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

Abstract

Inert gas welding technology with wolfram electrodes requires DC current for welding steel and AC current for welding aluminium. In the first case a DC welding equipment, while in the latter one an AC welding equipment is necessary. 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 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 a simple, low-cost, modular welding equipment for both DC and AC welding. The solution developed by us 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.

A novel energy‐retaining inverter for AC arc welding machines

“…Inert gas welding technology with wolfram electrodes requires AC currents for welding aluminum. To control the welding characteristics, the output current, instead of the voltage, is regulated 5–16. Therefore, if we want to obtain more stable characteristics of arc welding and good arc welding beads, we need to reduce the output ripple current 17, 18.…”

Implementation of an improved power supply with simple inverters for arc welding machine

“…That is, when the next positive period comes, the output current starts to charge from the initial value, Iv . The commutation time can be as short as possible to guarantee a minimized arc breaking and achieve a better welding process . The same process occurs in the negative half‐cycles of i o .…”

“…Arc welding machines are needed for development of a nation and widely used for construction and car manufacturing industries. There are two kinds of arc welding approaches, driven, respectively, by alternating (AC) and direct (DC) currents [1][2][3][4][5][6][7][8][9][10]. For the DC straight polarity method, the heat generated during the arcing period is mainly concentrated in the welded material.…”

“…Conventionally, Figure (a) shows one popular inverter topology, which is mainly composed of a high‐frequency full‐bridge (FB) DC/AC inverter and a low‐frequency half‐bridge (HB) inverter. In the AC arc welding applications, the amplitude of the load current i o can be up to several hundreds of amperes . A high rate of step change for the load current during the commutation period is a fundamental requirement to produce a standard square wave and to avoid arc extinction.…”