Patent ID: 6600134
Filing Date: 2003-07-29
Classification: B23K

Abstract:
A power supply connectable to a source of AC line voltage for AC electric arc welding by an AC arc current across a gap between an electrode and a workpiece, said power supply comprising a high capacity transformer to convert said line voltage to an AC output voltage, a rectifier for converting said AC output voltage to a DC voltage between a positive terminal and a common terminal at generally zero voltage and a negative terminal and said common terminal, a first switch for connecting said positive terminal to said common terminal across said gap when a given logic is applied to said first switch, a second switch for connecting said negative terminal to said common terminal across said gap when a given logic is applied to said second switch, a pulse width modulator having an input and an output from which is directed an output signal in the form of pulses created at a frequency of at least 18 kHz, said pulses of said output signal each having a width controlled by said input of said pulse width modulator, a controller for creating alternately a first switch gate signal for a first time and a second switch gate signal for a second time, first means for operating said first switch by said output signal during said first time, second means for operating said second switch by said output signal during said second time whereby said AC current has a positive portion during said first time and a negative portion during said second time.