Comprehensive Analysis of Negative Energy Feedback–Based Mistuning Correction Strategy in Wireless Power Transfer Systems

ABSTRACT Impedance mismatching is a common phenomenon in wireless power transfer (WPT) systems. Especially in the charging process, the random impedance fluctuation caused by factors such as resonant parameter drift and coils misalignment can seriously decrease the power transfer ability. Therefore, a negative energy feedback mechanism is utilized in this study to convert the reactive power generated by the mistuning state back into active power for mistuning correction. In contrast to universal techniques like frequency tracking and resonant parameter compensation, this technology allows for complete decoupling of the interrelationship among resonant frequency, resonant parameter, and resonant state without requiring auxiliary control or detection circuits. This results in excellent response speed and robustness at a minimal cost of an additional energy storage capacitor and two switches. In this paper, the operation principle, convergence, and features of the negative energy feedback process are comprehensively analyzed. Furthermore, a 50‐W prototype operating under longitudinal misalignments of 3–6 cm, lateral misalignments up to 8 cm, and angular misalignments up to 45° was built, and the experimental results demonstrate close agreement with theoretical calculations.