AC
V s i s
D
1
D
4
D
3 i o
R
L v o
D
2

Y = y(t)
Y ave

1
T
T

0 y ( t ) dt
Y rms




T
1
T

0 y ( t )
2 dt


 1 / 2

1. Gopal K.Dubey :
Fundamental of Electrical Drives
,
2 nd Edition, Alpha Science, 2001
2. Rahid H. Muhammad :
Power Electronics-Devices,
Circuits and Applications
, 3 rd Edition, Pearson-Prentice
Hall, 2004
3. Subrahmanyam Vedam :
Electric Drives
,
Concepts and
Application
, Tata McGraw-Hill, 2001

•
•
•
•
•

?
DEFINITION
:
Power Electronics combine :
Power static and rotating power equipment for generation, transmission and distribution of electric power
Electronics solid state devices and circuit for signal processing to meet the desired control objectives
Control steady state and dynamic characteristics of closed-loop system
Power Electronics : the applications of solid-state electronics for the control and conversion of electric power.

Industrial electronics can be defined as the control of industrial machinery and processes through the use of electronic circuits and systems

POWER
Control
Analog / Digital
Electronics
Devices /
Circuit
Power
Equipment
Static / Rotating
ELECTRONICS
Relationship of PE to power, electronics and control

:
To convert or to process and control the flow of electric power by supplying voltages and currents in a form that is optimally suited for user loads
Basic Block Diagram
Power
Input
Source
Power
Output
V i
, i i Power
Processor
V o
, i o
Load
Building Blocks :
•Input Power, Output Power
 Power Processor
 Contoller
Conroller measurement reference

The goal of PE is to control the flow of energy from an electrical source to an electrical load with :
high efficiency
high availability
high reliability
small size
light (least) weight
low cost
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 .

Static Application : DC Power Supply
Drive Application : Air-Conditioning System

example
• Supply from TNB: 50Hz, 240V RMS
(340V peak). Customer need DC voltage for welding purpose, say.
• TNB sine-wave supply gives zero DC component!
• We can use simple half-wave rectifier.
A fixed DC voltage is now obtained.
This is a simple PE system.
Average output voltage :
V o

V m


How if customer wants variable DC voltage?
More complex circuit using SCR is required .
Average output voltage :
By controlling the firing angle α, the output DC voltage (after conversion) can be varied.
Obviously this needs a complicated electronic system to set the firing current pulses for the SCR.

PE rapid growth due to:
 Advances in power (semiconductor) switches
 Advances in microelectronics (DSP,VLSI, microprocessor/microcontroller, ASIC)
 New ideas in control algorithms
 Demand for new applications

 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% saving compared to thermostat-controlled system.
- Lighting using electronics ballast boost efficiency of fluorescent lamp by 20%.

2. Environtment issues
 Nuclear safety : nuclear plant remain radioactive for thousands of years.
 Burning of fossil fuel
- Emits gases such as SO
2
(coal burning), etc
, CO (oil burning), SO
2
, NO x
- Create global warming (green house effect), acid rain and urban pollution from smokes.
 Possible Solution by application of PE . Examples:
- Renewable energy resources
- Centralization of power stations to remote non-urban area (mitigation)
- Electric vehicles

Conversion scheme from electric to electric by static switch control information
INPUT
POWER
POWER
PROCESSOR
PROCESSED
OUTPUT
POWER dc-ac conv.
dc-dc conversion ac-dc conv.
ac-ac conversion

AC input DC output
DC CHOPPER : DC-DC Converter
DC input
DC output
INVERTER : DC-AC Converter
DC input AC output

Power Semiconductor devices
(Power Switches)
Power switches: work-horses of PE systems.
Power switch
Operates in two states :
– Fully on. i.e.
switch closed.
– Conducting state
Switch ON (fully closed)
– Fully off , i.e.
switch opened.
– Blocking state
Power switch never operates in linear mode.
Switch OFF (fully opened)
Can be categorised into three groups:
– Uncontrolled: Diode :
– Semi-controlled: Thyristor (SCR).
– Fully controlled: Power transistors: e.g. BJT,
MOSFET, IGBT, GTO, IGCT

WHY POWER ELECTRONICS IS SO IMPORTANT TODAY?

ELECTRICAL POWER CONVERSION AND CONTROL AT HIGH
EFFICIENCY

APPARATUS AT LOW COST, SMALL SIZE, HIGH RELIABILITY AND
LONG LIFE

VERY IMPORTANT ELEMENT IN MODERN ELECTRICAL POWER
PROCESSING AND INDUSTRIAL PROCESS CONTROL

FAST GROWTH IN GLOBAL ENERGY CONSUMPTION

ENVIRONMENTAL AND SAFETY PROBLEMS BY FOSSIL AND
NUCLEAR POWER PLANTS

INCREASING EMPHASIS OF ENERGY SAVING AND POLLUTION
CONTROL BY POWER ELECTRONICS

GROWTH OF ENVIRONMENTALLY CLEAN SOURCES OF POWER
THAT ARE POWER ELECTRONICS INTENSIVE (WIND,
PHOTOVOLTAIC AND FUEL CELLS)
Fig.3

