Single-stage electrolytic capacitor-less AC-DC converter with high frequency isolation for EV charger

This paper proposes a new single-stage ac-dc converter with high frequency isolation which is suitable for on-board EV/PHEV chargers. The proposed single-stage structure does not have a diode bridge at the input stage and electrolytic capacitor at the dc-link. The two single-phase full-bridge converters play a double role as both ac-dc converter for PFC and the primary-side circuit of the isolated dc-dc converter. They are configured such that the fundamental components of the chopped ac voltages are cancelled at the primary winding voltage of the transformer, thus reducing magnitude of the magnetizing current which results in reduced volume and core loss. Also, the proposed converter can achieve ZVS turn on of switches and ZCS turn off of diodes. A 3-kW prototype of the proposed converter is built and tested to verify the validity of the proposed operation.