The Research On Control System Of The Digitized IGBT Spot-welding Inverter Power Based On DSP

With the further application of microcomputer and DSP in the welding field, the numbelization of spot welding machine becomes inevitable trend. The successful application of power inverter technology in resistance spot welding leads to a more promising future for developing of spot welders in precision and intelligent. At present, the main circuit by using IGBT switch technique has developed perfectly. Being a new generation of microprocessor in control system, DSP (digital signal processor) is being selected to replace existing SCM (Single Chip Microprocessor) technique. The subject was proposed from this background, in which the design and development of intelligent control system for soft switch inverter of spot welding were implemented.The topological structure and operating principle of the main circuit of the soft-switching spot-welding inverter power were sudied in the paper, and the time sequence and generated method of drive pulse which fitted full-bridge phase-shifted zero-voltage soft-switching spot-welding inverter power constant-current output were discussed in detail too.In this paper, the TMS320LF2407A Demo module was used to generate PWM drive pulse for full-bridge zero-voltage spot-welding inverter circuit, and the formula to calculate the output current's value changing with the phase-shifting angle was built. The frequency, of the PWM pulse could be set and revised conveniently by a program.A system have designed base on DSP and peripheral circuit including sample circuit of current flow, IGBT drive, dsplay circuit, keyboard circuit and so on. Applying the moduling skills in software designing, except the main program, the interrupting vector table introduced, every function has its subprogram, so the happening of interrupt will swift to corresponding subprogram. Software program comprise the fundtion signal output and sequential control of PWM, sampling of current flow, LCD display, fuzzy control. Computer simulation is the means in this article, during lucubrating the inversion electric source in the soft-switching mode. Model building elements of familiar components has been discussed, and non-linear resistance model of the dynamic resistance durning spot welding. To built system emulate model by components, namely IGBT spot-welding inverter power-supply system, and to built PWM curve generator model, realized the sinulation successfully.The control system we have designed has simple structure, operating fast can meet the need of the inverter-based spot welder, and has such functions as parameter setting up, parameter showing etc, capable of the multi parameters and information sampling and processing of the spot welding process, has some theory and practical value of the realization of the inverter-based spot welder's process and quality intelligent control.