Armature reaction field and winding inductances of slotless permanent-magnet brushless machines

The paper describes an improved two-dimensional (2-D) analytical model for predicting the winding inductances and the armature reaction field of slotless permanent magnet brushless machines. Results from the model are compared to those deduced from finite element analyses, existing one dimensional (1-D) and 2-D analytical models and measurements. It is shown that the radial thickness of the airgap winding can have a significant effect on both the winding inductances and the armature reaction field.