Power supply apparatus for arc-utilizing apparatus

摘要

An input rectifier of a power supply apparatus rectifies a selected one of two, higher and lower AC voltages applied to it. First and second inverters are connected in the output of the input rectifier. A high-frequency transformer is connected to the output of each of the first and second inverters. An output rectifier is connected to the output of each of the high-frequency transformers. When the higher one of the two AC input voltages is applied to the input rectifier, a switching circuit connects the first and second inverters in series between output terminals of the input rectifier. When the lower AC voltage is applied to the input rectifier, the switching circuit connects the first and second inverters in parallel between the output terminals of the input rectifier. When the first and second inverters are connected in series between the output terminals of the input rectifier, a voltage balancing control unit operates to suppress imbalance between input voltages to the first and second inverters.