The invention discloses a topology main circuit of a zero-
voltage soft switching arc welding inverter, which comprises a leading leg, a lagging leg and a full-bridge phase-shifting
resonance circuit. The leading leg and the lagging leg are formed by high-power insulated gate bipolar transistors; the full-bridge phase-shifting
resonance circuit consists of inverse parallel diodes of the transistors and parallel capacitors of the transistors; the full-bridge phase-shifting
resonance circuit is accessed to a primary side of a high-frequency
transformer through a resonance
inductance and
leakage inductance; a secondary winding of the high-frequency
transformer outputs inverted power supply; the front end of the resonance
inductance is connected with a current sampling winding in series; the secondary
inductance is connected with the winding of the high-frequency
transformer after the secondary inductance is connected with an electric switch; and the electric switch is connected with a
control circuit, and samples primary current of the high-frequency transformer through the current sampling winding. The topology main circuit realizes switching of the electric switch by the
control circuit, can increase the primary current value of the transformer by opening the electric switch under idle load and
light load, and can reduce
circulating current of the circuit and increase
power factor by
cutting off the electric switch during over loading, thereby avoiding a
magnetic core heating severely so as to damage elements and devices, and realizing zero-
voltage switching of all main power devices in a loading range.