| 摘要 |
PURPOSE:To enable the rotating directions and speeds of AC machines to be detected with always stable accuracy by rectifying the electromotive force in synchronization to the rotating vector obtained through operation of the electromotive force. CONSTITUTION:Electromotive force is operated from the terminal voltage and current of an AC machine 10. From this electromotive force, magnetic flux is operated with a magnetic flux operator 18. The phase of the magnetic flux having been operated is advanced by 90 deg. with a vector rotator 20 so that the magnetic flux having been phase shifted becomes in-phase when it is forward rotation with respect to the electromitive force vector and anti-phase when it is backward rotation. Further an electromotive force rectifier (R1 thru R3, switching elements 22 thru 26, R4, operational amplifier 28) is provided and the electromotive force is synchronously rectified in synchronization to either one of positive or negative half wave of the magnetic flux having been phase-shifted by the rotator 20. From the polarity and magnitude of the rectified output voltage EUVW, the rotating directions and speeds of the AC machine are detected. |
