| 摘要 |
The present invention provides an active power filter capable of reducing the los of an amplifier when a compensating current is little, and a power converting device. The active power filter is arranged between a three-phase AC voltage supply and the power converting device for reducing the noise caused by a common-mode current flowing into a power line, comprising a variable DC power supply forobtaining electricity from the power line, changing into random DC output voltage and outputting; a current detecting unit plugging with the power line and a detecting line for outputting a common-mode current detecting signal via detecting the common-mode current by the detecting line; an amplifier for amplifying the common-mode current detecting signal by a double amplifying ratio via taking the DC output voltage of the DC power supply as the power supply voltage, and causing the current to flow between the grounded power line and the ground; and a voltage detecting unit for detecting the output amplitude of the amplifier and changing the DC output voltage of the variable DC power supply according to an output amplitude detecting signal detected by the voltage detecting unit. |
