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Unformatted text preview: See discussions, stats, and author profiles for this publication at: Power Electronics 15 May 2018 Book · June 2018 CITATIONS READS 0 3,544 1 author: Bilal Abdullah Nasir Hawijah Technical Institute 36 PUBLICATIONS 98 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Design and Implementation of Micro-Hydro-Electric Power Station View project hydrogen production from water View project All content following this page was uploaded by Bilal Abdullah Nasir on 14 June 2018. The user has requested enhancement of the downloaded file. Power Electronics Dr. Haider Kh. Easa Dr. Bilal Abdullah Nasir Dr. Ali Abdullabas Dr. Sameer Saadoon ii Preface The last four decades witnessed a huge progress in the eld of electrical engineeringpower electronic branch, according to the eorts and researches of thousands of scientists all around the world in this eld. This caused a technological revolution in power electronic that we witness today part of it, and the coming generation will witness the other parts. Despite the large number of researches and studies, there was a decisive landmark that pushed the wheel of this revolution, the thyristor was one of these inventions. The thyristor is an electronic key which permits the electrical current to cut and passing through despite the many kinds of sophisticated and sensitive electronic devices. The invention of the thyristor wide opened the door on power electronic science, the science that gives the problem the modern industry the ability of auto-control when dealing with high voltages and currents. For the thyristor which has a high power handling and good eciency in the systems of power transfer. In despite of the passing four decades since the start of studying the power electronic as a curriculum in the Iraqi Institutes and Universities, but the library is lacking for such a book which covers all the subjects and aspects of power electronics and their engineering applications in electrical power systems. This book is written in a simple and easy English-Language to cover all the subjects taught in this eld to the students of technical college and college of engineering in the fourth year of their study-Electrical and electronic engineering departments-and also to the students in the nal year of their study in Electrical department in the technical institutes. This book contains dierent subjects in separative chapters together with analysing the important circuits and explaining the function of the practical circuits. These subjects are organized in an accumulative manner. Each chapter contains examples with their answers and tutorial questions at the end of each chapter, in order to enhance the comprehension of it. The rst eight chapters concentrating on the basics of power electronic, they give the student a wide prospective on the thyristor, its construction, characteristics, how its functioning and protecting, the way of its ring and commutation. The chapters also cover the applications of thyristor in the rectication of alternating current (A.C.) and showing also the practical circuits and their applications in a simple way. They give the reader a special importance toward switching ON and OFF of direct current (D.C.) circuits and how to control them. After that they demonstrate the inversion of D.C. to A.C. with variable frequency by controlling the time of conducting and dis-conducting of the thyristor used in the system. Finally, they give special importance to switch ON and OFF the A.C. circuits and the controlling function for both single-phase and three-phase systems. iii iv The last chapter (chapter nine) of this book specialized in demonstrating the most important applications in the eld of power electronics. The chapter shows the industrial applications of the thyristor in the eld of controlling the speed of electrical motors which they are widely spread in industry especially D.C. motors, 3-phase induction motors and three-phase synchronous motors. Finally, We hope that this book will be useful for the students, engineers and technicians. Contents Preface 1 1 Power Electronic Concepts 3 1.1 Pre-test . . . . . . . . . . . . . . . . . 