Contents i SYLLABUS osmania university UNIT - I POWER SEMICONDUCTOR DIODES AND TRANSISTORS Types of Power Diodes General Purpose Diodes, Fast Recovery Diodes Their Characteristics and Applications, Bipolar Junction Transistors, Power MOSFETs P- Channel, N-Channel, IGBTs Basic Structure and Working, Steady State and Switching Characteristics, Comparison of BJT, MOSFET and IGBT, Their Applications, SCRs Static and Dynamic Characteristics, Two Transistor Analogy, ETO, MTO, IGCT Characteristics. UNIT - II POWER TRANSISTOR AND RECTIFIERS Turn-On and Turn-Off Mechanism of BJT, Power MOSFET, IGBTs, SCR Trigger Circuits R, RC and UJT Triggering Circuits, Triggering Circuits for Single Phase Bridge Rectifier and Choppers, Driver Circuits of MOSFET, IGBT and BJT, The Various Commutation Methods of SCRs, Protection of SCRs. UNIT - III CONTROLLED RECTIFIERS AND CONVERTERS Principles of Controlled Rectification, Study of Single Phase and Three Phase Half Controlled and Full Controlled Bridge Rectifiers With R, RL, RLE Loads, Effect of Source Inductances, Dual Converters Circulating Current Mode and Circulating Current Free Mode Control Strategies. UNIT - IV CHOPPERS,, CYCL CLOCONVERTERS AND A.C VOL OLTAGE CONTROLLER Classification of Choppers A, B, C, D and E, Switching Mode Regulators Study of Buck, Boost and Buck Boost Regulators, Cuk Regulators, Principle of Operation of Single Phase Bridge Type Cyclo Converters and Their Applications, Single Phase A.C Voltage Controllers With R, and RL Loads.
ii Contents UNIT - V INVERTERS Principle of Operation of Single Phase Inverters, Three Phase Bridge Inverters (180 and 120 Modes) Voltage Control of Inverters, Single Pulse Width Modulation, Multiple Pulse Width Modulation, Sinusoidal Pulse Width Modulation, Comparison of Voltage Source Inverters and Current Source Inverters, Elementary Multilevel Inverters.
Contents iii power electronics FOR b.e. (o.u) Iii year i semester (COMMON TO EEE & IE) CONTENTS UNIT - I [POWER SEMICONDUCTOR DIODES AND TRANSISTORS]... 1.1-1.60 1.1 INTRODUCTION... 1.2 1.2 APPLICATIONS OF POWER ELECTRONICS... 1.2 1.3 ADVANT ANTAGES AND DISADVANT ANTAGES OF POWER ELECTRONICS... 1.3 1.4 POWER DIODES AND THEIR CHARACTERISTICS... 1.4 1.5 TYPES OF POWER DIODES AND THEIR APPLICATIONS... 1.9 1.5.1 Types of Power Diodes... 1.9 1.5.1.1 General Purpose Diode Classification... 1.9 1.5.1.2 Fast Recovery Diode... 1.12 1.5.1.3 Schottky Diode... 1.14 1.5.2 Applications of Power Diodes... 1.15 1.6 POWER TRANSISTORS... 1.16 1.6.1 Bipolar Junction Transistors (BJTs) s)... 1.16 1.6.1.1 Structure of BJTs... 1.17 1.6.1.2 Steady State Characteristics of BJT... 1.18 1.6.1.3 Switching Characteristics of BJT... 1.21 1.6.1.4 Safe Operating Area of BJT (SOA)... 1.23 1.6.1.5 Advantages, Disadvantages and Applications of BJT... 1.24
