A high-frequency high-efficiency three-level LCC converter for high-voltage charging applications

For high-voltage charging applications, this paper introduces a variable-frequency zero-voltage-switching three-level LCC resonant converter, which is able to utilize the parasitic components of the high-turns-ratio transformer. By applying the three-level structure in the primary side, low-voltage MOSFETs can be used to minimize the conduction loss. Therefore, the switching frequency can be increased to shrink the size of passive components. In addition, a simulation-based process is presented for designing the resonant-tank parameters as a trade-off among the efficiency, power density and component stresses. The principle of operation for the converter is analyzed and verified on a 3 kW, 200 kHz, 10 kV charger prototype.