| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply circuit which improves a power factor with reference to an AC power supply, which suppresses a harmonic current, in which the efficiency of an AC-DC conversion is high and which reduces noise. SOLUTION: A power supply circuit is provided with a bridge rectifying circuit D1, with an active filter ACF and with a DC-DC converter DCC. The power supply circuit is provided with a voltage doubler rectifying circuit DRE, with switching circuits SWe, SWD which change over the voltage doubler rectifying circuit DRE and the bridge rectifying circuit D1 and with a means S1/SEC which makes the active filter circuit ACF operatable/imoperable. Then, when a load is low, the circuit ACF is made inoperable, and the double voltage of the voltage doubler rectifying circuit DRE is output to the converter DCC. When the load is high, the circuit ACF is operated, and the voltage of the circuit D1 is stepped up so as to be output to the converter DCC. |
