A multi-resonant converter for non-contact charging with electromagnetic coupling

A parallel resonant power converter (PRC-LLCC) is analyzed for automatic inductive charging applications. The tank circuit of this power converter consists of a leakage inductance, a magnetizing inductance and two power capacitors with an inductive output filter. This converter allows the transfer of power without oversizing the inverter and a soft-switching mode of the transistors. The soft-switching mode and the sensitivity to the load variation, the coupling factor and the air gap (6-8 mm) are studied using the first harmonic method. The choice of the working range and the validity limit of the analysis method are presented. Theoretical results are validated experimentally with a 3 kW prototype.