Three-phase DC-type isolated electric vehicle charger featuring zero voltage switching

This work presents a flexible isolated soft-switched AC-DC converter well-suited for implementing a Fast DC-type electric vehicle battery charger. The proposed topology is based on a modified direct-conversion galvanic isolated AC-DC forward-type converter featuring zero-voltage-switching or ZVS. The proposed circuit modifications allows the system to perform well in terms of losses when the converter is designed to cope with a wide range of electric vehicle battery voltages, e.g. 200 to 1000 V. In fact, the new functionality added limits the typical large free-wheeling times which would occurs in the state-of-art solutions for low battery voltage levels. This yield to great reduction on conduction losses in the semiconductors. The paper gives a detailed description of the proposed circuit, and suited modulation and feedback control schemes. Simulation results are shown attesting the feasibility and also verifies the advantages of the presented power converter for a 50 kW application.