Constant Load Voltage Characteristics in a Parallel-Parallel-Compensated Wireless Power Transfer System

This paper discusses load voltage characteristics in a parallel-parallel-compensated wireless power transfer (WPT) system. In this paper, the load voltage characteristic is analyzed at three resonant frequencies. As a result, the resonant frequencies to obtain a constant load voltage characteristic is theoretically derived, and thus, the voltage-source operation at the load side is achieved. The derived resonant frequencies fluctuate according to the coupling coefficient and the resistive load value. Therefore, this paper adopts a resonant frequency tracking control method to keep the load voltage constant even if the coupling coefficient and the resistive load value fluctuate. Experimental results exhibit the constant load voltage characteristic of the parallel-parallel-compensated WPT systems and agree with results of the theoretical analysis.