The intermediate frequency welding power supply is a three-phase balanced load, which has a much smaller impact on the power grid than single-phase AC welding, which reduces the requirements of the power supply system. Because the primary input frequency of the resistance welding transformer is higher, the volume and weight of the transformer can be greatly reduced. It is only 1/4 to 1/3 of the AC transformer of the same power, the output welding current is DC, the power factor is as high as 90%, the thermal efficiency is high, the welding time is short, and the transformer power required under the same welding capacity is only AC About 1/2 of the transformer power, the energy saving effect is remarkable.