Abstract: Average output characteristics curve is proposed by calculate rate of changes of average arc current and average arc voltage for pulsed metal inert gas(MIG) welding in a period of pulse. In addition, arc operating points of dynamic stability are analyzed for intersection of average output characteristics curve of a pulse cycle for arc welding power and arc static characteristics curve. A control strategy is obtained for pulsed MIG welding using average output characteristics in a pulse cycle. At the same time, digital arc welding power source of I/I mode control based on arc voltage feedback is realized by using double-loop control. Arc welding power adapts to change of arc length perturbation in the case of wire-feed speed stability. Droplet transfer of one-drop per pulse has achieved in pulsed arc welding process. Finally, through arc length step test shows that wire melting rate tracked arc length change immediately, there is a good dynamic performance adjustment and maintain dynamic stability for arc length. This is concluded that pulsed welding process is stable, weld appearance is beautiful. It is verified that the analysis process is correct and the design process is feasibly by experiment.

Key words: Arc length, I/I mode control, Output characteristics, Pulsed metal inert gas(MIG) welding