Mathematical modelling and digital control for power supplies of current pulsed for welding machine

This work presents the development of a welding machine MIG/MAG (metal gas inerte/metal active gas) whose exit current is pulsed, the control was developed starting from a simplified mathematical model, what allowed the elaboration of a program of simpler digital control. The mathematical model was based on equivalent circuits of the components of the process. These equivalent circuits allowed to characterize a variable of the process denominated stick out, this was modeled as being a variable resistance, allowing the control of the welding as being function just of that resistance. The circuits were simulated in MATLAB/SIMULINK and their data were compared with experimental results, allowing to validate the proposed model. The digital control was developed with base in the acquisition of current data and voltage through sensor, and digital processed using the microcontroller PIC16F877. The project of the potency circuit was elaborated with characteristics similar to the welding machines conventional and commercially available. An implementation was developed in the form of a prototype in real scale with use of power structures and IGBT, with capacity of up to 300 amperes. The experimental results are compared with the theoretical data, the one that allows do one analyzes comparative and of acting of the system