Reversed-output current-assisted ZVS phase-shift PWM DC-DC power converter using synchronous rectifier

A new reversed-output current-assisted full-bridge ZVS phase-shift PWM DC-DC power converter with a high-frequency transformer has been developed and its characteristics are discussed. Power MOSFETs operating as synchronous rectifier switching devices in the transformer secondary side are implemented in the rectifier stage to reduce conduction power losses and also to extend the ZVS commutation area of the transformer primary side power MOSFETs from the rated load to no load by using reversed output current. The steady-state operation of the proposed phase-shift PWM controlled DC-DC power converter is described in comparison with the conventional ZVS phase-shift PWM DC-DC power converter using diode rectifiers. The practical effectiveness of the proposed ZVS phase-shift PWM DC-DC power converter is proved by using 2.5 kW-32kHz circuit prototype. A 97% efficiency of the proposed isolated DC-DC power converter is achieved.