Digital control system for pulsed GMAW based on DSP

A novel digital control system for the pulsed gas metal arc welding (GMAW) was presented,which was established with TMS320F2812 based on DSP (digital signal processor),and a dual closed-loop control of welding current and arc length was realized. The topology of a full-bridge soft-switching circuit by adopting saturable inductor was proposed. By adopting the PWM (pulse-width modulation) generation modules integrated in DSP and selecting reasonable mode,the digital control of PWM signal was realized. The design of the control system software was also discussed. Parameter-varying PI algorithm was applied to adjust the peak phase and base phase of welding current for pulsed GMAW.Aiming at the self-regulating ability shortcomings of the arc in the current control mode,a fuzzy controller for the arc voltage was designed. Experiments show that the developed digital control system can meet the design requirements and adjust arc length quickly and stably,the current waveform consistency is good,the welding process is stable and the welding appearance is perfect.