Research On Digital Pulse MIG Welding Based On DSP&CPLD

In this paper, the key issues the whole digitization process pulsed MIG welding power doexist in the following related research programs: anti-jamming solutions, digital PWMwaveform generator program, pulsed MIG welding current, voltage control scheme, arclength control scheme, melt drops transitional control program, digital wire feed systemcontrol panel solutions and digital programs.First, based on the analysis of pulsed MIG welding droplet transfer form and arc lengthcontrol study of existing methods, as well as to find relevant papers and analyze relevantforeign prototype, decided to use control methods arc voltage and welding current doubleclosed loop. Constant loop control functions performed by the current, according to the rootof the droplet transfer process for sixth, establish different PI parameter data for differentsegments, segment type PI adjusted according to the welding process. Stable welding arcvoltage arc length by a closed-loop feedback loop to control, to achieve a pulse droplettransfer one drop. Synergistic control strategy, by adjusting the base value of the weldingcurrent and arc voltage feedback loop time algorithm plays the role of a stable arc. Alsodesigned a digital PWM controller and protection circuits, the use of secondary current/arcvoltage feedback to adjust the output waveform, the primary transformer peak currentfeedback control strategy to protect the power devices.In this paper, the more popular "DSP+MCU" digitized pulse MIG welding in actual useproblems raised "DSP+CPLD+MCU" control scheme, and on the basis of the design ofhardware and software. DSP is responsible for A/D sampling, PWM pulse waveform output,variable parameter PI control segment, arc length control, welding process control,closed-loop feedback control wire feeder, single-chip digital display panel in charge of theparameters given other tasks, CPLD responsible for IGBT drive waveform generation andprotection of IGBT and the like. Displayed a "digital tube+LED" on the control panel display,photoelectric encoder input key combination, to achieve the output of the welding parameters,welding parameter display and waveform data generation and other functions.After completing the hardware and software design, prototyping one. In the prototype,the design of the control system debugging, testing, welding and aging, etc., including theIGBT drive waveform test, overcurrent protection test, over voltage protection test, thermalprotection testing, functional testing and welding Process welding the entire performance test.The test results show that the designed system functions can work, welding spatter, weldappearance, basically reached the design requirements. Finally, this paper summarizes the main work done, and noted that the actual prototypedevelopment process problems for the existing problems and to propose improvements to thenext work plan.