Full‐Range Adaptive Charging Control for PT‐Symmetric Wireless Power Transfer Systems Under Variable Load and Mutual Inductance

ABSTRACT This paper presents a full‐range adaptive charging control strategy for PT‐symmetric wireless power transfer (WPT) systems, specifically designed to address the challenges of fluctuating mutual inductance, variable loads, and extended transmission distances in dynamic applications such as drone in‐flight charging. The proposed method achieves seamless constant‐current (CC) and constant‐voltage (CV) charging across a wide range of mutual inductance and load variations. Leveraging the frequency‐splitting phenomenon inherent in PT‐symmetric circuits, the system identifies secondary‐side resonant characteristics that traditional methods often fail to detect. Mutual inductance and load variations are dynamically estimated through primary‐side voltage and current measurements, eliminating the need for direct communication with the secondary side. A hybrid control strategy is adopted: Phase‐shift control is applied in the strong coupling region to ensure CC/CV operation, while pulse‐width modulation (PWM) control maintains output voltage regulation under weak coupling. The system adaptively adjusts the operating frequency and compensates for mutual inductance variations in real time, ensuring stable energy transfer across coupling region transitions. Experimental validation confirms the method's effectiveness, demonstrating a rapid control strategy switching time of 287 ms and a 56.7% expansion in the CV charging range compared to conventional approaches. This work introduces a robust, scalable, and adaptive control framework for PT‐symmetric WPT systems, significantly improving energy delivery stability and operational flexibility under dynamic wireless charging conditions.