Study On Control System Of Aluminum Alloy Pulsed MIG Welding Based On DSP

Sub-spraying transferring is a ideal method of droplet transferring to aluminumalloy welding. But because control scope is narrow and adjust processing iscomplicated, which makes it difficult to be achieved. In this paper, the control idea ofaluminum alloy pulsed MIG welding sub-spraying transferring is come up, and itestablishs digital control system based on DSP chip and achieves droplet sub-sprayingtransferring.The hardware circuit of control system is designed based on dsPIC30F6010chipas a core of control. The inverter power main circuit is consist of full-bridge inverterwith IGBT. The paper analyzes the principle of main circuit in detail. The switchsignal which controls IGBT is generated by the DSP chip internal PWM module. Theoutput of welding current is controlled by adjusting the duty cycle of PWM. Besides,it detaily introduces some peripheral hardware circuit such as IGBT driver circuit,current and voltage feedback circuit, the time control circuit and wire feed systemcircuit and so on.The control of droplet sub-spraying transferring is to control the arc lengthessentially. The paper uses a modulize programming software, applies C language forwelding main program, A/D subroutings program and PI control program. It achievesarc length closed-loop control. The system of high-speed video camera imageacquisition and welding signal acquisition is builded, and is used to acquisite andanalyze welding process signal for testing the output performance of the controlsystem.The experimental results shows that the control system of aluminum alloy pulsedMIG welding not only makes the welding current and voltage output stable and speedwire feeder constant, but also can control arc length within the zone of sub-sprayingtransferring, and avoid unsteady welding process.