The method for reducing intrinsic shaft voltage by suitable selection of pole-arc coefficient in fractional slot permanent magnet synchronous machines

摘要

Fractional slot Permanent magnet synchronous machines (FSPMSMs) are widely used in electric vehicles, industrial automation, wind power, and other field. The bearing damage and premature failure occur frequently due to the shaft voltage. Actually, with certain pole and slot number combinations will generate a net dissymmetry flux to induce intrinsic shaft voltage, even without rotor eccentricity, inter-turn short circuit or other faults. In this paper proposes a novel mitigation method based on suitable selection of pole-arc coefficient by analytical analysis. Then, the optimal pole-arc coefficient is verified and corrected by finite element analysis(FEA). Determination of the optimal pole-arc coefficient by analytical analysis In the following analytical analysis, the permeability of the rotor yoke and stator core are assumed as infinite. In addition, to ensure precision and save time, a superposition method should be adopted to determine the optimal pole-arc coefficient, where the optimal value was firstly calculated by analytical analysis, then was corrected constantly by FEA to reach an exact value.