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

This paper investigates a 2-dimensional (2-D) analytical magnetic field prediction for
doubly-salient machines. Using the subdomain technique, the effects of saliency on both the rotor
and stator structures as well as their interactions are considered. The approach can be used for
magnetic 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 teeth
wound, non-overlapping winding with alternate teeth wound and 2-layer overlapping winding. To
enable the analytical solution of the governing partial differential equations, the stator and rotor
iron is assumed to be infinitely permeable and therefore the saturation effects are neglected. The
proposed approach is used in two case studies: (1) to calculate the armature reaction magnetic field
distribution of a three-phase slotted brushless machine with surface inset magnets and (2) to
compute the magnetic field distribution of a four-phase switched reluctance motor. Note that the
proposed approach cannot be employed in the case of machines with considerable saturation
effects. The analytical results are compared with those obtained from finite element analyses to
validate the analytical calculations.