| 摘要 |
PROBLEM TO BE SOLVED: To provide a power converting circuit capable of bringing power factor closer and closer to 1, suppressing the higher harmonic distortion of input power, and outputting stable DC voltage at the time of start-up or no-load. SOLUTION: A rectifier 2 outputs AC voltage whose input AC signal is full-wave rectified. A coil 3, a diode 4, a capacitor 5, and a MOSFET switch 7 convert the input AC power into output DC power to supply it to a DC load 6. A multiplier 21 attenuates for controlling an AC current similar signal obtained from an Ac current detecting circuit 20 based on the signal proportional to DC output obtained from a DC voltage detecting circuit 14. A comparing circuit 22 compares the attenuated and controlled AC current similar signal with the AC voltage similar signal obtained from an AC current detecting circuit 19, and its error output controls driving of a pulse width modulator 23. The pulse width modulator 23 outputs a duty pulse corresponding to the error output and controls the MOSFET switch 7.
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