Computer-Aided Design in Magnetics

Transcription

1 Computer-Aided Design in Magnetics

2 D. A. Lowther P. P. Silvester Computer-Aided Design in Magnetics With 84 illustrations Springer-Verlag Berlin Heidelberg New York Tokyo

3 D. A. Lowther Associate Professor of Electrical Engineering McGill University Montreal H3A 2A7 Canada P. P. Silvester Professor of Electrical Engineering McGill University Montreal H3A 2A 7 Canada Library of Congress Cataloging in Publication Data Lowther, D. A. Computer-aided design in magnetics. Bibliography: p. Includes index. 1. Magnetic devices-design and construction-data processing. 2. Computer-aided design. I. Silvester, P. P. II. Title. TK454.4.M3S by Springer-Verlag New York Inc. Softcover reprint of the hardcover 1 st edition 1986 All rights reserved. No part of this book may be translated or reproduced in any form without written permission from Springer-Verlag, 175 Fifth Avenue, New York, New York 10010, U.S.A. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. Media Conversion and Typesetting by House of Equations, Newton, New Jersey. lsbn-13: DOl: / e-lsbn-13:

4 Preface Computer-aided design has come of age in the magnetic devices industry. From its early beginnings in the 1960s, when the precision needs of the experimental physics community first created a need for computational aids to magnet design, CAD software has grown to occupy an important spot in the industrial designer's tool kit. Numerous commercial CAD systems are now available for magnetics work, and many more software packages are used in-house by large industrial firms. While their capabilities vary, all these software systems share a very substantial common core of both methodology and objectives. The present need, particularly in medium-sized and nonspecialist firms, is for an understanding of how to make effective use of these new and immensely powerful tools: what approximations are inherent in the methods, what quantities can be calculated, and how to relate the computed results to the needs of the designer. These new analysis techniques profoundly affect the designer's approach to problems, since the analytic tools available exert a strong influence on the conceptual models people build, and these in turn dictate the manner in which they formulate problems. The impact of CAD is just beginning to be felt industrially, and the authors believe this is an early, but not too early, time to collect together some of the experience which has now accumulated among industrial and research users of magnetics analysis systems. In its early versions, this book has been used by students in the authors' one-semester course at McGill University. It has also served as the cornerstone for numerous short courses given to industrial audiences. The authors wish to acknowledge their indebtedness to Dr. G. K. Cambrell, for his meticulous reading of the manuscript, and to Dr. E. M. Freeman, for our many discussions and his contributions to an early draft of several chapters. Particular thanks are due, however, to the many colleagues and students whose suggestions, help, and numerous examples have shaped this book. D. A. Lowther P. P. Silvester

5 Contents Preface v Introduction Analysis Methods in Electromagnetics The System Life-Cycle Computing Equipment for CAD Finite Element Analysis Systems Magnetic Material Representation Modelling of B-H Curves Management of Material Property Files Data Entry and Editing Complex Magnetic Materials Curve Modelling Theory The Potential Equations of Magnetics Electromagnetic Fields and Potentials Potential Problems of Electromagnetics Magnetic Scalar Potentials Time-Varying Potential Problems Rotational and Translational Symmetries Problem Modelling and Mesh Construction Geometric Modelling and Discretization Mesh Generation and Editing Multi-Model Operations and Model Libraries Batch and Interactive CAD Systems Practical Mesh Construction Automating the Mesh-Building Task Assembly of Problems III

6 Vlll Field Problems in Magnetic Devices Analysis in Design Analysis by Successive Refinement Subproblem Analysis Boundary Conditions Geometric Shape Alteration Reducing Three Dimensions to Two Planning the Solution Postprocessing Operations in CAD Inductance Calculations A Transformer Design Problem Mutual Inductances Force Calculations Local Field Values Linear Time-Varying Problems Electrosta tic Calculations Effects of Numerical Approximations Postprocessing Systems for Magnetics Postprocessor Structure and Use Manipulation of Local Data Mathematical Postprocessor Operations Graphic Displays of Results Graphic Input The Custom Postprocessor CAD Systems Present and Future System Structure Processes in CAD Interactive Command Languages Programmability of CAD Systems Workstation Layout Interactive CAD Systems for Magnetics Batch-Run CAD Systems The Literature of CAD in Magnetics Publications on Magnetics CAD An Annotated Bibliography Index Contents