A series resonant converter for arc-striking applications

Initiation of a plasma conduction state requires a relatively large voltage to ionize the gas. A new version of the series resonant converter is proposed that uses the magnetizing inductance of the transformer for resonance. This converter is not suitable for most power supply applications, but the unique load characteristics associated with plasma loads make this type of converter well suited for arc striking, while allowing safe operation during the plasma state. A feature of the resonant converter is that the controller need not be complex, thus making it suitable for application in competitive industrial systems. Possible transformer configurations are investigated, which include an air core and a number of ferrite-cored transformers. The series resonant converter with the best-suited transformer is verified experimentally in a tungsten inert gas welding application.