Communication-Less Receiver-Side Resonant Frequency Tuning Method for Magnetically Coupled Wireless Power Transfer Systems

The performance of wireless power transfer (WPT) systems using magnetic resonant coupling is drastically degraded by the resonant frequency shift. In this paper, we propose a communication-less receiver-side resonant frequency tuning method using a variable reactor based on a Class-D power inverter. The proposed method can compensate for the residual reactance in the receiver without any communication being required between the transmitter and receiver. Further, the effectiveness of the proposed method is evaluated through circuit simulations assuming a 1 kW-class 85-kHz WPT system for electric vehicle charging. It is observed that resonant frequency tuning can be achieved by maximizing the power received at the load.