| 摘要 |
PURPOSE:To provide technical and economical advantages by obtaining the actual speed of an induction motor purely electrically, thereby eliminating a speed detector. CONSTITUTION:A maximum value and the phase difference of current values are detected by the maximum current detector and phase difference detector 304. A torque corresponding to the current value is detected from a function table by a torque detector 305. Further, a slip detector 306 obtains from the function table a slip corresponding to the torque. A phase difference detector 308 detects the phase, and the output of the detector 308 is applied to 2Hz command frequency generating means 2,309, and the output 8 of the 2Hz is inputted to a comparator 320. Here, a slip amount is obtained by the 2Hz command frequency to obtain the actual speed. |
