Patent ID: 6194684
Filing Date: 2001-02-27
Classification: H01F

Abstract:
A method of controlling the inductance in the output circuit of a D.C. electric arc welder operated over a given current range as a weld current is applied to a gap between an electrode and a workpiece, said method comprising:a) providing an inductor with a generally constant inductance over said current range for charging a capacitor connected in parallel with said gap;b) providing a choke having at least one winding, said choke having an inductance that gradually varies over said current range, said choke comprising a high permeability core having first and second pole pieces and an inductance controlling air gap, said air gap defined by end surfaces on said first and second pole pieces, said end surfaces being spaced from one another and facing one another, said end surfaces of said first and second pole pieces having corresponding inner and outer edges and a middle portion between said inner and outer edges, at least a portion of the middle portion of said corresponding end surfaces being spaced apart at a varying distance to vary the inductance of said choke over a current range, at least a portion of the middle portion of said end surfaces being spaced apart a distance greater than the distance between said inner and outer edges of said end surfaces; and,c) connecting said choke in series with said gap and between said gap and said capacitor.