Contents

Preface six

1 Introduction 1

1.1 Introduction to Power Processing 1

1.2 Several Applications of Power Electronics 7

1.3 Elements of Power Electronics 9

References

1 Converters in Equilibrium 11

2 Principles of Steady State Converter Analysis 13

2.1 Introduction 13

2.2 Inductor Volt-Second Balance, Capacitor Cliarge Balance, and the Small-Ripple Approximation 15

2.3 Boost Converter Exanaple 22

2.4 Cuk Converter Example 27

2.5 Estimating the Output Voltage Ripple in Converters Containiiig Two-Pole

Low-Pass Filters 31

2.6 StimmLtry of Key Points 34 References 34 Problems 35

3 Steady-State Equivalent Circuit Modeling, Loss, and Efficiency 39

3.1 The DC Transformer Model 39

3.2 Inclusion of Inductor Copper Loss 42

3.3 Construction ofEquivalentCircuit Model 45

3.3.1 Inductor Voltage EquatioQ 46

3.3.2 Capacitor Current Equation 46

3.3.3 Complete Circuit Model 47

3.3.4 Effictency 48

3.4 How to Obtain the Input Port ofthe Model 50

3.5 Example: Inclusion of Semiconductor Ctjnduction Losses in the Boost

Converter Model 52

З.Й Summary of Key Point.4 56

References 56

Problems 57

Switch Rcljziition 63

4.1 Switch Applicatitjns 65

4.1.1 Single-Qiiadi-atit Switches 65

4.1.2 Cutrent-BidirectioQal Two-Quadrant Switches 67

4.1.3 Voltage-Bidirectioaal Two-Quadrant Switches 71

4.1.4 Four-Quadrant Switches 72

4.1.5 Synchronous RectiFters 73

4.2 A Brief Survey of Power Seniicondnctor Devices 74 4.2.1 Power Diode.s 75 42.2 Metal-Oxide-SemicoQductor Field-Effect Transistor (MOSFET) 78

4.2.3 Bipolar Junction Transistor (BJT) 81

4.2.4 Insulated Gate Bipolar Transistor (IGBT) 86

4.2.5 Thyrtstors (SCR. GTO, MCT) 88

4.3 Switching Lo.ss 92

4.3.1 Transistor Switching with Clamped Inductive Load 93

4.3.2 Diode Recovered С h;trge 96

4.3.3 Device Capacitances, and Lealtage. Package, and Stray Inductances 98

4.3.4 Efficiency vs. Switchitig Frequency 100

4.4 Summary of Key Points 101 References 102 Probiem.s 103

The DiiiCoiitJttuous Cottduction Mode 107

5.1 Origin of the Discondnuous Conduction Mode, and Mode Boundaiy 108

5.2 Analysis of the Ct)nversionRntinM(AO 112

5.3 Boost Conveiter Example 117

5.4 Sunimai of Results and Key Points 124 Problems 126

Converter Circuits 131

6.1 Circuit Manipulations 132

6.1.1 Inversion of Source and Load 132

6.1.2 Cascade Connection of Converters 134

6.1.3 Rotation of Three-Terminal Cell 137

6.1.4 DLffereatial Connection of the Load 138

6.2 A Short List of Converters 143

6.3 Transfortner l.solation 146

6.3.1 Fnll-Bridge and Half-Bridge Isolated Buck Converters 149

6.3.2 Forward Ctmverter 154

6.3.3 Push-Ptill Isolated Back Converter 159

6.3.4 Flyback Converter 161

6.3.5 Boost-Derived Isolated Converters 165

6.3.6 Isolated Version.s of the SEPIC and the Cuk Converter 168

6.4 Converter Evaluation and Design 171

6.4.1 Switch Stre.ss and Utilization 171

6.4.2 DesigQ Using Computer Spreadsheet 174

6.5 Surainary of Key Points 177 Referetice.4 177 Problems 179

П Converter Dynamics and Control 185

7 AC Equiviilent Circuit Modeling 187

7.1 Introduction 187

7.2 The Ba.4ic AC Modeling Approach 192

7.2.1 Averaging die Inductor Waveforms 193

7.2.2 Di,4CU,4.4ion of the Averaging Approximation 194

7.2.3 Averaging the Capacitor Waveform.s 196 12.4 The Average Input Current 197

7.2.5 Perturbation and Linearization 197

7.2.6 Con.struction nf the Small-SigntUEqiiivaletitQrciiit Model 201

7.2.7 Discu.4sioo of the Perturbation and Linearization Step 2Ш 7.2.S Results for Several Ba.sic Convetters 204 7.2.9 Example: A Nonideal Hyback Converter 204

7.3 State-Space Averaging 213 13.1 Tlie State Equation.4 of a Network 213

7.3.2 The Basic State-Space Averaged Model 216

7.3.3 Discussion of the State-Space Averaging Result 217

7.3.4 Example: State-Space Averaging of a Nonideal Buck-Boost Converter 221

7.4 Circuit Avetitging and Averaged Switch Modeling 226

7.4.1 Obtaining a Time-Invariant Circuit 228

7.4.2 Circuit Averaging 229

7.4.3 PerturbatioQ and Linearization 232

7.4.4 Switch Networks 235

7.4.5 Example: Averaged Switch Modeling of Conduction Losses 242

7.4.6 Example: Averaged Switch Modeling of Switching Los.ses 244

7.5 The Canonical Circuit Model 247 7.5.1 Development of the Canonical Circuit Model 248