Effect of eccentricity on radial force production in bearingless motors

Abstract

In bearingless machines, an extra three-phase winding is added to the stator to allow the production and control of radial force acting on the rotor. The radial force analysis is normally carried out assuming the rotor is centred in the airgap. The analytical solution of this centred condition is developed for an ideal model of the machine. When the rotor is not centred, radial force due to unbalanced magnetic pull is also produced. This presentation is about how rotor eccentricity affects the radial force production in bearingless machines based on a simplified model, as compared to the analytical solution of the net radial force equation in centred rotor conditions.