Speed control method for AC motors and an apparatus for the control

摘要

A frequency converter applies a variable voltage with a variable frequency to an AC motor coupled with a load. At least one frequency region is set up for the variable frequency. The ratio of a percentage input voltage expressed in terms of a percentage of the rated input voltage of the AC motor, to a corresponding percentage input frequency expressed in terms of a percentage of the rated input frequency of the AC motor, is set less than 1 within the frequency region thus set. Also an apparatus for the AC motor control provided.