Modular power source for electric arc welding with three stages ; output chopper with first and second polarity and a welder including such chopper ; MIG welding methods using such modular power source or such output chopper

摘要

A three stage power source for an electric arc welding process comprising an input stage (I) having an AC input and a first DC output signal (DC#1); a second stage (II) in the form of an unregulated DC to DC converter having an input connected to the first DC output signal (DC#1), a network of switches switched at a high frequency with a given duty cycle to convert the input into a first internal AC signal, an isolation transformer with a primary winding driven by the first internal high frequency AC signal and a secondary winding for creating a second internal high frequency AC signal and a rectifier to convert the second internal AC signal into a second DC output signal (DC#2) of the second stage (II); with a magnitude related to the duty cycle of the switches and, a third stage (III) to convert the second DC output signal (DC#2) to a welding output for welding wherein the input stage (I) and the second stage (II) are assembled into a first module and the third stage (III) is assembled into a second module connectable to the first module.