Mathematical Modelling andDigital Control forPowerSupplies ofCurrent Pulsed forWelding Machine
P. Vieira, Augusto Corr · 2005
Thisworkpresents thedevelopment ofawelding machine MIG/MAG(Metal Ga's Inerte/Metal Active Gas)whoseexit current ispulsed, thecontrol was developed starting fromasimplified mathematical model, whatallowed theelaboration ofa programofsimpler digital control. Themathematical model was based on equivalent circuits ofthecomponents oftheprocess.Theseequivalent circuits allowed tocharacterize avariable oftheprocessdenominated stick out,this was modeled asbeing avariable resistance, allowing thecontrol ofthewelding asbeing function just ofthat resistance. Thecircuits were simulated inMATLAB/SIMULINKandtheir data were compared withexperimental results, allowing tovalidate theproposed model. Thedigital control was developed withbaseinthe acquisition ofcurrent data andvoltage through sensor,anddigital processed using themicrocontroller PIC16F877. Theproject ofthepotencycircuit was elaborated withcharacteristics similar tothe welding machines conventional andcommercially available. Animplementation was developed inthe formofaprototype inreal scale with useofpower structures andIGBT, withcapacity ofup to300 amperes.Theexperimental results arecompared withthetheoretical data, theonethat allows doone analyzes comparative andofacting ofthesystem.