Compound Analytical Model Dedicated to the Prediction of the Features of Fractional-Slot PMSMs

Abstract

The paper is aimed at a simple analytical approach to predict the no-and on-load features of fractional-slot permanent magnet synchronous machines (FSPMSMs). The proposed approach is based on the combination of: (i) a formulation of the no-load air gap flux density based on the resolution of the Maxwell equations, and (ii) the magnetic equivalent circuit (MEC) of the stator. The resulting compound analytical model is iteratively solved using a Newton-Raphson algorithm where the stator MEC incorporates position-dependent magneto-motive force (MMF) sources yielded by the no-load air gap flux density formulation along with those due to the armature magnetic reaction. Prior to do so, a comparison, based on the tradeoff accuracy/CPU time, of three stator MEC networks is carried out. Following the MEC selection, the proposed approach is applied to three case studies which differ by their slot per pole and per phase number and by the permanent magnet arrangement, leading to the prediction of their no-and on-load features. The obtained analytical results are validated by finite element analysis.