A unity power factor single-stage contactless power transfer system using variable frequency-phase shift control

This paper presents a variable frequency-phase shift(VF-PS) control method used in series/series compensated inductive contactless power transfer (ICPT) system with unity-power- factor input. VF-PS control searches proper working point automatically, which provides a way avoiding considering the complex ICPT output characteristics caused by the changing coupling coefficient and load and ensures ZVS switching. With the proposed control strategy, the function of power factor correction (PFC) is naturally achieved, and then the traditional front-end PFC stage can be removed. The mathematical relationship between maximum output power, output voltage and coupling coefficient is derived. Simulation and experiment work verified the proposed control method and mathematical derivation.