Electric Drives

744 Pages·2011·171.605 MB·English

by  Vedam Subrahmanyam

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Electric Drives
Concepts and Applications
Second Edition
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ABOUT THE AUTHOR
Vedam Subrahmanyam received his MSc (Engineering) degree in Electrical
Machine Design from Madras University in 1963 and his PhD from IIT Madras in
1973. He joined ITT Madras in 1966 and served as a Professor in the department of
Electrical Engineering. Prior to this, he had taught for two years at Visweswaraya
Regional College of Engineering, Nagpur, and Regional Engineering College,
Warangal, as a faculty member. A popular academician, he has guided several
research students at the MTech and PhD levels.
Prof. Subrahmanyam has published around 60 articles in national and interna-
tional journals and has also presented papers at international conferences. He has
attended programmes in Germany and worked as a faculty member at the Uni-
versity of Dar-es-Salaam for two years. He is the author of well-acclaimed books
like Power Electronics: Devices, Converters, Applications and Thyristor Control
of Electric Drives, the latter published by Tata McGraw-Hill.
The McGroW'Hill Companies
Electric Drives
Concepts and Applications
Second Edition
Vedam Subrahmanyam
Former Professor
Department of Electrical Engineering
Indian Institute of Technology
Chennai
m
L J
Tata McGraw Hill Education Private Limited
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Electric Drives, 2e
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Cover: SDR
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Dedicated to my beloved
mother late Smt Seshamma
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Contents
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Preface XI
Introduction 1
1. Characteristics of Electric Motors 5
1.1 Introduction 5
1.2 Characteristics of DC Motors 6
1.3 Characteristics of a Three-phase Induction Motor 29
1.4 Characteristics of Synchronous Motors 46
1.5 Braking of Electric Motors 57
1.6 Starting of Electric Motors 75
Worked Examples 83
Problems 93
Multiple-Choice Questions 98
References 100
2. Dynamics of Electric Drives 101
2.1 Introduction 101
2.2 Classification of Electric Drives 102
2.3 Basic Elements of an Electric Drive 103
2.4 Dynamic Conditions of a Drive System 116
2.5 Stability Considerations of Electrical Drives 118
Worked Examples 123
Problems 127
Multiple-Choice Questions 128
References 129
3. Converters for Feeding Electric Motors 130
3.1 A General Survey of Converters
for Feeding Electric Motors 130
3.2 Phase Controlled Line Commutated Converters 143
3.3 DC Choppers 210
3.4 Inverters 224
3.5 Cycloconverters 243
3.6 AC Voltage Controller 246
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Contents
Worked Examples 273
Problems 286
Multiple-Choice Questions 290
References 291
4. Control of Electric Motors 293
4.1 Induction Motor Drives 295
4.2 Synchronous Motor Drives 343
4.3 DC Drives 367
4.4 Permanent Magnet Synchronous Motor 413
4.5 Classification of Permanent Magnet Synchronous Motors 419
4.6 Cycloconverter-fed Synchronous Motor 425
Worked Examples 429
Problems 448
Multiple-Choice Questions 458
References 464
5. Rating and Heating of Motors 466
5.1 Requirements of a Drive Motor 466
5.2 Power Losses and Heating of Electric Motors 466
5.3 Heating and Cooling of an Electric Motor 468
5.4 Classes of Duty and Selection of Motor 474
Worked Examples 491
Problems 494
Multiple-Choice Questions 495
References 496
6. Control Techniques for Electrical Drives 497
6.1 Introduction 497
6.2 Basic Features of an Electric Drive 499
6.3 Block Diagram Representation of Drive Systems 500
6.4 Signal Flow Graph Representation of the Systems 504
6.5 Transfer Functions 505
6.6 Transient Response of Closed Loop Drive Systems 517
6.7 Frequency Response Approach 524
6.8 Stability of Controlled Drives 531
6.9 Compensation and the Use of Controllers
to Improve the Performance 543
Worked Examples 587
Problems 598
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O
Contents
Multiple-Choice Questions 601
References 602
7. Drives for Specific Applications 603
7.1 Drive Considerations for Textile Mills 604
7.2 Steel Rolling Mills 609
7.3 Cranes and Hoist Drives 615
7.4 Cement Mills 625
7.5 Sugar Mills 629
7.6 Machine Tools 631
7.7 Paper Mills 633
7.8 Coal Mines 635
7.9 Centrifugal Pumps 636
7.10 Turbocompressors 642
7.11 Summary of Thyristorised AC and DC Drives 645
Multiple-Choice Questions 650
References 652
8. Microprocessors and Control of Electrical Drives 653
8.1 Introduction 653
8.2 Dedicated Hardware Systems versus
Microprocessor Control 654
8.3 Application Areas and Functions of Microprocessors
in Drive Technology 656
8.4 Control of Electric Drives Using Microprocessors 663
8.5 Some Aspects of Control System Design
of Microprocessor Based Variable Speed Drives 698
8.6 Stepper Motors 699
Multiple-Choice Questions 709
References 710
Appendix A 711
Appendix B 721
Index 727
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