This is the first lecture on power electronics. This lecture has been targeted to under-graduate students of electrical and electronics engineering.

1. Introduction to Power Electronics
(Lecture-1)
R S Ananda Murthy
Associate Professor and Head
Dept. of Electrical & Electronics Engineering,
Sri Jayachamarajendra College of Engineering,
Mysore 570 006
R S Ananda Murthy Introduction to Power Electronics

2. Fuel Shares of Primary Energy Supply
Oil 32.8 %
Coal
27.2 %
*Other 0.8 %
10.2 %
Biofuels
2.3 %
Hydro
5.8 %
Nuclear
Natural Gas
20.8 %
Hydro 1.4 %
Nuclear 0.7 %
Natural Gas
7.2 %
Oil 23.6 %
Biofuels 24.5 %
*Other 0.3 %
Coal
42.3 %
Source: International Energy Agency (IEA)
R S Ananda Murthy Introduction to Power Electronics

3. Graph of Depletion Function of Fuels
1900 1950 2000 2050 2100 2150 2200 2250 2300
Coal
Oil
Natural Gas
Uranium
0
EnergyProductioninJoules
1.2
1.0
0.8
0.6
0.4
0.2
x 10
18
Years
Depletion Function:
, , are constants
for a particular type of fuel.
R S Ananda Murthy Introduction to Power Electronics

4. Hazards Caused by Burning of Fossil Fuels
Ozone layer
depletion
Global warming
Combustion
of fossil fuels
Acid rain Photochemical
oxidants (Visibility)
Fine Inorganic
Particles
Health effects
Volatile Organic
Compounds
We need to reduce consumption of fossil fuels because it
causes environmental pollution and health hazards.
Therefore we have to harness energy needed for
development from other sustainable sources like solar and
wind.
R S Ananda Murthy Introduction to Power Electronics

5. Higher Energy Efficiency Saves Fuels
G
TurbineSteam
Power
Loss
%
Power
Left
%
65 35
100 %
2.5 34.1
1.2 33.7
Step-up
Voltage to
Transmission
Level
Step-down
Voltage to
Sub-transmission
Level
1.6 33.2
2.5 32.4
Step-down
Voltage to
Distribution
Level
IM
2.0 31.7
Switchgear
Induction Motor
Pump
12.0 27.9
40.0 16.7
Generator
Efficiency
Overall efficiency:
This shows that every kW
of output power saved
results in a saving of 6 kW
of fuel power at the
generating site.
R S Ananda Murthy Introduction to Power Electronics

6. What is Power Electronics?
Power electronics is the technology associated with
efficient conversion and control of electric power by using
power semiconductor devices.
Power electronics encompasses the use of electronic
components, the application of circuit theory and design
techniques, and the development of analytical tools toward
efficient electronic conversion, control, and conditioning of
electric power. — Definition given by IEEE Power
Electronics Society.
R S Ananda Murthy Introduction to Power Electronics

7. Goal of Power Electronics
Efficient conversion, conditioning, or processing and
control of electric power using solid-state semiconductor
devices in order to supply high quality power to the load
causing minimum pollution of environment and the utility
supply circuit.
R S Ananda Murthy Introduction to Power Electronics

8. Block Diagram of a Power Processor
Converter
Control Circuit
or
Triggering Circuit
Control
Signals
Reference
Feedforward
Feedback
Raw
Electrical
Power
Output
Electrical
Power
in the Form
Required by
Load
Converter has power switching semiconductor devices and
energy storing elements like inductors and capacitors.
Resistive elements are avoided in converters because they
cause power loss and reduce efficiency.
Controller switches on/off the switching devices present in
the converter.
R S Ananda Murthy Introduction to Power Electronics

9. 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 of
power conversion.
R S Ananda Murthy Introduction to Power Electronics

10. Types of Converters
Symbol
Rectifier
Input Output
A.C. at
constant voltage
and frequency
D.C. at
variable voltage
Inverter
D.C. at
constant voltage
A.C. at
desired voltage
and frequency
Chopper
D.C. at
constant voltage
D.C. at
desired voltage
Cycloconverter
A.C. at
constant voltage
and frequency
A.C. at
desired voltage
and frequency
A.C. Voltage
Controller
A.C. at
constant voltage
and frequency
A.C. at
desired voltage
and input frequency
Converter Type
ACVC
R S Ananda Murthy Introduction to Power Electronics

11. Power Electronics Vs Signal Processing
In Power Electronics —
The focus is on power conversion at the highest possible
efficiency using very small control signals.
Semiconductor devices work as switches.
Power handled may range from a few watts to several
mega-watts.
In Signal Processing —
Semiconductor devices generally work as controlled
sources in the linear region of their characteristics.
The focus is on information processing with minimum loss
of information.
Power handled will be of the order of few milli-watts or few
watts.
R S Ananda Murthy Introduction to Power Electronics

12. Multidisciplinary Nature of Power Electronics
Power
Electronics
Electrical
Machines
Power
Systems
Circuit
Theory
Solid State
Physics Signal
Processing
Systems and
Control Theory
Analog
Electronics
Digital
Electronics
Simulation and
Computing
Electromagnetics
Microcontrollers
R S Ananda Murthy Introduction to Power Electronics

13. Course Outline
1 Introduction to Power Electronics
2 Applications of Power Electronics
3 Power Semiconductor Devices
4 A.C. Voltage Controllers
5 Controlled Rectifiers
6 D.C.-to-D.C. Converters (Choppers)
7 Inverters
R S Ananda Murthy Introduction to Power Electronics

14. Suggested Books
M. H. Rashid, “Power Electronics: Circuits, Devices and
Applications”, 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 and
Applications”, Thomson Vikas Publications.
B. K. Bose, “Modern Power Electronics and A.C. Drives”,
Pearson Education, 2002.
R S Ananda Murthy Introduction to Power Electronics

15. Next Lecture...
In the next lecture we will describe some applications of power
electronics. This will help in recognizing the importance of
power electronics in real life and give motivation for studying
power electronics.
Thank You.
R S Ananda Murthy Introduction to Power Electronics