CONTROLLER FOR INDUCTION MOTOR

摘要

PURPOSE: To provide optimum exciting current by computing and outputting the characteristic curve of exciting current at the detected or estimated rotational speed of an induction motor vs. the maximum output of an induction motor. CONSTITUTION: An exciting current control means 2 obtains a curve of the rotational speed of an induction motor 8 VS. maximum output, and takes exciting current corresponding to a summit when the maximum output curve is at such a speed as has the peak as an exciting current command Io'* and the maximum exciting current which permits the induction motor 8 not to generate flux saturation as the exciting current command Io'* when at such a speed as has no peak to output it. The maximum efficiency curve for the rotational speed and load of the induction motor 8 is obtained to provide the exciting current command Io'* according to the locus of the maximum efficiency curve. It is thus possible to operate the induction motor 8 with the maximum output control of maximum efficiency.