| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a controller for an induction motor capable of detecting, with high accuracy and sufficient rapidity, the rotational frequency and rotational direction of the induction motor under a free running condition by shortening required detection time. <P>SOLUTION: A current control loop is constituted on two fixed coordinates orthogonal to each other. When the induction motor 1 is under a running condition, a current command value for frequency detection is given, and a pulse signal superimposed with a current feedback value on the fixed coordinates is extracted. The pulse signal is converted on a rotating coordinates with a predetermined coordinate rotating frequency and the frequency of the pulse signal on the rotating coordinates is detected, thus determining the free-running rotational frequency and rotational direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
