textbook on power electronics and · ernakulam 682 016, kochi, kerala ... † nagpur 0-9021734563...

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is designed to serve as a useful text for undergraduate and postgraduate courses in engineering, engineering services examination, GATE, IETE/AMIE and various other competitive examinations. The book would also be a valuable reference for practising engineers, who are involved in the design and development of power electronics converters.

Simple and cogent style of presentationIn-depth details of modern power semiconductor devices such as power transistors, thyristors, TRIACs, GTOs, SITs, SITHs, MOSFETs, IGBTs, UJTs, PUTs, etc.Text has been supplemented with detailed illustrations, examples, exercises, MCQs, and review questionsExtensive comparative analysis of power converters for design criteriaDetails about linear regulators and thyristor protection circuitsApplications of controllers in speed control of DC and AC motor drivesDetailed component specifications for circuit designsUninterrupted power supply systems, and various types of resonant convertersEmerging applications of microprocessors in industrial applications

Highlights••

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••••••

Harish C Rai PhD is former Professor, Department of Electrical and Electronics Engineering, Chhotu Ram State College of Engineering (presently Deenbandhu Chhotu Ram University of Science and Technology), Murthal, Haryana. He obtained his graduate and postgraduate degrees from Delhi College of Engineering, and PhD (Electrical Engineering) from Indian Institute of Technology, New Delhi. He has been awarded the prestigious Dr S Radhakrishnan Memorial National Teacher's Award 1997; Spardha Shree Award 1999, and Teachers' Excellence Award 2000. He has about 37 years of experience in administration including teaching undergraduate courses in the areas of electrical machines, control engineering, power electronics, power system, etc. He has presented several papers in international and national conferences. His current interest areas include electrical machines, control of electrical machines and biomedical electronics.

Textbook onPower Electronics andIndustrial Applications

CBS Publishers & Distributors Pvt LtdNew Delhi • Bengaluru • Chennai • Kochi • Kolkata • Mumbai

Hyderabad • Jharkhand • Nagpur • Patna • Pune • Uttarakhand

Harish C RaiPhD (Electrical Engg, IIT, Delhi), FIE (India), FIETE, MISTE, MAeSI

FormerProfessor, Department of Electrical and Electronics Engineering

CR State College of Engineering(Presently Deenbandhu Chhotu Ram University of Science and Technology)

Murthal, Haryana 131039

Controller of ExaminationsDirector, Academic Affairs

Director, Research Project Monitoring CellDirector, Organization and Development

GGS Indraprastha University, DelhiAdvisor, All India Council of Technical Education

(Ministry of Human Resource and Development, Delhi)


ISBN: 978-93-86827-86-9

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First Edition: 2018

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Disclaimer

Science and technology are constantly changingfields. New research and experience broaden thescope of information and knowledge. The authorhas tried his best in giving information availableto him while preparing the material for this book.Although, all efforts have been made to ensureoptimum accuracy of the material, yet it is quitepossible some errors might have been leftuncorrected. The publisher, the printer and theauthor will not be held responsible for anyinadvertent errors or inaccuracies.

to

My respected parents

Late Sh Balraj

Late Smt Ram Devi

My lively children, Shivanshu and Himanshu

My loving wife, Sangeeta;

and Shipra and grandson Vivaan, whose

affection is always appreciated

Preface

Power electronics is an interdisciplinary area of applied science that functions using the membersof thyristor family, control electronics to control the ‘switch ON’ and ‘switch OFF’ processes of

the devices and principles of control theory. The invention of thyristor has revolutionized all fieldsof conversion and control, namely AC to DC, DC to DC, DC to AC and AC to AC. Hence, there isa necessity for understanding the thyristor and its family members, principles of power converters,for their efficient use in the industry. Power semiconductor technology is rapidly developing, afterthe advent of fast switching power devices with increasing voltage and current limits. Powerswitching devices such as power BJTs, power MOSFETs, SITs, IGBTs, MCTs, SITHs, SCRs, TRIACs,GTOs, and other semiconductor devices are finding increasing application in a wide range ofproducts. With the availability of faster switching devices, the applications of modernmicroprocessors in synthesizing the control strategy for gating power devices to meet the conversionspecifications are widening the scope of power electronics.

