Abstract:In the EV (electric vehicle) wireless charging system, the charging process of the loaded lithium battery is constant current followed by constant voltage. Therefore, the WPT(wireless power transfer) system needs to have the ability to achieve two output states at the same time, and smoothly switch between the two output states. Based on this, this article analyzes the conditions for achieving load independent constant current and constant voltage output in a bilateral LCC(inductor-capacitor-capacitor) topology, and provides a parameter design method. In response to the possibility of random displacement in different directions in the system, a bidirectional coaxial planar coil structure is adopted, where the primary coil is composed of two coils wound in opposite directions, inner and outer, in series. The proposed EV wireless charging system has the ability to simultaneously achieve constant current/voltage output through simulation and experimental verification, and can still achieve stable output under multi-directional offset conditions.