POWER
ELECTRIC
SYSTEMS
DC AND AC REGULATED POWER SUPPLIES
ELECTRO CHEMICAL PROCESSES
HEATING AND LIGHTING CONTROL
ELECTRONIC WELDING
POWER LINE VAR AND HARMONIC COMPENSATION
HIGH VOLTAGE DC SYSTEM
PHOTOVOLTAIC AND FUEL CELL CONVERSION
VARIABLE SPEED CONSTANT FREQUENCY SYSTEM
SOLID STATE CIRCUIT BREAKER
INDUCTION HEATING
MOTOR DRIVES
POWER ELECTRONICS APPLICATIONS
Fig.4

POWER ELECTRONICS IN ENERGY SAVING

CONTROL OF POWER BY ELECTRONIC SWITCHING IS MORE EFFICIENT
THAN RHEOSTATIC CONTROL

ROUGHLY 65% OF GENERATED ENERGY IS CONSUMED IN ELECTRICAL
DRIVES – MAINLY PUMPS AND FANS

VARIABLE SPEED FULL THROTTLE FLOW CONTROL CAN IMPROVE
EFFICIENCY BY 30% AT LIGHT LOAD

LIGHT LOAD REDUCED FLUX OPERATION CAN FURTHER IMPROVE
EFFICIENCY

VARIABLE SPEED AIR-CONDITIONER/HEAT PUMP CAN SAVE ENERGY BY
30%

20% OF GENERATED ENERGY IS USED IN LIGHTING

HIGH FREQUENCY FLUORESCENT LAMPS ARE 2-3 TIMES MORE EFFICIENT
THAN INCANDESCENT LAMPS
Fig.5

WIND ENERGY SCENARIO
 MOST ECONOMICAL, ENVIRONMENTALLY CLEAN AND SAFE “GREEN”
POWER

ENORMOUS WORLD RESOURCES – TAPPING 10% CAN SUPPLY ELECTRICITY
DEMAND OF THE WHOLE WORLD

COMPETETIVE COST WITH FOSSIL FUEL POWER (5 Cents/kWH, $1.00/kW)

TECHNOLOGY ADVANCEMENT IN POWER ELECTRONICS, VARIABLE SPEED
DRIVES AND VARIABLE SPEED WIND TURBINES

GERMANY IS THE WORLD LEADER ( MW) – NEXT IS USA (2600 MW)

CURRENTLY, 1.0% ELECTRICITY NEED IN USA – WILL INCREASE TO 5% BY
2020

CURRENTLY, 13% ELECTRICITY NEED IN DENMARK – WILL INCREASE TO
40% BY 2030

STATISTICAL AVAILABILITY – NEEDS BACK-UP POWER

KEY ENERGY SOURCE FOR FUTURE HYDROGEN ECONOMY
Fig.6

PHOTOVOLTAIC ENERGY SCENARIO

SAFE, RELIABLE, STATIC AND ENVIRONMENTALLY CLEAN

DOES NOT REQUIRE REPAIR AND MAINTENANCE

PV PANELS ARE EXPENSIVE
(CURRENTLY AROUND $5.00/W, 20
CENTS/kWH)

SOLAR POWER CONVERSION EFFICIENCY – AROUND 16%

APPLICATIONS:
SPACE POWER
ROOF TOP INSTALLATIONS
OFF-GRID REMOTE APPLICATIONS

SPORADIC AVAILABILITY –REQUIRES BACK-UP POWER

CURRENT INSTALLATION (290 MW):
JAPAN – 45%
USA – 26%
EUROPE – 21%

TREMENDOUS EMPHASIS ON TEC HNOLOGY ADVANCEMENT
Fig.7

FUEL CELL POWER SCENARIO

HYDROGEN AND OXYGEN COMBINE TO PRODUCE ELECTRICITY AND WATER

SAFE, STATIC, HIGH EFFICIENCY AND ENVIRONMENTALLY CLEAN

FUEL CELL TYPES:
PROTON EXCHANGE MEMBRANE (PEMFC)
PHOSPHORIC ACID (PAFC)
DIRECT METHANEL (DMFC)
MOLTEN CARBONATE (MCFC)
SOLID OXIDE (SOFC)

GENERATE HYDROGEN BY ELECTROLYSIS OR BY REFORMER (FROM GASOLINE,
METHANOL)

BULKY AND VERY EXPENSIVE AT PRESENT STATE OF TECHNOLOGY

SLOW RESPONSE

POSSIBLE APPLICATIONS:
FUEL CELL CAR, PORTABLE POWER, BUILDING COGENERATION, DISTRIBUTED
POWER FOR UTILITY, UPS SYSTEM

A LOT OF FUTURE PROMISE
Fig.9

AIR
COMPRESSED
AIR
GASOLINE
OR
METHANE
REFORM
ER
O
2
FUEL
CELL
CONVER
TER
MOTOR
ELECTRICITY FROM H
2
PEMFC
WATER
GRID
ELECTRO
LYSIS
WIND
TURBINE
WIND
GENERAT
OR
2
H
STORAGE
(LIQUID
OR GAS)
ELECTRICITY
+
ULTRA-CAPACITOR
OR
BATTERY
FUEL CELL CAR WITH THE CONCEPT OF HYDROGEN ECONOMY
Fig.10