The book Power Electronics and Its Industrial Applications is a reflection of the entire subject, andexplains all the aspects in detail with elaborate explanation and illustrations. The book begins withan introduction to thyristors, TRIACs, asymmetrical thyristors, GTOs, power transistors, powerMOSFETs and hybrid devices. The entire content is divided into 18 chapters. The control circuitsdescribed for various applications using thyristors are not meant to be commercially feasible butprovide the basic understanding necessary for synthesizing more sophisticated controllers.

Chapter 1 contains an overview of power electronics and its applications in brief.Chapters 2–4 are devoted to power semiconductor devices, rectifying circuits, filters and Zenor

diodes and thyristor and its family.Chapters 5–7 deal with triggering devices, firing and commutation circuits. These chapters

introduce different members of thyristor family and describe characteristics, working principlesand application of DIACs, TRIACs, MOSFETs, IGBTs, UJT, PUTs etc. The triggering andcommutation of SCRs have also been included. Controlled rectifiers, DC to DC converters, ACvoltage controllers, AC to AC converters, cycloconverters and inverters are widely discussed topicsin power electronics are reviewed in Chapters 8–12 with emphasis on the circuits and waveforms.

Thyristorised controlled DC and AC motors are covered extensively in Chapters 13–14.Chapters 15 and 16 present with thyristor protection circuits and their industrial applications

using solid state devices for the control of DC and AC motors and circuits used for various controlpurposes like heating, welding and many other industrial applications and also elaborate somemicroprocessors based applications.

Chapter 17 deals with regulated power supply; industrial drives applications usingmicroprocessor are detailed in Chapter 18.

Each chapter is supplemented with elaborate illustrations, solved examples and multiple choicequestions to provide an aid in comprehension of principles involved. At the end of the book, multiplechoice questions (MCQs) from various examinations like Engineering Services Examination (IES),GATE and many other competitive examinations have been included.

The book will be useful to college and university students as well as engineers working inindustry. I hope this book will be of immense use to the teachers and students of technical institutes.Suggestions from students and teachers for improvement in future editions of this book are welcome.

Harsh C Rai

Acknowledgements

I thank all my undergraduate students who suggested that I should write this book and indeed, all those who have encouraged me in this venture. I derive immense pleasure in expressing

my sincere thanks to Prof Yogesh Singh, Vice Chancellor, Delhi Technological University;Prof Annu Singh Lather, Pro Vice Chancellor, Delhi Technological University, for the invaluableencouragement throughout this work. I am indebted to his guidance and invaluable suggestions.

I express my gratitude to Prof SS Murthy, former Vice Chancellor, Central University ofKarnataka; Prof BP Singh; Prof ZH Zaidi, former Vice Chancellor, MJP Rohilkhand University,Bareilly, Prof Bhim Singh, Department of Electrical Engineering, IIT, Delhi, for sparing their valuabletime and providing useful guidance on various chapters.

I thank my colleagues, Prof Alok Mittal, Member Secretary, AICTE, New Delhi; Prof JRP Gupta(NSIT, Delhi); Prof DR Bhaskar (DTU); Prof VK Sharma (NIT, Uttarakhand); Prof DR RominderRandhwa, Director, Guru Tegh Bahadur Institute of Technology; Prof SS Tyagi, Director, BSAInstitute of Technology, Haryana and Prof Lajpat Rai, IIT, Delhi with whom I have discussedpower electronics while teaching courses on this subject.

I express my gratitude to my brother Dr Mahesh Popli (Income Tax Department), Rajasthan;Dr Vikas Gupta (DU); Mr Pankaj Munjal, Director, Training and Development, RVIT, Bijnore;Brig Pradeep Upmanu; Dr Nitin Malik, GGS Indraprastha University and Mr Ankit Popli for theirimmense help and constructive criticism on the manuscript.

My special thanks are due to Sh RC Taneja and late Sh KR Munjal for their moral support whichhas enabled me to complete this work. I am grateful to Sh Satish Kumar Jain (Mataji), CMD andSh Varun Jain (Director), CBS Publishers & Distributors Pvt Ltd, New Delhi, for his patience,goodwill and cooperation. I express my gratitude to Mr YN Arjuna (Senior Vice President Publishing,Editorial and Publicity); Mrs Ritu Chawla (AGM Production); Mr Sumit Bhel; Ms Sanjubala Tripathy(Copy Editor) and Mrs Madhu Srivastva (Data Vision), for their skillful service and immense helpin editing and figure work of the manuscript.

