| 摘要 |
PURPOSE: To suppress harmonic current well by converting the AC input current to an converter into a sine wave current through application of an active filter having capacity one tenth or less of the load capacity of a diode rectifier. CONSTITUTION: A twelve step capacitor input rectifier 60 is connected with transformers 51, 52 having star and delta connected secondary windings, respectively, with the primary winding thereof being connected in parallel with each other. A current transformer 3 for injecting the compensation current from an active filter, in series, into a system is connected, on the secondary thereof, with an active filter 80. The active filter 80 comprises a PWM converter 81 generating a harmonic voltage for canceling the harmonic current, and a control circuit 82. A current detector 41 detects multiplexed input current to the transformers 51, 52 from the rectifier, the control circuit 82 operates a harmonic based on a detection current IL1 and the converter 81 generates a harmonic Vc for canceling the harmonic current thus suppressing the harmonic well. |
