| On account of the high efficiency of welding and low cost, CO2 welding is widely used on mild steel, low alloy steel and all-position welding. But it is badly restricted to be used in high quality production welding because of numbers of spatters in CO2 welding. In recent years, the study which adopts the waveform control to reduce the welding spatter has been going on profoundly day by day. It is difficult for analog control to satisfy to the requirement of waveform control. So it is of significance and useful value to apply the digital technology into modern power source and CO2 welding waveform control.In this paper, the study of digital control system of dual-processor consistes of MCU and DSP was executed, especially was paid more attention to DSP control system which includes the hardware system and software system. The hardware includes the minimum system of DSP, voltage and current sample circuit, detective circuit of the key time of CO2 welding short-circuit startness and endness, magnetic biasing and overcurrent protective circuit. The software system includes program of two-circuit PWM signal between which there was phasic difference of 180 degreed,A/D conversion, PID counting subroutine, asynchronous communication between DSP and Micro-chip Unit (MCU), protective program and so on. A flatform was constructed to study digital control of the arc power and a condition was created to the profound study of digital control technology.In this paper, simulation model about the power digital control system was set up by experiment and the parameters of PI control rule were found by taking MATLAB as a tool.Some relational experiments were carried out. The result shows that the hardware circuit and software program designed in study were both fit to the requirement, that the digital control system designed in this paper could be use to study on the digital technology of arc welding power source, that CO2 short-circuit transfer welding could be realized.
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