Plasma power supply chopper

Abstract

The invention relates to a plasma power supply chopper which is connected between a power supply and a load and comprises a three-phase rectifier, a switching tube, a control circuit and a reactor, wherein the three-phase rectifier, the switching tube and the reactor are sequentially connected, the reactor is connected with the load, the control circuit is connected between the switching tube and the load; the switching tube is an insulated gate electrode bipolar transistor; the control circuit comprises a drive circuit, a pulse width modulator, a given circuit and a feedback circuit; the switching tube is connected with the drive circuit, the drive circuit, the pulse width modulator and the given circuit are sequentially connected, the feedback circuit is connected with the pulse width modulator and the load; and the feedback circuit is a shunt or current sensor. The invention has the advantages of small drive power, simple structure, rapid response and high reliability, and is convenient to control and easy to maintain.

Description

technical field [0001] The present invention relates to plasma cutting machines, and more particularly to choppers for plasma cutting machines. Background technique [0002] The air plasma cutting machine is a new type of thermal cutting equipment. Its working principle is to use compressed air as the working gas and a high-temperature and high-speed plasma arc as the heat source to partially melt the metal to be cut, and at the same time use high-speed airflow to melt the melted metal. The metal blows away, forming a narrow kerf. This equipment can be used for cutting various metal materials such as stainless steel, aluminum, copper, cast iron, carbon steel, etc. It not only has fast cutting speed, narrow kerf, smooth incision, small heat-affected zone, low workpiece deformation, simple operation, but also has remarkable advantages. energy saving effect. [0003] A chopper is a device connected between a constant DC power supply and a load circuit to change the average va...

AI Technical Summary

Problems solved by technology

The earliest chopper devices used were silicon rectifiers and silicon-controlled rectifiers. Due to the disadvantages of this type of rectifier, such as operating frequency limited to 50Hz, large reactor size, and slow response, ordinary transistor choppers and field effect tube rectifiers were developed.

This type of chopper overcomes the shortcomings of the above-mentioned choppers, but the problem that follows is that ordinary transistor choppers are driven by current, so the driving power is large; and although field effect transistors are driven by voltage, the driving efficiency is low, but Its conduction loss is relatively large, and the ability to control current under high withstand voltage is low, that is, the power of a single device is low, and it needs to be used in parallel in high-power applications, and the problems of dynamic current sharing and large tube volume caused by parallel connection will cause problems. It brings trouble to the physical structure design, circuit design and maintenance of the chopper, and greatly reduces the working reliability

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