Frequency components analysis of an induction machine under different fault conditions

摘要

The frequency components of an induction machine due to different types of internal faults and their combinations are studied in this paper. Instead of taking a look at the current and control signals directly, this paper studies the impact caused by the basic inner structure on the inductances and their frequency components. Modified winding function and equivalent air-gap length are computed such that the combinations of internal faults can be accommodated. Static and dynamic eccentricity reshape the air-gap in a direct manner, while saturation brings third order harmonics, which instead can be equivalently considered as the effect caused by the fluctuation of air-gap length. Thus eccentricity faults and saturation have combined impacts on the equivalent air-gap length. Modified winding function accounting for all space harmonics simplifies the computation of inductances, and is also adequate for the case with rotor asymmetry. By extracting frequency components, different internal fault features are revealed. ANSYS/Maxwell is employed to simulate different cases to verify the theoretical analysis.