Fixed-Frequency Parity-Time Symmetric Operation Using a Dual-Side Active Tuning Method for Wireless Power Transfer Systems

In conventional parity-time (PT)-symmetric wireless power transfer (WPT) systems, capacitance drift, an unavoidable factor in practical applications, can induce detuning between the transmitter (Tx) and receiver (Rx), thereby degrading system performance. Additionally, significant frequency variations arising from the frequency-dependent nonlinear saturation gain can lead to regulatory non-compliance and complicate filter design. This paper proposes a simple dual-side active tuning method to achieve fixed-frequency PT-symmetric operation. Synchronous series compensators (SSCs) are introduced to ensure balanced energy distribution between the Tx and Rx. Active matching adjustment is required only on the Rx-side compensator, whereas the Tx-side compensator self-adjusts automatically. Theoretical analysis indicates that both the output voltage and transfer efficiency remain robust against variations in compensation capacitance, self-inductance, coupling coefficient, and load. Moreover, a parallel inductor at the inverter output achieves zero-voltage switching (ZVS) across the entire operating range. Experimental results demonstrate that the system maintains a constant output voltage across a wide coupling coefficient range (0.109-0.518), even with over 14% variation in compensation capacitance and 10.68% variation in self-inductance.