| 摘要 |
PURPOSE: To achieve improvement in power factor and reduction in noises by turning on/off an active filter by the output current value on the secondary side of a power supply apparatus. CONSTITUTION: This power supply apparatus is constituted of a control circuit 1 of an active filter, an on/off control circuit 2 for controlling the on/off of a transistor FET2, a diode D3 for rectifying the output of the secondary side, a smoothing capacitor C2 for smoothing the output on the secondary side and the like. In addition, the apparatus comprises a detecting resistor Rs, which detects the output current on the secondary side, and a differential amplifier circuit 3, which inputs the voltage across the detecting resistor Rs. Furthermore, the apparatus is constituted of a photocoupler PC, which insulates the primary side and the secondary side, a transistor for switching on/off the photocoupler and a transistor for feeding the power supply into the active filter circuit. When the output current on the secondary side increases and a specified value becomes abnormal, the power is supplied into an active-filter control circuit, and the active filter circuit is operated. |
