Analytical Calculation of Stray Magnetic Field in Interior Permanent Magnet Synchronous Motor Under Static Eccentricity Considering Nonlinear and Nonuniform Magnetic Saturation

Nonlinear magnetic saturation occurs in the rotor magnetic bridge area because of the complex rotor structure in the interior permanent magnet synchronous motor (IPMSM), and the degrees of nonlinear magnetic saturation in the rotor region corresponding to different magnetic pole are quite different under the state of the stator-rotor eccentricity, that makes it difficult to calculate the stray magnetic field of the IPMSMs under eccentricity. This article proposes an analytical method of the stray magnetic field in IPMSMs considering influence of asymmetric and nonuniform saturation. First, a dual iteration technique of magnetic saturation is developed to solve the air-gap magnetic field of the IPMSMs under static eccentricity and the effect of eccentricity on the complex relative permeability (CRP) is also considered. Second, extended the air-gap domain vector magnetic potential to the outer air domain using the subdomain method to solve the stray magnetic field under static eccentricity. Then, the effects of different materials, different magnetic bridge structures and different static eccentricities on the no-load leakage coefficient are analyzed. Finally, the effectiveness of the proposed analytical calculation method (ANA) is verified by a special eccentricity simulation device, the computational error is 3.92% compared to the experimental results. The computational speed is improved by 91.3% compared to the finite element method (FEM).