Lecture-1 : Introduction to Power Electronics

Introduction to Power Electronics(Lecture-1)

R S Ananda Murthy

Associate Professor and HeadDept. of Electrical & Electronics Engineering,

Sri Jayachamarajendra College of Engineering,Mysore 570 006

R S Ananda Murthy Introduction to Power Electronics

Fuel Shares of Primary Energy Supply

Oil 32.8 %

Coal27.2 %

*Other 0.8 %

10.2 %Biofuels

2.3 %Hydro

5.8 %Nuclear

Natural Gas20.8 %

Hydro 1.4 %Nuclear 0.7 %

Natural Gas7.2 %

Oil 23.6 %

Biofuels 24.5 %*Other 0.3 %

Coal42.3 %

Source: International Energy Agency (IEA)


Graph of Depletion Function of Fuels

1900 1950 2000 2050 2100 2150 2200 2250 2300

Coal

OilNatural Gas

Uranium0

Ene

rgy

Pro

duct

ion

in J

oule

s1.2

1.0

0.8

0.6

0.4

0.2

x 1018

Years

Depletion Function:

, , are constantsfor a particular type of fuel.


Hazards Caused by Burning of Fossil Fuels

Ozone layerdepletion

Global warmingCombustionof fossil fuels

Acid rain Photochemicaloxidants (Visibility)

Fine InorganicParticles

Health effects

Volatile OrganicCompounds

We need to reduce consumption of fossil fuels because itcauses environmental pollution and health hazards.Therefore we have to harness energy needed fordevelopment from other sustainable sources like solar andwind.


Higher Energy Efficiency Saves Fuels

G

TurbineSteam

PowerLoss

%

PowerLeft%

65 35

100 %

2.5 34.1

1.2 33.7

Step-upVoltage to

TransmissionLevel

Step-downVoltage to

Sub-transmissionLevel

1.6 33.2

2.5 32.4

Step-downVoltage toDistribution

Level

IM

2.0 31.7Switchgear

Induction Motor

Pump

12.0 27.9

40.0 16.7

Generator

Efficiency

Overall efficiency:

This shows that every kWof output power savedresults in a saving of 6 kWof fuel power at thegenerating site.


What is Power Electronics?

Power electronics is the technology associated withefficient conversion and control of electric power by usingpower semiconductor devices.Power electronics encompasses the use of electroniccomponents, the application of circuit theory and designtechniques, and the development of analytical tools towardefficient electronic conversion, control, and conditioning ofelectric power. — Definition given by IEEE PowerElectronics Society.


Goal of Power Electronics

Efficient conversion, conditioning, or processing andcontrol of electric power using solid-state semiconductordevices in order to supply high quality power to the loadcausing minimum pollution of environment and the utilitysupply circuit.


Block Diagram of a Power Processor

Converter

Control Circuitor

Triggering Circuit

ControlSignals

Reference

Feedforward

Feedback

RawElectrical

Power

OutputElectrical

Powerin the FormRequired by

Load

Converter has power switching semiconductor devices andenergy storing elements like inductors and capacitors.Resistive elements are avoided in converters because theycause power loss and reduce efficiency.Controller switches on/off the switching devices present inthe converter.


Example of a Power Processor

Converter 1

Controller Controller

Converter 2

A.C. supply

fixed voltage

at 50 Hz

or 60 Hz

A.C. supply

variable voltage

and frequency

A.C.

motor

−

+

Power processor

CD.C.

A.C. A.C.

A power processor may have more than one stage ofpower conversion.


Types of Converters

Symbol

Rectifier

Input Output

A.C. atconstant voltageand frequency

D.C. atvariable voltage

InverterD.C. at

constant voltage

A.C. atdesired voltageand frequency

ChopperD.C. at

constant voltageD.C. at

desired voltage

CycloconverterA.C. at

constant voltageand frequency

A.C. atdesired voltageand frequency

A.C. VoltageController

A.C. atconstant voltageand frequency

A.C. atdesired voltage

and input frequency

Converter Type

ACVC


Power Electronics Vs Signal Processing

In Power Electronics —The focus is on power conversion at the highest possibleefficiency using very small control signals.Semiconductor devices work as switches.Power handled may range from a few watts to severalmega-watts.

In Signal Processing —Semiconductor devices generally work as controlledsources in the linear region of their characteristics.The focus is on information processing with minimum lossof information.Power handled will be of the order of few milli-watts or fewwatts.


Multidisciplinary Nature of Power Electronics

PowerElectronics

ElectricalMachines

PowerSystems

CircuitTheory

Solid StatePhysics Signal

Processing

Systems andControl Theory

AnalogElectronics

DigitalElectronics

Simulation andComputing

Electromagnetics

Microcontrollers


Course Outline

1 Introduction to Power Electronics2 Applications of Power Electronics3 Power Semiconductor Devices4 A.C. Voltage Controllers5 Controlled Rectifiers6 D.C.-to-D.C. Converters (Choppers)7 Inverters


Suggested Books

M. H. Rashid, “Power Electronics: Circuits, Devices andApplications”, 3 Edition, Pearson, 2003.Ned Mohan, Tore M. Undeland, and Willium P. Robbins,“Power Electronics: Converters, Applications, and Design”,John Wiley, 3rd Edition.Cyril W. Lander,“Power Electronics : Principles andApplications”, Thomson Vikas Publications.B. K. Bose, “Modern Power Electronics and A.C. Drives”,Pearson Education, 2002.


Next Lecture...

In the next lecture we will describe some applications of powerelectronics. This will help in recognizing the importance of

power electronics in real life and give motivation for studyingpower electronics.

Thank You.


Lecture-1 : Introduction to Power Electronics

Technology

Transcript of Lecture-1 : Introduction to Power Electronics