Abstract: In order to design high-power arc-welding inverters rationally‚a smal- l signal model of the main circuit in the high-power arc-welding inverter was established‚based on the analysis of the main circuit in the high-power arc-welding inverter with phase-shifted full bridge zero-voltage-switched PWM （FB ZVS-PWM）．An approximate as-sumption was proposed during the model analysis in view of the effect of the leakage inductance in power transformer‚which causes a significant effect on the model precision．The magnitude and phase characteristics of the contro- l to-out -put transfer function of the model which varied with different model factors‚were also analyzed．The results showthat‚although rational design of the output filter inductor plays an important role in reducing the sputter in CO 2 weld-ing‚the model itself can not solve the problem of spatter completely．Implementing the intellective inverter is the key to success．

Key words: phase-shifted control, pulse width modulation, arc-welding inverter, modeling, simulation