Sneak Circuits of Power Electronic Converters

Sneak Circuits of Power Electronic Converters

Work on sneak circuits and related analysis methods for power converters contributes to the reliability of power electronic systems worldwide. Most books on the subject focus on electronic systems; this book is perhaps the first to examine power electronic systems. The authors describe sneak circuit phenomena in power converters, introduce SCA methods for power electronic systems, and propose how to eliminate and make use of sneak circuits.

This book:

• highlights the advanced research works in sneak circuit analysis by a leading author in the field
• is original in its treatment of power electronics converters, going beyond the electronic system level
• is suitable for both introductory and advanced levels
• offers guidelines for industry professionals involved in the design of power electronic systems, enabling early detection of potential problems

This book is geared for researchers and graduate students in electrical engineering, as well as engineers and researchers in power electronics. Researchers in power electronics reliability will also find it to be a helpful resource.

About the Authors xi

Preface xiii

Acknowledgments xvii

1 Sneak Circuit and Power Electronic Systems 1

1.1 Reliability of Power Electronic Systems 1

1.2 Sneak Circuit 2

1.2.1 Definition of Sneak Circuit 2

1.2.2 Examples of Sneak Circuits 3

1.2.3 Basic Causes of Sneak Circuit 9

1.3 Sneak Circuit Analysis 10

1.3.1 Definition of Sneak Circuit Analysis 10

1.3.2 History of Sneak Circuit Analysis 10

1.3.3 Methods of Sneak Circuit Analysis 11

1.3.4 Benefits of Sneak Circuit Analysis 12

1.3.5 Relationship between Sneak Circuit Analysis and other Safety Techniques 13

1.4 Power Electronic System and Sneak Circuit Analysis 14

1.5 Arrangement of this Book 15

References 15

Part I SNEAK CIRCUIT PHENOMENA

2 Sneak Circuits of Resonant Switched Capacitor Converters 19

2.1 Introduction 19

2.2 Sneak Circuits of Basic RSC Converter 19

2.2.1 Sneak Circuits of Basic Step-Down RSC Converter 20

2.2.2 Sneak Circuits of Basic Step-Up RSC Converter 27

2.2.3 Sneak Circuits of Basic Inverting RSC Converter 34

2.2.4 Sneak Circuit Performance of Basic RSC Converters 37

2.3 Sneak Circuits of High-Order RSC Converter 37

2.3.1 Sneak Circuits of High-Order Step-Down RSC Converter 38

2.3.2 Sneak Circuits of High-Order Step-Up RSC Converter 47

2.4 Summary 57

References 57

3 Sneak Circuits of DC-DC Converters 59

3.1 Introduction 59

3.2 Buck Converter 59

3.2.1 CCM of Buck Converter 59

3.2.2 DCM of Buck Converter 61

3.2.3 Operating Conditions of Buck Converter 62

3.3 Boost Converter 63

3.3.1 CCM of Boost Converter 63

3.3.2 DCM of Boost Converter 65

3.3.3 Operating Conditions of Boost Converter 66

3.4 Buck-Boost Converter 67

3.4.1 CCM of Buck-Boost Converter 67

3.4.2 DCM of Buck-Boost Converter 68

3.4.3 Operating Conditions of Buck-Boost Converter 70

3.5 Sneak Circuit Conditions of Buck, Boost, and Buck-Boost Converters 71

3.6 Cúk Converter 71

3.6.1 Normal Operating Mode of Cúk Converter 71

3.6.2 Sneak Circuit Phenomena of Cúk Converter 74

3.6.3 Experimental Verification of Cúk Converter 81

3.7 Sepic Converter 84

3.7.1 Normal Operating Mode of Sepic Converter 84

3.7.2 Sneak Circuit Phenomena of Sepic Converter 89

3.7.3 Experimental Verification of Sepic Converter 91

3.8 Zeta Converter 91

3.8.1 Normal Operating Mode of Zeta Converter 94

3.8.2 Sneak Circuit Phenomena of Zeta Converter 98

3.8.3 Experimental Verification of Zeta Converter 100

3.9 Sneak Circuit Conditions of Cúk, Sepic, and Zeta Converters 102

3.10 Summary 103

References 103

4 Sneak Circuits of Soft-Switching Converters 105

4.1 Introduction 105

4.2 Sneak Circuits of Full-Bridge ZVS PWM Converter 105

4.2.1 Normal Operating Mode of FB ZVS PWM Converter 106

4.2.2 Zero Voltage Switching Conditions of FB ZVS PWM Converter 112

4.2.3 Sneak Circuit Phenomena of FB ZVS PWM Converter 112

4.2.4 Operating Conditions of FB ZVS PWM Converter 118

4.2.5 Experimental Verification of FB ZVS PWM Converter 119

4.3 Sneak Circuits of Buck ZVS Multi-Resonant Converter 122

4.3.1 Normal Operating Mode of Buck ZVS MR Converter 123

4.3.2 Sneak Circuit Phenomenon of Buck ZVS MR Converter 126

4.3.3 Simulation Verification of Buck ZVS MR Converter 128

4.4 Sneak Circuits of Buck ZVT PWM Converter 128

4.4.1 Normal Operating Mode of Buck ZVT PWM Converter 130

4.4.2 Sneak Circuit Phenomenon of Buck ZVT PWM Converter 133

4.4.3 Simulation Verification of Buck ZVT PWM Converter 136

4.5 Summary 137

References 137

