Novel Online Static Eccentricity Detection and Evaluation in Permanent Magnet Generators

Static eccentricity is a fault strongly related to the manufacturing process of electrical machines and the incorrect positioning of the rotor inside the stator. As such, it is important to develop reliable tests, aiming for the diagnosis and severity evaluation of this fault before the machine is sent to the customer. There have been issues with the detection of static eccentricity in induction motors online, especially in motors producing principal slot harmonics, while the most reliable tests have been offline ones. The area of static eccentricity detection in permanent magnet generators is yet lacking widely adopted diagnostic procedures of low complexity. In this work, the authors will evaluate most common methods for their capacity to detect the static eccentricity in direct drive permanent magnet generators, while under operation. While current methods will be shown to fail, the authors will propose a novel online method capable of producing reliable diagnostic outcomes.