iv Contents 1.6.2 Power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs)... 1.25 1.6.2.1 Depletion Type MOSFET... 1.27 1.6.2.2 Enhancement Type MOSFET... 1.29 1.6.2.3 Switching Characteristics... 1.32 1.6.2.4 Safe Operating Area (SOA) of PMOSFET... 1.33 1.6.2.5 Advantages, Disadvantages and Applications of MOSFET... 1.34 1.6.3 Insulated Gate Bipolar Transistor (IGBT)... 1.34 1.6.3.1 Structure of IGBT... 1.34 1.6.3.2 Steady State Characteristics... 1.36 1.6.3.3 Switching Characteristics... 1.37 1.6.3.4 Safe Operating Area (SOA) of IGBT... 1.39 1.6.3.5 Advantages, Disadvantages and Applications of IGBT... 1.39 1.7 COMPARISONS OF BJT, MOSFET AND IGBT AND THEIR APPLICATIONS... 1.40 1.8 SILICON CONTROLLED RECTIFIERS (SCR)... 1.41 1.8.1 Static V-I -I Characteristics... 1.41 1.8.1.1 Reverse Blocking Mode... 1.42 1.8.1.2 Forward Blocking Mode... 1.42 1.8.1.3 Forward Conduction Mode... 1.42 1.8.2 Dynamic Characteristics... 1.43 1.8.3 Advantages, Disadvantages and Applications of SCR... 1.45 1.9 TWO TRANSISTOR ANALOG OGY... 1.46 1.10 EMITTER TURN-OFF THYRISTOR (ETO)... 1.48 1.11 INTEGRATED TED GATE COMMUTATED TED THYRISTOR (IGCT)... 1.50 1.12 MOS TURN-OFF THYRISTOR (MTO)... 1.51 1.13 SOLVED PROBLEMS... 1.52
Contents v UNIT - II [POWER TRANSISTOR AND RECTIFIERS]... 2.1-2.60 2.1 INTRODUCTION... 2.2 2.2 TURN-ON AND TURN-OFF MECHANISM OF BJT... 2.2 2.3 TURN-ON AND TURN-OFF MECHANISM OF PMOSFET... 2.2 2.4 TURN-ON AND TURN-OFF MECHANISM OF IGBT... 2.2 2.5 SCR TURN-ON METHODS... 2.2 2.6 SCR TRIGGERING CIRCUITS... 2.3 2.6.1 Resistance Triggering Circuit (R-Triggering)... 2.5 2.6.2 Resistance-Capacitance Triggering Circuit (RC-Triggering)... 2.7 2.6.3 Unijunction Transistor (UJT)... 2.9 2.6.3.1 UJT Triggering Circuits... 2.12 2.7 RECTIFIERS... 2.15 2.7.1 Halfwave Rectifiers... 2.15 2.7.2 Single Phase Fullwave Rectifier with Split Supply... 2.23 2.7.3 Single Phase Bridge Rectifier... 2.28 2.8 DRIVER CIRCUITS FOR BJT,, MOSFET AND IGBT... 2.32 2.8.1 Driver Circuit for BJT... 2.32 2.8.2 Driver Circuit for MOSFET... 2.34 2.8.3 Driver Circuit for IGBT... 2.36 2.9 COMMUTATION TION METHODS OF SCR... 2.37 2.9.1 Natural Commutation... 2.38 2.9.2 Forced Commutation... 2.38 2.9.2.1 Resonant Commutation (Class A-Commutation)... 2.38 2.9.2.2 Self Commutation (Class-B Commutation)... 2.41 2.9.2.3 Auxiliary Commutation (Class-C Commutation)... 2.43 2.9.2.4 Complementary Commutation (Class-D Commutation)... 2.44 2.9.2.5 External Pulse Commutation (Class-E Commutation)... 2.46 2.9.2.6 Line Communication (Class-F Commutation)... 2.47
vi Contents 2.10 PROTECTION OF SCR... 2.50 2.10.1 di/dt Protection... 2.51 2.10.2 dv/dt Protection... 2.51 2.10.3 Overvoltage Protection... 2.52 2.10.4 Over Current Protection... 2.53 2.10.5 Electronic Crowbar Protection... 2.53 2.11 GATE TURN-OFF THYRISTOR (GTO)... 2.53 2.11.1 Construction of a GTO... 2.54 2.11.2 Principle of Operation of GTO... 2.55 2.11.3 Steady State Output and Gate Characteristics... 2.57 2.11.4 Dynamic Characteristics of a GTO... 2.58 2.11.5 Advantages, Disadvantages and Applications of GTO... 2.60 UNIT - III [CONTROLLED RECTIFIERS AND CONVERTERS]... 3.1-3.114 3.1 INTRODUCTION... 3.2 3.2 PRINCIPLES OF PHASE CONTROLLED RECTIFIERS... 