# Advanced Multilevel Converters and Applications in Grid Integration

1. Edition December 2018

496 Pages, Hardcover*Wiley & Sons Ltd*

**978-1-119-47586-6**

A comprehensive survey of advanced multilevel converter design, control, operation and grid-connected applications

Advanced Multilevel Converters and Applications in Grid Integration presents a comprehensive review of the core principles of advanced multilevel converters, which require fewer components and provide higher power conversion efficiency and output power quality. The authors - noted experts in the field - explain in detail the operation principles and control strategies and present the mathematical expressions and design procedures of their components.

The text examines the advantages and disadvantages compared to the classical multilevel and two level power converters. The authors also include examples of the industrial applications of the advanced multilevel converters and offer thoughtful explanations on their control strategies. Advanced Multilevel Converters and Applications in Grid Integration provides a clear understanding of the gap difference between research conducted and the current industrial needs. This important guide:

* Puts the focus on the new challenges and topics in related areas such as modulation methods, harmonic analysis, voltage balancing and balanced current injection

* Makes a strong link between the fundamental concepts of power converters and advances multilevel converter topologies and examines their control strategies, together with practical engineering considerations

* Provides a valid reference for further developments in the multilevel converters design issue

* Contains simulations files for further study

Written for university students in electrical engineering, researchers in areas of multilevel converters, high-power converters and engineers and operators in power industry, Advanced Multilevel Converters and Applications in Grid Integration offers a comprehensive review of the core principles of advanced multilevel converters, with contributions from noted experts in the field.

Preface xvii

Part I A review on Classical Multilevel Converters 1

1 Classical Multilevel Converters 3

Gabriel H. P. Ooi, Ziyou Lim, and Hossein Dehghani Tafti

1.1 Introduction 3

1.2 Classical Two-Level Converters 3

1.3 The Need for Multilevel Converters 4

1.4 Classical Multilevel Converters 5

1.5 Multilevel Applications and Future Trends 12

References 14

2 Multilevel Modulation Methods 17

Ziyou Lim, Hossein Dehghani Tafti, and Harikrishna R. Pinkymol

2.1 Introduction 17

2.2 Carrier-Based Sinusoidal Pulse-WidthModulation Methods 19

2.3 Space Vector Modulation (SVM) 24

2.4 Summary 27

References 28

3 Mathematical Modeling of Classical Three-Level Converters 29

Gabriel H. P. Ooi

3.1 Introduction 29

3.2 Three-Level Diode-Clamped Inverter Topology 29

3.3 Three-Level Flying-Capacitor Inverter Topology 38

3.4 Summary 44

References 44

4 Voltage BalancingMethods for Classical Multilevel Converters 45

Gabriel H. P. Ooi, Hossein Dehghani Tafti, and Harikrishna R. Pinkymol

4.1 Introduction 45

4.2 Active Balancing by Adding dc Offset Voltage to Modulating Signals 45

4.3 Measurement Results for dc Offset Modulation Control 47

4.4 Natural Balancing by using Star Connected RC Filter 49

4.5 Measurement Results for the Natural Balancing Method 59

4.6 Space Vector Modulation with the Self-Balancing Technique 59

4.7 Summary 61

References 63

Part II Advanced Multilevel Rectifiers and their Control Strategies 65

5 Unidirectional Three-Phase Three-Level Unity-Power Factor Rectifier 67

Gabriel H. P. Ooi and Hossein Dehghani Tafti

5.1 Introduction 67

5.2 Circuit Configuration 67

5.3 Proposed Controller Scheme 70

5.4 Experimental Verification 80

5.5 Summary 86

References 86

6 Bidirectional and Unidirectional Five-Level Multiple-Pole Multilevel Rectifiers 89

Gabriel H. P. Ooi

6.1 Introduction 89

6.2 Circuit Configuration 89

6.3 Modulation Scheme 91

6.4 Design Considerations 93

6.5 Comparative Evaluation 95

6.6 Control Strategy 101

6.7 Experimental Verification 103

6.8 Summary 105

References 105

7 Five-Level Multiple-Pole Multilevel Vienna Rectifier 107

Gabriel H. P. Ooi and Ali I. Maswood

7.1 Introduction 107

7.2 Operating Principle 108

7.3 Design Considerations 110

7.4 Control Strategy 112

7.5 Validation 115

7.6 Summary 116

References 117

8 Five-Level Multiple-Pole Multilevel Rectifier with Reduced Components 119

Gabriel H. P. Ooi

8.1 Introduction 119

8.2 Operation Principle 120

8.3 Modulation Scheme 122

8.4 Control Strategy 123

8.5 Design Considerations 128

8.6 Validation 131

8.7 Experimental Verification 131

8.8 Summary 132

References 134

9 Four-Quadrant Reduced Modular Cell Rectifier 137

Ziyou Lim

9.1 Introduction 137

9.2 Circuit Configuration 139

9.3 Operating Principle 139

9.4 Design Considerations 141

9.5 Control Strategy 144

9.6 Comparative Evaluation of Classical MFCR and Proposed RFCR 148

9.7 Experimental Verification 149

References 160

Part III Advanced Multilevel Inverters and their Control Strategies 163

10 Transformerless Five-Level/Multiple-Pole Multilevel Inverters with Single DC Bus Configuration 165

Gabriel H. P. Ooi

10.1 Introduction 165

10.2 Five-Level Multiple-Pole Concept 166

10.3 Circuit Configuration and Operation Principles 167

10.4 Modulation Scheme 176

10.5 Design Consideration 176

10.6 Accuracy of the Current Stress Calculation 184

10.7 Losses in Power Devices 189

10.8 Discussion 197

References 199

11 Transformerless Seven-Level/Multiple-Pole Multilevel Inverters with Single-Input Multiple-Output (SIMO) Balancing Circuit 201