1.2 Diode . . . . . . . . . . . . . . . . . 3 4 1.2.1 Forward biasing . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2.2 Reverse biasing 5 1.2.3 Diode characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 Transistor 1.4 Transistor biasing . 1.5 Common-Emitter output characteristic . . . . 1.6 Self-test . . . . . . . . . . . . 1.7 Thyristor . . . . . . . . . . . . . . . . 8 1.8 Thyristor construction . . . . . . . . . . . . . 8 1.9 Post-test 1.3.1 . . . . . . . . . . . . . . . . . . . . . . . . . Transistor construction . . . . . . . . . . . . . . . . . . . . 1.8.1 . . . . . . . . . . . . . 1.10 Standard answers . . . . . 7 . . . . 7 9 . . . . . . . . . . . . . 9 . . . . . . . . . . . . . . 10 . . . . . . . . . Pre-test . . . 2.2 Single phase, uncontrolled, half wave rectier with resistive load . 12 2.3 Single phase, uncontrolled, full wave rectier with resistive load . 13 2.4 Post-test . . . . . . . . . . . . . . 15 2.5 Standard answers . . . . . . . . . . . . . . 15 2.6 Pre-test . . . . . . . . . . . . . . . 15 2.7 Three phase, uncontrolled, half wave rectier with resistive load . 17 2.8 Three phase, full wave, uncontrolled rectier with resistive load . 19 2.9 Eect of source impedance-overlap phenomena . . . . . . 11 2.1 . . 6 . 2 Uncontrolled Rectication . 5 . Thyristor family . . . . . . . . . . . . . . . . . . . . . . . . . 5 11 . . . . . . 21 . . . . . . . . . . . . . . 23 . . . . . . . . . . . . . . 24 3 Application of Transistor and Operational Amplier in Power Electronics 25 2.10 Post-test . . 2.11 Standard answers 3.1 Pre-test . . . . . . . . . . . . . . . . . 26 3.2 Power Transistors . . . . . . . . . . . . . . 26 3.2.1 Bipolar junction transistor (B J T) . . . . . . . . . . . . . 3.2.2 MOSFET 3.2.2.1 27 . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Enhanced type . . . . . . . . . . . . . . . . . . . . . 28 i CONTENTS ii 3.2.2.2 3.2.3 Depletion type . . . . . . . . . . . . . . . . . . . . . 29 IGBT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.3 The power transistor as a switch . . . . 29 3.4 Over driven operation of the power transistor as a switch . . . 31 3.5 Post-test 3.6 . . . . . . . . . . . . . . . . . 32 Standard answers . . . . . . . . . . . . . . 32 3.7 Pre-test . . . . . . . . . . . . . . . 33 3.8 The Unijunction Transistor . . . . . . . . . . . 34 3.8.2 3.9 Post-test . . . . 3.8.1 . . . Construction, electrical symbol and characteristics . . . . 34 UJT as a relaxation oscillator . . . . . . . . . . . . . . . . 35 . . . . . . . . . . . . . . . 37 3.10 Standard answers . . . . . . . . . . . . . . 39 3.11 Pre-test . . . . . . . . . . . . . . . 39 3.12 Operational amplier . . . . . . . . . . . . . 41 3.13 Open-loop operational amplier . . . . . . . . . . 41 3.14 Inverting Amplier. . . . . 42 . . . . . . . . . . . . 3.15 Non-inverting Amplier . . . . . . . . . . . . 43 3.16 Inverting summing operational amplier . . . . . . . . 43 3.17 Non-inverting summing amplier . . . . . . . . . . 44 3.18 Subtractor operational amplier . . . . . . . . . . 45 3.19 Integrator operational amplier . . . . . . . . . . 45 . . . 3.20 Dierentiator operational amplier . . . . . . 46 3.21 Operational amplier as zero-crossing detector . . . . . . 48 3.22 Operational amplier as comparator . . . . . . . 48 . . 3.23 Thyristor triggering circuit using operational amplier as a comparator 49 3.24 Post-test . . . . . . . . . . . . . . . . 50 3.25 Pre-test . . . . . . . . . . . . . . . . . 52 . . . . . . . . . . . . . . 54 3.27 Photo-conductive cell . . . . . . . . . . . . . 54 3.26 Opto-electronics: 3.28 Photo-diode . . . . . . . . . . . . . . . 54 3.29 Photo-transistor . . . . . . . . . . . . . . 55 3.30 Light Emitting Diode (LED) . . . . . . . . . . . 