Patent ID: 6054674
Filing Date: 2000-04-25
Classification: B23K

Abstract:
A DC power supply apparatus for arc-utilizing apparatus, comprising:a power supply input terminal adapted to selectively receive a first AC voltage, a second AC voltage about twice as high as said first AC voltage, and a third AC voltage higher than said second AC voltage;a rectifier circuit for rectifying the AC voltage applied to said power supply input terminal;a voltage-reducing converter for receiving and reducing an output voltage of said rectifier circuit;a switch connected in parallel with said voltage-reducing converter;first and second smoothing capacitors;a first switching circuit for selectively connecting said first and second smoothing capacitors in series and in parallel to said voltage-reducing converter;first and second DC-to-high-frequency converting circuits connected to said first and second smoothing capacitors, respectively;first and second transformers to which outputs of said first and second DC-to-high-frequency converting circuits are respectively applied;a high-frequency-to-DC converter for converting high-frequency outputs of said first and second transformers into DC voltages; anda control unit for rendering said voltage-reducing converter operative and also causing said first switching circuit to connect said first and second smoothing capacitors in series when the voltage applied to said power supply input terminal is said third AC voltage, said control unit causing said switch to be closed and causing said first switching circuit to connect said first and second smoothing capacitors in series when the voltage applied to said power supply input terminal is said second AC voltage, and causing said switch to be closed and causing said first switching circuit to connect said first and second smoothing capacitors in parallel when the voltage applied to said power supply input terminal is said first AC voltage.