Improving the Transmission Distance of Wireless Power Transfer Systems Using Coplanar Double-Coil Coupler

A method to improve the transmission distance of the wireless power transfer system is proposed using a coupler in which the transmit and receive coils are coplanar double-coil, respectively. Compared with the traditional two-coil coupler, the coupler adds a passive coil on the same plane of the primary side and the secondary side respectively, which does not occupy the power transmission space. The circuit model using series compensation is established. The frequency characteristics and power transfer capability of the system are analyzed. The resonant frequency is optimized. The proposed coupler is found to have stronger coupling and lower coil self-induced voltage than the two-coil system, which is suitable for long-distance wireless power transfer. Finally, a simulation model was built to achieve a transmission distance of 50cm and transmission power of 4kW.