POWER ELECTRONICS. Alpha. Science International Ltd. S.C. Tripathy. Oxford, U.K.

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1 POWER ELECTRONICS S.C. Tripathy Alpha Science International Ltd. Oxford, U.K.

2 Contents Preface vii 1. SEMICONDUCTOR DIODE THEORY Introduction Charge Densities in a Doped Semiconductor Junction Diode Methods of Making Junctions General Purpose Power Diode Potential Barrier at Thermal Equilibrium Current Flow in Semi Conductor Diode No Applied Bias (VP > OV) Forward Bias Condition (VD > OV) Reverse Bias Condition (VD < OV) Zener Region Silicon Versus Germanium Temperature Effects Resistance Levels Diffusion Capacitance and Transition Capacitance Simplified Equivalent Circuit Zener Diode Light Emitting Diode (LED) 1.20 References POWER DIODES AND TRANSISTORS Introduction Power Diode Types Reverse Recovery Characteristic of Power Diode Bipolar Junction Transistor (BJT) Power Transistor Structure Terminal Connections Light and Other Radiation Principle of Bipolar Junction Transistor Operation Transistor Amplifying Action Steady-State Characteristics BJT as a Switch BJT Switching Performance V-I Characterstic of Power Transistor Switching Limits 2.22 References 2.23

3 X Contents DIODES RECTIFIERS Introduction Half-wave Rectifier Circuit Resistive Load Circuit RC Load Circuit RL Load Circuit Half-Wave Rectifier with RE Load 3.10 References 3.11 MOSFET AND IGBT Introduction Field Effect Transistor Types of Field Effect Transistors Depletion Type N-Channel MOSFET Structure V-I Characteristics Enhancement Type MOSFETS JFET and Depletion MOSFET Small Signal Model MOSFET Gate Protection Enhancement MOSFET Bias Circuits Power MOSFET Comparison of Power MOSFET With BJT Gate Drive Circuit For MOSFET IGBT (Insulated-Gate-Bipolar-Transistor) Basic Structure 4.15 References 4.16 PSPICE: SIMULATION SOFTWARE Introduction Circuit Description and Analysis Nodes Circuit Elements Element Values Format for Passive Elements Element Models Source Analysis Type 5.10 Output Variables PSPICE Output Commands Format on Output Files Loading on PC Signal Approximation Diode Model 5.8 References

4 Contents xi 6. THYRISTOR (SCR) Introduction Modes Of Operation SCR V-I Characteristics Two-Transistor Model of SCR Transient Condition SCR Ratings Switching Characteristic of SCR During Turn-On Method to Improve di/dt and dv/dt Ratings Snubber Circuit Electronic Crowbar Protection Gate Protection Heating and Cooling of SCR 6.24 References THYRISTOR FAMILY, TIMING AND OP-AMP CIRCUITS Introduction Shockley Diode Diac Triac BI-Directional SCR Light Activated Silicon Controlled Rectifier Gate Turn off Thyristor MOS Controlled Thyristor FET Controlled Thyristor Static Induction Thyristor Reverse Conducting Thyristor (RCT) Asymmetrical SCR (ASCR) Emitter Turn-Off Thyristor (ETO) Uni-Junction Transistor Programmable UJT (PUT) Silicon Controlled Switch Silicon Unilateral Switch Silicon Bilateral Switch Timer Operational Amplifier Op-Amp Characteristics Equivalent Circuit of Op-Amp Inverting Amplifier Logarithm and Exponential Amplifiers 7.30 References 7.31

