Unbalanced Reflected Impedances and Compensation of TS Dynamic Wireless Charging System

A three-phase dynamic wireless charging system with balanced primary currents can yield a constant induced voltage. Compared with a three-phase primary and three-phase secondary system, a three-phase primary and single-phase secondary (TS) system has a simpler coil structure and circuit topology on the secondary side but its reflected impedances are unbalanced among three phases and vary with the position. In order to obtain balanced primary currents, the suitable three-phase inverter and compensation topology need to be studied. This article accurately describes the unbalanced reflected impedances of the TS system and reveals its impedance characteristics varying with position. The three-phase LCC topology for the TS system is provided to solve the problems of unbalanced and varying reflected impedances and the resonance conditions are also given. In addition, the corresponding topology and adjustment method of the inverter are proposed to ensure its balanced primary currents and constant induced voltage. Furthermore, a prototype was implemented to verify the topology and control method.