A Flexible Wireless Power Transfer System With Switch Controlled Capacitor

Wireless power transfer (WPT) with a switch-controlled capacitor (SCC) is proposed in this paper for compensating load impedance which is related to the coupling coefficient of coils and the load variations. In general, the power supply in the WPT system is desired to output constant voltage under varied load impedance. In the proposed WPT system, the resonant capacitor in the primary side is replaced by an SCC and only diode full-bridge rectifier in the secondary side is used. The SCC realizes adjustable capacitor which makes it flexible to control the capacitance. At the same time, the modulation of the SCC aims to guarantee an inductive input impedance of the WPT system, achieving soft switching and reducing the high switching losses of the high-frequency inverter. In order to verify the feasibility of the proposed method, mathematical analysis, and experimental validations have been thoroughly performed. The experiment results show that the WPT system maintains a stable output voltage by through the regulation of the SCC according to the load variations.