Hossein Dehghani Tafti and Gabriel H. P. Ooi

11.1 Introduction 201

11.2 Circuit Configuration and Operating Principles 201

11.3 SIMO Voltage Balancing Circuit 204

11.4 Design Considerations 208

11.5 Experimental Verification 212

11.6 Summary 215

References 215

12 Three-Phase Seven-Level Three-Cell Lightweight Flying Capacitor Inverter 217

Ziyou Lim

12.1 Introduction 217

12.2 LFCI Topology 219

12.3 Circuit Configuration 220

12.4 Operational Principles 220

12.5 Modulation Scheme 228

12.6 Design Considerations 230

12.7 Harmonic Characteristics 234

12.8 Experimental Verification 247

References 250

13 Three-Phase Seven-Level Four-Cell Reduced Flying Capacitor Inverter 251

Ziyou Lim

13.1 Introduction 251

13.2 Circuit Configuration 251

13.3 Operation Principles 252

13.4 Design Considerations 254

13.5 Flying Capacitor Voltage Balancing Control 259

13.6 Experimental Verification 264

14 Active Neutral-Point-Clamped Inverter 275

Ziyou Lim

14.1 Introduction 275

14.2 Circuit Configuration 277

14.3 Operating Principles 277

14.4 Design Considerations 279

14.5 Multiple Voltage Quantities Enhancement Control 280

14.6 Common Mode Reduction 298

References 316

15 Multilevel Z-Source Inverters 319

Muhammad M. Roomi

15.1 Introduction 319

15.2 Two-Level ZSI 321

15.3 Three-Level ZSI 324

15.4 Modulation Methods for Three-Level Z-Source NPC Inverter 332

15.5 Modulation Method for Three-Level Dual Z-Source NPC Inverter 335

15.6 Reference Disposition Level-Shifted PWM for Non-ideal Dual Z-Source Network NPC Inverter 350

15.7 Applications of ZSI 363

15.8 Summary 365

References 367

Part IV Grid-Integration Applications of Advanced Multilevel Converters 369

16 Multilevel Converter-Based Photovoltaic Power Conversion 371

Hossein Dehghani Tafti, Georgios Konstantinou, and Josep Pou

16.1 Introduction 371

16.2 Three-Level Neutral-Point-Clamped Inverter-Based PV Power Plant 371

16.3 Seven-Level Cascaded H-Bridge Inverter-Based PV Power Plant 390

16.4 Summary 407

References 407

17 Multilevel Converter-basedWind Power Conversion 413

Md Shafquat Ullah Khan

17.1 Introduction 413

17.2 Wind Power Conversion Principles 413

17.3 Multilevel Converters in Wind Power Conversion 416

17.4 Grid-Connected Back-to-Back Three-Phase NPC Converter 418

17.5 Summary 429

References 429

18 Z-Source Inverter-Based Fuel Cell Power Generation 433

Muhammad M. Roomi

18.1 Introduction 433

18.2 Fuel Cell Power Conversion Principles 436

18.3 Modelling of the PEMFC 437

18.4 Circuit Configuration 439

18.5 Control Strategy 440

18.6 Validation 442

18.7 Summary 451

References 453

19 Multilevel Converter-Based Flexible Alternating Current Transmission System 455

Muhammad M. Roomi and Harikrishna R. Pinkymol

19.1 Introduction 455

19.2 A Space Vector Modulated Five-Level Multiple-pole Multilevel Diode-Clamped STATCOM 456

19.3 Summary 470

References 470

Index 473

ALI I. MASWOOD, PHD, is an Associate Professor at Nanyang Technological University, Singapore. He received his first class B & M. Eng from Moscow Power Engineering Institute and Ph. D degree from Concordia University, Canada. Having taught in Canada for some time, he joined NTU, Singapore. Dr. Maswood is an Associate Editor, IET PEL, author of more than 100 journal and conference papers and a number of patents. His research interests are in unity PF converters, harmonics, multilevel converters, and modulation techniques. He is the recipient of several national and international grants that include the Qatar Foundation & Rolls Royce.

HOSSEIN DEHGHANI TAFTI, PHD, received B.Sc. and M.Sc. degrees in electrical engineering and power system engineering from Amirkabir University of Technology, Iran, in 2009 and 2011, respectively, and a Ph.D. degree in electrical engineering from Nanyang Technological University, Singapore, in 2017. From February to August 2016, he was on a research exchange program with the University of New South Wales, Australia, where he was working in the control of multilevel grid-connected converters. From August to October 2017, he was a Researcher with Aalborg University, Denmark, where he was working on the constant power generation of photovoltaic power plants. Since January 2018 he has worked as a research fellow at Nanyang Technological University. His research interests include photovoltaic power plants, multilevel converters, renewable energy, and fault-ride-through capabilities of power converters.