Patent ID: 9421630
Filing Date: 2016-08-23
CPC Classification: B23K

Claim Text:
1. A method of providing an output welding current through a gap in a welding circuit between an electrode and a workpiece according to a setpoint current value in a TIG welder, said method comprising the steps of: providing the TIG welder, said TIG welder comprising: selectively connecting said transformer secondary winding to said welding circuit using said SCR network during a first portion of a voltage half-cycle to provide current to said welding circuit; and selectively connecting said background power supply to said welding circuit through said SCR network of said main power supply during a remaining portion of said voltage half-cycle using said SCR network, wherein: selectively connecting said transformer secondary winding to said welding circuit comprises operating at least one SCR in said SCR network in a conductive state according to said SCR control signals so as to connect said transformer secondary winding to said welding circuit during said first portion of said voltage half-cycle, and selectively connecting said background power supply to said welding circuit comprises latching said at least one SCR using current from said background power supply so as to maintain said at least one SCR in said conductive state during said remaining portion of said voltage half-cycle.