| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that a conventional power unit for arc machining has a low power factor and resultantly power-supply equipment has been inevitably large. <P>SOLUTION: The power unit for arc machining is equipped with a primary rectifying circuit for rectifying a power source, a choke coil and a diode connected in series, a smoothing capacitor for smoothing the output from the diode, a transistor for switching the output from the choke coil, an inverter circuit for converting the smoothed voltage to a high frequency AC voltage, a main transformer for transforming the high frequency AC voltage to the machining voltage, and a secondary rectifying circuit for transforming the output from the main transformer to DC voltage. The power unit is further provided with an input voltage detecting circuit for detecting the output terminal voltage of the primary rectifying circuit, and a power factor improving control circuit which outputs a switching element driving signal for switching the switching transistor at high frequencies when the value of the input voltage detecting signal is lower than that of a reference voltage setting signal, while stopping outputting the switching element driving signal when the value of the detecting signal is large. <P>COPYRIGHT: (C)2004,JPO |
