Power Electronics
By: Dr. Shahram Javadi
Department of Electrical Engineering
Sh.javadi@iauctb.ac.ir
By: Dr. Shahram Javadi
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Syllabus Outline
1. Introduction To Power Electronic
2.
3.
4.
5.
6.
7.
8.
9.
10.
Power Diodes
Diode Rectifiers
Thyristors
Control Rectifiers
AC Voltage Controllers
Thyristor Commutation Techniques
Power Transistors
DC to DC Choppers
DC to AC Inverters
By: Dr. Shahram Javadi
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•Text books: •Sources!!!
Muhammad H. Rashid
“Power Electronics”,3rd Edition,
Prentice Hall, 2004
By: Dr. Shahram Javadi
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COURSE EVALUATION
COURSE WORK
(Continuous Assessment)
10%
Assignment & Quiz
20%
FINAL EXAMINATION
TOTAL
By: Dr. Shahram Javadi
70%
100%
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Lecture 1: Introduction to Power Electronics
By: Dr. Shahram Javadi
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Power
 Electrical Power Generation
 Transmission
 Distribution
Electronics
 Deals with the study of power
semiconductor switching devices and their
V-I characteristics.
 Electronic circuits using these power
devices for power conversion and output
power control for Various applications.
By: Dr. Shahram Javadi
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History of Power Electronics




Mercury arc rectifier (year 1900).
Metal tank rectifier.
Grid controlled vacuum tube rectifier.
SCR (Silicon Controlled Rectifier)
• The 1st Thyristor developed by Bell labs in
1956.
• 1st Commercial grade SCR developed by
“ General Electric Co. “ in 1958.
By: Dr. Shahram Javadi
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Power Electronic Applications
Commercial Applications






Air conditioners
Central refrigeration.
UPS
Elevators
Emergency lamps
Heating systems
By: Dr. Shahram Javadi
Domestic Applications
 Cooking
equipments.
 Lighting & heating
 Air conditioners.
 Refrigerators.
 Freezers.
 Personal
Computers.
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Power Electronic Applications
Telecommunications
Transportation
 Battery chargers.
 Traction control of
electric vehicles.
 DC power supply & UPS
 Battery chargers for
 Mobile cell phone
electric vehicles.
battery chargers.
 Electric locomotives.
 Street cars & trolley
buses.
By: Dr. Shahram Javadi
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Power Electronic Applications
Utility Systems





