Large air-gap coupler for inductive charger for electric vehicles

A novel magnetic coupler with large air gap is presented. It is developed for the electric vehicle's automatic inductive charger. The new inductive coupler proposed has sufficient exciting inductance even if it has a large air gap. The calculated exciting inductance is 40 /spl mu/H at 2 turns of winding and 5 mm air gap, which agrees well with the measured value. In order to assess the generation of heat caused by the eddy current, the magnetic flux densities in the inductive charger and also a flat iron plate, to which the inductive charger is attached, are calculated. The conversion efficiency with the coupler and a MOSFET full-bridge inverter of 100 kHz is 97% at 8.3 kW output.