56 3.31 Some applications . . . . . . . 57 3.32 Post-test . . 3.33 Standard answers . . . . . . . . . . . . . . . . . . . . . 59 . . . . . . . . . . . . . . 61 4 Thyristor Concepts In Power Electronics 63 CONTENTS 4.1 Pre-test . 4.2 4.3 iii . . . . Thyristor denition and characteristics . . . . . . Thyristor Family: . . . . . . . . . . . . 4.4 Post-test . . . . . . . . . . . . . 4.5 Standard answers . . . . . . . . . . . . . . 69 4.6 Pre-test . . . . . . . . . . . . . . . 70 4.7 Thyristor representation by two transistors: . . . . . . . 70 4.8 Post-test 4.9 Standard answers . . . . . . . . . . . . . . 63 . . 64 . . 66 . 68 . . . . . . . . . . . . . 73 . . . . . . . . . . . . . . 74 . . . . . . . . . . . . . . 74 4.11 Modes of Thyristor Triggering (ring) . . . . . . . 4.10 Pre-test . . . . . . . . . 75 4.12 Behavior of Anode current during thyristor Turn-ON . . . . 75 4.13 Post-test . . 76 . . . . . . 4.14 Standard answers . . . . . . 4.15 Pre-test . . . . . . . 4.16 The thyristor turn-OFF (commutation) . . . . . 4.17 Turn-OFF behaviour: . . . . . . . . . . 4.18 Post-test . . . . . . . . . . . . . . . . . . . . . . . . . 77 . . . . . . . . 77 . . . 78 . . . 80 . . 81 . . . . . 4.19 Standard answers . . . . . . . . . . . . . . 81 4.20 Pre-test . . . . . . . . . . . . . . . 82 4.21 Series and parallel operation of thyristors . . . . . . . 82 . . . . 4.21.1 Series operation . . . . . . . . . . . . . . . . . . . . . . . . 4.21.2 Parallel operation . . . . . . . . . . . . . . . . . . . . . . . 4.22 Post-test . 83 . . . . . . . . . . . . . . 84 4.23 Standard answers . . . . . . . . . . . . . . 84 4.24 Pre-test . . . . 82 . 4.25 Thyristor protection: . . . . . . . . . . . . . 86 . . . . . . . . . . . . . 87 4.25.1 Over-voltage protection: . . . . . . . . . . . . . . . . . . . 87 4.25.2 Over-current protection: . . . . . . . . . . . . . . . . . . . 87 4.25.3 Gate protection: . . . . . . . . . . . . . . . . . . . . . . . . 88 4.26 Post-test . . . . . . . . . . . . . . 90 4.27 Standard answers . . . . . . . . . . . . . . . 91 4.28 Pre-test . . . . . . . . . . . . . . . 94 4.29 Thyristor triggering techniques . . . . . . . . . . 94 4.30 Thyristor triggering circuits . . . . . . . . . . . 100 4.31 Post-test . . . . . 4.32 Standard answers . . . . . . . . . . . . . . 102 . . . . . . . . . . . . . . 102 5 Controlled Rectication 105 CONTENTS iv 5.1 Pre-test . 5.2 Half-wave, controlled-rectier with resistive-load 5.3 . . . . . . . . . . . . . . . . 105 . . . . . 105 Single-phase, half-wave, controlled rectier with resistive-inductive load . . . . . . . . . . . . . . . . . 5.4 Post-test . . . . . . . . . . . . . . . . 111 5.5 Pre-test . . . . . . . . . . . . . . . . . 113 5.6 Single-phase, half-wave, controlled rectier with inductive load and freewheeling diode . 5.7 109 . . . . . . . . . . . . . 114 Single-phase, half-wave controlled rectier with inductive-load and back e.m.f . . . . . . . . . . . . . . . . 115 5.8 Post-test . . . . . . . . . . . . . . . . 119 5.9 Pre-test . . . . . . . . . . . . . . . . . 120 . . 121 5.10 Single-phase, controlled, full-wave rectier with resistive-load 5.11 Single-phase, full-wave, controlled rectier with resistive-inductive load . . . . . . . . . . . . . . . . . . 122 5.12 Single-phase, full-wave, controlled rectier with resistive-inductive . . . . . . . 122 5.13 Uncontrolled bridge rectier with a thyristor. load and back e.m.f . . . . . . . . . . . . 124 5.14 Post-test . . . . . . . . . . . . . . . . 127 5.15 Pre-test . . . . . . . . . . . . . . . . . 129 . . . . . . . 130 5.16 Three-phase, half-wave controlled rectier: 5.16.1 With resistive load: . . . . . . . . . . . . . . . . . . . . . . 130 5.16.2 With resistive-inductive load . . . . . . . . . . . . . . . . . 133 5.17 Post-test: . . . . . . . . . . . . . . . . 135 5.18 Pre-test . . . . . . . . . . . . . . . . . 137 5.19 Fully-controlled, full-wave 3-phase bridge rectier . . . . . 138 5.20 Post-test: . . . . . . . . . . . . . . . . 142 5.21 Pre-test . . . . . . . . . . . . . . . . . 