Three stage power source for electric arc welding with the first stage having a DC-DC converter with a soft switching circuit

摘要

A three stage power source (PS7) 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 (240) 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 (250) with a primary winding (252) driven by the first internal high frequency AC signal and a secondary winding (254) 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) has a regulated DC to DC converter (62) with a boost power switch having an active soft switching circuit.