Analytical Analysis of the Open-Circuit External Field of Interior Permanent Magnet Synchronous Motors under the Eccentricity Fault

Aiming at diagnosing the eccentricity fault of interior permanent magnet synchronous motors (IPMSMs), this paper analytically calculates the radial component of the open-circuit external field of a typical traction IPMSM under the eccentricity fault. Firstly, the radial component of the open-circuit air-gap field is calculated by an Equivalent Magnetic Circuit model considering the temporal and spatial distribution of the changing air-gap length. Then, the radial component of the open-circuit external field is calculated based on improved attenuation coefficients. Finally, the pattern of how the eccentricity fault impacts the open-circuit external field is analyzed. It is found that the open-circuit external field is sensitive to the eccentricity fault and thus is capable to be adopted as a diagnostic signal of that fault.