| 摘要 |
PURPOSE:To perform switching quickly and to prevent damage due to spark by using bidirectional semiconductor elements comprising inverse parallel elements of voltage driving type transistors, and electronically switching taps which are provided in the intermediate parts of the windings of an induction motor. CONSTITUTION:Commercial power sources U to W are rectified in a rectifying and regenerating circuit 1, and DC is obtained. The DC is converted into AC in an inverter part 2, and an induction motor M is rotated. When the power of the induction motor M is regenerated, the semiconductors in the inverter part 2 are controlled by switching. The inverter part 2 comprises the bridge circuits of transistors Tr1 to Tr6 and diodes D1 to D6. The Tr1 to Tr6 are controlled with a main control circuit 3, and ACs are generated. Power is regenerated with the diodes D1 to D6. Switching circuits 4 and 5 are constituted of inverse parallel circuits of three sets of self-extinguishing type voltage driving Trs. One circuit is selected with an output control circuit 6. Terminals (u) to (w) or intermediate taps u1 to w1 of the windings of the motor M are switched. Therefore, high speed switching is performed without spark, and a long life is implemented. |
