Abstract: Through the analysis of phase-shifted soft-switching full-bridge power converter characteristics,a soft-switching arc welding power system topology of peak-current mode control is proposed.The full-bridge model of arc welding power is equated to Buck model using small-signal analysis method.Buck model works in continuous conduction mode or discontinuous conduction mode under different load conditions.Based on circuit theory,the boundary points of static characteristics in one PWM working process cycle of phase-shifted full-bridge zero-voltage-switch are analyzed with theoretical derivation.The adjustment range of welding parameters is directly determined by the boundary curves of arc welding power output characteristics.Thus,it can achieve the required output characteristics of arc welding power source by using different control strategies.