Comparison Study on SS and Double-Sided LCC Compensation Topologies for EV/PHEV Wireless Chargers

This paper compares the characteristics of the series–series and double-sided Inductor-Capacitor-Capacitor (LCC) compensation topologies for electric vehicle (EV) wireless chargers. Both the well-tuned and mistuned topologies for the two compensation methods are analyzed in detail. The mistuning considered here is mainly caused by the variations of the relative position between the primary and secondary sides. The output power displacements caused by mistuning are compared for both compensation topologies, as well as the impacts of the load variations on the performances of the mistuned topologies. The voltage and current stresses on components are also studied. The comparative result shows that the double-sided LCC compensation topology is less sensitive to mistuning. A double-sided LCC-compensated EV wireless charger system with up to 7.7-kW output power is built to verify the analysis results. A peak efficiency of 96% from dc power source to battery load is achieved.

I. Introduction

Wireless charging is gaining recognition as a preferred charging method for electric vehicles (EVs) [1]– [6] due to its advantages of convenience, safety, reliability, and weather-proof features. There are three types of wireless charging for EVs or plug-in hybrid EVs (PHEVs): static wireless charging, in which parked cars are charged; semidynamic charging, in which decelerating cars before traffic signals are charged or cars are charged opportunistically; and dynamic charging, in which normally running vehicles are charged [5], [7], [8]. A typical EV/PHEV wireless charging system is shown in Fig. 1. It consists of an ac/dc converter with power factor correction, a high-frequency dc/ac converter, primary and secondary coils with compensation circuits, and a rectifier or a power regulator with a filter [9]. Distinguishing from traditional conductive chargers (usually plug-in), the wireless charger takes advantage of the alternating magnetic field within a large gap to transfer power instead of physical connection or a regular transformer.