A coreless hybrid coil design for the wireless power charging system

Abstract

In the dynamic magnetic coupling wireless charging system, the optimal design of the resonant coil structure is one of the key technologies to ensure the power transmission with the high efficiency. In this paper, based on the good static characteristics of system, a hybrid structure coil is proposed to improve the efficiency and the dynamic anti-offset ability of system. Based on the simplified circuit model of the PP compensation network, the efficiency and the output power of system under the optimal load impedance are derived based on Kirchhoff voltage law. According to the efficiency expression, the number of the turns of the hybrid coil and the radius of the coil are optimized, and the parameter design method of the hybrid coil under the specific environment is given. In order to evaluate the dynamic performance of the system, a quantitative evaluation index is given, which synthesizes three kinds of the dynamic characteristics of the axial, the radial and the angular. Finally, the feasibility of the designed coil is verified by the finite element simulation.