Finally, I appreciate the patience and solid support of my family—my wife Sangeeta Rai; childrenShivanshu, Shipra and Himanshu.

Harsh C Rai

Contents

1. ROLE OF POWER ELECTRONICS APPLICATIONS 1–6

1.0 Introduction 11.1 Applications of Power Electronics 11.2 Advantages and Disadvantages of Thyristor Converter Systems 2

1.2.1 Advantages 21.2.2 Disadvantages 2

1.3 Power Semiconductor Converters 2

2. POWER SEMICONDUCTOR DEVICES 7–26

2.0 Introduction 72.1 Limitations of Practical Semiconductor Switches 82.2 Power Semiconductor Devices 82.3 Power Diode 8

2.3.1 Types of Power Diode 92.3.2 General Purpose Diodes 102.3.3 Fast Recovery Diodes 102.3.4 Schottky Diodes 10

2.4 Performance Parameters of Power Diodes 102.5 Series and Parallel Connected Diodes 11

2.5.1 Series Operation of Diodes 122.5.2 Parallel Operation of Diodes 14

2.6 Power Bipolar Junction Transistors (BJTs) 142.6.1 Safe Operating Area (SOA) 152.6.2 Switching Characteristics of Bipolar Transistor 162.6.3 Advantages of Bipolar Transistor as a Switch 172.6.4 Performance Parameters of BJT 17

2.7 Base Drive Requirements (Design of Drive Circuits for BJTs) 182.7.1 Base Drive Circuits 182.7.2 Base Current Drive Circuit with Both Positive and Negative Voltages 192.7.3 Base Drive Circuit with Anti-saturation Diodes 20

2.8 Power Mosfet (Metal Oxide Semiconductor Field Effect Transistor) 202.8.1 Safe Operating Area of MOSFETs 212.8.2 Advantages of Power MOSFETs over Power Transistors 212.8.3 Disadvantages 22

2.9 Hybrid Devices 222.9.1 Insulated Gate Bipolar Transistor (IGBT) 222.9.2 FET Controlled Thyristors 23

2.10 Thyristor 24Exercise 26

Review Questions 26

Preface vii

x Textbook on Power Electronics and Industrial Applications

3. RECTIFYING CIRCUITS, FILTERS AND ZENER DIODES 27–773.0 Introduction 273.1 Half-wave Rectifier 283.2 Full-wave Rectifier 313.3 Bridge Rectifier 333.4 Advantages and Disadvantages of Bridge Rectifier over Centre-tap Rectifier 343.5 Multiphase Rectifiers 35

3.5.1 Three-phase Half-wave Rectifier with Resistive Load or Single-way 353.5.2 Bridge Rectifier with Resistive Load (Double-way) 37

3.6 Three-phase Full-wave or Six-phase Half-wave Rectifier 403.7 m-Phase Rectifier Circuit Relations 413.8 Transformer Utility Factor (TUF) 433.9 Rectifier Performance 44

3.10 KVA Rating of Transformer 463.11 Effect of Leakage Reactance 463.12 Diode Load and Current Rating 493.13 Peak Reverse Voltage in Polyphase Rectifiers 493.14 Filters 50

3.14.1 Inductor Filter 503.14.2 Capacitor Filter or C-filter 513.14.3 L-C Filter 533.14.4 R-C Filter 54

3.15 Zener Diodes 553.16 Voltage Stabilizer 56

3.16.1 Voltage Stabilizer Using Zener Diode 563.17 Metal Rectifiers 57

Exercises 75Multiple Choice Questions 75Review Questions 77

4. THYRISTOR AND ITS FAMILY 78–121

4.0 Introduction 784.1 Thyristors and Its Applications 78

4.1.1 Applications 784.2 Thyristor Family 794.3 Thyristor Construction 794.4 Comparison of Transistor with Thyristor 824.5 Principle of Operation of Thyristors 82

4.5.1 Volt-ampere Characteristics 824.5.2 Thyristor Gate Characteristics 84

4.6 Two-transistor Model of Thyristor 854.7 Thyristor Transient Characteristics 864.8 Thyristor Types 87

4.8.1 Phase-control Thyristors 884.8.2 Fast-switching Thyristors/Asymmetrical Thyristors (ASCRs) 884.8.3 Gate Turn Off (GTO) Thyristor 884.8.4 TRIAC 934.8.5 Reverse-conducting Thyristors (RCT) 96

