IGBT protection circuit and method used in AC argon arc welding machine

Abstract

The invention provides an IGBT protection circuit for an alternate current argon arc welding machine. The IGBT protection circuit is connected to an IGBT and comprises a detection circuit, a first time delay circuit, an OR gate, an inverter circuit, a switch unit, a second time delay circuit and a drive unit, wherein the detection circuit is connected to the grid electrode of the IGBT and is used for detecting breakdown signals of the IGBT and outputting a signal, the first time delay circuit is used for receiving the signal output by the detection circuit, the OR gate receives a low-level signal and the signal output by the first time delay circuit, the inverter circuit receives the signal output by the OR gate and inverts the signal, the switch unit receives the signal output by the inverter circuit and carries out breakover according to the output signal, the second time delay circuit receives the signal output by the switch unit, and the drive unit receives the signal output by the second time delay circuit and outputs a zero-level drive signal for cutting off the grid voltage of the IGBT. The invention further provides an IGBT protection method for the alternate current argon arc welding machine.

Description

technical field [0001] The invention relates to an AC argon arc welding technology, in particular to the technical field of IGBT overcurrent protection for an AC argon arc welding machine. Background technique [0002] AC argon arc welding is the abbreviation of AC tungsten argon arc welding. It refers to the welding process that uses the output current that is alternated according to a certain period, uses tungsten electrodes as welding electrodes, and high-purity argon as a shielding gas. It is referred to as AC argon arc welding ( TIG), commonly used in the welding of non-ferrous metals (aluminum, magnesium, copper, etc.) and ferrous metals (stainless steel, carbon steel, etc.). AC argon arc welding machine not only has many advantages of DC positive welding, but also can use the cathode crushing (atomization) effect of AC negative half-wave to remove the oxide film on the surface of aluminum, magnesium and its metals. It is widely used in aluminum, magnesium and its meta...

AI Technical Summary

Problems solved by technology

[0003] Since the overcurrent capability of the IGBT (Insulated Gate Bipolar Transistor) is not ideal, it is easy to be damaged when the circuit state is abnormal. The protection of the switching device IGBT of the inverter circuit in the AC argon arc welding machine is a key point and difficulty

The commonly used protection circuit idea is to cut off the gate power supply of the IGBT when the detection circuit is abnormal. The drive of the IGBT mostly uses a dedicated hybrid integrated driver, such as the M579 series of Mitsubishi and the EXB series of Fujitsu, which integrate the detection and In the protection link, once an overcurrent is detected, it will respond quickly and turn off the IGBT. Even if the interference signal or the overcurrent signal is eliminated, the drive will not resume. However, in practical applications, grid interference, external interference and self-generated interference will all affect the machine The reliability judgment will have an impact. Once a misjudgment occurs, the machine will stop working and cannot automatically recover, which will affect normal work.

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