| 摘要 |
PURPOSE:To smoothly rotate a DC motor at a low speed operation time by dropping a voltage applied to the motor when the motor is operated at a low speed operation time to lengthen the conduction time of a thyristor. CONSTITUTION:If a speed control signal applied to a control unit 14 is the prescribed speed V or higher, a switch 22 is closed, switches 21, 23 are opened to control the rotating speed. If the signal is less than the prescribed speed V, the unit 14 opens the switch 22 and closes the switches 21, 23 to control the rotating speed. Then, the peak value of the AC current applied to a thyristor 12 decreases, and the conducting phase is advanced. Accordingly, a pulsating current of long conduction time is generated. Thus, the rotating irregularity of a motor 1 can be prevented to improve the positioning accuracy of a tool. |
