| 摘要 |
PURPOSE:To obtain a stable rising characteristic by fixing the voltage applied across the motor to a reference level when the difference between the rotating speed of the motor detected by a detecting means and a target rotating speed exceeds a prescribed value. CONSTITUTION:When the difference between a target and actual rotating speeds exceeds a prescribed value, a readout means 16 reads out the storing data of a storing means 17, namely, a reference phase angle and the reference phase angle is used as the firing phase angle of a triode AC switch 2 in a phase angle correcting section 15 under the control of a controlling system switching section 13. As a result, the control of a motor 3 is switched from the feedback control to the control where the firing phase angle of the triode AC switch 2 is fixed to the reference phase angle stored in the storing means 17. Therefore, when the reference phase angle is fixed to the firing phase angle of the triode AC switch 2 in the initial state of starting motor or in the stage when the target rotating speed is changed, a stable rising characteristic can be obtained irrespective of load variation. |
