Power distribution control using switching devices for multiple charging system in resonant magnetic coupling

The resonant magnetic coupling (RMC) method has gained tremendous attention for its prospective features such as a large charging range or multiple device charging (multi-charging) application. In multi-charging systems, however, the receiving power ratio among the receivers is determined by coupling coefficient (k) or quality (Q) factor of each resonant coil. Therefore, it is difficult to supply appropriate power from single transmitter to plural receivers at the same time in various situations. To solve this problem, we apply a new efficiency control technique using non-linear devices. Two switches are connected to the resonant capacitance of receiving resonant coil in parallel and are turned on/off alternately at the transmission frequency. With this technique, receiving power ratio among the receivers can be controlled over a wide range at high efficiency.