Analysis of the eccentricity in a low-speed slotless permanent-magnet wind generator

This paper presents the analytical analysis of different eccentricities in the rotor of a novel slotless wind power generator. The analytical expressions for the air gap eccentricity have been derived and the effects of these eccentricities on the air gap flux density, the resultant unbalanced magnetic pull and the induced emf are investigated. The analysis shows a strong pull in the case of static eccentricity, which is not seen when the case of elliptic eccentricity for example. The analysis shows also that the induced emf per coil can vary very much but due to the series connection of the coil per phase emf is uniform but has higher rms value than in the case of healthy machine. The analytical equations are verified for the case of healthy machine on a constructed laboratory prototype.