A novel multi-level phase-controlled resonant inverter with common mode capacitor for wireless EV chargers

A novel multi-level phase-controlled resonant inverter is presented in this paper. The inverter is intended for wireless energy transfer systems. The proposed converter topology is obtained with two identical multi-level dc-ac inverters, connected in parallel through two common-mode capacitors. To overcome high voltage and current stresses across the switches, the proposed topology splits the voltage and current in each phase so that high power applications are possible with the proposed converter. An asymmetrical phase-shift modulation with a constant frequency regulates the output voltage in order to overcome the drawback of a wide range of operating frequency that occurs in conventional wireless power topologies. Theoretical and simulation results of the proposed circuit show that the converter performance is suitable for high power contactless electric vehicle (EV) chargers. The performance of the proposed converter is confirmed with experimental results using 8 inch air gap coreless transformer, which has dimension 2.5 by 2.5 feet. The converter is tested at 120 V input with the output of 120 V at a full power of 1 kW with a maximum efficiency of 93.7%.