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Power Electronic Converters: Dynamics and Control in Conventional and Renewable Energy Applications

ISBN: 978-3-527-34022-4
720 pages
December 2017
Power Electronic Converters: Dynamics and Control in Conventional and Renewable Energy Applications  (352734022X) cover image

Description

Filling the need for a reference that explains the behavior of power electronic converters, this book provides information currently unavailable in similar texts on power electronics.
Clearly organized into four parts, the first treats the dynamics and control of conventional converters, while the second part covers the dynamics and control of DC-DC converters in renewable energy applications, including an introduction to the sources as well as the design of current-fed converters applying duality-transformation methods. The third part treats the dynamics and control of three-phase rectifiers in voltage-sourced applications, and the final part looks at the dynamics and control of three-phase inverters in renewable-energy applications.
With its future-oriented perspective and advanced, first-hand knowledge, this is a prime resource for researchers and practicing engineers needing a ready reference on the design and control of power electronic converters.
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Table of Contents

Preface xiii

About the Authors xv

Part One Introduction 1

1 Introduction 3

1.1 Introduction 3

1.2 Implementation of Current-Fed Converters 6

1.3 Dynamic Modeling of Power Electronic Converters 7

1.4 Linear Equivalent Circuits 8

1.5 Impedance-Based Stability Assessment 12

1.6 Time Domain-Based Dynamic Analysis 14

1.7 Renewable Energy System Principles 17

1.8 Content Review 19

References 20

2 Dynamic Analysis and Control Design Preliminaries 27

2.1 Introduction 27

2.2 Generalized Dynamic Representations – DC–DC 27

2.2.1 Introduction 27

2.2.2 Generalized Dynamic Representations 29

2.2.3 Generalized Closed-Loop Dynamics 30

2.2.4 Generalized Cascaded Control Schemes 33

2.2.5 Generalized Source and Load Interactions 38

2.2.6 Generalized Impedance-Based Stability Assessment 40

2.3 Generalized Dynamic Representations: DC–AC, AC–DC, and AC–AC 42

2.3.1 Introduction 42

2.3.2 Generalized Dynamic Representations 44

2.3.3 Generalized Closed-Loop Dynamics 48

2.3.4 Generalized Cascaded Control Schemes 50

2.3.5 Generalized Source and Load Interactions 54

2.3.6 Generalized Impedance-Based Stability Assessment 56

2.4 Small-Signal Modeling 57

2.4.1 Introduction 57

2.4.2 Average Modeling and Linearization 60

2.4.3 Modeling Coupled-Inductor Converters 64

2.4.4 Modeling in Synchronous Reference Frame 66

2.5 Control Design Preliminaries 77

2.5.1 Introduction 77

2.5.2 Transfer Functions 77

2.5.3 Stability 84

2.5.4 Transient Performance 95

2.5.5 Feedback-Loop Design Constraints 100

2.5.6 Controller Implementations 103

2.5.7 Optocoupler Isolation 108

2.5.8 Application of Digital Control 109

2.6 Resonant LC-Type Circuits 110

2.6.1 Introduction 110

2.6.2 Single-Section LC Filter 112

2.6.3 LCL Filter 113

2.6.4 CLCL Filter 115

References 117

Part Two Voltage-Fed DCDC Converters 123

3 Dynamic Modeling of Direct-on-Time Control 125

3.1 Introduction 125

3.2 Direct-on-Time Control 127

3.3 Generalized Modeling Technique 129

3.3.1 Buck Converter 131

3.3.2 Boost Converter 134

3.3.3 Buck–Boost Converter 136

3.3.4 Superbuck Converter 140

3.4 Fixed-Frequency Operation in CCM 142

3.4.1 Buck Converter 143

3.4.2 Boost Converter 146

3.4.3 Buck–Boost Converter 149

3.4.4 Superbuck Converter 153

3.4.5 Coupled-Inductor Superbuck Converter 157

3.5 Fixed-Frequency Operation in DCM 163

3.5.1 Buck Converter 164

3.5.2 Boost Converter 167

3.5.3 Buck–Boost Converter 170

3.6 Source and Load Interactions 173

3.6.1 Source Interactions 173

3.6.2 Input Voltage Feedforward 174

