Characteristic analysis of permanent magnet synchronous generators with slotless stator structure considering magnetic/mechanical air-gap using semi-3D analytical method

In this paper, we analyze a permanent magnet synchronous generator (PMSG) with a slotless stator considering the magnetic and mechanical air-gap using the semi-3D analytical method. Characteristic analyses of the PMSG are various methods, such as numerical method and analytical method. The three-dimensional (3D) analysis method is among the various methods, but it requires a long analysis time complex mathematics. On the other hand, the semi-3D analytical method with the numerical method has advantages can be simple analyzed. The slotless stator structure radial flux PMSG has a consistent magnetic energy in its air-gap. Its cogging torque does not generate, unlike the slotted stator structure. However, the slotless structure-type has a relatively larger magnetic air-gap than the slotted structure. Therefore, during the analysis of the open circuit field (OCF) and the armature reaction field (ARF), we consider the magnetic and mechanical air-gap to ensure accurate analysis. In addition, owing to the large air-gap, the analysis should include the variation of the flux density in the z-direction. The correction function can be defined such that it factors the flux density in the z-direction. In addition, the unknown parameter in the correction function can be obtained using the 3D finite element method (3D FEM) according to the magnetic air-gap. The resulting flux density in the air-gap can be obtained using the semi-3D analytical method. Therefore, the back-EMF can be obtained by performing an accurate analysis, and we confirmed that the experimental results are in good agreement with the 3D analysis results. In the full manuscript, we will present the mathematical model and physical phenomenon used to aid the related research and industrial applications.