Simple and efficient model for slotless eccentric surface-mounted PM machines

In this study, the equivalent boundary method is applied for modelling of the air gap flux density in the eccentric surface-mounted permanent magnet (PM) machines. In the presented model, neither conformal transformations nor perturbation analysis methods are applied. In this approach, a two-dimensional Poisson solution for the eccentric PM machines is developed. Therefore, the proposed model is simple, precise and efficient. To make the solution of the Poisson equation in the eccentric air gap easy, the concept of the equivalent boundary method is exploited to find an equivalent concentric geometry for the eccentric problem. All the claimed theorems are mathematically approved. The model is valid for static and dynamic eccentricities at no-load and on-load conditions. Using the analytically predicted air gap flux density, electromagnetic torque, back-EMF and the resulted radial force are computed. The correctness of the predicted results is validated by means of finite-element analysis.