Receiver Capacitor Selection Method for Reducing Leakage Magnetic Field in Double-Sided Wireless Power Transfer System

In wireless power transfer (WPT) system, some of the magnetic fields generated from the transmitter (TX) are not transferred to the receiver (RX), but leak into the air. In particular, in a double-sided WPT system that can charge two RXs simultaneously with one TX, the leakage magnetic field is increased. There are several methods to reduce the leakage magnetic field, but all of those methods require additional equipment and are focused on the 1 TX-1 RX WPT system. This paper proposes a method to reduce the leakage magnetic field in the double-sided WPT system by adjusting the current phase difference of each coil without using any equipment. In addition, we introduce how to select the optimal RX capacitor to make the phase difference that reduces the leakage magnetic field. By applying the proposed method, the leakage magnetic field can be reduced by up to 43.7 % and at least 11.1 % at the observation point compared to the conventional method.