3.2 3.3 SINGLE PHASE CONTR-OLLED RECTIFIERS... 3.3 3.4 SINGLE PHASE HALF WAVE CONTROLLED RECTIFIER... 3.3 3.4.1 Half Wave Controlled Rectifier With Resistive Load (R)... 3.3 3.4.2 Half Wave Controlled Rectifier With Resistive Inductive Load (RL)... 3.8 3.4.3 Half Wave Controlled Rectifier With Inductive Load and Flywheel Diode (RLE)... 3.11 3.5 FULL WAVE CONTROLLED RECTIFIERS... 3.13 3.5.1 Mid Point Configuration With Resistive Load oad... 3.13 3.5.2 Full Wave Controlled Rectifier With Transformer Leakage Reactance and Load Reactance... 3.16 3.5.3 Full Wave Controlled Bridge Rectifiers... 3.21 3.5.3.1 Fully Controlled Bridge Rectifier With RL Load... 3.22 3.5.3.2 Fully Controlled Bridge Rectifier With Flywheel Diode (RLE)... 3.24
Contents vii 3.5.3.3 Half Controlled Bridge Rectifier With Resistive Load... 3.30 3.5.3.4 Half Controlled Bridge Rectifier With Inductive Load (RL)... 3.32 3.6 THREE PHASE CONTROLLED RECTIFIERS... 3.43 3.6.1 Procedural Steps to Draw 3-φ Voltage (or) Current Waveforms... 3.43 3.7 THREE PHASE HALF WAVE CONTROLLED RECTIFIER... 3.44 3.7.1 Three Phase Half Wave Controlled Receifier With Resistive Load (RL)... 3.44 3.7.2 3-φ Half Wave Controlled Rectifier With Inductive Load... 3.48 3.8 THREE PHASE FULL WAVE CONTROLLED RECTIFIER... 3.55 3.8.1 Three Phase Full ull Wave Midpoint Half Controlled Rectifier... 3.55 3.8.2 Bridge Type 3-φ Half Controlled Rectifier With Resistive Load... 3.64 3.8.3 Bridge Type 3-φ Half Controlled Rectifier With RL Load and Flywheel Diode... 3.70 3.8.4 Bridge Type 3-φ Fully Controlled Rectifier with RL Load... 3.75 3.8.5 Bridge Type 3-φ Fully Controlled Rectifier with RL Load... 3.79 3.9 EFFECT OF SOURCE INDUCTANCE... 3.84 3.9.1 Single Phase Full Converter... 3.85 3.9.2 Three Phase Full Converter Bridge... 3.88 3.9.3 Relation Between Delay Angle (α) ) and Overlap Angle (μ)... 3.89 3.10 DUAL CONVERTERS... 3.92 3.10.1 Dual Converter Without a Circulating Current... 3.95 3.10.2 Dual Converter With Circulating Current... 3.95 3.10.3 Comparison of Circulating Current Mode and Non-Circulatory Mode Dual Converter... 3.101 3.11 CONTROL STRATEGIES TEGIES... 3.103 3.11.1 Time Ratio Control... 3.103 3.11.2 Current Limit Control (CLC)... 3.105 3.12 SOLVED PROBLEMS... 3.108
viii Contents UNIT - IV [CHOPPERS, CYCLOCONVERTERS AND A.C VOLTAGE CONTROLLER]... 4.1-4.92 4.1 INTRODUCTION... 4.2 4.2 CHOPPERS... 4.2 4.2.1 Chopper Principle... 4.2 4.2.2 Analysis of Step Down Chopper With Resistance Load... 4.3 4.2.3 Analysis of Step Down Chopper With RLE Load... 4.6 4.2.4 Fourier Analysis of Output Voltage Wave... 4.11 4.3 CLASSIFICATION OF CHOPPER... 4.15 4.3.1 Type ype-a Chopper... 4.15 4.3.2 Type ype-b Chopper... 4.18 4.3.3 Type ype-c C Chopper... 4.20 4.3.4 Type ype-d -D Chopper... 4.23 4.3.5 Type ype-e -E Chopper... 4.26 4.4 SWITCHING MODE REGULATORS... 4.27 4.4.1 Step Down (Buck) Regulator... 4.28 4.4.2 Step Up (Boost) Regulator... 4.31 4.4.3 Buck Boost Regulator... 4.33 4.4.4 Cuk Regulator... 4.35 4.4.5 Full Bridge Regulator... 