Inverter AC waveform control method and control circuit

Abstract

The invention discloses an inversion alternating current waveform control method which comprises the following steps: a wave control pulse signal and an inversion trigger signal are generated, wherein the wave control pulse signal is ahead of the inversion trigger signal in phase position; a current value I of a given current is judged; when the I is less than I1, the wave control pulse signal is converted into a first spike pulse signal, wherein the I1 is a first current threshold value; when the I is greater than I2, the wave control pulse signal is converted into a second spike pulse signal, wherein the I2 is a second current threshold value; the inversion trigger signal triggers inversion processing on a pre-output voltage and outputs an inverted voltage; when the I is less than the I1, the pre-output voltage is a sum of a given voltage and the first spike pulse signal; when the I is greater than the I2, the pre-output voltage is a sum of the given voltage and the second spike pulse signal; when the I is greater than the I1 and less than the I2, the pre-output voltage is the given voltage, and a big segment, a medium segment and a small segment of the current can be processed respectively. The invention further provides an inversion alternating current waveform control circuit.

Description

technical field [0001] The invention relates to the field of electric welding machine control, in particular to an inverter AC waveform control method and a control circuit. Background technique [0002] In the inert gas tungsten shielded welding (TIG welding) of aluminum and its alloys, since the surface of the aluminum material will chemically react with the oxygen in the air to form an oxide film, the melting point of this oxide film is much higher than that of the aluminum material. In DC TIG welding with positive polarity connection, the surface of the molten pool is covered by an oxide film, which cannot meet the welding process requirements, and the welding cannot be performed. When the negative polarity connection method is adopted, the tungsten rod is the positive pole, and the electrons are emitted from the workpiece to the tungsten pole, which has the effect of cleaning the oxide film, but the tungsten pole burns seriously, and the weld penetration is not enough. ...

AI Technical Summary

Problems solved by technology

However, this control method has a good welding effect under the condition of medium and small welding current, but under the condition of high current of 400-630A, the arc noise is very loud, which seriously deteriorates the working environment of the welder, and the welder cannot bear it.

At the same time, the high di / dt brought by the square wave current commutation under the condition of large current will generate a high voltage spike, and it is difficult to absorb this spike, which will seriously threaten the safety of the switching elements of the secondary inverter circuit , reducing the reliability of the machine

Images