The Design For Variable Polarity TIG Welding Electrical Power System Of Digital Control

Variable Polarity TIG welding is one kind of positive and negative half-wave electric current time, the peak-to-peak value all can be independent controled unassymetrical square-wave welding method, it is widely applied in the aluminum and the aluminum alloy welding.The article has consulted the massive domestic and foreign literature material, analyzed the development survey, the tendency and the research progresses of the Variable Polarity TIG welding electrical power, and proposes one kind of the double contravariant electric circuit structure of the variable polarity TIG welding, namely the main power source circuit used two levels to invert, the frist inversion selectes the IGBT entire bridge inversion method, the second inversion is also the IGBT entire bridge type inversion structures. This article thoroughly research the main variable polarity TIG welding circuit principle of work, and carries on the design of the main circuit parameter. Moreover, using the MATLAB software carry on the modelling, the simulation.to the Variable Polarity TIG welding electrical power system, Its simulation profile and experimental profile contrast are basic same.The control system uses the PWM pattern control mode, the frist invertor uses the PWM3525 control circuit PWM special-purpose actuation chip M57962L to carry on the actuation, the second invertor uses the 555 control circuit, through the control pulse and light pair TLP250 actuates carries the second contravariant electric circuit. In addition, but also introduces the protection circuit.On the basis of introducing the features of digital signal processing technology, the paper discussed the application of DSP in the welding and the control system and working principle. To the low precision, poor real-time and complicated circuit of the traditional welding controlle and parameters testing system, considering the advantage of digital system, such as high speed calculation, high processing precision. we chose TMS320F2812 DSP for the control core. The paper design the principle frame of digital control system,each part software and hardware are designed by modularization. Software programs are built , including the main,A/D conversion module,PID calculation,A/D conversion module and introduce the anti-interference measure.The test result indicates the Variable Polarity TIG welding electrical power system that this article develops is stable reliable, also output electric current in DCEP period peak-to-peak value IP and in DECK period peak-to-peak value In, frequency and plus and minus half-wave breakover are all independent adjustable, satisfies the aluminum and the aluminum alloy welding craft demand. So it is one kind of ideal welding power source.