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Because of inverter welding power energy, materials, good control performance, fast dynamic response, easy real-time control and other notable features, has been abroad welding industry's attention. Modern power electronics technology and high-power inverter technology continues to mature, and promote the upgrading of inverter welding power source. MMA / TIG welding machine is a set of manual arc welding, DC TIG and pulsed TIG welding multifunctional welder, welder this model has been widely used in automobiles, locomotives, chemicals, shipbuilding and other industrial areas of the welding . This article is a comprehensive home and abroad on the MMA / TIG welding power status and development trend of research, based on the research design is based on 80C196KB microcontroller MMA / TIG welder, experiments show that the design of the hardware to fully meet the requirements of WSM welder, while is small, the control circuit is simple, low cost, reliable, high control precision series of advantages. This paper first introduces MMA / TIG welder main circuit structure and working principle. Main circuit mainly by the rectifier circuit, the inverter circuit, the output frequency transformer and a rectifier circuit composed of four parts. Inverter circuit used single-ended forward inverter topology, the inverter frequency is selected to 25KHz, and IGBT as the main circuit switching power components. Then details the MMA / TIG welding machine control circuitry. In 80C196KB as the core control circuit comprises: smallest single-chip system, preset parameters and display circuit, pulse width modulation circuit, data acquisition circuit, drive circuit and protection circuit. Using pulse width modulation control method, the collected current signal negative feedback control by the PI regulator ASIC SG3525 PWM output, in order to achieve the purpose of controlling the external characteristics of welding. Secondly describes the control system software design and program structure. According to MMA / TIG welder welding methods in different timing requirements, the design of the control system software, focusing on the main program and interrupt service routines. In programming take several commonly used software anti-jamming measures, such as watchdog timer, redundant instructions, digital filtering, gives the process flow diagram and some key procedures. Finally, the welder performed offline and online debugging, and gives the relevant waveforms. The results show that: the design of MMA / TIG welder to achieve pulse TIG, DC TIG and manual welding requirements.
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