A Wireless Power Transfer System With Dual Switch-Controlled Capacitors for Efficiency Optimization

This article proposes a novel wireless power transfer (WPT) system with switch-controlled capacitor (SCC) where variable capacitance and efficiency optimization are realized. The optimum asymmetrical voltage cancellation (OAVC) control is applied to realize wide-ranging soft-switching operation for the active bridge converters. The pulsewidth of the active bridge inverter regulates the output voltage, and the pulsewidth of the active bridge rectifier optimizes power delivery efficiency. The SCCs in the transmitter and the receiver sides are regulated for the zero-voltage switching operation and the resonant condition, respectively. The online estimation of mutual inductance is carried out to adapt the coupling deviations of the WPT system in real time. A 650-W prototype is built to verify the feasibility of the proposed WPT system and the effectiveness of the OAVC control. The experimental results show quite good performance and efficiency improvement for the WPT system at various loads.