3.6.3 Load Interactions 176

3.6.4 Output-Current Feedforward 177

3.7 Impedance-Based Stability Issues 179

3.8 Dynamic Review 181

References 186

4 Dynamic Modeling of Current-Mode Control 189

4.1 Introduction 189

4.2 Peak Current Mode Control 190

4.2.1 PCM Control Principles 190

4.2.2 Development of Duty-Ratio Constraints in CCM 192

4.2.3 Development of Duty-Ratio Constraints in DCM 195

4.2.4 Origin and Consequences of Mode Limits in CCM and DCM 196

4.2.5 Duty-Ratio Constraints in CCM 201

4.2.5.1 Buck Converter 201

4.2.5.2 Boost Converter 201

4.2.5.3 Buck–Boost Converter 202

4.2.5.4 Superbuck Converter 204

4.2.5.5 Coupled-Inductor Superbuck Converter 205

4.2.6 Duty-Ratio Constraints in DCM 205

4.2.6.1 Buck Converter 205

4.2.6.2 Boost Converter 206

4.2.6.3 Buck–Boost Converter 206

4.2.7 General PCM Transfer Functions in CCM 207

4.2.8 PCM State Spaces and Transfer Functions in CCM 209

4.2.8.1 Buck Converter 209

4.2.8.2 Boost Converter 211

4.2.8.3 Buck–Boost Converter 213

4.2.8.4 Superbuck Converter 215

4.2.8.5 Coupled-Inductor Superbuck Converter 219

4.2.9 PCM State Spaces in DCM 222

4.2.9.1 Buck Converter 222

4.2.9.2 Boost Converter 222

4.2.9.3 Buck–Boost Converter 223

4.3 Average Current-Mode Control 224

4.3.1 Introduction 224

4.3.2 ACM Control Principle 225

4.3.3 Modeling with Full Ripple Inductor Current Feedback 226

4.4 Variable-Frequency Control 230

4.4.1 Introduction 230

4.4.2 Self-Oscillation Modeling – DOT and PCM Control 231

4.5 Source and Load Interactions 239

4.5.1 Output Current Feedforward 240

4.6 Impedance-Based Stability Issues 243

4.7 Dynamic Review 244

4.8 Critical Discussions on PCM Models and Their Validation 249

4.8.1 Ridley’s Models 249

4.8.2 The Book PCM Model in CCM 252

4.8.3 Evaluation of PCM-Controlled Buck in CCM 253

4.8.4 Evaluation of PCM-Controlled Boost in CCM 258

4.8.5 Concluding Remarks 259

References 260

5 Dynamic Modeling of Current-Output Converters 265

5.1 Introduction 265

5.2 Dynamic Modeling 267

5.3 Source and Load Interactions 269

5.3.1 Source Interactions 269

5.3.2 Load Interactions 270

5.4 Impedance-Based Stability Issues 271

5.5 Dynamic Review 272

References 275

6 Control Design Issues in Voltage-Fed DCDC Converters 277

6.1 Introduction 277

6.2 Developing Switching and Average Models 279

6.2.1 Switching Models 279

6.2.2 Averaged Models 287

6.3 Factors Affecting Transient Response 291

6.3.1 Output Voltage Undershoot 292

6.3.2 Settling Time 294

6.4 Remote Sensing 304

6.4.1 Introduction 304

6.4.2 Remote Sensing Dynamic Effect Analysis Method 304

6.4.3 Remote Sensing Impedance Block Examples 306

6.4.4 Experimental Evidence 307

6.5 Simple Control Design Method 310

6.5.1 DDR-Controlled Buck Converter 312

6.5.2 PCM-Controlled Buck Converter 315

6.5.3 DDR-Controlled Boost Converter 321

6.5.4 PCM-Controlled Boost Converter 325

6.6 PCM-Controlled Superbuck Converter: Experimental Examples 330

6.6.1 Introduction 330

6.6.2 Discrete-Inductor Superbuck 331

6.6.3 Coupled-Inductor Superbuck 332

6.7 Concluding Remarks 334

References 334

Part Three Current-Fed Converters 339

7 Introduction to Current-Fed Converters 341

7.1 Introduction 341

7.2 Duality Transformation Basics 341

7.3 Duality-Transformed Converters 345

7.4 Input Capacitor-Based Converters 351

References 352

8 Dynamic Modeling of DDR-Controlled CF Converters 355

8.1 Introduction 355

8.2 Dynamic Models 356

8.2.1 Duality Transformed Converters 358

8.2.1.1 Buck Converter 358

8.2.1.2 Boost Converter 365

8.2.1.3 Noninverting Buck–Boost Converter 368

8.2.1.4 CF Superbuck Converter 372

8.2.2 Input Capacitor-Based Converters 376

8.2.2.1 Buck Power-Stage Converter 377

8.2.2.2 Boost Power-Stage Converter 383

8.2.2.3 Noninverting Buck–Boost Power-Stage Converter 387

8.3 Source and Load Interactions 390

8.3.1 CF-CO Converters 390