5 Pulse) xii Contents 8. SERIES AND PARALLEL CONNECTION OF SCRs, THEIR GATE CHARACTERISTICS AND FIRING CIRCUITS Introduction Series Connection Dynamic Equalizing Circuit Parallel Connection of SCRs Gate Characteristics of SCRs Gate Circuit SCR Firing (Triggering) Circuits 8.17 References CONTROLLED RECTD7BERS Introduction Single Phase Half Wave Converter with R Load Single Phase Half Wave Converter with RL Load Mid-Point Full Wave Converter with RL Load Single Phase Two Pulse Converter with Discontinuous Load Current Dual Converter Multiphase Converters Three Phase Fully Controlled Converter with RLE-Load Three Phase Semieonverter Effect of Source Impedance on Converter Operation 9.33 References SCR COMMUTATION CIRCUITS Introduction Class A Commutation (Load Commutation) Class B Commutation (Resonant Class C Complementary Voltage Commutation Class D Impulse Commutation Class E External Pulse Commutation Class F Line Commutation Class G Current Commutation References AC VOLTAGE CONTROLLERS Introduction Phase-Angle Control Single-Phase Half-Wave Voltage Controller Single-Phase Full-Wave Voltage Controller with R Load Harmonic Analysis Single-phase Full-Wave Voltage Controller with RL Load Integral Cycle Control Sequence Control of AC Voltage Controller (Transformer Tap Changer) Three Phase Full-Wave Regulator References 11.21

6 Contents xiii 12. CYCLOCONVERTERS Introduction Basic Principle Practical Cycloconverter Circuits Step Up Cycloconverter (Single-Phase Mid Point Type) Step-Down Cycloconverter (Single Phase): R Load Step-Down Cycloconverter with RL Load Waveform for 3-phase to Single-Phase Half-Wave Cycloconverter Output Voltage (Three Phase to Single Phase Cycloconverter) Non-Circulating Current Scheme Bridge Type Cycloconverter Load-Commutated Cycloconverter Three-Phase to Three-Phase Converter Firing Angle Control by Cosine Modulating Signal References D.C. CHOPPER Introduction Principle of Step Down Chopper Operation Pulse Width Modulation (PWM) Step Up Chopper Step Down Chopper With RLE Load: (Transient Analysis) Step-Up/Step-Down Chopper Chopper Classification SCR Chopper Commutation Circuits Jones Chopper (Voltage Commutated Chopper) Morgan Chopper (Current Commutated Chopper) Load Commutated Chopper References INVERTERS Introduction Classification of Inverters Classification of SCR Based Inverters Single-Phase Half Bridge Voltage Source Inverters Performance Indices of Square-Wave Inverters Voltage Control of Single-Phase Inverter by PWM Principle of Operation of Three-Phase Inverters Comparison Between 120 and 180 Conduction Schemes Modified McMurrary Inverter Design of Commutation Circuit Modified McMurray Full-Bridge Single-Phase Inverter McMurrary Bedford Inverter Modified McMurrary-Bedford Inverter 14.45

7 Off XIV Contents Other Types of Inverters Current Source Inverter (CSI) Voltage and Frequency Control of Inverter References DC-DC SWITCH MODE REGULATORS, SM-POWER SUPPLIES, AND RESONANT PULSE CONVERTERS Introduction Buck Regulator (Step Down Regulator) Boost Regulator Buck-Boost Regulator Cuk Regulator Switch Mode Regulator with Isolation Isolated SMPS (Switch Mode Power Supply) Uninteruptible Power Supply - Line UPS Resonant Pulse Converters Zero-Voltage Switching Resonant Converter References SOLID-STATE MOTOR CONTROL AND ELECTRICAL DRIVES Introduction Application of Solid-State Controls Introduction to Rectifier Circuits DC Motor Drive Systems Three Phase Full Converter Fed DC Drive Three Phase Dual Converter DC Drive Choppers Power Electronic Control of AC Drive Starting Methods of Induction Motor Thyristorised Starting Speed Control Voltage Control by Power Electronic Method Additional Methods of Speed Control for Induction Motors Speed Control of Induction Motors Using Static Rotor-Resistance Control Inverters Slip-Power Recovery Schemes Synchronous Motor Drives References Appendix A: Probable Values of General Physical Constants Appendix B: Symbols of Power Semiconductor Devices B. 1 Appendix C: Multiple Choice Questions C. 1 A.l Index l.l

VALLIAMMAI ENGINEERING COLLEGE DEPARTMENT OF ELECTRONICS AND INSTRUMENTATION

VALLIAMMAI ENGINEERING COLLEGE DEPARTMENT OF ELECTRONICS AND INSTRUMENTATION Sem / Branch : V /EIE Subject code /Title: EI2301/Industrial Electronics UNIT-1 POWER DEVICES 1. What are the different methods