Two-Dimensional Analytical Modeling for Slotless Spoke-Type Permanent Magnet Synchronous Machines Considering Ferromagnetic Parts Permeability

In this article, a 2-D analytical electromagnetic model based on the separation of variables method (SVM) is proposed for spoke-type interior permanent magnet (PM) slotless machines. The novelties and contributions consist of: 1) considering the finite permeability of interpole irons of the rotor and 2) considering the rotor as a single composite subdomain. In addition, the structure is reduced to 1/p or 0.5/p, where p is the number of poles, because of the possibility of anti-periodic and symmetric field distribution. The proposed model is effective both in terms of preprocessing formulation and computational burden. It is shown that the motor quantity calculations will solely require the magnetic vector potential, which is directly obtained from SVM formulation. The results of the proposed analytical model are compared with those of the finite element method, showing the accuracy and effectiveness of the proposed model.