A High Frequency Wireless Power Transfer System for Electric Vehicle Charging Using Multi-layer Non-uniform Self-resonant Coil at MHz

A high power, high frequency wireless power transfer system for EV applications is proposed in this paper with lightweight and compact coil design. Leveraging a multi-layer non-uniform self-resonant coil, no external capacitor is needed for compensation and the high frequency conduction loss is mitigated by sharing current between multiple copper layers. Prototype coils with 200 mm radius are fabricated and tested, achieving quality factor over 450 at 3 MHz. The optimized design for both coils and a GaN-based power stage are detailed and validated experimentally. Experimental tests show 93.2% dc-dc efficiency with 2.4kW transferred across a 100 mm air gap.