A 600W 6.78MHz Wireless Charger for an Electric Scooter

This paper presents a 600 W electric scooter wireless charging solution operating at a frequency of 6.78 MHz. At the transmitter end, a load-independent Class EF push-pull (differential) inverter with GaN transistors was used to drive a 33 cm square-shaped copper pipe coil. A full-wave voltage-tripler Class D rectifier with silicon Schottky diodes was connected to a 24 cm-by-26 cm trapezoidal receiver coil (also made of copper pipe) mounted underneath the steel frame of the scooter. In order to reduce the eddy current and magnetic losses in the steel chassis, parts of the electric scooter frame were shielded with copper tape. With the battery recharging in situ at 600 W, the IPT system achieved a DC-to-DC efficiency of 84 %.