5 Sneak Circuits of other Power Electronic Converters 139

5.1 Introduction 139

5.2 Sneak Circuits of Z-Source Inverter 139

5.2.1 Operating Principles of Z-Source Inverter 140

5.2.2 Sneak Circuits of Z-Source Inverter 144

5.2.3 Simulation Verification of Z-Source Inverter 147

5.3 Sneak Circuits of Synchronous DC-DC Converters 148

5.3.1 Equivalent Circuit of Synchronous Buck Converter 149

5.3.2 Normal Operating Principle of Synchronous Buck Converter 150

5.3.3 Sneak Circuits of Synchronous Buck Converter 152

5.3.4 Sneak Circuit Condition of Synchronous Buck Converter 154

5.3.5 Simulation Verification of Synchronous Buck Converter 155

5.4 Summary 156

References 157

Part II SNEAK CIRCUIT ANALYSIS METHODS

6 Sneak Circuit Path Analysis Method for Power Electronic Converters 161

6.1 Introduction 161

6.2 Basic Concepts 161

6.2.1 Directed Graph 161

6.2.2 Adjacency Matrix 162

6.2.3 Connection Matrix 164

6.2.4 Switching Function and Transfer Matrix 166

6.2.5 Switching Network and Switching Boolean Matrix 167

6.3 Sneak Circuit Path Analysis Based on Adjacency Matrix 169

6.3.1 Directed Graph and Adjacency Matrix of Power Electronic Converter 169

6.3.2 Searching Algorithms 170

6.3.3 Current Path Search in Power Electronic Converter 173

6.3.4 Sneak Circuit Path Judgment in Power Electronic Converter 174

6.3.5 Sneak Circuit Path Analysis Software Based on Adjacency Matrix 174

6.4 Sneak Circuit Path Analysis Based on Connection Matrix 178

6.4.1 Generalized Connection Matrix of Power Electronic Converter 178

6.4.2 Identification of False Current Loop 179

6.4.3 Example 181

6.4.4 Sneak Circuit Loop Analysis Software Based on Connection Matrix 184

6.5 Sneak Circuit Path Analysis Based on Switching Boolean Matrix 184

6.5.1 Switching Boolean Matrix of Power Electronic Converter 184

6.5.2 Invalid Switching Vector Criteria 190

6.5.3 Example 191

6.5.4 Sneak Circuit Path Analysis Software Based on Switching Boolean Matrix 194

6.6 Comparison of Three Sneak Circuit Path Analysis Methods 196

6.7 Summary 197

References 197

7 Sneak Circuit Mode Analysis Method for Power Electronic Converters 199

7.1 Introduction 199

7.2 Mesh Combination Analytical Method 200

7.2.1 Mesh and Connecting Piece 200

7.2.2 Basic Graph Algorithms 200

7.2.3 Mesh Combination Method 201

7.3 Sneak Operating Unit Analytical Method 204

7.3.1 Mesh Combination Results of Cúk Converter 204

7.3.2 Effective Operating Units of Cúk Converter 205

7.3.3 Sneak Operating Units of Cúk Converter 209

7.4 Sneak Circuit Operating Mode Analytical Method 210

7.4.1 Sneak Circuit Phenomenon of Cúk Converter Caused by Variations of Topology 211

7.4.2 Sneak Circuit Phenomenon of Cúk Converter Caused by Changing of Current Direction 212

7.5 Results of Sneak Circuit Mode Analysis Method on Cúk Converter 216

7.6 Summary 219

References 220

Part III ELIMINATION AND APPLICATION OF SNEAK CIRCUITS

8 Elimination of Sneak Circuits in Power Electronic Converters 223

8.1 Introduction 223

8.2 Sneak Circuit Elimination for RSC Converters 224

8.2.1 Parameter Design Principle 224

8.2.2 Topology Improvement Scheme 225

8.2.3 Examples 227

8.3 Sneak Circuit Elimination for Z-Source Inverter 230

8.3.1 Restricted Operating Conditions 230

8.3.2 Topology Improvement 230

8.4 Sneak Circuit Elimination for Buck ZVT PWM Converter 233

8.4.1 Topology Improving Scheme I 234

8.4.2 Topology Improving Scheme II 236

8.4.3 Simulation Verification 240

8.5 Summary 240

References 241

9 Application of Sneak Circuits in Power Electronic Converters 243

9.1 Introduction 243

9.2 Improvement of Power Electronic Converter Based on Sneak Circuits 243

9.2.1 Operating Principle of Boost ZCT PWM Converter 243

9.2.2 Sneak Circuit Paths of Boost ZCT PWM Converter 247

9.2.3 The Improved Control Method of Boost ZCT PWM Converter 248

9.3 Reconstruction of Power Electronic Converter Based on Sneak Circuits 252

9.3.1 Structure of Boost ZCT PWM Converter 253

9.3.2 Performance of the Modified Boost ZCT PWM Converter 253

9.4 New Functions of Power Electronic Converter Based on Sneak Circuits 258

9.4.1 PFC Principle of Cúk Converter 258

9.4.2 PFC Implementation of Cúk Converter 262

9.5 Fault Analysis of Power Electronic Converter Based on Sneak Circuits 264

9.5.1 Adjacency Matrix of Diode-Clamped Three-Level HB Inverter 265

9.5.2 Electrical Characteristics of Diode-Clamped Three-Level HB Inverter 267

9.5.3 Failure Criterion of Diode-Clamped Three-Level HB Inverter 268

9.5.4 Simulation Verification of Diode-Clamped Three-Level HB Inverter 271

9.6 Summary 272

References 274

Index 277

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