High voltage DC transmissions (HVDC).
Static VAR compensation.
Fuel cells.
Energy storage systems
Boiler feed water systems.
By: Dr. Shahram Javadi
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Function of Power Electronics in Utility Applications
Converter
Source
Load
Controller
Enabling technology providing interface between two (ac/dc)
electrical systems
 E.g.
 Interconnection of two asynchronous ac systems
 dc to ac conversion is required to connect fuel cells or
photovoltaics to the utility grid
By: Dr. Shahram Javadi
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Listing of Power Electronic Applications
Distributed generation (DG)
 Renewable resources (wind and photovoltaic)
 Fuel cells and micro-turbines
 Storage: batteries, super-conducting magnetic energy
storage, flywheels
Power electronics loads: Adjustable speed drives
Power quality solutions
 Dual feeders
 Uninterruptible power supplies
 Dynamic voltage restorers
Transmission and distribution (T&D)
 High voltage dc (HVDC) and medium voltage dc
 Flexible AC Transmission Systems (FACTS): Shunt and
Series compensation, and the unified power flow
controller
By: Dr. Shahram Javadi
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Power Device Capabilities & Resulting Power Electronic Structures
Thyristor
IGCT
Power (VA)
108
106
By: Dr. Shahram Javadi
MOSFET
IGCT
IGBT
104
102
IGBT
Thyristor
Power Semiconductor Devices and their Capabilities
 Polarity of voltage blocked and direction of current conduction
 Switching speeds and power ratings
MOSFET
101 102 103 104
Switching Frequency (Hz)
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History
By: Dr. Shahram Javadi
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Structure of Power Electronic Systems
Voltage-Link Systems
 Transistors and diodes that
can block voltage of only
one polarity
AC1
AC2
Current-Link Systems
 higher power bipolar voltageblocking capabilities of
thyristors
Solid State Switches
 bidirectional voltage blocking
AC1
AC2
and current conduction
By: Dr. Shahram Javadi
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Role of Power Electronics in Important Utility Applications
Distributed Generation (DG) Applications Power electronic
interface depends on the source characteristics
Wound rotor
Induction Generator
Isolated
DC-DC
Converter
AC
Wind
Turbine
DC
DC
Generator-side
Converter
AC
Grid-side
Converter
Wind Power Generation with
Doubly Fed Induction Motors
By: Dr. Shahram Javadi
PWM
Converter
Max. Powerpoint Tracker
Utility
1f
Photo-voltaics Interface
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Role of Power Electronics in Important Utility Applications
Power Electronic Loads: Adjustable Speed Drives
Switch-mode
Converter
Utility
Motor
Rectifier
By: Dr. Shahram Javadi
Controller
20
Role of Power Electronics in Important Utility Applications
Power
•
•
•
•
Quality Solutions for
voltage distortion
unbalances
voltage sags and
swells
power outage
Power Electronic
Interface
Load
Dynamic Voltage Restorers (DVR)
Feeder 1
Rectifier
Load
Feeder 2
Dual Feeders
By: Dr. Shahram Javadi
Inverter
Filter
Critical
Load
Energy
Storage
Uninterruptible Power Supplies
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Role of Power Electronics in Important Utility Applications
Transmission and Distribution: DC Transmission
most flexible solution for connection of two ac systems
AC1
AC2
HVDC
By: Dr. Shahram Javadi
AC1
AC2
MVDC
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Role of Power Electronics in Important Utility Applications
Transmission and Distribution: Flexible AC Transmission Systems
(FACTS)
EE
P  1 2 sin 
X
Series Compensation
E2
E1
E1
I
E3
-
E3
+
E2
jX
Utility
STATCOM
Shunt
converter
Shunt Compensation
By: Dr. Shahram Javadi
Series
converter
Shunt and Series Compensation
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Power Devices
 Power diodes
 Metal-Oxide-Semiconductor Field-Effect
Transistor (MOSFET)
 Bipolar Junction Transistor (BJT)
 Insulated Gate Bipolar Transistor (IGBT)
 Thyristors (SCR, GTO, MCT)
By: Dr. Shahram Javadi
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By: Dr. Shahram Javadi
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Applications of Power Devices
By: Dr. Shahram Javadi
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Power Diode
By: Dr. Shahram Javadi
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Diode Characteristics
By: Dr. Shahram Javadi
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Comparison between different types of Diodes
General
Purpose Diodes
Fast Recovery
Diodes
Schottky Diodes
Upto 6000V &
3500A
Upto 6000V and
1100A
Upto 100V and
300A
Reverse recovery
time – High
Reverse recovery
time – Low
Reverse recovery
time – Extremely
low.
trr  0.1s to 5s
trr  a few nano sec
trr  25 s
By: Dr. Shahram Javadi
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Comparison between different types of Diodes
General
Purpose Diodes
Fast Recovery
Diodes
Schottky Diodes
Turn off time –
High
Turn off time –
Low
Turn off time –
Extremely low
Switching
frequency – Low
(Max 1KHz)
Switching
frequency – High
(Max 20KHz)
Switching
frequency – Very
high.
(Max 30KHz)
VF  0.7 to 1.2V
VF  0.8 to 1.5V
VF  0.4 to 0.6V
By: Dr. Shahram Javadi
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BJT
By: Dr. Shahram Javadi
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BJT Characteristics
By: Dr. Shahram Javadi
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BJT Switching Times
By: Dr. Shahram Javadi
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MOSFET
By: Dr. Shahram Javadi
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n-channel Enhancement MOSFET Characteristics
Linear
region
Saturation
region
VGS3
VGS2
ID
VGS1
Drain Characteristics
VDS
By: Dr. Shahram Javadi
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n-channel Depletion MOSFET
ID
D
G
VDS
+
VGS

