Development of Wireless Communicator for Receiver Current Phase Control in 6.78MHz Resonant Inductive Coupling Wireless Power Transfer

Recently, resonant inductive coupling wireless power transfer (RIC-WPT) systems operating at 6.78 MHz for charging mobile and consumer electronic devices placed in a wide area have attracted researchers’ attention. In RIC-WPT systems, methods employing reactance compensators utilizing semiconductor switches have been proposed to match the resonant frequencies between the transmitter and receiver. To implement such a reactance compensator on the receiver side, synchronization between the transmitter and receiver control signals is required. In other words, a constant phase difference must be maintained between the control signal on the transmitter side and that on the receiver side. Therefore, this study presents the development of a radio frequency (RF) wireless communication method for the receiver side control in a 6.78 MHz RIC-WPT system. The communication system adopts quadrature demodulation and a phase-locked loop to maintain a constant phase difference between the transmitted reference signal and the demodulated signal. The experimental results indicate that the output power fluctuation caused by the developed communication circuit is expected to be less than 10%, suggesting its potential applicability to 6.78 MHz RIC-WPT systems.