A new, simple, low-cost, modular arrangement of high power factor for both DC and AC welding

Inert gas welding technology with wolfram electrodes requires DC current for welding steel and AC current for welding aluminium. A wide choice of DC welding equipment is available on the market at fairly reasonable prices. Regarding AC welding equipment, the situation is not so simple. They are much more complicated equipment at relatively high prices. For aluminium welding, in the case of an AC welding equipment, welding current has to change with a frequency of 30-200 Hz periodically and rectangularly that the electron flow of changing direction should break the oxide layer on the aluminium surface. However, this technology requires a fairly smooth, but modulated current amplitude at both polarities. Besides, the polarity change of welding current of high rate of rise is a fundamental requirement to avoid arc extinction. If it is not met, the arc should be ignited at every polarity change by a high voltage igniter that has numerous drawbacks. The paper shows simple, low-cost, modular welding equipment for both DC and AC welding. The solution developed by the authors contains one or more DC welding equipment, depending on the current requirements, and an output AC inverter of full bridge connection of a suitable rated current. The results of the development are justified by laboratory tests.