4.37 4.5 CYCLO CONVERTERS... 4.39 4.5.1 Single Phase Cycloconverter... 4.41 4.5.1.1 Centre Tapped Transformer (or) Mid Point Cycloconverter... 4.41 4.5.1.2 Bridge Type Cycloconverter... 4.45 4.5.2 Three Phase Cycloconverters... 4.48 4.5.2.1 Three Phase to Single Phase Cycloconverter... 4.48 4.5.2.2 Three Phase to Three Phase Cycloconverter... 4.52 4.5.3 Reduction of Output Voltage Equation... 4.55 4.5.4 Applications of Cycloconverters... 4.57
Contents ix 4.6 A.C VOLTAGE CONTROLLERS... 4.60 4.6.1 Principle of ON-OFF Control... 4.60 4.6.2 Principle of Phase Angle Control... 4.65 4.6.3 Single Phase Half Wave with R-L -Load oad... 4.66 4.6.4 Single Phase Full Wave with R-L -Load... 4.69 4.6.5 Single Phase Full Wave with R-L Load... 4.74 4.6.6 Three-Phase Half Wave with R-L -Load... 4.78 4.6.7 Three-Phase Full Wave with R-L -Load oad... 4.79 4.6.8 Advantages, Disadvantages and Applications of A.C Voltage Controllers... 4.84 4.7 SOLVED PROBLEMS... 4.84 UNIT - V [INVERTERS INVERTERS]... 5.1-5.50 5.1 INTRODUCTION... 5.2 5.2 PRINCIPLE OF OPERATION OF AN INVERTER TER... 5.2 5.3 SINGLE PHASE INVERTERS... 5.3 5.3.1 Single Phase Half Bridge Inverter... 5.3 5.3.2 Single Phase Full Bridge Inverter... 5.7 5.3.3 Steady State Response of Single Phase Inverters... 5.8 5.4 THREE PHASE INVERTERS... 5.13 5.4.1 180 Conduction Mode... 5.14 5.4.2 120 Conduction Mode... 5.18 5.4.3 Comparison of 180 and 120 Conduction Schemes... 5.23 5.5 VOLTAGE CONTROL OF INVERTER... 5.26 5.5.1 External Control of A.C Output Voltage... 5.27 5.5.2 External Control of the D.C Input Voltage oltage... 5.27 5.5.3 Internal Control of Inverter... 5.28 5.5.3.1 Series Inverter Control... 5.29 5.5.3.2 Pulse Width Modulation Control... 5.30
x Contents 5.6 PULSE WIDTH MODULATION TION... 5.30 5.6.1 Single Pulse Width Modulation... 5.30 5.6.2 Multiple Pulse Width Modulation... 5.32 5.6.3 Sinusoidal Pulse Width Modulation... 5.33 5.7 VOLTAGE GE SOURCE AND CURRENT SOURCE INVERTERS... 5.35 5.7.1 Voltage Source Inverter (VSI)... 5.35 5.7.2 Current Source Inverter (CSI)... 5.35 5.8 COMPARISON OF VOL OLTAGE GE SOURCE INVERTER AND CURRENT SOURCE INVERTER... 5.36 5.9 ELEMENTAR ARY MULTI-LEVEL INVERTERS TERS... 5.37 5.9.1 Diode Clamped Multi-level Inverter (DCMI)... 5.38 5.9.1.1 Operation of Diode Clamped Multi-level Inverter...... 5.40 5.9.1.2 Features of Diode Clamped Multi Level inverter... 5.42 5.9.1.3 Advantages and Disadvantages of Diode Clamped Multi-Level Inverter... 5.43 5.9.2 Flying Capacitor Multi-Level Inverter (FCMLI)... 5.43 5.9.2.1 Operation of FCMLI... 5.45 5.9.2.2 Features of FCMLI... 5.46 5.9.2.3 Advantages and Disadvantages of (FCMLI)... 5.46 5.9.3 Cascaded Multi-Level Inverter (CMLI)... 5.47 5.9.3.1 Operation of Cascaded Multi-Level Inverter (CMLI)... 5.49 5.9.3.2 Features of Cascaded Multi-Level Inverter... 5.50 5.9.3.3 Advantages and Disadvantages of Cascaded Multi-Level Inverter (CMLI)... 5.50 EXPECTED UNIVERSITY QUESTIONS Expected University Questions with Answers... E.1 - E.8