Analytical modelling and prototyping a slotless surface‐inset PM machine

An analytical model is proposed for the prediction of the no‐load air gap magnetic flux density and the armature reaction in the slotless surface‐inset PM machines. For this purpose, the exact 2D solution of the Poisson equation is derived. In the modelling process, the rotor salient poles are taken away and some surface magnetisation currents are considered at the borders of the removed salient poles. The contribution of this work is finding the value of the surface magnetisation currents such that the rotor saliency is accurately considered. The field solution in the provided surface‐mounted PM machine is simply obtained by the separation of variables method. The machine back‐EMF and its inductances is obtained by the predicted flux density due to the PMs and the stator currents, respectively. In addition, using the resultant air gap flux density in the Maxwell stress tensor, the developed electromagnetic torque is computed. Finally, the ability of the proposed model is evaluated by finite element analysis as well as experimental tests.