The Research On MMA/TIG Welding Machine Based On 80C196KB MCU

At present the inverting welding source has received serious attention in welding session at home and abroad because it has the energy conservation, material saving, good control performance, quick dynamic response, easy real-time control and so on. The development of modern power electronics and high-power inverter technology continues to mature, which promot the renovation of the inversion welding source. The MMA/TIG welding machine is a multi-purpose welding machine which includes the manual arc welding, DC TIG welding and pulse TIG welding, this model welding machine has widely applied in industrial field, automobile, rolling stock, chemical industry, ships weldings and so on. Based on the research and the development tendency of MMA/TIG welding power source, a MMA/TIG welding machine by 80C196KB MCU was researched and designed. Experiments show that the hardware completely satisfy the request of the MMA/TIG welding machines, simultaneously it has a series of merits such as small volume, simple control circuit, low cost, reliable use and higher control precision.Firstly, the structure and principle of main circuit with MMA/TIG welding were introduced in this paper. The main circuit includes rectifier, inverter, high-frequency transformer and the later rectifier. The inverting circuit is the single-end forward inverter topology, the inverting frequency was 25KHz and the switching power units are IGBT.Secondly, the control circuit of MMA/TIG welder was introduced in detail. The control circuit includes minimum system of single chip, parameters preset and display circuit, PWM circuit, data acquisition circuit, drive circuit, protect circuit. Acquired current signal were inverse feed backed with PWM, then, output of the chip SG3525 were controlled through PI regulator. As a result, the external characteristic was controlled.Then, the design of software and the program structure for control system were analyzed. The software for control system was designed according to the timing requirements, the main program and the interrupt service program were highlighted. Several software anti-interference measures were taken, such as WDT, redundancy directive, digital filtering. The program flow chart and some of the key program were also showed.Finally, the offline and online debugging were done for this power source, and the relevant oscillograph traces were given. The experiment showed that the WSM-TIG welding machine can realize pulse TIG, direct TIG and the manual welding request After the debugging, specimens were welded to test this power source, it is proved that this power source is suitable.