A Tuning Method for Wireless Power Transfer System against Dual-side Capacitance Drift Based on Equivalent Impedance Decoupling

This paper proposes a tuning method for wireless power transfer (WPT) system against dual-side capacitance drift based on equivalent impedance decoupling (EID). In the proposed method, the imaginary part of the primary and secondary impedance caused by capacitance drift can be decoupled and compensated directly so that the system oscillation of the existing tuning methods is avoided. By adjusting the conduction angle of the secondary semi-active rectifier and the operating frequency, the system can be tuned for high efficiency and unity power factor. The experimental results prove that the proposed method can improve the system efficiency by 10% under 20% dual-side capacitance drift.