Compensation Network Design Method for Capacitive Power Transfer System Considering Coupling Variation

In capacitive power transfer systems, the coupling variation is inevitable due to the air gap variation and coupler misalignment. This paper proposes a new compensation network design method for capacitive power transfer systems tolerant to coupling variation. The proposed method effectively transforms the input impedance of the compensation network into a single resistive point in the presence of coupling variations. The new design method is derived based on two-port network analyses and provides practical design guidelines applicable to various capacitive power transfer systems. The proposed methods offer minimized VA rating and enhanced power transfer capability by achieving a zero-phase angle operation under coupling variations. Also, the designed network can be modified for the preselected phase angle to guarantee the zero-voltage-switching operation with higher efficiency. A design example is presented, and its effectiveness is validated through simulations and experimental results.