Contents xi

4.8.6 Static Induction Thyristor 974.8.7 Light-activated Silicon-controlled Rectifiers (LASCRs) 974.8.8 FET-controlled Thyristors (FET-CTHS) 974.8.9 MOS-controlled Thyristors (MCT) 97

4.9 Series and Parallel Operations of Thyristors 994.10 Ratings of Thyristors 101

4.10.1 Performance Parameters of Thyristors 1024.10.2 Surge Current Rating 1034.10.3 I2t Rating 1044.10.4 di/dt Rating 1044.10.5 Junction Temperature 1044.10.6 Power Dissipation 1044.10.7 Thermal Resistance 1054.10.8 Transient Thermal Impedance 1064.10.9 Recurrent and Non-recurrent Current Ratings/Average Current Rating (Recurrent) 1064.10.10 RMS Current (Recurrent) 107

4.11 Relative Performance of Power Electronic Devices 1084.12 Comparison between Transistors and Thyristors 110

Exercise 116Multiple Choice Questions 116Review Questions 120

5. THYRISTOR TRIGGERING DEVICES 122–148

5.0 Introduction 1225.1 Triggering Devices 1225.2 Unijunction Transistor 1225.3 Characteristics and Applications of UJT 129

5.3.1 Complementary Unijunction Transistor (CUJT) 1295.4 Programmable Unijunction Transistor (PUT) 129

5.4.1 Theory of Operation 1305.4.2 Relaxation Oscillator Using PUT 1315.4.3 Applications 132

5.5 Diac 1325.5.1 Theory of Operation 133

5.6 Silicon-controlled Switch (SCS) 1345.7 Silicon Unilateral Switch (SUS) 136

5.7.1 Theory of Operation of SUS 1365.8 Silicon Bilateral Switch (SBS) 1375.9 Shockley Diode 139

5.10 Opto-isolators 139Exercise 146

Multiple Choice Questions 146Review Questions 147

6. THYRISTOR FIRING CIRCUITS—TURN-ON SYSTEMS 149–178

6.0 Introduction 1496.1 Requirements for Triggering Circuits 1496.2 Firing Circuit Design Considerations 150

xii Textbook on Power Electronics and Industrial Applications

6.3 Requirements of Firing Circuits 1516.4 Thyristor Firing Circuits 152

6.4.1 Resistance Triggering (R-Triggering) 1526.4.2 Thyristor-contactor Triggering 1526.4.3 R–C Firing Circuit (AC Phase Switching Circuit) 152

6.5 Full-wave Control of AC with One Thyristor 1536.6 Light Activated SCRs (LASCRs) Control Circuit 1536.7 Pulse Transformer Triggering 1546.8 Control of Converter 1566.9 Firing Angle Control 156

6.9.1 Linear Control of Phase Angle, 1576.9.2 Cosine Wave-crossing Method 160

6.10 Integral Cycle Method 1626.11 Firing of SCR by UJT 1636.12 Triac Firing Circuit 1646.13 Phase Control of SCR by Pedestal and Ramp 1646.14 SCR Phase Control by Temperature or Light 1656.15 On-off Pulse Control of Thyristor by Saturable Reactor 1666.16 Blocking Oscillator 166

Exercise 177Multiple Choice Questions 177

7. THYRISTOR COMMUTATION CIRCUITS—TURN-OFF SYSTEMS 179–196

7.0 Introduction 1797.1 Turn-off mechanism 180

7.1.1 Thyristor Turn-off Technique 1807.1.2 Thyristor Turn-off Circuits 181

7.2 Commutation of a Thyristor 1837.2.1 Natural Commutation 1837.2.2 Forced Commutation 183

7.3 Conditions for Commutation 1837.4 Classification of Forced Commutation Methods 183

7.4.1 Class A—Commutation by Resonating Load 1847.4.2 Class B—Self-commutation by an L–C Circuit 1847.4.3 Class C—Turn-off a Charged Capacitor Switched by a Load-carrying SCR 1857.4.4 Class D Turn-off—A Charged Capacitor Turned on by an Auxiliary

