Introduction to Power Electronics lecture1
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This document outlines the syllabus for an Advanced Power Electronics course taught by Dr. Kamal Ramadan at Misruta University. The syllabus covers topics including 3-phase converters, inverters, DC choppers, cycloconverters, and applications of power electronics. It also provides the course evaluation breakdown, textbook information, and contact details for the instructor. Power electronics concepts are introduced, including the goals of power electronics systems, static and drive applications, and common power electronics converters. An overview of current issues in power electronics like renewable energy and the environment is presented.
Introduction to Power Electronics lecture1
- 1. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 1 Misruta University Faculty of Engineering Electrical & Electronic Engineering Dept. M.Sc. Program EE627 Advanced Power Electronics Lecture 1 General Introduction 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 1 Syllabus: 1. Converters: 3-phase full-wave controlled bridge converter operation, load side, supply side quantities, i/p power factor, shunt capacitor compensation, inverter mode operation- single phase rectifiers with motor load 1. Fully controlled rectifier drives Operation, 3-phase rectifiers with freewheeling and regeneration. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 2
- 2. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 2 3. Inverters: 3-phase step-wave 5. Inverters circuits: Skelton inverter circuit, operation, modes of operation, analysis, and measurement of harmonic distortion 6. 3-Phase pulse width modulation 7. Controlled Inverter Circuits Sinusoidal pulse width modulation, pwm voltage waveforms applied to balanced 3-phase resistive & inductive load. Syllabus cont.: 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 3 8. DC choppers Drives: Class A chopper, class B chopper, class C two quadrant operation chopper, class D chopper, class E four quadrant chopper. 9. Cycloconverters: single phase, phase-controlled dual cycloconverter 10 Power Electronics applications: Facts devices, SVC, Tcsc, Multilevel inverters, switched mode power supplies. Syllabus cont.: 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 4
- 3. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 3 PercentageComponent Evaluation 60Final exam Course Works 40 15Midterm 1 15Midterm 2 10Assignments 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 5 Grading Instructor: Dr. Kamal Ramadan Email: amalramadan8@gmail.com Office hours: Mon 3:00 - 4:00 pm Textbook: Erickson and Maksimovic, Fundamentals of Power Electronics, second edition, Springer, ISBN 0-7923-7270-0. Denis Fewson; Introduction to Power Electronics; London 9 Sydney ~ Auckland; Co-published in the USA by Oxford University Press, Inc., New York 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 6
- 4. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 4 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 7 INTRODUCTION TO POWER ELECTRONICS SYSTEMS 1.Definition of Power Electronics DEFINITION: To convert, i.e to process and control the flow of electric power by supplying voltages and currents in a form that is optimally suited for user loads. 1.1 Introduction to Power Processing DC-DC conversion: Change and control voltage magnitude AC-DC rectification: Possibly control dc voltage, ac current DC-AC inversion: Produce sinusoid of controllable magnitude and frequency AC-AC cycloconversion: Change and control voltage magnitude and frequency 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 8
- 5. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 5 Control is invariably required 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 9 High efficiency is essential • High efficiency leads to low power loss within converter • Small size and reliable operation is then feasible • Efficiency is a good measure of converter performance 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 10
- 6. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 6 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 11 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 12
- 7. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 7 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 13 Rating Vs Applications 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 14
- 8. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 8 Basic block diagram Building Blocks: – Input Power, Output Power – Power Processor – Controller17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 15 2. Power Electronics (PE) Systems Goals: To convert electrical energy from one form to another,(i.e. from the source to load) with: – highest efficiency, – highest availability – highest reliability – lowest cost, – smallest size – least weight. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 16
- 9. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 9 3. Static applications Involves non-rotating or moving mechanical components. Examples: DC Power supply, Un-interruptible power supply, Power generation and transmission (HVDC), Electroplating, Welding, Heating, Cooling, Electronic ballast 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 17 4. Drive applications Intimately contains moving or rotating components such as motors. Examples: Electric trains, Electric vehicles, Air-conditioning System, Pumps, Compressor, Conveyer Belt (Factory automation). 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 18
- 10. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 10 Application examples Static Application: DC Power Supply 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 19 Drive Application: Air-Conditioning System 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 20
