Electrical Machines and Drive Systems Third Edition John Hindmarsh BSc (Eng), CEng, MIEE Formerly Senior Lecturer, University of Manchester Institute of Science and Technology Alasdair Renfrew BSc, PhD, CEng, MIEE Senior Lecturer, University of Manchester Institute of Science and Technology Newnes OXFORD AMSTERDAM BOSTON LONDON NEW YORK PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO Ad Maiorem Dei Gloriam Newnes An imprint of. Elsevier Science Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Wobum MA 01801-2041 First published 1982 Second edition 1985 Third edition 1996 Reprinted 1999 Transferred. to digital printing 2002 Copyright (cid:14)9 1996, John Hindmarsh and Alasdair Renfrew. All rights reserved The right of John Hindmarsh and Alasdair Renfrew to be identified as the authors of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988 No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W 1T 4LP. Applications for the copyright holder's written permission to reproduce any part of this publication should be addressed to the publisher British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloguing in Pubflcation Data A catalogue record for this book is available from the Library of Congress ISBN 0 7506 2724 7 _ r i i visit our website at www, newnespress.com ,,, J_ ii ii Contents Authors'preface to the Third Edition vii Authors'preface to the Second Edition ix Authors'preface to the First Edition X 1,ist of symbols XI..I Introduction and review of basic theory 1.1 Aim of the book 1 1.2 Foundation theory 3 1.3 Equivalent circuits 14 1.4 Power-flow diagram 17 N.B. Instead of an Index, the Example Numbers are given below with an indication of the topics covered. 2 Transformers Example Nos. 20 2.1 Solution of equations 2O ParameterS; Regulation 2.1-2.3 3-winding; 3-phase 2.4-2.6 3-phase parameters and performance 2.7-2.9 System and parallel operation 2.10-2.11 2.2 Symmetrical components 33 1-phase unbalanced loading 2.12 3 D.C. Machines 37 3.1 Revision of equations 37 3.2 Solution of equations 39 Winding m. m.f s and design 3.1-3.3 Electromechanical performance and testing 3.4-3.8 Iv Contents 3.3 Per-unit notation 50 Drive performance 3.9-3.12 3.4 Series motors 58 D.C. and A. C. operation 3.13-3.15 Speed~torque relationships 3.16-3.19 3.5 Braking circuits 4-quadrant operation 3.20-3.21 3.6 Permanent-magnet machines 72 D. C. machine magnet design 3.22 4 Induction machines 77 4.1 Revision of equations 77 4.2 Solution of equations 82 Parameter measurement and changes; General performance; Maximum torque; Per-unit notation 4.1-4.7 Power flow; Speed~torque curves 4.8-4.10 4.3 Constant- (primary) current operation: improved starting performance 102 Variable voltage/frequency; Optimum performance; Starting; Braking 4.11-4.18 4.4 Unbalanced and single-phase operation 4.19-4.21 117 4.5 Speed control by slip-power recovery 4.22-4.23 123 5 Synchronous machines 128 5.1 Summary of equations 128 5.2 Solution of equations 133 Parameters and excitation 5.1-5.3 5.3 Per-unit notation 139 Operational modes 5.4 5.4 Electromechanical problems 140 Poweg, maximum torque, power factog, load angle 5.5-5.12 5.5 Constant-current operation 155 Variable voltage~frequency; Optimum performance 5.13-5.15 5.6 Operating charts 5.16 164 5.7 Multi-machine problems 166 Parallel operation; Power-factor improvement 5.17-5.19 5.8 Salient-pole and reluctance-type machines, sYnchronising power 5.20-5.22 169 Transient behavlour; closed-loop control 177 6.1 Transient equations 178 6.2 Transfer functions 183 Contents v 6.3 Mechanical system 185 6.4 Transfer function for a drive with linear load 192 6.5 Linear control-system analysis methods 196 Square-wave, (ON~OFF)systems; Thermal transient 6.1-6.2 Starting; Acceleration times 6.3-6.6 Braking; Reversa# Stopping times 6.7-6.10 Speed and position contro# Oscillation; Stability; PI and P1D controllers 6.11-6.15 6.6 Duty cycles and ratings 222 Pulse loading 6.16-6.17 Typical duty cycles; Rolling mill; Traction 6.18-6.19 7 Power-electronic/electrical machine drives 232 7.1 Power-electronic devices 233 7.2 Chopper-controlled d.c. machine 7.1-7.2 237 7.3 Thyristor converter drives 246 Single-phase rectifier 7.3 Three-phase rectifier 7.4-7.5 7.4 Induction motor drives 258 Induction motor control 7.6 7.5 Vector (field-oriented) control 7.7 269 Slip-power recovery 7.8 7.6 Synchronous, brushless and reluctance drives 287 Comparison of main machine types 8 Mathematical and computer simulation of machine drives 295 8.1 Organisation of step-by-step solutions 296 8.2 Simulations for polyphase a.c. machines 298 8.3 Simulations for Thyristor bridge/d.c, machine drives 312 Single-phase bridge 8.1 Appendix A Table of Laplace transforms 317 Appendix B Voltage/current/power relationships for bridge-rectifier circuits 319 Appendix C Summary of equations for d-q simulations 323 Appendix D Tutorial examples with answers 331 Answers to tutorial examples 361 References 369 This Page Intentionally Left Blank Authors ' preface to the Third Edition This book commenced its life following