POWER-ELECTRONICS.ppt
- 1. Power 1 PART - A UNIT - 1 INTRODUCTION: Applications of power electronics, power semiconductor devices, control characteristics, types of power electronic circuits, peripheral effects, Power BJTs, switching characteristics, switching limits, base-drive control, introduction to IGBTs, isolation of gate and base drives. UNIT - 2 THYRISTORS: Introduction, characteristics, two transistor model, turn-on and turn off methods, di/dt and dv/dt protection, thyristor types, series and parallel operation of thyristors, thyristor firing circuits. 7 Hours UNIT - 3 COMMUTATION TECHNIQUES: Introduction, natural commutation, forced commutation: self-commutation,impulse commutation, resonant pulse commutation and complementary commutation. 6 Hours UNIT - 4 AC VOLTAGE CONTROLLERS: Introduction, principle of ON-OFF and phase control, single-phasebidirectional controllers with resistive and inductive loads. Single phase Transformer connection changers. Single phase Cycloconverter
- 2. Power 2 PART – B CONTROLLED RECTIFIERS: Introduction, principle of phase controlled converter operation, single-phase semi converters, full converters and dual converters. Principle of Three phase half wave converter. UNIT - 6 DC CHOPPERS: Introduction, principle of step-down operation, step-down chopper with RL loads, Principle of step-up operation, step-up chopper with Resistive load, performance parameters, Chopper classification (Class A to Class E). UNIT – 7 DC DRIVES: Introduction, Basic Characteristics of DC Motors, Operating modes, Single phase Drives. Stepper motor drive, Permanent Magnet stepper motors (bipolar and unipolar motor drive sequence) and Stepper Motor characteristics. UNIT - 8 INVERTERS: Introduction, principle of operation, performance parameters, single phase bridge inverters, Three phase inverters, voltage control of single phase inverters, current source inverter, variable DC link inverter,principles of switched mode power supply (SMPS).
- 3. Power 3 TEXT BOOK: 1. Power Electronics - M. H. Rashid, Prentice Hall of India Pvt. Ltd., (Pearson (Singapore -Asia)) New Delhi, 2002. REFERENCE BOOKS: 1. Power Electronics- M. D. Sing and Khanchandani K. B., Tata McGraw Hill Publishing Company Limited, Reprint 2001. 2. Power Electronics - Cyril W.Lander, 3 Edition, McGraw Hill, 1993. 3. Modern Power Electronics – P.C. Sen, 2 nd Edition S.Chand, 2000.
- 5. Power 5 Outline I. What is power electronics? II. The history III. Applications IV. A simple example V. About this course
- 6. Power 6 I. What is power electronics? 1) Definition 2) Relation with information electronics 3) The interdisciplinary nature 4) Position and significance in the human society
- 7. Power 7 Power Electronics: A more exact explanation: is the electronics applied to conversion and control of electric power. Range of power scale : milliwatts(mW) megawatts(MW) gigawatts(GW) 1) Definition The primary task of power electronics is to process and control the flow of electric energy by supplying voltages and currents in a form that is optimally suited for user loads.
- 8. Power 8 Conversion of electric power Other names for electric power converter: -Power converter -Converter -Switching converter -Power electronic circuit -Power electronic converter Electric Power Converter Power output Power input Control input Frequency, magnitude, number of phases AC (Alternating Current) Magnitude DC(Direct Current) Changeable properties in conversion Two types of electric power
- 9. Power 9 Classification of power converters DC AC AC AC to DC converter (Rectifier) AC to AC converter ( Fixed frequency : AC controller Variable frequency: Cycloconverter or frequency converter) DC DC to DC converter (Chopper) DC to AC converter (Inverter) Power output Power input
- 10. Power 10 Power electronic system Generic structure of a power electronic system Power Converter Power output Power input Controller Feedforward/Feedback Feedback/Feedforward Reference (commanding) ( measurements of output signals ) ( measurements of input signals ) Control is invariably required. Power converter along with its controller including the corresponding measurement and interface circuits, is also called power electronic system. Control input
- 11. Power 11 Typical power sources and loads for a power electronic system The task of power electronics has been recently extended to also ensuring the currents and power consumed by power converters and loads to meet the requirement of electric energy sources. -Electric Motor -light -heating -power converter -other electric or electronic equipment Power Converter Source Power input Power output Load Controller Reference -Electric utility -battery -other electric energy source -power converter Vi ii io Vo Feedback/ Feed forward
- 12. Power 12 A Classification of electronics by processing object 2) Relation with information electronics Electronics Information electronics: to process information Power electronics: to process electric power Other classifications of electronics Electronics Vacuum electronics: using vacuum devices, e.g, vacuum tubes devices Solid (Solid state) electronics: using solid state devices, e.g, semiconductor devices Electronics Applied electronics: application of electronic devices to various areas Physical electronics: physics,material,fabrication, and manufacturing of electronic devices
- 13. Power 13 3) The interdisciplinary nature William E. Newell’s description Electronics Power Power Electronics Continuous, discrete Control Power electronics is the interface between electronics and power.
- 14. Power 14 Relation with multiple disciplines Power electronics is currently the most active discipline in electric power engineering worldwide. Power electronics Systems & Control theory Circuit theory Signal processing Simulation & computing Electronics Solid state physics Electromagnetics Power systems Electric machines
- 15. Power 15 4) Position and significance in the human society Electric power is used in almost every aspect and everywhere of modern human society. Electric power is the major form of energy source used in modern human society. The objective of power electronics is exactly about how to use electric power, and how to use it effectively and efficiently, and how to improve the quality and utilization of electric power. Power electronics and information electronics make two poles of modern technology and human society—— information electronics is the brain,and power electronics is the muscle.
- 16. Power 16 II. The history The thread of the power electronics history precisely follows and matches the break-through and evolution of power electronic devices late 1980s mid 1970s 1957 1900 Mercury arc rectifier Vacuum-tube rectifier Thyratron Invention of Thyristor Power diode Thyristor Application of fast-switching fully-controlled semiconductor devices GTO GTR Power MOSFET Thyristor (microprocessor) IGBT Power MOSFET Thyristor (DSP) Pre-history 1st phase 2nd phase 3rd phase
- 17. Power 17 Trends It is estimated that in developed countries now 60% of the electric energy goes through some kind of power electronics converters before it is finally used. reduction of energy consumption leads to less pollution reduction of pollution produced by power converters direct applications to environment protection technology Power electronics has been making major contributions to: --better performance of power supplies and better control of electric equipment --energy saving --environment protection
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- 22. Power 22 IV. A simple example A simple dc-dc converter example Input source:100V Output load:50V, 10A, 500W How can this converter be realized?
- 24. Power 24 Dissipative realization Series pass regulator: transistor operates in active region
- 25. Power 25 Use of a SPDT switch SPDT: Single pole double throw
- 26. Power 26 The switch changes the dc voltage level
- 27. Power 27 Addition of low pass filter Addition of (ideally lossless) L-C low-pass filter, for removal of switching harmonics: Choose filter cutoff frequency f0 much smaller than switching frequency fs This circuit is known as the “buck converter”
- 28. Power 28 Addition of control system for regulation of output voltage
- 29. Power 29 Major issues in power electronics How to meet the requirement of the load or gain better control of the load How to improve the efficiency --for reliable operation of power semiconductor devices --for energy saving How to realize power conversion with less volume, less weight, and less cost How to reduce negative influence to other equipment in the electric power system and to the electromagnetic environment