Electrical Machines and Drives,

385 Pages·1997·13.25 MB·English

by  John Hindmarsh

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
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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
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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