Method and device for controlling modular chopped mode plasma cutting power source

Abstract

The invention discloses a method and a device for controlling a modular chopped mode plasma cutting power source. The method comprises the following steps of carrying out soft starting of open loop control on the output voltage of the power source, and then carrying out independent step closed loop control on the output current of a chopping module; and when the air gap breakdown and the arc striking are successful, enabling a digital controller to carry out the independent step closed loop control on the output current of the chopping module, and selecting different chopping modules to carry out closed loop control according to the instruction value iz of the total output current of the plasma cutting power source. The device comprises a total output instruction current setting module, a chopping module instruction current distribution module, a four-way digital PI (proportional-integral) algorithm module, a four-way PWM (pulse width modulation) signal module and a four-way current signal sampling module which are arranged in the digital controller. The method and the device have the advantages that the open loop control on the output voltage and the independent closed loop control on the output current are adopted, and the output voltage does not need to be detected in real time, so the control is simple; the frequent switching between a voltage loop and a current loop is not needed, the arc striking is easily successful, the reliability is high, and the service life is prolonged.

Description

technical field [0001] The invention belongs to the technical field of plasma cutting power supply, and in particular relates to a control method of a plasma cutting power supply based on a modular chopper topology. The method is realized based on an all-digital control high-power plasma cutting power supply system with a four-way chopper module. Background technique [0002] Air plasma arc cutting is a thermal cutting technology that uses the high temperature of the plasma arc to partially melt and evaporate the metal to be cut, and at the same time blows the melted metal away from the base material with the help of high-speed plasma airflow, thereby forming a narrow incision. The temperature of the plasma arc column is high, usually up to 18000 ~ 24000K, which is far beyond the melting point of all metals. It can cut any ferrous and non-ferrous metal materials and has a wide range of applications. Compared with laser cutting, it has the advantages of high production effici...

AI Technical Summary

Problems solved by technology

The inverter plasma cutting power supply adopts high-frequency inverter technology, which has the advantages of small size and light weight. However, the inverter plasma cutting power supply has high requirements for power devices, complex control circuits, harsh working environment, and low reliability.

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