8.3.1.1 Source Interactions 390

8.3.1.2 Load Interactions 391

8.3.2 CF-VO Converters 392

8.3.2.1 Source Interactions 392

8.3.2.2 Load Interactions 393

8.4 Impedance-Based Stability Assessment 394

8.5 Output-Voltage Feedforward 394

8.6 Dynamic Review 397

References 400

9 Dynamic Modeling of PCM/PVM-Controlled CF Converters 403

9.1 Introduction 403

9.2 Duty-Ratio Constraints and Dynamic Models under PCM Control 404

9.2.1 Buck Power-Stage Converter 405

9.2.2 Boost Power-Stage Converter 410

9.3 Duty-Ratio Constraints and Dynamic Models under PVM Control 413

9.3.1 CF Buck Converter 414

9.3.2 CF Superbuck Converter 418

9.4 Concluding Remarks 420

References 420

10 Introduction to Photovoltaic Generator 423

10.1 Introduction 423

10.2 Solar Cell Properties 424

10.3 PV Generator 429

10.4 MPP Tracking Methods 432

10.5 MPP Tracking Design Issues 436

10.5.1 Introduction 436

10.5.2 General Dynamics of PV Power 437

10.5.3 PV Interfacing Converter Operating at Open Loop 439

10.5.4 PV Interfacing Converter Operating at Closed Loop 447

10.5.4.1 Reduced-Order Models: Intuitive Model Reduction 452

10.5.4.2 Reduced-Order Models: Control-Engineering-Based Method 454

10.5.4.3 Reduced-Order Model Verification 455

10.6 Concluding Remarks 461

References 461

11 Photovoltaic Generator Interfacing Issues 465

11.1 Introduction 465

11.2 Centralized PV System Architecture 465

11.3 Distributed PV System Architectures 465

11.4 PV Generator-Induced Effects on Interfacing-Converter Dynamics 470

11.4.1 Introduction 470

11.4.2 PV Generator Effects on Converter Dynamics 474

11.4.2.1 Buck Power-Stage Converter 476

11.4.2.2 Boost Power-Stage Converter 477

11.4.2.3 CF Superbuck Converter 480

11.5 Stability Issues in PV Generator Interfacing 482

11.5.1 Buck Power-Stage Converter 483

11.5.2 CF Superbuck Converter 485

11.5.3 Concluding Remarks 488

11.6 Control Design Issues 488

References 488

Part Four Three-Phase Grid-Connected Converters 491

12 Dynamic Modeling of Three-Phase Inverters 493

12.1 Introduction 493

12.2 Dynamic Model of Voltage-Fed Inverter 494

12.2.1 Average Model of Voltage-Fed Inverter 494

12.2.2 Linearized State-Space and Open-Loop Dynamics 499

12.2.3 Control Block Diagrams of Voltage-Fed Inverter 503

12.2.4 Verification of Open-Loop Model 503

12.3 Dynamic Model of Current-Fed Inverter 507

12.3.1 Average Model of Current-Fed Inverter 507

12.3.2 Linearized Model and Open-Loop Dynamics 510

12.3.3 Control Block Diagrams of Current-Fed Inverter 512

12.3.4 Verification of Open-Loop Model 512

12.4 Source-Affected Dynamics of Current-Fed Inverter 515

12.4.1 Source Effect: Photovoltaic Generator 517

12.4.2 Source Effect: Experimental Validation 520

12.5 Dynamic Model of Current-Fed Inverter with LCL-Filter 524

12.5.1 Average Model of Current-Fed Inverter with LCL-Filter 525

12.5.2 Linearized State-Space and Open-Loop Dynamics 527

12.6 Summary 528

Appendix 12.A 528

References 530

13 Control Design of Grid-Connected Three-Phase Inverters 533

13.1 Introduction 533

13.2 Synchronous Reference Frame Phase-Locked-Loop 533

13.2.1 Linearized Model of SRF-PLL 536

13.2.2 Control Design of SRF-PLL 538

13.2.3 Damping Ratio and Undamped Natural Frequency 541

13.2.4 Control Design Example and Experimental Verification 541

13.2.5 The Effect of Unbalanced Grid Voltages 544

13.3 AC Current Control 547

13.3.1 Current Control in the dq-Domain 548

13.3.2 Current Control in Voltage-Fed Inverters 548

13.4 Decoupling Gains 559

13.5 Grid Voltage Feedforward 562

13.6 Cascaded Control Scheme in Current-Fed Inverters 563

13.6.1 Control Block Diagrams 564

13.6.2 Control Design of Cascaded Loops 566

13.6.3 Instability Caused by RHP-Pole 570

13.6.4 Stability Assessment Using the Nyquist Stability Criterion 574

13.6.5 Design Example: Three-Phase Photovoltaic Inverter 574

13.7 Case Study: Instability Due to RHP-Pole 581

