| 摘要 |
PURPOSE:To perform the noise restraining operation with good efficiency in such a manner as to enhance an energy saving effect by connecting the first series resonance circuit to the output side of a converter and the second series resonance circuit between the respective lines of the output side of an inverter when the voltage fluctuation of an a.c. supply reaches a designated value. CONSTITUTION:When a preset voltage drop is caused in a commercial three- phase alternating current power, control signals are generated from a control circuit 100 according to detection signals from voltage fluctuation detecting devices 70, 80, 90 and input to bases of transistors 34, 44, 54, 64 to turn on the transistors. Whereupon, a series resonance filter 30 is shunt and connected in parallel to the output side of a converter 2, and series resonance filters 40, 50, 60 are respectively connected between the terminals of an inverter 4. Accordingly, the higher harmonic components of d.c. power of the converter 2 are absorbed and removed by the series resonance filter 30, and the higher harmonic components of the inverter 4 are absorbed and removed by the series resonance filters 40, 50, 60, so that higher harmonic power is not supplied to an a.c. motor 5 so as to restrain the generation of noise. |