Switching SCR 1877.4.5 Class E Turn-off—with an External Source of Pulse for Commutation 1897.4.6 Class F—AC Line Commutation 190

7.5 Jones Turn-Off Circuit 1907.6 Performance of SCR with Different Loads 191

7.6.1 SCR with Resistive Load 1917.6.2 SCR with Inductive Load 1917.6.3 SCRs with Diodes in AC Inductive Circuits 1927.6.4 Voltage Change, dv/dt 1937.6.5 Rectifier with Back EMF Load 193Exercise 195

Multiple Choice Questions 195

Contents xiii

8. AC TO DC CONVERTER CONTROLLED RECTIFIER 197–264

8.0 Introduction 1978.1 Circuit Nomenclature of Rectifiers 1978.2 Classification of Converters 1988.3 Industrial Applications of Converters 1988.4 Effect of R–L Load 1988.5 Effect of Commutating Diode or Free-wheeling Diode 1998.6 Controlled Rectifiers 199

8.6.1 Single-phase Controlled Rectifier Circuits 1998.6.2 Half-wave Controlled Rectifier with Resistive Load (One-quadrant) 1998.6.3 Half-wave Controlled Rectifier with R–L Load 2018.6.4 Half-wave Rectifier with Inductive Load and Flywheeling Diode 203

8.7 Bi-Phase Half-Wave (Single-way) or Single-phase Full-Wave ControlledRectifier (Two Quadrant) 204

8.7.1 Single-phase Full-wave Controlled Rectifier with Resistive Load 2048.7.2 Single-phase Full-wave Controlled Rectifier with R–L Load 2058.7.3 A Single-phase Full-wave Phase-controlled Converter with

Freewheeling Diode 2068.8 Single-Phase Full-Wave Phase Controlled Converter Using Bridge Principle

(Double-way) 2078.8.1 Single-phase Half-controlled Bridge (Semibridge Converter) 2088.8.2 Bridge with Two Thyristors, Two Diodes and a Freewheeling Diode 2098.8.3 Single-phase Half-Controlled Bridge with Two Thyristors and Two

Diodes in the Same Arm 2118.8.4 Single-phase Full-wave Fully-controlled Bridge 2128.8.5 Single-phase Fully-controlled Bridge Using Four Thyristors 212

8.9 Single-phase Bridge Inverter 2168.10 Power Flow 2168.11 Transformer Rating 2188.12 Harmonics 2188.13 Discontinuous Conduction 2198.14 Single-phase Full-wave Converter with Discontinuous Current 2198.15 Load Voltage and Harmonics 221

8.15.1 Distortion Factor 2228.15.2 Displacement Factor 2228.15.3 Power Factor 222

8.16 Three-phase Thyristor Converter 2238.16.1 Three-phase Half-wave Converters 2238.16.2 Three-phase Semiconverters 2278.16.3 Three-phase Full Converters 2308.16.4 Three-phase Dual Converters 232

8.17 Six-phase Half-wave (or Single-way) 2338.18 Effect of Transformer Leakage Inductance 2358.19 Regulation 2388.20 Equations for p-Pulse Converter 2398.21 Factors Affecting the Choice of any Converter Circuits 240


xiv Textbook on Power Electronics and Industrial Applications

9. DC-TO-DC CONVERTERS—CHOPPERS 265–306

9.0 Introduction 2659.1 DC Chopper 265

9.1.1 Step-down Chopper (Buck Converter) 2659.1.2 Step-up Chopper (Boost Converter) 2689.1.3 Step-down and Step-up Chopper (Buck–Boost Converter) 269

9.2 Chopper Classification 2719.3 Chopper Configurations 2729.4 Types of Chopper 273

9.4.1 Series Turn-off Chopper 2739.4.2 Parallel Capacitor Turn-off Chopper 276

9.5 Two Quadrant Chopper 2809.6 Four Quadrant Chopper 2829.7 Morgan Chopper 2839.8 Jones Chopper 2849.9 Thyristor Commutation in Circuits 285

9.9.1 Forced Commutation 2859.9.2 Current Commutated Chopper 2889.9.3 Load Commutated Chopper 289

9.10 Multiphase Chopper 2919.11 Effects of Source and Load Inductance 2929.12 Switching Mode Regulators 292

9.12.1 Step-down or Buck Regulator 2939.12.2 Step-up or Boost Regulator 2949.12.3 Buck–boost Regulator 2959.12.4 Cuk Regulator 296Exercises 303


