Comparison of Two Finite-Permeability Subdomain Models for Surface-Mounted Permanent-Magnet Machines Considering Magnetic Saturation

Contrary to traditional subdomain analytical models, the finite-permeability subdomain models can consider the finite magnetic permeability of ferromagnetic material. Therefore, the finite-permeability subdomain models can consider the magnetic saturation of motors. However, it is still unclear what differences these analytical models exhibit when studying magnetic saturation. The work proposed here aims to fill this literature gap by comparing two finite-permeability subdomain models of surface-mounted permanent-magnet machines (SMPMMs) considering magnetic saturation. The first model considers the boundary conditions in radial and tangential directions for stator teeth and slots region. In the second, the permeability variation in these regions is modeled through the Fourier series and the Cauchy product. These two models are evaluated for the magnetic field distribution and electromagnetic performance of SMPMMs. This study shows that both models can effectively handle magnetic saturation problems, but the first model is more accurate but time-consuming than the second model. The second model has a more significant error in low saturation conditions. Choosing appropriate harmonics and allowable errors can significantly reduce calculation time. The comparison is validated by the finite-element method and experimental results.