Control circuit for automatic high-frequency interference resistance of induced arc of plasma cutting machine

Abstract

The invention discloses a control circuit for automatically resisting high-frequency interference of an induced arc of a plasma cutting machine. The control circuit comprises a plasma cutting machinepower supply part, an arc striking high-voltage generator, an arc striking high-voltage filtering circuit, a small-arc striking circuit, a cutting torch and a workpiece, the small-arc striking circuitcomprises an arc striking capacitor, an arc striking resistor, an alternating current contactor KA1, an arc striking safety and an arc striking cable; the control circuit is characterized that the alternating current contactor KA1 adopts an even number of branch circuits, the current from the arc striking cable enters from the half branch circuit and then flows out from the other half branch circuit and enters one end of the cutting torch after passing through the arc striking safety, so that the currents flowing through the alternating current contactor are equal but opposite in direction, so that high-frequency interference and high-frequency radiation formed during arcing and arc extinguishing are counteracted, and the purposes of shielding wires or twisted pairs are achieved.

Description

technical field [0001] The invention relates to the technical field of arc ignition control of a plasma cutting machine power supply, in particular to a control circuit for automatically resisting high-frequency interference of an arc ignition line of a plasma cutting machine. Background technique [0002] At present, there are two common high-frequency arc ignition control system circuits: short-circuit type and non-short-circuit type. figure 1 and figure 2 shown. The composition of the arc ignition circuit of the non-short-circuit plasma cutting machine is as follows: figure 1 As shown, it includes a plasma cutting machine power supply part 1, an arc ignition high voltage generator 2, an arc ignition high voltage filter circuit 3, a small arc ignition circuit 4, a cutting torch 5, and a workpiece 6. Among them, the plasma cutting machine power supply part 1 is composed of AC filter capacitors C1-C3, rectifier filter capacitors C4-C9, DC filter capacitors C10-C11, recti...

AI Technical Summary

Problems solved by technology

[0005] However, under the non-short-circuit type high-frequency arc ignition, the arc ignition frequency is high and the radiation is very strong. In addition, the arc ignition AC contactor is opened and closed under the high-voltage arc ignition state, which is easy to produce surge impact, which makes the plasma cutting machine The high-frequency radiation generated during high-frequency arc ignition will easily pass from the cutting torch of the plasma cutting machine to other circuit parts inside the plasma cutting machine, forming high-frequency interference on the high-frequency circuit itself of the plasma cutting machine and other external high-frequency radiation, resulting in high-frequency interference. High-frequency radiation, causing malfunction of the control system inside the plasma cutting machine power supply, and damage to key chips such as fast recovery diodes, IGBTs, and ICs

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