Multi-objective optimization of capacitive wireless power transfer systems for electric vehicle charging

This paper presents a methodology for multi-objective optimization of capacitive wireless power transfer (WPT) systems for electric vehicle charging that allows for a favorable tradeoff between power transfer density and efficiency. By quantifying the tradeoff between these two objectives, this multi-objective optimization approach can inform engineering decisions, given the requirements of a particular charging application. The capacitive WPT system considered in this paper utilizes L-section matching networks with air-core inductors and capacitors realized using the parasitic capacitances of the system. The proposed optimization methodology incorporates constraints on achievable matching network capacitances, realizable inductor designs, and fringing electric fields set by safety considerations. The models used in the optimization methodology are validated using a 12-cm air-gap 6.78-MHz prototype capacitive WPT system, which transfers 589 W, achieving a power transfer density of 19.6 kW/m2 and an efficiency of 88.2%.