Elementary subdomain technique for magnetic field calculation in rotating electrical machines with local saturation effect

Abstract

PurposeThe most significant point to be introduced in the subdomain technique (i.e. based on the formal resolution of Maxwell’s equations applied in subdomain) is the local saturation effect. This paper aims to present a novel contribution on the improvement in the two-dimensional (2-D) technique in polar coordinates by focusing on the local saturation.Design/methodology/approachThe rotor and stator regions are divided into elementary subdomains (E-SDs) which are characterized by general solutions to the first harmonic of magnetostatic Maxwell equations. These E-SDs are connected in the two directions (i.e. r- and θ-edges). Newton–Raphson (NR) iterative algorithm is used for nonlinear magnetic field analysis.FindingsThe proposed model is relevant for different types of rotating electrical machines; as an example, the semi-analytical model has been implemented for spoke-type permanent-magnet (PM) machines (STPMMs). The magnetic field calculations have been performed for nonlinear B(H) curve and compared to nonlinear finite element method (FEM) predictions. The semi-analytic results are in good agreement with those obtained numerically, considering both amplitude and waveform.Originality/valueA new model for full prediction of magnetic field in the rotating electrical machines with the local saturation effect is presented.