143 5.22 Overlap in single-phase, full-wave circuits . . . . . . . 144 5.23 Over-lap in controlled 3-phase rectier . . . . . . . . 145 5.24 Post-test . . . . . . . . 148 . . . . . . . . 6 D.C. to D.C. Converters (D.C. chopper) Pre-test . . . . . . . . . . . 151 6.2 DC/DC converter (DC chopper) . . . . . . . . . . 152 6.3 Typical commutation circuit of D.C. chopper . . . . . . 152 6.4 Chopper types: . . . . . . . . . . . . 153 6.5 Analysis of output waveform: . . . . . . . . . . . 155 6.6 . . . . . . . . . 151 6.1 6.5.1 Resistive load . . . . . . . . . . . . . . . . . . . . . . . . . 155 6.5.2 Resistive-inductive load with baack e.m.f. . . . . . . . . . 156 Parallel capacitor-saturable core inductor commutation D.C. chopper (Morgan circuit): . . . . . . . . . . . . . 158 6.7 Step-up chopper: . . . . . . . . . . . . . 159 6.8 Multi-phase chopper: . . . . . . . . . . . . . 160 6.9 Factors governing the chopper performance . . . . . . . 160 6.10 Post-test . . 6.11 Standard answers . . . . . . . . . . . . . . . 161 . . . . . . . . . . . . . . 161 7 A.C. Regulators (Controllers) 165 CONTENTS v 7.1 Pre-test . . . . . . . . . . . . . . 165 7.2 Single-phase A.C. regulator . . . . . . . . . . . 166 7.3 Another circuits of single-phase A.C. regulator . . . . . . 170 7.4 Post-test: . . . . . . . 174 7.5 7.6 7.7 3-phase, A.C. Regulator . . . . . . . Standard answers . . . . . . . . . . . . . . 175 Pre-test . . . . . . . . . . . . . . . 176 . . . . . . . . . . . . 177 . . . . . . . 7.7.1 circuit conguration 7.7.2 3-phase, line-controlled A.C. regulator with star-connected resistive-load 7.7.3 . . . . . . . . . . . . . . . . . . . . . 177 . . . . . . . . . . . . . . . . . . . . . . . . . 178 3-phase, line-controlled A.C. regulator with delta-connected resistive-load . . . . . . . . . . . . . . . . . . . . . . . . . . 178 7.7.4 speed control of 3-phase induction motor by variation of line-voltage (stator-voltage) using 3-phase A.C. regulator . 179 7.8 Post-test . . . . . . . . . . . . . . . . 180 7.9 Pre-test . . . . . . . . . . . . . . . . . 182 7.10 A.C. /A.C. cycloconverter . . . . . . . . . . . . 183 7.11 3-phase to single-phase cycloconverter . . . . . . . . 183 7.12 3-phase to 3-phase cycloconverter . . . . . . . . . 185 . . . . . . . 185 7.14 Frequency multiplication cycloconverter . . . . . . . . 187 7.15 Post-test . . . . . . . . 188 . 7.13 Single-phase to single-phase cycloconverter . . . . . . . . 8 D.C. to A.C. Converters (Inverters) . . . . . . . 193 8.1 Pre-test . . . . . . . . . . 193 8.2 Single-phase and three-phase inverters . . . . . . . . 194 8.2.1 Inverter commutation circuits 8.2.2 Single-phase parallel-inverter . . . . . . . . . . . . . . . . . 198 . . . . . . . . . . . . . . . . 195 8.3 Analysis of parallel-inverter circuit with resistive load . . . . 199 8.4 Single-phase series inverter . . . . . . . . 201 8.5 Limitations of the series inverter circuit . . . . . . . . 204 8.6 Single-phase modied series inverter . . . . . . . . . 204 8.7 Frequency-Range of series inverter . . . . . . . . . 205 8.8 Single-phase, half-bridge inverter . . . . . . . . . . 206 8.9 Single-phase, bridge inverter . . . . . . . . . 207 . . . . . 8.10 Forced commutation circuit of single-phase bridge inverter . 8.11 Voltage control of single-phase bridge inverter . . 8.12 Three-phase bridge Inverter . . . . . . 8.13 Post-test . . . . . . . . . . . . . 208 . . . . 210 . . . . . 212 . . . . . 213 9 Power Electronic Application in Speed Control of Electrical Motors 218 9.1 Pre-test . . . . . . . 9.2 Introduction to speed control . . 9.3 D.C. motors speed control . . 9.4 Speed control of synchronous motors . . . . . . . . . 221 9.5 Torque-speed characteristics . . . . . . . . . . . 223 9.6 D.C. motor starting . . . . . . . . . . . 226 9.7 D.C. motor speed control using power electronic systems . . . 226 9.8 Controlled rectiers . . . . . . . 227 9.9 Single-phase bridge fully controlled rectier . . . . . . . 227 . . . . . 