Variable polarity TIG welding arc stability and its control

Arc blowing out and current impacting at commuting often occur in variable polarity inverter TIG welding. Equivalent capacitors and inductors of the main circuit slower the current commuting speed and cause arc blowing out. Equivalent resistance of welding arc decreases suddenly and causes current impacting when DCEP (direction current electrode positive) is commuting to DCEN (direction current electrode negative). Appending coupling inductor to the second stage inverter circuit and using a pre-cutting PI control strategy can solve the problem of arc stability effectively.