By: Dr. Shahram Javadi
+
S

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Drain Characteristics
Linear
region
Saturation
region
VGS3
VGS2
ID
VGS1
VDS
By: Dr. Shahram Javadi
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Transfer Characteristics of MOSFET
IDSS
ID
VGS(OFF)
By: Dr. Shahram Javadi
VGS
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Switching Times of MOSFET
VG
V1
t
V1
VGSP
VT
td(on)
By: Dr. Shahram Javadi
tr
td(off) tf
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Semiconductor Cross-section of IGBT
By: Dr. Shahram Javadi
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IGBT
By: Dr. Shahram Javadi
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Characteristics of IGBT CM 400HA-24H
800
12
VGE=15V
Output collector characteristics
640
IC
AMPS
480
VGE=10V
320
VGE=9V
160
0
8
2
4
6
8
VGE=7V
10
VCE (Volts)
By: Dr. Shahram Javadi
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Transfer Characteristics of IGBT
800
VCE=10V
640
IC
AMPS
480
Tj=250C
320
Tj=1250C
160
0
VGE
2
4
8
6
VGE(TH)
By: Dr. Shahram Javadi
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12
14
IC Vs VGE Characteristics
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Advantages of IGBT






Combines the advantages of BJT & MOSFET
High input impedance like MOSFET
Voltage controlled device like MOSFET
Simple gate drive, Lower switching loss
Low on state conduction power loss like BJT
Higher current capability & higher switching
speed than a BJT. ( Switching speed lower
than MOSFET)
By: Dr. Shahram Javadi
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Applications of IGBT






ac and dc motor controls.
General purpose inverters.
Uninterrupted Power Supply (UPS).
Welding Equipments.
Numerical control, Cutting tools.
Robotics & Induction heating.
By: Dr. Shahram Javadi
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DEVICE SYMBOLS & CHARACTERISTICS
By: Dr. Shahram Javadi
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Control Characteristics of Power Devices
By: Dr. Shahram Javadi
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Control Characteristics of Power Devices
By: Dr. Shahram Javadi
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Control Characteristics of Power Devices
By: Dr. Shahram Javadi
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Control Characteristics of Power Devices
By: Dr. Shahram Javadi
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Comparison between different commonly used Thyristors
 Line Commutated Thyristors available
up to 6000V, 4500A.
 Ex: Converter grade (line
commutated) SCR.
 V / I rating: 5KV / 5000A
 Max. Frequency: 60Hz.
 Switching time: 100 to 400sec.
 On state resistance: 0.45m.
By: Dr. Shahram Javadi
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Example of Inverter Grade Thyristor Ratings




