A phase - shifted full - bridge ZVS PWM converter with auxiliary branch is presented. The operation principle and the circuit parameters of the converter are analyzed in detail. The proposed scheme is verified on the prototype converter, the power and the operating frequency of which are respectively 1 KW and 100 KHz. Simulating and experimental results proved that the duty cycle loss can be effectively reduced and the impact on the ZVS range of the lagging leg switches can be minimized through the function of this auxiliary circuit.