- 11. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 11 5. Power Electronics Converters AC to DC: RECTIFIER DC to DC: CHOPPER DC to AC: INVERTER 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 21 6. Current PE issues a. Energy scenario Need to reduce dependence on fossil fuel: – coal, natural gas, oil, and nuclear power resource. Depletion of these sources is expected. Tap renewable energy resources: – solar, wind, fuel-cell, ocean-wave Energy saving by PE applications, examples: – Variable speed compressor air-conditioning system: 30% savings compared to thermostat-controlled system.17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 22
- 12. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 12 – Lighting using electronics ballast boost efficiency of fluorescent lamp by 20%. b. Environment issues Nuclear safety. – Nuclear plants remain radioactive for thousands of years. Burning of fossil fuel – emits gases such as CO2, CO (oil burning), SO2, NOX (coal burning) etc. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 23 – Creates global warming (green house effect), acid rain and urban pollution from smokes. Possible Solutions by application of PE. Examples: – Renewable energy resources. – Centralization of power stations to remote non-urban area. (mitigation). – Electric vehicles. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 24
- 13. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 13 7. PE growth PE rapid growth due to: – Advances in power (semiconductor) switches – Advances in microelectronics (DSP, VLSI, microprocessor/microcontroller) – New ideas in control algorithms – Demand for new applications PE is an interdisciplinary field: – Digital/analogue electronics – Power and energy – Microelectronics 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 25 – Control system – Computer, simulation and software – Solid-state physics and devices – Packaging – Heat transfer 8. Power semiconductor devices (Power switches): Power switches: work-horses of PE systems. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 26
- 14. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 14 Operates in two states: – Fully on. i.e. switch closed. Conducting state – Fully off , i.e. switch opened. Blocking state Power switch never operates in linear mode. Can be categorised into three groups: 1. Uncontrolled: Diode 2. Semi-controlled: Thyristor (SCR). 3. Fully controlled: Power transistors: e.g. BJT, MOSFET, IGBT, GTO, IGCT17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 27 Photos of Power Switches 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 28
- 15. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 15 9. Power Diode When diode is forward biased, it conducts current with a small forward voltage (Vf) across it (0.2-3V) When reversed (or blocking state), a negligibly small leakage current (A to mA) flows until the reverse breakdown occurs. Diode should not be operated at reverse voltage greater than Vr17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 29 Reverse Recovery When a diode is switched quickly from forward to reverse bias, it continues to conduct due to the minority carriers which remains in the p-n junction. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 30
- 16. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 16 When reversed (or blocking state), a negligibly small leakage current (A to mA) flows until the reverse breakdown occurs. Diode should not be operated at reverse voltage greater than VR 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 31 Softness factor, Sr This factor given by: o r tt tt S 1 12 For Snap-off: Sr=0.3 For Soft-off: Sr=0.817/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 32
- 17. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 17 10. Types of Power Diodes a. Line frequency diode (general purpose): • On state voltage: very low (below 1V) • Large trr (about 25 s) (very slow response) • Very high current ratings (up to 5kA) • Very high voltage ratings(5kV) •Used in line-frequency (50/60Hz) applications such as rectifiers 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 33 b. Fast Recovery Diode • Very low trr (< 1 s). • Power levels at several hundred volts and several hundred amps • Normally used in high frequency circuits c. Schottky Diode • Very low forward voltage drop (typical 0.3V) • Limited blocking voltage (50-100V) • Used in low voltage, high current application such as switched mode power supplies. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 34
- 18. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 18 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 35 11. Thyristor (SCR) 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 36
- 19. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 19 If the forward break-over voltage (Vbo) is exceeded, then SCR “self-triggers” into the conducting state. The presence of gate current will reduce Vbo. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 37 “Normal” conditions for thyristors to turn on: – the device is in forward blocking state (i.e Vak is positive) – a positive gate current (Ig) is applied at the gate Once conducting, the anode current is latched. Vak collapses to normal forward volt-drop, typically 1.5-3V. In reverse -biased mode, the SCR behaves like a diode.17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 38
