New design solution for static eccentricity in single stator-single rotor axial flux induction motors

This study proposes a new design solution for static eccentricity in axial flux induction motors (AFIMs). There are two definitions for static eccentricity in AFIMs. In the first approach, that is, commonly used for double-side machines, the rotor axis does not coincide with the stator bore but rotor rotates around its own shaft. So, the air-gap of motor is not uniform. Usually, in single stator-single rotor arrangement the rotor integrates with rotating parts of mechanical load. So, when static eccentricity occurs, air-gap length remains uniform. Rotor axis remains parallel with stator axis whereas it does not coincide with the stator bore. Based on the authors' knowledge, the latter approach has not been considered before. Therefore in this study a new definition for static eccentricity factor in direct drive is presented. Also, an optimisation is done to decrease the effect of static eccentricity on motor performance. The mathematical model of studied motor in transient and steady state is used based on d-q axis theory. In particular, the proposed model considers the effect of core saturation, and both approaches for modelling static eccentricity. Finally, studied motor is constructed and tested. All parameters of studied motor are calculated based on experimental measurements.