228 . . . . . . . . . . . . . . . . . . . . . . . . 221 . . . . . . . . . 221 . . . . 219 9.10 single-phase bridge, half-controlled rectier . . 9.11 3-phase bridge, fully-controlled rectier . . . . . . . . 231 9.12 D.C. chopper . . . . . . . . 233 . . . . . 9.12.1 Step-down chopper . . . . . . . . . . . . . . . . . . . . . . . . 233 9.12.2 Step-up chopper . . . . . . . . . . . . . . . . . . . . . . . . 233 9.12.3 Two-quadrant chopper . . . . . . . . . . . . . . . . . . . . 234 9.13 Post-test . . . . . . . . . . . . . . . . 237 9.14 Pre-test . . . . . . . . . . . . . . . . . 239 . . . . . . . . . . 240 9.15 Induction motor speed control 9.15.1 Construction and operation . . . . . . . . . . . . . . . . . 241 9.15.2 Equivalent circuit of induction motor . . . . . . . . . . . . 241 9.15.3 Speed control methods of induction motor . . . . . . . . . 244 9.15.3.1 Pole changing 9.15.3.2 Stator voltage control 9.15.3.3 Line Frequency control (frequency voltage control) 9.15.3.4 Rotor Resistance Control . . . . . . . . . . . . . . . 249 9.16 Post-test . . . . . . . . . . . . . . . . . 245 246 . . . . . . . . . . . . . . 251 9.17 Standard answers . . . . . . . . . . . . . . 252 9.18 Pre-test . . . . . . . . . . . . . . . 252 . . . . . . . . 254 . . . . . . . . . . . . . . . . . . . . . . . 245 . 9.19 Speed control of synchronous machines 9.19.1 Construction of 3-phase synchronous machines 9.19.2 Synchronous motor starting . . . . . . . . . . . . . . . . . 254 9.19.2.1 Start with variable-frequency supply 9.19.2.2 Start as an induction motor 9.20 Equivalent circuit model . . . . . 9.21 Power and Torque characteristics . . . . 9.22 Speed control methods . . . . . . . . . . . . . 255 . . . . . . . . . . . . . 255 . . . . . . . . . 254 . . . . . 255 . . . . . . 256 . . . . . . 258 9.22.1 Frequency control . . . . . . . . . . . . . . . . . . . . . . . 258 9.22.2 Self controlled synchronous motor 9.23 Post-test . . 9.24 Standard answers . . . . . . . . . . . . . 260 . . . . . . . . . . . . . . 261 . . . . . . . . . . . . . . 262 vi LIST OF FIGURES vii List of Figures 1.1 Silicon diode V-I characteristic curve. . . . . . . . . . . . . . . . 4 1.2 PN Junction Diode - Forward Biased . . . . . . . . . . . . . . . 5 1.3 PN Junction Diode - Reverse Biased . . . . . . . . . . . . . . . . 5 1.4 Transistor construction and symbol. . . . . . . . . . . . . . . . . 6 1.5 Transistor baising . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.6 Common-Emitter output charcteristics. 1.7 Transistor as a switch 1.8 Thyrisor construction and symbol. 1.9 Thyristor construction . . . . . . . . . . . . . . . . . . . . . . . . 1.10 Thyristor Family . . . . . . . . . . . . . . 7 . . . . . . . . . . . . . . . . . . . . . . . . 7 . . . . . . . . . . . . . . . . . 8 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.11 Circuit diagram of question (1), post-test. . . . . . . . . . . . . . 10 2.1 Single phase uncontrolled half wave rectier with resistive load. . 12 2.2 Single-phase mid-point or center-tap. . . . . . . . . . . . . . . . . 14 2.3 Single-phase bridge connection. . . . . . . . . . . . . . . . . . . . 14 2.4 Three-phase, uncontrolled, half wave rectier. 17 2.5 Output voltage wave form. 2.6 Three phase uncontrolled full wave rectier with resistive load. 2.7 Output voltage wave form. 2.8 The overlap phenomenon in controlled rectiers. 3.1 Bipolar junction transistor (BJT). . . . . . . . . . . . . . . . . . 27 3.2 Input characteristics. . . . . . . . . . . . . . . . . . . . . . . . . 27 3.3 Output characteristics . . . . . . . . . . . . . . . . . . . . . . . . 3.4 N-Channel enhanced MOSFET. 3.5 Insulated gate bipolar junction (IGBT). 3.6 IGBT output and transfer characteristics. 3.7 The power transistor can be used as an electronic switch. . . . . 30 3.8 Circuit diagram of example 1. . . . . . . . . . . . . . . . . . . . . 30 3.9 Over driven operation of the power transistor as a switch. . . . . ....
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