Analytical Approach for Calculating Magnetic Field Distribution in Surface Mount PM Motor Including Stator Slot Effect

This paper presents an analytical approach to describe the magnetic field distribution in a slotted surface mounted permanent magnet motor. The novelty of the proposed approach is that the radial and tangential components of relative permeance are expressed analytically, which significantly enhances accuracy of field prediction including stator slot effects. This mathematical description can be adjusted by changing two key design parameters-slot depth and width. Furthermore, this paper introduces an analytical description of the tangential field distribution due to the winding, which leads to a purely analytical approach for calculating overall magnetic field distribution. Based on the derived expression for magnetic field distribution, the performance variables under any load conditions can be calculated. Finite element analysis has been used to verify the proposed analytical results, which match very well. This in-depth analytical study enables one to investigate the effect of slots with both radial and tangential components.