| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a power supply and a method for controlling the voltage of the power supply, wherein the power factor of an entire device mounted with a switching power supply is improved and distortion in input current can be reduced. SOLUTION: This power supply comprises a DC-DC converter circuit 10 which contains a switching transistor Q and converts commercial alternating currents into direct currents, a current transformer CT which is disposed so that lamp current detection signals from a lamp regulator 30 fed from the same power supply system is superposed in series with choke coil current detection signals applied to the current detection terminals on the control amplifier 22 of an active filter control circuit 20, and an active filter control circuit 20 which controls constant-voltage the switching transistor Q so that a combined value of the consumed current of the lamp regulator 30 and the consumed current of the DC-DC converter circuit 10 is turned into a sine wave.</p> |
