TWO-DIMENSIONAL ANALYTICAL MAGNETIC FIELD CALCULATIONS FOR DOUBLY-SALIENT MACHINES

This paper investigates a 2-dimensional (2-D) analytical magnetic field prediction fordoubly-salient machines. Using the subdomain technique, the effects of saliency on both the rotorand stator structures as well as their interactions are considered. The approach can be used formagnetic field calculation in machines with any combination of rotor- and stator-pole number.Three different stator winding structures are considered: non-overlapping winding with all teethwound, non-overlapping winding with alternate teeth wound and 2-layer overlapping winding. Toenable the analytical solution of the governing partial differential equations, the stator and rotoriron is assumed to be infinitely permeable and therefore the saturation effects are neglected. Theproposed approach is used in two case studies: (1) to calculate the armature reaction magnetic fielddistribution of a three-phase slotted brushless machine with surface inset magnets and (2) tocompute the magnetic field distribution of a four-phase switched reluctance motor. Note that theproposed approach cannot be employed in the case of machines with considerable saturationeffects. The analytical results are compared with those obtained from finite element analyses tovalidate the analytical calculations.