| 摘要 |
PURPOSE:Te obtain a speed controller for an induction motor which can deal with abrupt drop of rotary speed due to disturbance by providing an instantaneous speed measuring means in addition to an average speed measuring means and controlling the firing angle immediately upon dropping of the instantaneous speed, measured through the instantaneous speed measuring means, below a predetermined level. CONSTITUTION:Instantaneous speed of an induction motor 2 is measured by the use of interrupting function of a microcomputer 5. The microcomputer 5 counts up the time of interruption every time when an interruption signal is received. If the time of interruption is even, a timer 10 is stopped while when the count of the timer 10 exceeds a predetermined value, judgment is made that the speed of the induction motor 2 has dropped and operation for advancing the firing angle is carried out. |
