| 摘要 |
PROBLEM TO BE SOLVED: To realize a circuit system for improving power factor of a flyback converter at a low cost. SOLUTION: This flyback converter comprises a series circuit of an AC power supply 31 and a bridge rectifier 12, a filter capacitor 13, a primary winding 14a of a transformer 14 for forming a closed circuit with the capacitor 13 and the main switch element 15, and an oscillation control circuit 16 connected to the control electrode of the element 15. In this case, a series circuit of first and second diodes 1 and 2, connected in series with the same polarity poles opposed, is connected in parallel with an AC power supply 31. Then, a third diode 3 is connected between the connecting point of the first and second diodes 1 and 2 and a prescribed terminal of the capacitor 13, and a first snubber capacitor 4 is connected between the connecting point of the first and second diodes 1 and 2 and the connecting point of the winding 14 and the element 15.
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