10. AC VOLTAGE CONTROLLERS 307–331

10.0 Introduction 30710.1 Types of AC Voltage Controllers 30710.2 AC Phase Voltage Controllers 308

10.2.1 Single-phase Half-wave Controller with Resistive Load 30810.2.2 Single-phase Full-wave Voltage Controller with Resistive Load 310

10.3 Harmonics of Output Voltage and Current for Resistive Load 31210.4 Single-Phase Voltage Controller with R–L Load 31410.5 Harmonic Analysis of Single-phase Full-wave Controller with R–L Load 31710.6 Gating Signals 31810.7 Three-phase Full-wave Controller 31910.8 Synchronous Tap Changer (Single-phase Transformer Tap Changer) 32010.9 Integral Cycle Control of Voltage Controller 322

10.10 Features of Phase Control of AC Voltage Controllers 32310.10.1 Gate Pulse Requirements to Trigger Thyristor of AC Voltage Controllers 323Exercises 329


Contents xv

11. AC-TO-AC CONVERTERS—CYCLOCONVERTERS 332–360

11.0 Introduction 33211.1 Types of Cycloconverters 332

11.1.1 Single-phase Cycloconverter 33311.1.2 Three-phase Cycloconverters 339

11.2 Input Displacement Factor 34711.2.1 Features of Cycloconverters 34911.2.2 Load and Source Harmonics 349

11.3 Circulating Current Mode of Operation of Cycloconverter 35011.4 Effect of Source Inductance on the Performance of Cycloconverters 35311.5 Comparison of the Cycloconverter and DC Link Converter 353


12. DC-TO-AC CONVERTERS—INVERTERS 361–408

12.0 Introduction 36112.1 Industrial Applications 36112.2 Types of Inverter 361

12.2.1 Inverters Based on the Method of Commutation 36212.2.2 Inverters Based on the Method of Connections 36212.2.3 Inverters Based on the Control Source 362

12.3 Forced Commutated Inverters 36212.3.1 Parallel Capacitor Commutated Inverters 36312.3.2 Series Commutated Inverter 36512.3.3 Impulse Commutated Inverters 368

12.4 Voltage Source Inverters (VSI) 37412.4.1 Single-phase Voltage Source Inverters 37412.4.2 Three-phase Bridge Voltage Source Inverter 376

12.5 Voltage and Frequency Control 38012.5.1 Control of Voltage Supplied to the Inverter 38012.5.2 Control of Voltage within the Inverter 38112.5.3 Control of Voltage Delivered by Inverter 381

12.6 Current Source Inverter 38112.6.1 Inverter Operation Modes 382

12.7 Current Source versus Voltage Source Inverters 38412.8 Load-commutated Inverters 385

12.8.1 Single-phase Inverter 38512.8.2 Three-phase Inverter 386

12.9 Forced-commutated Inverters 38612.9.1 Auto Sequential Commutated Inverter (ASCI) 38612.9.2 Individual Auxiliary Bridge Commutated Inverter (IABCI) 38912.9.3 Third Harmonic Auxiliary Commutated Inverter (THACI) 390

12.10 Control Circuit for Square wave Inverter 39112.11 Pulse Width Modulated Inverters 392

12.11.1 Single Pulse Width Modulation 39212.11.2 Multiple Pulse Width Modulation 39312.11.3 Sinusoidal Pulse Width Modulation (SPWM) 394

xvi Textbook on Power Electronics and Industrial Applications

12.12 Harmonic Reduction 39512.12.1 Harmonic Elimination Using Different Transformer Connections 39512.12.2 Harmonic Elimination Method 396

12.13 Control Circuit for PWM Inverter 398Exercises 406


13. THYRISTORISED CONTROLLED DC MOTORS 409–465

13.0 Introduction 40913.1 Speed Control of DC Motors 41013.2 Phase Controlled Converters 412

13.2.1 Single phase Separately Excited DC Motor Drives 41313.2.2 Analysis for Continuous Armature Current 41413.2.3 Torque Speed Characteristics 41613.2.4 Analysis for Discontinuous Armature Current 41613.2.5 General Analysis 41713.2.6 Analytical Method 419

