Abstract: The FB-ZVZCS-PWM eonverter subjoined a block capacitor into the FB-ZVS-PWM converter. At the freewheeling interval,the primary current is attenuated fast to zero and maintained. And then, power devices of the static leg become a Zero-Current-Switch (ZCS),power devices of the shifted leg become a Zero-Voltage-Switch(ZVS). In this way, on the one hand the IGBT with tail current can be easily used for fullbridge soft-switching converter, on the other hand additional circuiting energy is greatly reduced. At the same time, small duty cycle loss,lower secondary parasitic ringing and wide soft-switching load range are achieved. Finally,based on above achievement, a 10 kW class arc welding power source prototype with FB-ZVZCS-PWM converter has been developed. Due to the considerable decrease of switching losses,the temperature-rising of this soft-switching arc welding power source is vety low. The temperature measurement shows that it is almost 20 CC lower than that of a hard-switching arc welding power source with the same output power. At the same time,the power devices of the arc welding power source operate under the zero-switching situation,which reduces the current and voltage stress. Therefor the reliability of the arc welding power source is improved greatly.