A High-Power Large Air-Gap Multi-MHz dc-dc Capacitive Wireless Power Transfer System for Electric Vehicle Charging

This paper presents a record 4.2-kW large air-gap multi-MHz dc-dc capacitive wireless power transfer (WPT) system suitable for electric vehicle charging, using a passive power combining architecture-based inverter paralleling technique. A comprehensive system design methodology is presented, and the tradeoffs between system efficiency, field safety limits and air breakdown limits are discussed. The effectiveness of the proposed inverter paralleling technique in maintaining constant output power and mitigating the timing and component tolerance related mismatches between the paralleled inverters are thoroughly investigated. The analytical findings are validated using simulations. Finally, the outcomes of this analysis are experimentally validated using a 6.78-MHz, 12-cm air-gap prototype capacitive WPT system that transfers 4.2 kW dc power, which to the author’s best knowledge is the highest power large air-gap dc-dc capacitive WPT system ever reported.