Full digital control of I/I mode pulsed MIG welding based on triple closed loop control

This paper presents a full digital control strategy for pulsed MIG/MAG welding based on digital signal processor(DSP) control.One droplet per one pulse(ODPP) is maintained with the proposed control strategy which is characterized by I-I mode with adaptive voltage compensation(AVC).Welding database with different materials and diameters is established according to wire feed speed.Arc length is detected during each pulse period and the melting rate is changed.Moreover, real time compensation for the volt drop across the wire stickout is made to ensure the arc length constant while stickout changing.Operation principles are analyzed and control block diagram composed of triple closed loop is also presented.Experimental results show that the proposed method is feasible and universal.Constant arc length is realized when wire stickout changes.The welding process is stable and the welding bead is also good with the proposed method.