Study Of Digital IGBT Inverter Welding Machine

The study of the digital welding machine system has becoming a hotspot with the development of the welding technologies, control technologies and information technologies. The research presented here concentrated on the control system of the digital IGBT inverter welding machine. The main circuit and hardware of digital control system are designed.This paper introduced the concept of digital welding machine analyses the advantages compared to traditional welding machine. According to current research status in domestic and overseas and the characteristics of digital signal processing, this paper illuminated necessity and content for this article. The paper gives design thoughtfulness and project for the digital inverter welding machine. DSP's characteristics are briefly introduced and the process of designing control system based on DSP is also detailed explained. Furthermore, DSP's type is selected as controller based on the controlling requirements of arc-welding power.Main circuit, which applies IGBT full-bridge inverter structure with its frequency of 20 KHz, is made up of rectifier, filter, high-frequency transformer and output reactance. The key points and parameters of the design are discussed in detail. Even computer simulation for the main circuit is researched using Matlab.In the digital control system of the welding inverter, the type of DSP is TMS320LF2407, produced by TI Company. It has high speed (40 MHz) and precision (16bits), and provides the ability to realize the digital control system. Under the action of main modules: DSP minimize system, parameters presetting and display module, voltage and current real time sampling module and protect module, real time close loop control and real time protect of the welding power is applied. Using universal PWM method means to control output power and output characteristic through controlling IGBT switch on time. A special separate frequency circuit is designed. It can separate two pulses to trigger IGBT after they are magnified by exclusive drive module M57959L. The system real time sample output current and welding voltage, and use PI control algorithm realize the purpose of control output characteristics of welding power.Through the experiment, the waveforms of voltage and current, PWM and drive of IGBT are collected. And the control system meets the requirement of the arc welding inverter. At last, some advices on farther research of the welding machine are given after the summarization, which will make a well ground for tomorrow's research of the digital welding machine system.