| 摘要 |
PURPOSE:To make it possible to suppress generation of hunting in a speed control by giving an excessive signal to and saturating a speed governor outputting a current command value, when the speed actual value decreases of an electric motor to a small value not larger than a detection limit. CONSTITUTION:A microprocessor 10, in which a low speed limit is set to the speed actual value, memorizes the current actual value of a DC electric motor 4 in the point of time its speed is detected to decrease to a small value not more than the low speed limit, inputting an excessive signal in order to saturate a speed governor 12. The memorized current actual value is fetched to the speed governor 12 applying a brake, and by outputting the current actual value as a current command value, the DC electric motor 4 is switched from a speed control to a current control, so that the motor 4 can be stably operated by the current control even when the speed actual value can not be detected. In this way, an effect, possible to avoid a speed unstable of the electric motor at the time of its very low speed operation, is obtained. |