13.8 Summary 583

References 583

14 Reduced-Order Closed-Loop Modeling of Inverters 587

14.1 Introduction 587

14.2 Reduced-Order Model of Voltage-Fed Inverter 587

14.2.1 Closed-Loop Model with AC Current Control 588

14.2.2 Closed-Loop Model with SRF-PLL 591

14.2.3 Closed-Loop Input Admittance 595

14.2.4 Output Impedance with Grid Voltage Feedforward 596

14.2.5 Impedance Characteristics of Voltage-Fed Inverters 602

14.3 Reduced-Order Model of Current-Fed Inverter with L-Type Filter 602

14.3.1 Closed-Loop Model with Cascaded Control Scheme 602

14.3.2 Effect of Input Voltage Control Bandwidth 605

14.3.3 Effect of AC Current Control Bandwidth 606

14.3.4 Experimental Verification: Measured Impedance d-Component 608

14.3.5 Effect of SRF-PLL 609

14.3.6 Effect of Grid Voltage Feedforward on Impedance d-Component 610

14.3.7 Effect of Grid Voltage Feedforward on Impedance q-Component 615

14.4 Closed-Loop Model of Current-Fed Inverter with LC-Type Filter 619

14.4.1 Experimental Verification of Impedance Model 625

14.4.2 Impedance Characteristics of Inverter with LC-Filter and Feedforward 630

14.5 Summary 630

References 630

15 Multivariable Closed-Loop Modeling of Inverters 633

15.1 Introduction 633

15.2 Full-Order Model of Current-Fed Inverter with L-Type Filter 633

15.2.1 Verification of Dynamic Model 643

15.3 Experimental Verification of Admittance Model 646

15.4 Full-Order Model of Current-Fed Inverter with LCL-Type Filter 648

15.4.1 Verification of Closed-Loop Model 653

15.4.2 Measured Output Impedance of PV Inverter 656

15.5 Summary 659

References 660

16 Impedance-Based Stability Assessment 663

16.1 Introduction 663

16.2 Modeling of Three-Phase Load Impedance in the dq-Domain 664

16.3 Impedance-Based Stability Criterion 667

16.4 Case Studies 669

16.4.1 Instability Due to High-Bandwidth PLL in Weak Grid 669

16.4.2 Instability Due to Control Delay in Feedforward Path 674

16.5 Summary 678

References 678

17 Dynamic Modeling of Three-Phase Active Rectifiers 681

17.1 Introduction 681

17.2 Open-Loop Dynamics 681

17.3 Verification of Open-Loop Model 688

17.4 Experimental Results 691

17.5 Summary 695

References 695

Index 697

 

 

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Author Information

Teuvo Suntio is Professor in Power Electronics at Tampere University of Technology, Finland. He has been also Adjunct Professor in Control Engineering at the Aalto University (TKK) in 2001-2011, and in Power Electronics at the University of Oulu since 2004. He has also served 20 years in power electronics industry as a design engineer and an R&D manager prior to starting the academic career in 1998. He has authored or co-authored over 200 international conference and journal articles, supervised close to 100 MSc students as well as 18 PhD students during the nineteen years in academy.

Tuomas Messo is Assistant Professor in Power Electronics at Tampere University of Technology, Finland. His current research aims to identify the source of harmonic resonance problems reported in grid-connected power electronic systems through dynamic modeling and mitigating the problems by shaping the inverter impedance. His teaching activities include basic power electronic courses and advanced courses, which concentrate on DC-DC converter design and dynamic analysis of three-phase DC-AC converters.

Joonas Puukko is with ABB Oy High Power Drives in Helsinki, Finland. Previously he was with ABB Oy Solar Inverters and ABB Inc. United States Corporate Research. He obtained his PhD from Tampere University of Technology, Finland, for a work on dynamics of grid-connected three-phase converters. He has expertise in hardware and control system design in various power electronics applications ranging from few tens of watts to hundreds of kilowatts.
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