13.3 Comparison between Semi Converter and Full Converter 42013.4 Single-phase Series DC Motor Drives 42113.5 Three-phase Drives 42513.6 Dual Converters 42913.7 Dual Converter with Circulating Current 43013.8 Advantages and Disadvantages of Dual Converters with and without

Circulating Current 43213.9 Power Factor, Supply Harmonics and Ripple in Motor Current of Phase

Controlled DC Drives 43213.10 Chopper Controlled DC Drives 43213.11 Regenerative Braking 43413.12 Dynamic Braking 43513.13 Speed Regulation by Different Methods 436

13.13.1 Speed Regulation by Armature Voltage Control 43613.13.2 Speed Regulation by Armature Current Control 43713.13.3 Speed Control of DC Series Motor 43813.13.4 Speed Control of Separately-excited DC Shunt Motor 43813.13.5 Voltage Dependent Resistor Method of Speed Regulation of DC Shunt

Motor with Changes in Supply Voltage 43913.13.6 Speed Regulation Using Saturable Reactor 44013.13.7 Motor-speed Regulation by One Thyristor 44113.13.8 DC Chopper Speed Control 442

13.14 Reversible Drives 44413.14.1 Armature Current Reversal 44413.14.2 Field Current Reversal 444

13.15 Selection of the Drives for Speed Reversal 44613.16 25 kV AC Traction Drives Using Semiconductor Converter Controlled DC Motors 446


Contents xvii

14. THYRISTORISED CONTROLLED AC MOTORS 466–500

14.0 Introduction 46614.1 Speed Control of Three-phase Induction Motors 46614.2 Various Schemes of Speed Control of Induction Motor 46714.3 Constant Frequency Operation of Induction Motor 468

14.4.1 Steady State Analysis at Constant Frequency 46914.4 Variable Frequency Operation of Induction Motor 47014.5 Operation of Induction Motor from Non-sinusoidal Voltage Source 47314.6 Speed Control of Induction Motor 474

14.6.1 AC Voltage Controller or Stator Voltage Control 47414.6.2 Variable Voltage and Variable Frequency Control 47814.6.3 Variable Current and Variable Frequency Control 47914.6.4 Slip Power Recovery Control 48014.6.5 Induction Motor Control by Choppers, or Rotor Resistance 484

14.7 Static Scherbius Drive 48714.8 Commutatorless Kramer Drive System/Power Factor Improvement Method 48814.9 Variable Speed Constant Frequency Generation (VSCF) 489

14.9.1 Slip Ring Induction Motor and Cycloconverter 48914.9.2 Squirrel Cage Induction Machine and Cycloconverter Scheme 490

14.10 Speed Control of Synchronous Machines 49014.11 Synchronous Motor Control 49214.12 Starting of Synchronous Motor 49414.13 Comparison between AC and DC Drives 49514.14 Choice between AC and DC Drives 495


15. FAULTS AND PROTECTION 501–519

15.0 Introduction 50115.1 Current 50115.2 Voltage 50215.3 Snubber Circuit 503

15.3.1 Design of Snubber Circuits 50315.4 dv/dt Protection 50415.5 Protection 50515.6 di/dt Protection 505

15.6.1 Thyristor di/dt Calculation 50515.7 Overvoltage Protection 506

15.7.1 Voltage Protection by Selenium Diodes and Metal Oxide Varistors 50615.8 Over Current Protection 506

15.8.1 Fuse 50715.8.2 Electronic Crowbar Over Current Protection 50815.8.3 Control Logic for Over Current Protection Circuit 508

15.9 GATE Protection 51015.10 Thyristor Mounting 51015.11 Heat Sinks 511

xviii Textbook on Power Electronics and Industrial Applications


16. INDUSTRIAL APPLICATIONS USING SOLID-STATE DEVICES 520–550

16.0 Introduction 52016.1 Residential Applications 52016.2 Heating 52116.3 Induction Heating 52216.4 Electric Welding 52316.5 Resistance Welding 52416.6 Seam Welding 52516.7 AC Static Switches 52616.8 DC Static Switch 52616.9 Flasher Circuits 527

