| 摘要 |
PROBLEM TO BE SOLVED: To take a sufficient countermeasure against harmonic over a wide load range by performing stabilized operation where a sinusoidal input waveform can be sustained for not only a heavy load but also a light load. SOLUTION: A non-harmonic current countermeasure control circuit 14 controls a switching transistor 5 at such a timing as an input current becomes a sine wave current and energy is stored in a choke transformer 4 before being supplied to a load through a diode 7 and a smoothing capacitor 8. A current flowing through the switching transistor is detected by a current transformer 41 and converted into a voltage level being inputted to a comparison circuit 47. On the other hand, an output voltage level being fed to a load is detected and inputted to the comparison circuit. If the output voltage level increases when a detected current quantity is dropped, the non-harmonic current countermeasure control circuit detects the overvoltage of output and turns off the switching transistor forcibly before switching control thereof is stopped.
|
