Energy-saving Principles and Technologies for Induction Motors

A unique guide to the integration of three-phase induction motors with the emphasis on conserving energy The energy-saving principle and technology for induction motor is a new topic, and there are few books currently available; this book provides a guide to the technology and aims to bringabout significant advancement in research, and play an important role in improving the level of motor energy saving Includes new and innovative topics such as a case study of energy saving in beam pumping system, and reactive compensation as a means of energy saving The authors have worked in this area for 20 years and this book is the result of their accumulated research and expertise. It is unique in its integration of three-phase induction motors with the emphasis on conserving energy Integrates the saving-energy principle, technology, and method of induction motors with on-site experiences, showing readers how to meet the practical needs and to apply the theory into practice. It also provides case studies and analysis which can help solve problems on-site

Autorentext

Wenzhong Ma, China University of Petroleum, China Lianping Bai, Beijing Information Science and Technology University, China

Klappentext
This book presents a comprehensive collection of energy-saving methods for applications using three-phase induction motors. Highlighted techniques include motor power and load matching, speed matching, mechanical properties matching, variable-frequency drives, pole-changing control, and soft characteristic matching. Readers are introduced to the methods of motor reactive power compensation and applications for efficient motors. The authors then analyze the economic operation and energy-saving calculations of three-phase induction motors, before discussing field testing and evaluating methods for motors.

• Provides a systematic guide to the technology and methods for designing energy-efficient induction motors
• Includes innovative topics such as a case study of energy savings in a beam pumping system and reactive compensation as a means of energy saving
• Integrates energy saving principles, technologies, and methods for three-phase induction motors with on-site experience so that readers can readily put theory to practice
• Covers more than 20 years of research data and engineering expertise Energy-saving Principles and Technologies for Induction Motors is a practical and handy collection of energy saving methods for power engineers, electric machine experts and design application engineers. Researchers in motor drive systems, design engineers and advanced power engineering students will also benefit from this reference text.

Inhalt
About the Authors xiii

Preface xv

About the Book xvii

1 Introduction 1

1.1 The Energysaving Status of an Electric Motor System 1

1.1.1 Basic Situation of an Electric Motor System in China 1

1.1.2 The Main Contents of Energy Saving for Electric Motors in China 2

1.1.3 Status of Energy Saving for Electric Motors in China and Abroad 2

1.2 Main Development Ways of Energy Saving for Electric Motor System 4

1.2.1 Efficiency Improvement of Y Series Asynchronous Motor 4

1.2.2 Promoting Frequency Speed Regulation Technology 5

1.2.3 Promoting HighEfficiency Motors and Permanent Magnet Motors 5

1.2.3.1 HighEfficiency Electric Motor: An Important Way of Energy Saving 5

1.2.3.2 Permanent Magnetic Electric Motor: A New Kind of HighEfficiency Motor 6

1.3 Energy Saving: The Basic National Policy of China 6

1.4 Main Contents of This Book 8

2 Overview of ThreePhase Asynchronous Motors 11

2.1 Basic Structure and Characteristics of ThreePhase Asynchronous Motors 11

2.1.1 Basic Characteristics of ThreePhase Asynchronous Motors 11

2.1.2 Basic Types of ThreePhase Asynchronous Motors 12

2.1.3 Basic Structure of ThreePhase Asynchronous Motors 12

2.1.3.1 Stator 13

2.1.3.2 Rotor 14

2.1.3.3 Air Gap 15

2.1.4 Basic Parameters of ThreePhase Asynchronous Motors 16

2.2 The Principle of a ThreePhase Asynchronous Motor 17

2.3 Working Characteristic of ThreePhase Asynchronous Motors 21

2.3.1 Equivalent Circuit of Asynchronous Motors 22

2.3.1.1 T Type Equivalent Circuit of Asynchronous Motor 22

2.3.1.2 Simplified Equivalent Circuit of Asynchronous Motors 23

2.3.2 Power Balance of Asynchronous Motors 23

2.3.3 Working Characteristics of ThreePhase Asynchronous Motors 25

2.3.3.1 Speed Characteristic 26

2.3.3.2 Stator Current Characteristic 26

2.3.3.3 Electromagnetic Torque Characteristic T = f (P2) 26

2.3.3.4 Stator Power Factor Characteristic 27

2.3.3.5 Efficiency Characteristic = f(P2) 27

2.4 Mechanical Characteristics of ThreePhase Asynchronous Motors 27

2.4.1 Three Types of Formulas of Mechanical Characteristics 27

2.4.1.1 Physical Formula of Mechanical Characteristics 27

2.4.1.2 Parameter Formula of Mechanical Characteristic 28

2.4.1.3 Practical Expression of Mechanical Characteristic 30

2.4.2 Inherent Mechanical Characteristic of Asynchronous Motors 31

2.4.3 ManMade Mechanical Characteristic of Asynchronous Motors 32

2.4.3.1 ManMade Characteristic of Reducing Stator Voltage 32

2.4.3.2 ManMade Characteristic of Connecting Symmetrical ThreePhase Resistances in the Rotor's Loop 33

2.4.3.3 ManMade Characteristic of Changing the Frequency of Stator Voltage 34

2.5 Startup of ThreePhase Asynchronous Motors 35

2.5.1 Starting Requirements of ThreePhase Asynchronous Motors 35

2.5.1.1 In Order to Minimize the Impact on the Grid, the Starting Current Should be Small 35

2.5.1.2 The Starting Torque Must Be Large Enough to Speed Up the Starting Process and Shorten the Starting Time 36

2.5.2 Conditions for Squirrel Cage Asynchronous Motors Starting Directly 36

2.6 Energy Efficiency Standards of ThreePhase Asynchronous Motors 37

2.6.1 Energy Efficiency Standards of IEC ThreePhase Asynchronous Motors 38

2.6.1.1 Standard Applicable Scope 38

2.6.1.2 Class Standards 38

2.6.1.3 Interpolation Calculation 39

2.6.2 Energy Efficiency Standards of ThreePhase Asynchronous Motors in the United States and EU 40

2.6.3 Energy Efficiency Standards of ThreePhase Asynchronous Motors in China 40

2.7 Mainstream Products of ThreePhase Asynchronous Motors 45

2.7.1 Brief Introduction of Existing Products of ThreePhase Asynchronous Motors 45 2.7.2 Characteristics of Main Series of Three Pha...