Pow er Electronics
ower Electronics
Introduction
Dr Taosif Iqbal
taosifiqbal@gmail.com
Power Electronics Outline
I. What is power electronics?
II. The history
III. Applications
IV. A simple example
V. About this course
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Power Electronics I. What is power electronics?
1) Definition
2) Relation with information electronics
3) The interdisciplinary nature
4) Position and significance in the human society
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Power Electronics 1) Definition
Power Electronics:
is the electronics applied to convert and control the
electric power.
Range of power scale :
milliwatts(mW) megawatts(MW) gigawatts(GW)
A more exact explanation:
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.
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Power Electronics Conversion of electric power
Electric Other names for electric
Power Power Power
input output
power converter:
Converter -Power converter
-Converter
Control -Switching converter
input -Power electronic circuit
-Power electronic converter
Changeable properties in
Two types of electric power
conversion
DC(Direct Current) Magnitude
Frequency, magnitude,
AC (Alternating Current)
number of phases
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Power Electronics Classification of power converters
Power
Power
output
output
Power
Power DC AC
input
input
AC to AC converter
AC AC to DC converter ( Fixed frequency : AC controller
(Rectifier) Variable frequency: Cycloconverter
or frequency converter)
DC DC to DC converter DC to AC converter
(Chopper) (Inverter)
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Power Electronics Power electronic system
Generic structure of a power electronic system
Power Power Power
input output
Converter
Control input
Feedforward/Feedback Feedback/Feedforward
Controller
( measurements of input signals ) ( measurements of output signals )
Reference
(commanding)
Control is invariably required.
Power converter along with its controller including the
corresponding measurement and interface circuits, is
also called power electronic system.
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Typical power sources and loads
Power Electronics for a power electronic system
Power input Power Power output
Source Load
Vi ii Converter io Vo
-Electric utility -Electric Motor
Feedback/
-battery -light
-other electric energy source Feed forward
-power converter -heating
Controller -power converter
Reference -other electric or
electronic equipment
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.
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Power Electronics Relation with multiple disciplines
Systems & Signal
Control theory processing
Circuit
Simulation &
theory
computing
Electric Power
machines Electronics
electronics
Power Solid state
systems physics
Electromagnetics
N. Mohan etal. Power electronics: converter, applications, and Design. 3rd ed., John Wiley & Sons,
2003
Power electronics is currently the most active
discipline in electric power engineering worldwide.
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4) Position and significance
Power Electronics 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.
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Power Electronics II. The history
Application
Applica ion of
fast-
fast-switching
Invention of fully-
fully-controlled
Thyristor semiconductor
devices GTO
GTR IGBT
Mercury arc rectifier Power diode Power MOSFET Power MOSFET
Vacuum-
Vacuum-tube rectifier Thyristor Thyristor Thyristor
Thyratron (microprocessor) (DSP)
1900 1957 mid 1970s late 1980s
Pre-
Pre-history 1st phase 2nd phase 3rd phase
The thread of the power electronics history precisely
follows and matches the break-through and evolution
of power electronic devices
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Power Electronics III. Applications
Industrial
Transportation
Utility systems
Power supplies for all kinds of electronic equipment
Residential and home appliances
Space technology
Other applications
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Power Electronics Industrial applications
Motor drives
Electrolysis
Electroplating
Induction heating
Welding
Arc furnaces and ovens
Lighting
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Power Electronics Transportation applications
Trains & locomotives
Subways
Trolley buses
Magnetic levitation
Electric vehicles
Automotive electronics
Ship power systems
Aircraft power systems
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Power Electronics Utility systems applications
High-voltage dc
transmission(HVDC)
Flexible ac transmission(FACTS)
Static var compensation &
harmonics suppression: TCR,
TSC, SVG, APF
Custom power & power quality
control
Supplemental energy sources :
wind, photovoltaic, fuel cells
Energy storage systems
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Power Electronics Power supplies for electronic equipment
Telecommunications
Computers
computer
Office equipment server
Electronic instruments
Portable or mobile
electronics
Telecommunication
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Power Electronics Residential and home appliances
Lighting
Heating
Air conditioning
Refrigeration & freezers
Cooking
Cleaning
Entertaining
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Power Electronics Applications in space technology
Spaceship power systems
Satellite power systems
Space vehicle power
systems
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Power Electronics Other applications
Nuclear reactor control
Power systems for
particle accelerators
Environmental
engineering
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Power Electronics 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.
Power electronics has been making major
contributions to:
--better performance of power supplies and better control of
electric equipment
--energy saving
--environment protection
reduction of energy consumption leads to less pollution
reduction of pollution produced by power converters
direct applications to environment protection technology
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Power Electronics IV. A simple example
A simple dc-dc converter example
Input source:100V
Output load:50V, 10A, 500W
How can this converter be realized?
R. Erickson and D. Maksimovic. Fundamentals of Power electronics. Kluwer Academic Publishers,
2001
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Power Electronics Dissipative realization
Resistive voltage divider
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Power Electronics Dissipative realization
Series pass regulator:
transistor operates in active region
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Power Electronics Use of a SPDT switch
SPDT: Single pole double throw
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Power Electronics The switch changes the dc voltage level
D = switch duty cycle
Ts = switching period
fs = switching frequency = 1/ Ts
DC Component of Vg(t) = average value
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Power Electronics 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”
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Addition of control system for
Power Electronics regulation of output voltage
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Power Electronics 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
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