| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive DC power supply exhibiting high power factor and excellent boosting capacity. SOLUTION: The DC power supply comprises a rectifying means 2, a reactor 3, a voltage doubler/rectifier circuit consisting of capacitors 3 and 4, a bidirectional switch 10 for short-circuiting an AC power supply 1 through the reactor 3, a zero-cross detecting means 9 of the AC power supply 1, a bidirectional switch control means 11 for turning the bidirectional switch 10 on/off in synchronism with zero-cross, and a bidirectional switch current detecting means 12. The bidirectional switch control means 11 can suppress the current value of the bidirectional switch below a predetermined level regardless of the load or the AC voltage by selecting the second control state for turning the bidirectional switch on/off a plurality of times during half period of the AC power supply by the detected current value of the bidirectional switch and the difference between the DC voltage and a target voltage, and can realize cost reduction incident to reduction in current capacity of the switch element as well as power factor improvement and DC voltage step-up. COPYRIGHT: (C)2006,JPO&NCIPI
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