Adaptive voltage control in fusion arc welding

Automatic voltage control (AVC) systems are commonly:used in gas tungsten are welding (GTAW) to maintain constant arc:length, Although AVCs usually perform adequately in most operating circumstances, there are conditions during which the traditional systems cause problems because the are voltage-to-are length gain K-arc, a feedforward gain, is not constant but varies with the nominal values of the are current and:voltage.,Thus, an AVC that has a fixed voltage set point will not maintain a fixed are length if the are current changes. In this paper, an adaptive controller is introduced that is capable of "identifying" the are sensitivity characteristic and adjusting the controller in,real time for optimum response without any a priori knowledge of the current/gain relationship.