ENERGY EFFICIENT ELECTRIC MOTORS Third Edition Revised and Expanded ALI EMADI

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ENERGY EFFICIENT ELECTRIC MOTORS Third Edition Revised and Expanded ALI EMADI

Preface

The main purpose of this new edition continues to be to provide
guidelines for selecting and utilizing electric motors on the basis of
energy efficiency and life-cycle cost. In previous editions of this
book, particular emphasis was given to three-phase and single-phase
induction motors in the 1–200 hp range since this was the range
offering maximum opportunities for energy savings. However, since
the second edition, there has been a growing demand in the
direction of solid-state intensive electric motor drives as adjustable
or variable speed drives. New electric motors such as brushless DC
and switched reluctance have also been mass-produced and made
commercially available. The impetus toward this expansion of
power electronics has been provided by recent advancements in the
areas of solid-state switching devices, control electronics, and
advanced microcontrollers, microprocessors, and digital signal
processors (DSP). These advancements facilitate high-tech
applications and enable the introduction of power electronic
converters with highest performance, maximum efficiency, and
minimum volume and weight. In fact, electric motors with advanced
power electronic drivers have real and significant potential for
improving not only efficiency and life-cycle cost, but also reliability,
performance, and safety.
In this edition, Chapters 1, 2, 4, 5, and 7 from the previous
editions have been updated, rearranged, and revised. These chapters
present energy-efficient single-phase and three-phase induction
motors comprehensively. Chapters 3, 6, 8, 9, and 10 are new.
Chapter 3 presents the fundamentals of power electronics applicable
to electric motor drives. Adjustable speed drives and their
applications are explained in Chapter 6. Advanced permanent
magnet (PM) and brushless DC (BLDC) motor drives as well as
switched reluctance motor (SRM) drives are presented in Chapters
8 and 9, respectively. Finally, utility interface issues including power
factor correction (PFC) and active filters (AF) are discussed in
Chapter 10.
I would like to acknowledge gratefully the contributions of many
graduate students at Illinois Institute of Technology in different
sections/chapters of this book. They are Mr. Brian Kaczor
contributing in Chapter 3, Mr. Timothy R. Cooke, Mr. Anthony
Villagomez, and Mr. Semih Aslan contributing in Chapter 6, Mr.
Manas C. Phadke and Mr. Aly A. Aboul-Naga contributing in
Chapter 8, Mr. Himanshu Ray, Ms. Alpa Bhesania, Mr. Madan M.
Jalla, Mr. Sheldon S. Williamson, Mr. Piyush C. Desai, and Mr.
Ranjit Jayabalan contributing in Chapter 9, and Mr. Ritesh Oza
and Mr. Abdolhosein Nasiri contributing in Chapter 10.
I would also like to acknowledge the efforts and assistance of

Contents

Preface v
1 Induction Motor Characteristics 1
1.1 Three-Phase Induction Motors 1
1.2 Single-Phase Induction Motors 17
2 Energy-Efficient Motors 32
2.1 Standard Motor Efficiency 32
2.2 Why More Efficient Motors? 35
2.3 What Is Efficiency? 35
2.4 What Is an Energy-Efficient Motor? 44
2.5 Efficiency Determination 48
2.6 Motor Efficiency Labeling 57
2.7 NEMA Energy-Efficient Motor Standards 59
vii
Copyright © 2005 by Marcel Dekker
3 Fundamentals of Electric Motor Drives 64
3.1 Power Electronic Devices 65
3.2 Electric Motor Drives 67
3.3 Single-Phase, Half-Wave, Controlled Rectifier 67
3.4 Single-Phase, Full-Wave, Controlled Rectifier 70
3.5 Phase-Controlled Induction Motor Drives 73
3.6 Control of DC Motors Using DC/DC Converters 79
Selected Readings 88
4 The Power Factor 90
4.1 What Is the Power Factor? 90
4.2 The Power Factor in Sinusoidal Systems 91
4.3 Why Raise the Power Factor? 93
4.4 How to Improve the Power Factor 95
4.5 The Power Factor with Nonlinear Loads 109
4.6 Harmonics and the Power Factor 114
4.7 Power Factor Motor Controllers 118
5 Applications of Induction Motors 128
5.1 General Discussion 128
5.2 Varying Duty Applications 136
5.3 Voltage Variation 139
5.4 Voltage Unbalance 145
5.5 Overmotoring 151
5.6 Polyphase Induction Motors Supplied by
Adjustable-Frequency Power Supplies 153
6 Adjustable-Speed Drives and Their Applications 168
6.1 The Importance of Electric Motor Drives 170
6.2 Motor Drive Parameters 172
6.3 The Impact of Motor Efficiency 174
6.4 Current Motor Technology 177
6.5 Advantages of Variable-Speed Motors 178
6.6 Government Regulation 179
6.7 Adjustable-Speed Drive Applications 185
Selected Readings 187
viii Contents
Copyright © 2005 by Marcel Dekker
7 Induction Motors and Adjustable-Speed Drive Systems 188
7.1 Energy Conservation 188
7.2 Adjustable-Speed Systems 191
7.3 Applications to Fans 250
7.4 Applications to Pumps 258
7.5 Applications to Constant-Torque Loads 267
8 Brushless DC Motor Drives 270
8.1 BLDC Machine Configurations 272
8.2 Modeling 277
8.3 BLDC Power Electronic Drivers 281
8.4 Sensorless Techniques for BLDC Motor Drives 284
Selected Readings 288
9 Switched Reluctance Motor Drives 292
9.1 History of Switched Reluctance Machine 295
9.2 Fundamentals of Operation 297
9.3 Machine Configurations 302
9.4 Dynamic Modeling of SRMs 307
9.5 Control of SRMs 316
9.6 Other Power Electronic Drivers 325
9.7 Advantages and Disadvantages 339
9.8 Generative Mode of Operation 348
9.9 Energy Conversion Cycle 352
Selected Readings 354
10 Utility Interface Issues 358
10.1 ASD Example 363
10.2 Power Factor Correction Methods 367
10.3 Active Power Filters 375
Selected Readings 381
Contents ix
Copyright © 2005 by Marcel Dekker