| 摘要 |
PURPOSE:To reduce distorsion of waveform, by dividing output voltage from a first power converting circuit through a plurality of capacitors connected in series then switching a changeover switch based on an output voltage. CONSTITUTION:A converter 1C comprises four diodes 12 connected into a bridge, and two capacitors 14 connected in series through a choke coil 13 between AC output terminals thereof. A changeover switch 5 for switching the input terminal at positive voltage side of an inverter 2 to positive voltage side of a DC capacitor 14 is provided, and the switch 5 is controlled through a control circuit 4. When a large voltage is provided from the inverter 2 in order to operate a motor 3 with high capacity, the control circuit 4 connects the changeover switch 5 to the positive voltage side of the DC capacitor 14. When the motor 3 is operated with low capacity, the changeover switch 5 is connected to mutual joint of the DC capacitor 14. |
