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Computer-aided design in magnetics. (English) Zbl 0593.73102

Berlin etc.: Springer-Verlag. VIII, 324 p. DM 138.00 (1986).
Chapter 1: In this chapter a brief account of electromagnetic device design by the conventional rule based method, its limitations and the development of the present day computer aided design (CAD) tools based on numerical field analysis has been given. The changing trends in CAD package development of fast computing devices with large memory, the hardware requirements and their interaction are discussed. Finally, the various tasks involved in the finite element analysis based CAD package has been briefly indicated.
Chapter 2: This chapter deals with the magnetic material characteristic representation in CAD systems. The mathematical model of the B.H. curves of magnetic materials with both isotropic and anisotropic properties are given. The data file arrangements of material characteristic, file editing through graphic and keybroad data entry, corrections for geometric anisotropy of devices and theory of curve modelling has also been given.
Chapter 3: The basic equations involved in electromagnetic field analysis are derived from Maxwell’s equations. Solutions are obtained through vector or scalar potentials. The application of potential theory for static and time varying field problems are illustrated by examples. Physical approximations, used in CAD packages to analyze devices with translational and rotational symmetry are discussed.
Chapter 4: This chapter deals with preprocessing tasks in computer aided design. The tasks are, the representation of geometric shape of devices, material characteristics and boundary conditions. A detailed mesh generation and editing procedures employed in Mag Net and MAGGY CAD packages are given with illustrations. Automatic mesh generation and problem definition tasks are also discussed. Problem definition task involves the material identification with source densities, setting up of boundary conditions and solver directives.
Chapter 5: This chapter emphasizes the fact that the problem formulation plays an important role in field analysis. Problem formulation depends greatly on what results are desired, which aspects to be included or ignored and what level of approximations can be used. Two approaches are discussed and illustrated with examples. The successive refinement approach uses simpler physical models and analytic techniques and proceeds to increasing complexities. In subproblem analysis detailed portions of problems are replaced by simpler ones which are obtained by refined analysis of only that part of the problem. The difficulties in formulating boundary conditions and their possible solutions are given by examples.
Chapter 6: This chapter deals with the post processing operations that are required to derive meaningful results from the numerical data obtained during the solution process. Inductances can be evaluated from energy or flux linkage based calculations. Forces are calculated by the method of virtual work or by Maxwell stress calculations. Flux densities in the device, loss densities, local field values and induced voltage can also be determined. It has been shown that the same procedures can be used for most of the electrostatic calculations. All of the above calculations are illustrated with suitable examples. The numerical approximations in the finite element analysis that are introduced due to integration, differentiation and arithmetic operations are also discussed.
Chapter 7: This chapter discusses as to how engineering results are obtained during postprocessing using the techniques proposed in the previous chapter. The postprocessor must be capable of performing vector analysis, vector and scalar algebra and interface with suitable display devices. It consists of three calculator modules, namely, a two- dimensional (field) calculator, a one-dimensional (curve) calculator and a zero-dimensional (numeric) calculator. The postprocessing operations used in Mag Net CAD package have been illustrated by examples.
Chapter 8: This chapter gives an overview of the CAD packages available for magnetics and related areas. CAD systems are classified as batch-run and interactive systems. In batch run systems, the user must specify all the input data regarding the geometry of the model, material characteristics, boundary conditions, solution technique and the required postprocessed results before he feeds the program for batch run. Interactive systems give ”second thought capability” to the user and he is permitted to interact extensively without altering the file structure. This chapter gives valuable informations about the batch-run systems such as MAGGY and TWODEPEP and about the interactive systems such as AOS- Magnetic, FLUX2D, MagNet and PE2D. The hardware systems used, nature and order of elements, the solution technique employed, the type of problem that could be solved, access, maintenance and the availability of documentation are discussed for all these CAD systems.
Chapter 9: This chapter gives a selective set of annotated references which are available in the form of textbooks, technical papers presented in conferences and papers published in professional journals.
Reviewer: S.Sankar

MSC:

74F15 Electromagnetic effects in solid mechanics
78A25 Electromagnetic theory (general)
74-04 Software, source code, etc. for problems pertaining to mechanics of deformable solids
74S99 Numerical and other methods in solid mechanics
74-02 Research exposition (monographs, survey articles) pertaining to mechanics of deformable solids
65Yxx Computer aspects of numerical algorithms

Software:

TWODEPEP