Analytical model including rotor eccentricity for bearingless synchronous reluctance motors

This paper deals with modelling of rotor eccentricity in a dual three-phase winding bearingless synchronous reluctance motors (BSyRMs). The motor includes two separate sets of three-phase windings: one for torque production and the other one for radial force production. For this motor, an improved analytical model with linear magnetic material is presented. The accuracy of the model depends on the accuracy of the inverse-airgap function. Typically, a series expansion is used for approximating the inverse-airgap function. In order to make the main-winding inductances depend on the radial position, at least the first two terms have to be included in the expansion, enabling calculation of the radial forces caused by unbalanced magnetic pull. The improved model is applicable, e.g., for stability analysis, time-domain simulations, or developing real-time control methods.