Reverse voltage generating circuit for rapid commutation of output current polarity in variable polarity arc welding power supply

The topology of variable polarity (VP) arc welding power supply is composed of a first inverting stage responsible for the adjustment of output current amplitude and a second inverting stage used for the commutation of output current polarity. A reverse voltage generating (RVG) circuit is proposed, which could be applied in the second inverting stage of a VP arc welding power supply to generate a stable reverse voltage with fixed amplitude during the commutation procedure and to make the commutation rate of output current more rapidly. First, a basic circuit unit is designed to illustrate the operating principle of the RVG circuit. Then, the Pspice simulations for the comparison between the RVG circuit and the conventional RC resonant circuit in the half-bridge applications of second inverting stage are carried out to illustrate the superiority of RVG circuit. Finally, an experimental prototype of VP arc welding power supply is established to test and verify the proposed RVG circuit. The experimental waveforms of output current and voltage demonstrate that the RVG circuit is effective and suitable for generating a stable reverse voltage with fixed amplitude, and realizing a rapid commutation of the output current polarity in VP arc welding power supply.