T24.7 - A 6.78-MHz kW-Level 15-cm Air-Gap Misalignment-Tolerant Capacitive Wireless Power Transfer System for EV Charging Employing Roadway-Vehicle DC-DC Converters

In capacitive wireless power transfer (CWPT) systems for EV charging, coupling variations arising from roadway-to-vehicle coupler misalignment or varying vehicle ground clearances lead to significantly changed output power and increased losses. This digest introduces a roadway-vehicle DC-DC converter (RVDC) based CWPT system that mitigates this issue by using two DC-DC converters, one on the roadway side and one on the vehicle side. These converters control the input and output DC link voltages of the system during coupling variations to maintain a constant output power while ensuring a resistive loading of the inverter, reducing losses. A comprehensive design methodology for the proposed RVDC based CWPT system is presented. A 6.78-MHz, 15-cm air-gap, 7-kW RVDC based CWPT prototype suitable for EV charging is designed and built. Experimental results with 1-kW output power demonstrate that the inverter loading phase and output power remain constant for up to 50% lateral misalignment.