Power Electronics, A First Course Simulations and Laboratory Implementations

POWER ELECTRONICS A FIRST COURSE

Enables students to understand power electronics systems, as one course, in an integrated electric energy systems curriculum

Power Electronics A First Course provides instruction on fundamental concepts related to power electronics to undergraduate electrical engineering students, beginning with an introductory chapter and moving on to discussing topics such as switching power-poles, switch-mode dc-dc converters, and feedback controllers.

The authors also cover diode rectifiers, power-factor-correction (PFC) circuits, and switch-mode dc power supplies. Later chapters touch on soft-switching in dc-dc power converters, voltage and current requirements imposed by various power applications, dc and low-frequency sinusoidal ac voltages, thyristor converters, and the utility applications of harnessing energy from renewable sources.

Power Electronics A First Course is the only textbook that is integrated with hardware experiments and simulation results. The simulation files are available on a website associated with this textbook. The hardware experiments will be available through a University of Minnesota startup at a low cost.

In Power Electronics A First Course, readers can expect to find detailed information on:

• Availability of various power semiconductor devices that are essential in power electronic systems, plus their switching characteristics and various tradeoffs
• Common foundational unit of various converters and their operation, plus fundamental concepts for feedback control, illustrated by means of regulated dc-dc converters
• Basic concepts associated with magnetic circuits, to develop an understanding of inductors and transformers needed in power electronics
• Problems associated with hard switching, and some of the practical circuits where this problem can be minimized with soft-switching

Power Electronics A First Course is an ideal textbook for Junior/Senior-Undergraduate students in Electrical and Computer Engineering (ECE). It is also valuable to students outside of ECE, such as those in more general engineering fields. Basic understanding of electrical engineering concepts and control systems is a prerequisite.

Ned Mohan, PhD, joined the University of Minnesota in 1975, where he is currently Oscar A. Schott Professor of Power Electronic Systems and Morse-Alumni Distinguished Professor. He is a Fellow of the IEEE and a member of the National Academy of Engineering. He is also a Regents Professor at the University and Minnesota and has published five six textbooks with Wiley.

Siddharth Raju is a Research Assistant Professor at the University of Minnesota and a co-author of Analysis and Control of Electric Drives: Simulations and Laboratory Implementation (2020). He is the founder of Sciamble Corp., a startup specializing in rapid real-time prototyping solutions.

List of Simulation and Hardware Implementation Example and Figures xiii

Preface xv

Acknowledgment xvii

About the Companion Website xix

Chapter 1 Power Electronics: An Enabling Technology 1

1.1 Introduction to Power Electronics 1

1.2 Applications and the Role of Power Electronics 2

1.3 Energy and the Environment: Role of Power Electronics in Providing Sustainable Electric Energy 4

1.4 Need for High Efficiency and High Power Density 8

1.5 Structure of Power Electronics Interface 9

1.6 Voltage-Link-Structure 11

1.7 Recent Advances in Solid-State Devices Based on Wide Bandgap (WBG) Materials 16

1.8 Use of Simulation and Hardware Prototyping 16

References 17

Problems 18

Chapter 2 Design of Switching Power-poles 21

2.1 Power Transistors and Power Diodes 21

2.2 Selection of Power Transistors 22

2.3 Selection of Power Diodes 24

2.4 Switching Characteristics and Power Losses in Power Poles 25

2.5 Justifying Switches and Diodes as Ideal 30

2.6 Design Considerations 31

2.7 The PWM IC 34

2.8 Hardware Prototyping 35

References 36

Problems 36

Appendix 2A Diode Reverse Recovery and Power Losses 37

Chapter 3 Switch-mode Dc-dc Converters: Switching Analysis, Topology Selection, and Design 41