- 20. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 20 Thyristor Conduction Thyristor cannot be turned off by applying negative gate current. It can only be turned off if Ia goes negative (reverse) This happens when negative portion of the of sine-wave occurs (natural commutation),17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 39 Another method of turning off is known as “forced commutation”, The anode current is “diverted” to another circuitry. Types of Thyristors a. Phase controlled – rectifying line frequency voltage and current for ac and dc motor drives – large voltage (up to 7 kV) and current (up to 4 kA) capability – low on-state voltage drop (1.5 to 3V)17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 40
- 21. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 21 b. Inverter grade – used in inverter and chopper. – quite fast. Can be turned-on using “force-commutation” method. c. Light activated – Similar to phase controlled, but triggered by pulse of light. – Normally very high power ratings d. Triac – Dual polarity thyristors 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 41 12. Controllable switches (Power Transistors) Can be turned “ON” and “OFF” by relatively very small control signals. Operated in SATURATION and CUT-OFF modes only. No “linear region” operation is allowed due to excessive power loss. In general, power transistors do not operate in latched mode. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 42
- 22. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 22 Traditional devices: Bipolar Junction Transistors (BJT), Metal Oxide Silicon Field Effect Transistor ( MOSFET), Insulated Gate Bipolar transistors (IGBT), Gate turn-off Thyristors (GTO) Emerging (new) devices: Gate Controlled Thyristors (GCT). 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 43 13. Bipolar Junction Transistor (BJT) 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 44
- 23. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 23 Ratings: Voltage: VCE < 1000, Current: IC <400A. Switching frequency up to 5 kHz. Low on-state voltage: VCE(sat) : 2-3V Low current gain ( < 10): Need high base current to obtain reasonable IC . Expensive and complex base drive circuit. Hence not popular in new products. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 45 14. BJT Darlington Pair Normally used when higher current gain is required17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 46
- 24. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 24 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 47 15. Metal Oxide Silicon Field Effect Transistor (MOSFET) 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 48
- 25. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 25 Ratings: Voltage VDS<500V, current IDS<300A. Frequency f >100 kHz. For some low power devices (few hundred watts) may go up to MHz range. Turning on and off is very simple. – To turn on: VGS =+15V – To turn off: VGS =0 V Gate drive circuit is simple 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 49 16. MOSFET characteristics Basically low voltage device. High voltage device are available up to 600V but with limited current. Can be paralleled quite easily for higher current capability. Internal (dynamic) resistance between drain and source during on state, RDS(ON) , limits the power handling capability of MOSFET. High losses especially for high voltage device due to RDS(ON) . 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 50
- 26. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 26 Dominant in high frequency application (>100kHz). Biggest application is in switched-mode power supplies. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 51 JFET – Junction Field Effect Transistor MOSFET -Metal Oxide Semiconductor Field Effect Transistor n-channel MOSFET (nMOS) & p-channel MOSFET (pMOS) The MOS Transistor 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 52 n+n+ p-substrate Field-Oxide (SiO2) p+ stopper Polysilicon Gate Oxide DrainSource Gate Bulk Contact CROSS-SECTION of NMOS Transistor
- 27. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 27 MOS transistors Symbols 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 53 D S G D S G G S D D S G NMOS Enhancement NMOS PMOS Depletion Enhancement B NMOS with Bulk Contact Channel 17. Insulated Gate Bipolar Transistor (IGBT) 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 54
- 28. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 28 Combination of BJT and MOSFET characteristics. – Gate behaviour similar to MOSFET - easy to turn on and off. – Low losses like BJT due to low on-state Collector-Emitter voltage (2-3V). Ratings: Voltage: VCE<3.3kV, Current,: IC<1.2kA currently available. Latest: HVIGBT 4.5kV/1.2kA. Switching frequency up to 100kHz. Typical applications: 20-50kHz. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 55 18. Gate turn-off Thyristor (GTO) Behave like normal Thyristor, but can be turned off using gate signal17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 56
- 29. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 29 However turning off is difficult. Need very large reverse gate current (normally 1/5 of anode current). Gate drive design is very difficult due to very large reverse gate current at turn off. Ratings: Highest power ratings switch: Voltage: Vak<5kV; Current: Ia<5kA. Frequency<5kHz. Very stiff competition: Low end-from IGBT. High end from IGCT 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 57 19. Insulated Gate-Commutated Thyristor (IGCT) Among the latest Power Switches. Conducts like normal thyristor (latching), but can be turned off using gate signal, similar to IGBT turn off; 20V is sufficient. 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 58
- 30. 17/03/2014 Dr. Kamal Ramadan; University of Misruta 30 Power switch is integrated with the gate-drive unit. Ratings: Voltage: Vak < 6.5kV; Current: Ia < 4 kA. Frequency < 1 kHz. Currently 10kV device is being developed. Very low on state voltage: 2.7V for 4 kA device 17/03/2014 Dr. Kamal Ramadan; Misruta University, 2014 59