Research On ARM Based Digital Control Of Pulse MIG Welding Inverter Supply

Pulse MIG welding is a kind of high quality welding method. It can control droplet transfer mode and size of melting pool by cyclical changed pulse current, thus improve the quality of weld beam. Previous welding supplies of pulse MIG welding controlled by analog circuit had many disadvantages, and digital control won wide concern because of the merits of flexible and accurate control, high integration level. Thereby, the author researched on ARM based digital control of pulse MIG welding inverter supply.On the basis of analyzing droplet transfer of pulse MIG welding, the author proposed overall program of control systems, includes: Selected full-bridge inverting circuit after comparing kinds of main circuit topology; Centralized adjustment mode, selected preset values of current and voltage by given wire feed rate; Adopted Pulse-Width Modulation (PWM) model and closed-loop control to adjust current and voltage timely; Designer selected the optimal control theory—the switch control (Bang-Bang control) as a control algorithm;. Designed the digital control system of pulse MIG welding based on ARM. The digital control system includes hardware circuit and software control system. Feedback circuits of current and voltage, protection circuits of overcurrent and superheat, display circuit, DC stabilized power supply and internal logic circuit of GAL22V10 are contained in hardware circuit. Software control system includes sequential control program, Pulse width modulation program, A/D conversion program, interrupt protection program and control algorithm program. Furthermore, author designed anti-jamming measure of hardware circuit and programs.The control system was debugged and the test welding experiments was carried: Connected hardware circuit and software control system, and tested whether the signals of control system could response timely and accurately; Built experimental platform by existing equipments, carried test welding experiments, and analyzed the performances of welding sources The experimental results demonstrate that control signals produced by control system are exact. Dynamic response of the signals is fast; The pulse width of current and voltage could be regulated in accordance with feedback signal timely, and achieved double closed loop adjustment; Test welding experiments proved welding power supply can work normally, the waveforms have the characteristics of DC pulse and provide reliable support for theoretical design.