A radial position control of induction type bearingless motor considering phase delay caused by the rotor squirrel cage

A squirrel cage induction type bearingless motor which has conventional four-pole stator windings and additional two-pole stator windings for the radial position control of the rotor has been proposed. The squirrel cage rotor windings can be seen as not only four-pole windings but also as two-pole windings. An equivalent circuit for one phase at the two-pole winding terminals is shown. The frequency response characteristics of effective current components in the radial force production are calculated. A phase lead-lag compensator is designed, and its effectiveness was shown. >