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.

Keywords

• Fractional-slot permanent magnet (PM) synchronous machines
• Maxwell equations
• surface-mounted PMs
• spoke-type PMs
• magnetic equivalent circuit
• no- and on-load features