Design Tradeoffs in a Multi-Modular Capacitive Wireless Power Transfer System

This paper investigates the tradeoffs involved in designing a single module in a multi-modular scalable capacitive wireless power transfer system suitable for stationary and in-motion electric vehicle charging. A matching network optimization is employed to design the module over a range of power levels, air-gap voltages, input and output voltages, and switching frequencies to evaluate impacts on its efficiency, safety, and practical implementation. Results indicate that increasing module power decreases the required matching network inductances, but at the cost of increased fringing fields. Increasing switching frequency, however, decreases both the required inductances and fringing fields. Maximum and minimum limits on module power and switching frequency are determined based on a detailed air-core inductor design procedure. These module-level results are currently informing the design of a kW-level multi-modular capacitive WPT system with a 12-cm air-gap and a target power transfer density of 50 kW/m(2).