Patent ID: 8269141

Claim:
A power source for an electric arc welding process having a topology with each stage of the topology defined by an input and an output signal, said power source comprising: an input stage being a converter having an AC input signal and a first fixed DC output signal, having a first magnitude, said first fixed DC output signal being on a first DC bus; a second stage in the form of an unregulated DC to DC converter having as an input signal said first fixed DC signal on said first bus, the second stage being unregulated such that the second stage is not adjusted by a real time feedback signal from the welding process and including: a network of switches switched at a high frequency with a given duty cycle to convert said first fixed DC input signal of said second stage into a first internal high frequency AC signal, said duty cycle being fixed during operation of said power source; an isolation transformer with a primary winding and a secondary winding for creating a second internal AC signal different than the first AC signal; and a rectifier to convert said second internal AC signal into a second fixed DC output signal not used for welding having a second magnitude related to said duty cycle of said switches, said second magnitude being less than said first magnitude, said second fixed DC output signal being on a second DC bus; and a third stage regulated converter which receives said second fixed DC signal as an input signal and is regulated by a feedback signal from the welding process, said third stage to convert said second fixed DC signal to an output signal used for welding, said third stage converting said second fixed DC signal separate and distinct of said input and second stages.