a suggestion that there was a need fo, practical assistance to be given in the subject through the medium of illustrated examples, to enable students to get to grips with machine theory. This still remains a major purpose of the book and the comprehensive coverage of both worked and tutorial examples, from fairly ba:+ic to quite advanced level, should be of assistance in giving deeper understanding, quite apart from meeting the needs of the two parties on opposite sides of the examination system and providing a handy reference volume on output calculations for recent graduates in industry and postgraduate studies. From the practical viewpoint, too, as in many engineering disciplines, machines are more and more regarded as only one of many elements in a much larger system which, in so many cases, demands knowledge of the techniques needed to control this system and how the machine interacts with these. A major part of this system is the incorporation of fast, heavy- duty electronic switches- the power-electronic drive is now almost considered as a system in itself. The second edition placed more emphasis on this and included more detail on the simulation of such 'elemental systems' for greater understanding. However, events have moved on further in that the micro-electronic revolution has permitted previously unachievable aims; for example, to make the cheap, rugged cage-rotor induction motor act, in the transient state at least, like the more expensive and more simply controlled d.c. machine and thereby replace the latter's previous position as the fast- re:+ponse, heavy-overload-duty variable-speed drive. The third edition of this book has been occasioned by this increasing pace of change in electrical drives as a result of the foregoing develop- m, mts. Announcement of 3.3kV IGBTs has brought compact, fast- viii Authors" preface to the Third Edition . . . . . . . . . . . . . . . . . .,, switching electronic devices into the fields of heavy-rail traction and industrial drives in the MW range and the ability of the modern drive to incorporate microprocessor-based modelling has produced substantial development in control theory for electrical drives. The revisions to the text include enhanced coverage of power-electronic systems and new material on closed-loop control systems as part of the chapter on Transient Response. A substantial section of the following chapter attempts a simplified explanation of the basis of Field-oriented (vector) control of cage-rotor induction motors, giving equations from which torque and flux can be estimated and thereby, through a fast current-control system, manipulated to copy the torque-efficient mecha- nism of the d.c. machine. It includes a description of how these increasingly common drives operate, from both control and electro- magnetic viewpoints. The authors hope that this section will be particularly useful to undergraduate and postgraduate students and academic staff seeking to understand 'vector-control' using only the bases of simple algebra and electrical circuits. New examples have been added to accompany the additions and revisions to the text and there is increasing emphasis on the electrical machine as part of a system which includes a motor, sensors, control equipment and power-electronic converters. The book retains its original objectives; it is still possible, using the worked examples, for the engineer or engineering student to analyse the electromechanical performance of an electrical drive system with reasonable accuracy, using only a pocket calculator. j.H. A.C.R. Sale, Cheshire Author's preface to the Second Edition The response to the first edition included a suggestion that the final section on simulation was somewhat limited in scope. This topic really requires a separate text to deal in depth with such a wide-ranging subject. N,,vertheless, an attempt has been made in the present edition to augment the introductory treatment so that with sufficient interest, extensive sirmlations could be undertaken on the basis of the material given. Al':hough this is really tending towards project or even long-term post- graduate work, requiring substantial computer-program development, its immediate importance is in the facility it provides to display computed performance, especially of power-electronic/machine circuits, which should give a better understanding of their special features. The author gratefully acknowledges permission to use the computational facilities at UMIST for this purpose. I'here are other changes in the text to include reference for example to unbalanced operation, permanent-magnet machines and the universal m~)tor. Also, the additional worked examples and tutorial examples should ensure that the rather wide topic of Electrical Drives is given sufficiently comprehensive coverage. Overall, the intention is to support the sugges- tion of teaching the subject by means of worked examples, after due preparation on the basic equations and with discussion of the problems and solutions. j. I4. Sale, Cheshire March 1985