3.1 DC-DC Converters 41

3.2 Switching Power-Pole in DC Steady State 41

3.3 Simplifying Assumptions 45

3.4 Common Operating Principles 46

3.5 Buck Converter Switching Analysis in DC Steady State 46

3.6 Boost Converter Switching Analysis in DC Steady State 51

3.7 Buck-Boost Converter Analysis in DC Steady State 57

3.8 Topology Selection 65

3.9 Worst-Case Design 66

3.10 Synchronous-Rectified Buck Converter for Very Low Output Voltages 66

3.11 Interleaving of Converters 71

3.12 Regulation of DC-DC Converters by PWM 71

3.13 Dynamic Average Representation of Converters in CCM 72

3.14 Bi-Directional Switching Power-Pole 74

3.15 Discontinuous-Conduction Mode (DCM) 75

References 86

Problems 86

Appendix 3A Average Representation in Discontinuous- Conduction Mode (DCM) 92

Chapter 4 Designing Feedback Controllers in Switch-mode Dc Power Supplies 97

4.1 Introduction and Objectives of Feedback Control 97

4.2 Review of Linear Control Theory 98

4.3 Linearization of Various Transfer Function Blocks 100

4.4 Feedback Controller Design in Voltage-Mode Control 106

4.5 Peak-Current Mode Control 113

4.6 Feedback Controller Design in DCM 123

References 124

Problems 124

Appendix 4A Bode Plots of Transfer Functions with Poles and Zeros 125

Appendix 4B Transfer Functions in Continuous Conduction Mode (CCM) 128

Appendix 4C Derivation of Parameters of the Controller Transfer Functions 134

Chapter 5 Rectification of Utility Input Using Diode Rectifiers 139

Rectifiers 139

5.1 Introduction 139

5.2 Distortion and Power Factor 140

5.3 Classifying the “Front-End” of Power Electronic Systems 148

Electronic Systems 148

5.4 Diode-Rectifier Bridge “Front-End” 148

5.5 Means to Avoid Transient Inrush Currents at Starting 156

5.6 Front-Ends with Bi-Directional Power Flow 157

References 157

Problems 157

Chapter 6 Power-factor-correction (PFC) Circuits And Designing the Feedback Controller And Designing the Feedback Controller 159

6.1 Introduction 159

6.2 Operating Principle of Single-Phase PFCS 159

6.3 Control of PFCS 162

6.4 Designing the Inner Average-Current-Control Loop 163

6.5 Designing the Outer Voltage-Control Loop 165

6.6 Example of Single-Phase PFC Systems 167

6.7 Simulation Results 168

6.8 Feedforward of the Input Voltage 169

6.9 Other Control Methods for PFCS 169

References 170

Problems 170

Appendix 6A Proof that Iˆ_S3/Iˆ_L2 =1/2

Appendix 6b Proof That V ̃_d I ĩ _L(s)=1 I 2 Vˆs/V_d R I 2/ 1+ s (R /2)C

Chapter 7 Magnetic Circuit Concepts 173

7.1 Ampere-Turns and Flux 173

7.2 Inductance l 174

7.3 Faraday’s Law: Induced Voltage in a Coil Due to

Time-Rate of Change of Flux Linkage 176

7.4 Leakage and Magnetizing Inductances 177

7.5 Transformers 179

Reference 182

Problems 182

Chapter 8 Switch-mode Dc Power Supplies 185

8.1 Applications of Switch-Mode DC Power Supplies 185

8.2 Need for Electrical Isolation 186

8.3 Classification of Transformer-Isolated DC-DC Converters 186

8.4 Flyback Converters 186

8.5 Forward Converters 198

8.6 Full-Bridge Converters 204

8.7 Half-Bridge and Push-Pull Converters 209

8.8 Practical Considerations 209

References 210

Problems 211

Chapter 9 Design of High-frequency Inductors and Transformers 215

9.1 Introduction 215

9.2 Basics of Magnetic Design 215

9.3 Inductor and Transformer Construction 216

9.4 Area-Product Method 216

9.5 Design Example of an Inductor 219

9.6 Design Example of a Transformer for a

Forward Converter 221

9.7 Thermal Considerations 221

References 222

Problems 222

Chapter 10 Soft-switching in Dc-dc Converters and

Half-bridge Resonant Converters 223

10.1 Introduction 223

10.2 Hard-Switching in Switching Power poles 223

10.3 Soft-switching in Switching Power-Poles 225

10.4 Half-Bridge Resonant Converter 228

References 230

Problems 230

Chapter 11 Applications of Switch-mode Power Electronics in Motor Drives, Uninterruptible Power Supplies, And Power Systems 231

11.1 Introduction 231

11.2 Electric Motor Drives 231

11.3 Uninterruptible Power Supplies (UPS) 244

11.4 Utility Applications of Switch-Mode

Power Electronics 244

Reference 246

Problems 246

Chapter 12 Synthesis of Dc and Low-frequency Sinusoidal Ac Voltages for Motor Drives, Ups, and Power Systems Applications 249

12.1 Introduction 249

12.2 Bidirectional Switching Power-Pole as the Building Block 250

12.3 Converters for DC Motor Drives (−Vd <vo <Vd) 254

12.4 Synthesis of Low-Frequency AC 260

12.5 Single-Phase Inverters 261

12.6 Three-Phase Inverters 266

12.7 Multilevel Inverters 280

12.8 Converters For Bidirectional Power Flow 281

12.9 Matrix Converters (Direct Link System) 283

References 284

Problems 284

Chapter 13 Thyristor Converters 287

13.1 Introduction 287

13.2 Thyristors (SCRs) 287

13.3 Single-phase, Phase-controlled Thyristor Converters 289

13.4 Three-Phase, Full-Bridge Thyristor Converters 294

13.5 Current-Link Systems 300

Reference 301

Problems 301

Chapter 14 Utility Applications of Power Electronics 303

14.1 Introduction 303

14.2 Power Semiconductor Devices and Their Capabilities 304

14.3 Categorizing Power Electronic Systems 305

14.4 Distributed Generation (DG) Applications 306

14.5 Power Electronic Loads 311

14.6 Power Quality Solutions 312

14.7 Transmission and Distribution (T&D) Applications 313

References 317

Problems 317

Index 319

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