Improved current control makes inverters the power sources of choice

Journal Article · Sat Feb 01 04:00:00 EST 1997 · Welding Journal

OSTI ID:471145

Yamamoto, H; Harada, S; Ueyama, T ^[1]

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1. Daihen Corp., Osaka (Japan). Welding Products Div.

It is now generally understood that by increasing the operating or switching frequency of a power source the size of the main transformer and main reactor can be shrunk. Thus, a 300-A DC welding power source weighing well under 100 lb can be produced. This makes the inverter power source an ideal choice for applications requiring equipment maneuverability. It is also generally understood that due to higher switching frequencies, a smoother output is obtained from inverter power sources. In the late 1980s, the company developed a new double-inverter power source by which inverted DC weld output is inverted back to AC weld output. This product was the first of its kind in the world. Again, the small compact size of this product was of great interest. Utilizing current waveform control, it was realized that fast response switching from electrode negative to electrode positive could be accurately controlled, offering benefits such as AC GTA welding with high-frequency start only, even at a low welding current. The primary benefit is the ability to limit the electrode positive half cycle to less than 5%. The electrode positive half cycle is responsible for tungsten erosion, which also creates the balling effect of a tungsten electrode. By limiting the electrode positive portion of the AC cycle to a very low level, a rather sharp point can be maintained on the tungsten, which creates a very concentrated, focused arc column. This ability provides excellent joint penetration in fillet welding of aluminum alloys, especially on thick plate. It also reduces the heat-affected zone in AC GTA welding of aluminum.

• OSTI ID: 471145
• Journal Information: Welding Journal, Journal Name: Welding Journal Journal Issue: 2 Vol. 76; ISSN 0043-2296; ISSN WEJUA3
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CONTROL
ELECTRIC CURRENTS
GAS METAL-ARC WELDING
INVERTERS
POWER SUPPLIES
WELDING MACHINES