Modelling permanent magnet excited uniform fields with rational approximations

• Published in: Compel 2024-07, Vol.43 (3), p.604-619
• Main Authors: Costa, Stefano, Costamagna, Eugenio, Di Barba, Paolo
• Format: Article
• Language: English
• Subjects: Accuracy; Algorithms; Approximation; Cutting speed; Cutting tools; Fields (mathematics); Finite element method; Flux density; Least squares method; Magnetostatics; Mathematical analysis; Meshless methods; Methods; Numerical analysis; Permanent magnets; Permeability; Rational functions; Vector potentials; Vectors (mathematics)
• ISSN: 0332-1649; 0332-1649; 2054-5606
• DOI: 10.1108/COMPEL-11-2023-0584

Purpose A novel method for modelling permanent magnets is investigated based on numerical approximations with rational functions. This study aims to introduce the AAA algorithm and other recently developed, cutting-edge mathematical tools, which provide outstandingly fast and accurate numerical computation of potentials and vector fields. Design/methodology/approach First, the AAA algorithm is briefly introduced along with its main variants and other advanced mathematical tools involved in the modelling. Then, the analysis of a circular Halbach array with a one-pole pair is carried out by means of the AAA-least squares method, focusing on vector potential and flux density in the bore and validating results by means of classic finite element software. Finally, the investigation is completed by a finite difference analysis. Findings AAA methods for field analysis prove to be strikingly fast and accurate. Results are in excellent agreement with those provided by the finite element model, and the very good agreement with those from finite differences suggests future improvements. They are also easy programming; the MATLAB code is less than 200 lines. This indicates they can provide an effective tool for rapid analysis. Research limitations/implications AAA methods in magnetostatics are novel, but their extension to analogous physical problems seems straightforward. Being a meshless method, it is unlikely that local non-linearities can be considered. An aspect of particular interest, left for future research, is the capability of handling inhomogeneous domains, i.e. solving general interface problems. Originality/value The authors use cutting-edge mathematical tools for the modelling of complex physical objects in magnetostatics.