EBOOK - Control of Induction Motors (Andrzej M. Trzynadlowski)


EBOOK - Kiểm soát động cơ cảm ứng (Andrzej M. Trzynadlowski) - 241 Trang.

More than half of the total electrical energy produced in developed countries is converted into mechanical energy in electric motors, freeing the society from the tedious burden of physical labor. Among many types of the motors, three-phase induction machines still enjoy the same unparalleled popularity as they did a century ago. At least 90% of industrial drive systems employ induction motors.

Most of the motors are uncontrolled, but the share of adjustable speedin duction motor drives fed from power electronic converters is steadily increasing, phasing out dc drives. It is estimated that more than 50 billion dollars could be saved annually by replacing all ‘‘dumb’’ motors with controlled ones. However, control of induction machines is a much more challenging task than control of dc motors. Two major difficulties are the necessity of providing adjustable-frequency voltage (dc motors are controlled by adjusting themagnitudeof supply voltage) and the nonlinearity and complexity of analytical model of the motor, aggrandized byparameter uncertainty.

CONTENTS:

1 Background 1
1.1 Induction Motors 1
1.2 Drive Systems with Induction Motors 3
1.3 Common Loads 4
1.4 Operating Quadrants 10
1.5 Scalar and Vector Control Methods 11
1.6 Summary 12
2 Construction and Steady-State Operation of
Induction Motors 15
2.1 Construction 15
2.2 Revolving Magnetic Field 17
2.3 Steady-State Equivalent Circuit 24
2.4 Developed Torque 27
2.5 Steady-State Characteristics 31
2.6 Induction Generator 36
2.7 Summary 40
3 Uncontrolled Induction Motor Drives 43
3.1 Uncontrolled Operation of Induction Motors 43
3.2 Assisted Starting 44
3.3 Braking and Reversing 47
3.4 Pole Changing 51
3.5 Abnormal Operating Conditions 52
3.6 Summary 54
4 Power Electronic Converters for Induction Motor
Drives 55
4.1 Control of Stator Voltage 55
4.2 Rectifiers 56
4.3 Inverters 64
4.4 Frequency Changers 69
4.5 Control of Voltage Source Inverters 71
4.6 Control of Current Source Inverters 81
4.7 Side Effects of Converter Operation in Adjustable Speed
Drives 88
4.8 Summary 91
5 Scalar Control Methods 93
5.1 Two-Inductance Equivalent Circuits of the Induction Motor 93
5.2 Open-Loop Scalar Speed Control (Constant Volts/Hertz) 97
5.3 Closed-Loop Scalar Speed Control 101
5.4 Scalar Torque Control 102
5.5 Summary 105
6 Dynamic Model of the Induction Motor 107
6.1 Space Vectors of Motor Variables 107
6.2 Dynamic Equations of the Induction Motor 111
6.3 Revolving Reference Frame 114
6.4 Summary 117
ix CONTENTS
7 Field Orientation 119
7.1 Torque Production and Control in the DC Motor 119
7.2 Principles of Field Orientation 121
7.3 Direct Field Orientation 124
7.4 Indirect Field Orientation 126
7.5 Stator and Airgap Flux Orientation 129
7.6 Drives with Current Source Inverters 134
7.7 Summary 135
8 Direct Torque and Flux Control 137
8.1 Induction Motor Control by Selection of Inverter States 137
8.2 Direct Torque Control 140
8.3 Direct Self-Control 148
8.4 Space-Vector Direct Torque and Flux Control 145
8.5 Summary 157
9 Speed and Position Control 159
9.1 Variables Controlled in Induction Motor Drives 159
9.2 Speed Control 161
9.3 Machine Intelligence Controllers 164
9.4 Position Control 173
9.5 Summary 175
10 Sensorless Drives 177
10.1 Issues in Sensorless Control of Induction Motors 177
10.2 Flux Calculators 179
10.3 Speed Calculators 183
10.4 Parameter Adaptation and Self-Commissioning 191
10.5 Commercial Adjustable Speed Drives 197
10.6 Summary 200
Literature 203
Glossary of Symbols 221
Index 225

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