Tunable Multistage Matching Network for Capacitive Wireless Power Transfer System

This paper presents a tunable multistage matching network (TMMN) for compensating variations in large air-gap capacitive wireless power transfer (WPT). The proposed multistage matching network is employed with a variable capacitor, whose capacitance value is suitably modified to compensate for misalignments and distance variations between couplers. This capacitor is connected at an intermediate port of the multistage matching network, allowing it to be realized using devices rated for a much lower voltage than the coupler voltage, which is rated at kilo-volt level for large air gap capacitive WPT system. A systematic methodology to design the proposed TMMN which maximizes its compensation range while maintaining low losses is also introduced. A 27.12-MHz prototype is designed, built and tested to validate the concept and design methodology.