| 摘要 |
PURPOSE:To provide a power supply unit in which input power-factor is high and input current waveform has less deformation while supplying smoothing DC power supply to an inverter. CONSTITUTION:On the input side of an inverter 1, an auxilliary DC power supply 6 is provided in the valley part of output voltage for a rectifier in order to supply voltage to the inverter instead of the rectifier, and further a switching means 15 is provided to form a side path for flowing the current via a switching device 3 from the rectifier after turning on the power supply 6 during the voltage supply duration from the power supply 6 to the inverter 1. Thus, the input current for the rectifier continuously flows in nearly overall duration of respective half cycles of AC power supply voltage waveform and its waveform becomes almost similar to a sine wave, so that harmonic wave elements included in the input current can be reduced while improving the smoothing operation of supply voltage to the inverter 1 and the input power-factor. |
