| 摘要 |
PURPOSE:To eliminate steps in speed due to time delay by providing plural sets of inverter circuits which supply powers to plural sets of different windings that are provided in an induction motor, and switching the windings and the inverter circuits. CONSTITUTION:Three-phase AC inputs (u) to (w) are rectified and smoothed in a rectifying and smoothing circuit 1, and a DC is generated. An inverter part I or II is driven, and ACs are generated. The ACs are supplied to different kinds of windings MI and MII of an induction motor M. When a speed command (a) is inputted into a control device 2 from, e.g., an external NC machine tool, one terminal of a switch 4 is selected with an output switching circuit 3 based on the program stored in a ROM and the received speed command. For example, at the time of high speed, the inverter part I and the winding MI are selected. At the time of low speed, the inverter part II and the winding MII are selected. When the high speed and the low speed are switched, the switch 4 is operated. Therefore, steps in speed due to time delay in switching are eliminated. |
