frequency switchable WPT system can offer a theoretical reference for practical reconfigurable wireless charging applications requiring dual operating frequencies.