16.10 Low Power Flasher 52716.11 AC Flasher 52816.12 High Speed Switch or Electronic Crowbar 52916.13 Time Delay Circuits 53016.14 Fan Regulator Using TRIAC 53016.15 Electrochemical 53116.16 Machining or Electrochemical Forming 53216.17 Static Circuit Breaker 53316.18 Illumination Level of Incandescent Lamp 53316.19 High Frequency Fluorescent Lighting 53416.20 Induction Cooking 53516.21 ‘One Shot’ Thyristor Trigger Circuit 53516.22 DC Circuit Breaker 53616.23 Overvoltage Protection 53616.24 Simple Battery Charger 53716.25 Battery Charging Regulator 53816.26 Thyristor Current Limiting Circuit Breaker 53916.27 Standby Inverters/Uninterruptible Power Supplies (UPS) 53916.28 Static Excitation Systems for Alternators 540

16.28.1 Brushless Excitation System 54016.28.2 Thyristorised Excitation System 541

16.29 Vibrofeeder Control 54116.30 High Voltage DC Transmission 543

16.30.1 Advantages 54316.30.2 Disadvantages of HVDC Transmission 543

16.31 Thyristor-switched Capacitors (TSC) 54416.32 Thyristor-controlled Inductors (TCI) 54516.33 Wind and Small Hydro-interconnection 54516.34 Switched Mode Power Supplies (SMPS) 546


Contents xix

17. REGULATED POWER SUPPLY 551–586

17.0 Introduction 55117.1 Regulated Power Supply 55117.2 DC and AC Power Supplies 55217.3 Classification of Voltage Regulator 552

17.3.1 Parameters of Voltage Regulator 55217.3.2 Linear Regulator 555

17.4 Complete Voltage Regulated Power Supply 56217.5 Current Regulator 56317.6 IC Voltage Regulators 563

17.6.1 Three-terminal Positive and Negative Voltage Regulators 56317.6.2 LM317 Adjustable Voltage Regulator 56517.6.3 Precision Voltage Regulator 565

17.7 Practical Power Supplies 56717.8 Switch Mode Regulator 567

17.8.1 Advantages and Disadvantages of Switching Regulators 56817.9 Switch Mode Regulators 569

17.10 Switching DC Power Supply 57017.10.1 Advantages of Switching Power Supplies 570

17.11 Basic Switching of Buck Regulator 57017.11.1 Losses and Efficiency 571

17.12 Linear Voltage Regulator Using MOSFET 57117.13 Powerline Disturbances 57117.14 Uninterruptible Power Supplies (UPS) 572

17.14.1 Rectifier 57317.14.2 Batteries 57317.14.3 Inverters 574Exercise 585


18. INDUSTRIAL DRIVES APPLICATIONS USING MICROPROCESSOR 587–609

18.0 Introduction 58718.1 Basics of Microprocessors and Microcomputers 588

18.1.1 Microprocessor (P) 58818.1.2 Memory ROM and RAM 58918.1.3 Input-Output (I/O) Interface 58918.1.4 Data Bus, Address Bus, and Control Bus 58918.1.5 Program or Computer Software 589

18.2 Principle of Microprocessor Based System 59018.3 Microprocessor Based Industrial Drives Applications 591

18.3.1 Measurement of Electrical Quantities Like Frequency 59118.3.2 Multiple Digit Display 59518.3.3 Microprocessor Based Control of Reversing DC Drives 59618.3.4 Microprocessor Based Speed Controller of DC Motor 59718.3.5 Microprocessor Based Temperature Monitoring and Control System 59918.3.6 Microprocessor Based Water Level Monitoring System 600

xx Textbook on Power Electronics and Industrial Applications

18.3.7 Computerized Numerically Controlled Machines (CNC Machine) 60118.3.8 Microprocessor Based Control of Firing Circuit of a Thyristor 60318.3.9 Microprocessor Based Speed Control of Three-phase Induction Motor 60318.3.10 Microprocessor Based Speed Control of Synchronous Motors 60518.3.11 Microprocessor Based Process Control System 606

18.4 Advantages of Microprocessor Based System 608Exercises 608


MCQ for Semiconductor Devices and Commutation from Various Examinations 610MCQ for Phase Controlled Rectifiers from Various Examinations 623MCQ for Choppers from Various Examinations 632MCQ for Inverters from Various Examinations 636MCQ for Electrical Drives from Various Examinations 642MCQ for Miscellaneous from Various Examinations 644

Index 649–652

textbook on power electronics and · ernakulam 682 016, kochi, kerala ... † nagpur 0-9021734563...

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