| 摘要 |
PURPOSE:To obtain the title power supply apparatus whose power factor is high, which maintains an effect to suppress an in-rush current and whose input distortion is reduced. CONSTITUTION:The output voltage of a diode bridge DB which rectifies an AC power supply VS is converted by a chopper circuit 1. The chopper circuit 1 is constituted by incorporating a switch SW and a diode D5 in such away that the chopper circuit 1 mainly performs a step-down operation in a specific period from the turning-on of a power supply and that the circuit mainly performs a step-up and step-down operation after the elapse of the specific period. In the specific period from the turning-on of the power supply, the chopper circuit 1 is operated as a step-down type in the same manner as in conventional cases, a power factor is made high and a function to suppress an input in-rush current is maintained. In addition, after the elapse of the specific period, the chopper circuit 1 is operated as a boosting and step-down type, an input current does not cause a quiescent period even when the voltage across both ends of a capacitor C1 is higher than the output voltage of the diode bridge DB, and an input distortion is reduced. |