V / I rating: 4500V / 3000A.
Max. Frequency: 20KHz.
Switching time: 20 to 100sec.
On state resistance: 0.5m.
By: Dr. Shahram Javadi
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Example of Triac Ratings
 Used in heat / light control, ac motor
control circuit
 V / I rating: 1200V / 300A.
 Max. Frequency: 400Hz.
 Switching time: 200 to 400sec.
 On state resistance: 3.6m.
By: Dr. Shahram Javadi
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Example of Power Transistor Ratings
 PT ratings go up to 1200V / 400A.
 PT normally operated as a switch in
CE config.
 Max. Frequency: 400Hz.
 Switching time: 200 to 400sec.
 On state resistance: 3.6m.
By: Dr. Shahram Javadi
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Example of Power MOSFET Ratings
 Used in high speed power converters
like inverters & choppers.
 Ratings up to 1000V / 100A.
 Example: MOSFET 800V / 7.5A
rating.
 Max. Frequency: 100KHz.
 Switching time: 1.6sec.
 On state resistance: 1.2m.
By: Dr. Shahram Javadi
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Example of IGBT Ratings
 Used in high voltage / current & high
frequency switching power applications
(Inverters, SMPS).
 Example: IGBT 2500V / 2400A.
 Max. Frequency: 20KHz.
 Switching time: 5 to sec.
 On state resistance: 2.3m.
By: Dr. Shahram Javadi
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Switch applications
•
•
•
•
•
Single quadrant switches
Current-bidirectional two-quadrant switches
Voltage-bidirectional two-quadrant switch
Four-quadrant switches
Synchronous rectifiers
By: Dr. Shahram Javadi
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The types of restricted switches
By: Dr. Shahram Javadi
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Some basic switch applications
By: Dr. Shahram Javadi
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A) Single-quadrant switches
The diode
By: Dr. Shahram Javadi
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A) Single-quadrant switches
•
•
The Bipolar Junction Transistor (BJT) and
The Insulated Gate Bipolar Transistor (IGBT)
By: Dr. Shahram Javadi
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A) Single-quadrant switches
The Metal-Oxide Semiconductor Field Effect Transistor (MOSFET)
By: Dr. Shahram Javadi
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B) Current-bidirectional two-quadrant switches
By: Dr. Shahram Javadi
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B) Current-bidirectional two-quadrant switches
MOSFET body diode
By: Dr. Shahram Javadi
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C) Voltage-bidirectional two-quadrant switches
By: Dr. Shahram Javadi
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D) Four-quadrant switches
By: Dr. Shahram Javadi
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D) Three ways to realize a four-quadrant switch
By: Dr. Shahram Javadi
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E) Synchronous rectifiers
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Switches comparison
Device Type
Year
made
Rated
Voltage
Rated
Current
Switching
Frequency
Rated
Power
Drive
Circuit
Comments
SCR
1957
6kV
3.5kA
500Hz
100s MW
Simple
Cannot turn-off using
gate signal
GTO
1962
4.5kV
3kA
2kHz
10s MW
Very
Difficult
King in very high
power
BJT
1960s
1.2kV
400A
5kHz
1 MW
Difficult
Phasing out in new
product
MOSFET
1976
500V
200A
1MHz
100 kW
Very
Simple
Good performance in
high frequency
IGBT
1983
3.3kV
1.2kA
100kHz
100s kW
Very
Simple
Best overall
performance
By: Dr. Shahram Javadi
69
Different types of Power Converters
 Diode rectifiers (uncontrolled rectifiers).
 Line commutated converters or AC to DC
converters (controlled rectifiers).
 AC voltage (RMS voltage) controllers (AC to AC
converters).
 Cyclo-converters (AC to AC converters at low
output frequency).
 DC choppers (DC to DC converters).
 Inverters (DC to AC converters).
By: Dr. Shahram Javadi
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AC to DC Converter
+
AC
Input
Voltage
Line
Commutated
Converter
DC Output
V0(QC)
-
Type of input: AC supply (fixed voltage &
frequency)
Type of output: DC voltage (variable)
By: Dr. Shahram Javadi
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Single Phase Diode Rectifier Circuit
By: Dr. Shahram Javadi
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Single Phase Ac-Dc Converter
By: Dr. Shahram Javadi
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Applications
 Speed control of DC motor in DC
drives.
 UPS.
 HVDC transmission.
 Battery Chargers.
By: Dr. Shahram Javadi
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AC Voltage Regulators
V0(RMS)
AC
Input
Voltage
fs
Vs
fs
AC
Voltage
Controller
Variable AC
RMSO/P Voltage
fS
Type of input: AC supply (fixed voltage & frequency).
Type of output: Variable AC RMS O/P voltage.
By: Dr. Shahram Javadi
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Single Phase Ac-Ac Converter
By: Dr. Shahram Javadi
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Applications
 Speed control of ac motors.
 Speed control of fans (domestic and
industrial fans).
 AC pumps.
By: Dr. Shahram Javadi
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Cyclo Converters
V0 , f0
AC
Input
Voltage
Vs
fs
Cyclo
Converters
Variable Frequency
AC Output
f0< fS
Type of input: AC supply (fixed voltage &
frequency).
Type of output: Variable frequency ac O/P
voltage.
By: Dr. Shahram Javadi
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Applications
 Traction vehicles
 Gearless rotary kilns.
By: Dr. Shahram Javadi
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DC Choppers
+ V0(dc)
+
Vs
-
DC
Chopper
Variable DC
Output Voltage
-
Type of input: Fixed DC supply voltage.
Type of output: Variable DC voltage.
By: Dr. Shahram Javadi
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Dc-Dc Converter
By: Dr. Shahram Javadi
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Applications
 Speed control of DC motors from a
DC supply.
 DC drives for sub-urban traction.
 Switching power supplies.
By: Dr. Shahram Javadi
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Inverters
DC
Supply
+
-
Inverter
(Forced
Commutation)
AC
Output Voltage
Type of input: Fixed DC supply voltage.
Type of output: AC O/P voltage.
By: Dr. Shahram Javadi
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Single Phase Dc-Ac Converter
By: Dr. Shahram Javadi
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Applications
Industrial AC drives using induction
and synchronous motors.
 Uninterrupted power supplies (UPS
system) used for computers,
computer labs.

By: Dr. Shahram Javadi
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Peripheral Effects
By: Dr. Shahram Javadi
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Peripheral Effects
 Induced current and voltage
harmonic into supply system, and at
the output of the converters.
 Distortion in the output voltage.
 Unwanted electromagnetic radiation.
 Interference with communication
circuits.
By: Dr. Shahram Javadi
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