Permanent magnet (de‐) magnetization and soft iron hysteresis effects

Abstract

PurposeThe purpose of this paper is to promote practical methods for the numerical modelling of hard magnetic materials and soft ferromagnetic materials in an engineering context (design of electrical machines).Design/methodology/approachObjectives achieved by the use of a practical, semi‐empirical material model that needs modest material data and computer resources. Methods: a focused theoretical specification and algorithm development; use of actual material data for algorithm validation; incorporation in commercial engineering software as a test harness. Approach: a practical engineering scheme using a macroscopic material model based on readily available materials data. Scope: numerical model of hard magnetic and soft ferromagnetic materials; scalar and vector hysteresis, major and minor loops.FindingsThe limited practicality of much of the literature, especially vector hysteresis; successful use of the model in an existing non‐linear numerical solver; energy conservation gives confidence in the results; the electric motor provides a good validation test case.Research limitations/implicationsPossible future research: application to more complicated material properties such as magneto‐relaxation.Practical implicationsThe paper extends the scope of computer‐aided engineering design of electrical machines. The impact on the developer: increased sale of an engineering software product. The impact on the design engineer: more efficient designs, reduced prototyping, reduced technical risk.Originality/valueThe algorithm that provides an effective material model; the focus on the practical issues of data and computational resources; the implementation of a theoretical construct in a large‐scale engineering design program. The value is to designers of electrical machines.