Analytical modeling of static eccentricities in axial flux permanent-magnet machines with concentrated windings

The aim of this paper is to calculate the static eccentricity (SE) of an axial flux permanent magnet (AFPM) machine by using general analytical model. The flux density of healthy condition in the air gap is calculated firstly, the radial and tangential magnetic flux density are obtained by Maxwell’s equations and Schwarz-Christoffel mapping. Next, a novelty bilinear mapping is introduced, the flux density under SE condition is obtained based on the precise magnetic flux density. Some important parameters, e.g., back EMF, cogging torque and on-load electromagnetic (EM) torque, are calculated and compared with healthy condition and finite element (FE) model. As for double rotor AFPM, eccentricity does not contribute nominal effect on the back EMF and EM torque, while the cogging torque is increased. At each section, FEM model were built to validate the analytical model, and the results showed that the analytical model predictions agree well with the observations from the FE results. Finally, the analytical model is verified via experimental results