Inverter welding machine is a kind of arc welding power supply using inverter technology, also known as arc welding inverter. The working principle is that the three-phase powerfrequency alternating current is rectified and filtered into direct current, and then through the alternating switch of high-power switching electronic components (such as IGBT), the inverter is converted into medium-frequency alternating current, and then rectified and filtered after transformer step-down, the final output stable DC welding current .Welding machine IGBT control mode is mainly two, one is a hard switch, the other is a soft switch. The biggest difference between the two is that soft switching theory IGBT does not have switching loss, only on-off loss.