| 摘要 |
PURPOSE:To improve the reliability of detecting the speed of a motor with a simple structure by detecting the secondary current of an induction motor and processing the detected output via a waveform shaper, an integrator, a peak holding circuit and a synthesizer. CONSTITUTION:The secondary current of an induction motor M is detected by a secondary current detector 1, and aoplied to the first and second gate pulse generators 2, 3. Waveform shapers 4, 5 produce rectangular wave pulse trains of time durations corresponding to the positive and negative half waves of the secondary current. This pulse train is integrated by integrators 6, 7, and the peak values are held by peak holding circuits 8, 9. The outputs of the holding circuits 8, 9 are synthesized to output an analog voltage which is proportional to the motor speed. |
