基于DSP的脉冲GMAW焊数字化控制系统

针对脉冲GMAW焊工艺要求,采用32位数字信号处理器TMS320F2812建立了基于DSP的数字化控制系统,实现了电流和弧长的双闭环全数字控制,取得了良好的控制性能.控制系统利用DSP内部集成的PWM产生模块,通过选择合适的工作方式实现了软开关主电路四路移相PWM信号的直接数字化控制.给出了系统控制原理及程序流程图,脉冲峰值和基值阶段采用变参数的数字PI控制,使得电流快速跟随给定信号,同时采用模糊控制方法对弧长进行闭环控制.结果表明,所设计的脉冲GMAW焊全数字控制系统满足设计要求,输出电流波形一致性好,可以实现快速、稳定的弧长调节,焊接过程稳定,焊缝成形美观.

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.