POWER ELECTRONICS – AN INTERDISCIPLINARY TECHNOLOGY
Fig.11

EVOLUTION OF POWER ELECTRONICS
Fig.12

POWER SEMICONDUCTOR DEVICE EVOLUTION

DIODE (1955)

THYRISTOR (1958)

TRIAC (1958)

GATE TURN-OFF THYRISTOR (GTO) (1980)

BIPOLAR POWER TRANSISTOR (BPT or BJT) (1975)
D

POWER MOSFET (1975) G
S

INSULATED GATE BIPOLAR TRANSIATOR
(IGBT)(1985)

STATIC INDUCTION TRANSISTOR(SIT) (1985)

INTEGRATED GATE-COMMUTATED
THYRISTOR (IGCT) (1996)
G
G

SILICON CARBIDE DEVICES
C
E
D
S
B
C
Fig.13

10 8
10 7
10 6
10 5
10 4
THYRISTOR
IGCT
GTO
IGBT IPM
IGBT
DISCRETE
10 3
10 2
TRIAC
POWER
MOSFET
10
10 !0
2 10 3 10 4 10 5 10 6
SWITCHING FREQUENCY (Hz)
POWER-FREQUENCY TRENDS OF THE DEVICES [5]

Comparison of Power MOSFET-IGBT-GTO-IGCT
_________________________________________________________________________________
Power MOSFET IGBT GTO IGCT
1.Voltage and current 100 V, 28 A* (dc) 1.2 kV, 50 A* (dc) 6 kV, 6000 A*(pk) 4.5 kV, 4000A*(pk)
ratings ( selected device for comparison)
2. Present power capability 1.2 kV, 50 A 3.5 kV, 1200 A or higher 6 kV, 6000 A
3. Voltage blocking Asymmetric Asymmetric* Asymmetric/Symmetric
6.5 kV, 3000 A
Asymmetric/Symmetric
4. Gating Voltage Voltage
5. Junc. Temp. range (

C ) -55 to 175 -20 to 150
Current Current
6. Safe operating area Square
7. Conduction drop (V) 2.24
Square
2.65
-40 to 125 -40 to 125
2 nd
breakdown Square
3.5
2.7
at rated current
8. Switching frequency 10
6
9. Turn-off current gain __
10. Turn-on
11. Turn-on time
12. Turn-off time
13. Snubber di/dt __
Hz
43 ns
52 ns
Yes or No
1 kHz - 20 kHz
__
__
0.9
 s
2.4
 s
Yes or No
400 Hz 1.0 kHz
4 to 5
500 A/
 s
1
3,000 A/
 s
5
 s
20
 s
2
 s
2.5
 s
Yes(heavy) Yes or No
14. Protection Gate control Gate control Gate control or Gate control or very fast fuse very fast fuse
15. Applications Switching power supply Motor drive Motor drives Motor drives
Low power motor drive UPS, Induction heating, etc. SVC, etc. HVDC, SVC, etc.
16.Comments Body diode can carry Large power range
full current but sluggish Very important dv/dt = 1000 V/
 s Built-in diode
High uncontrollable High uncontrollable
(t rr
= 150 ns) device currently
I pk
= 56 A
surge current surge current
* Reverse blocking available dv/dt = 4000 V/
 s
___________________________________________________________________________________________________________________
*Harris IRF140 *POWEREX PM50RVA120
7-pack IPM
*Mitshibishi
-FG6000AU-120D
*ABB 5SHY35L4512

ADVANCES AND TRENDS OF POWER SEMICONDUCTOR DEVICES

MODERN POWER ELECTRONICS EVOLUTION PRIMARILY FOLLOWED THE
POWER DEVICE EVOLUTION - WHICH AGAIN FOLLOED THE
MICROELECTRONICS EVOLUTION

GRADUAL OBSOLESCENCE OF PHASE CONTROL DEVICES (THYRISTOR,
TRIAC)

DOMINANCE OF INSULATED GATE CONTROLLED DEVICES (IGBT, Power
MOSFET)

POWER MOSFET WILL REMAIN UNIVERSAL IN LOW VOLTAGE HIGH
FREQUENCY APPLICATIONS

GRADUAL OBSOLESCENCE OF GTOs (LOWER END BY IGBTs AND HIGHER
END BY IGCTs)

REDUCTION OF CONDUCTION DROP IN HIGH VOLTAGE POWERMOSFET
AND IGBT
 SiC BASED DEVICES WILL BRING RENAISSANCE IN HIGH POWER
ELECTRONICS – DIAMOND DEVICES IN THE LONG RUN

LINE POWER QUALITY PROBLEMS AND HARMONIC STANDARDS

LARGE GROWTH OF DIODE AND THYRISTOR CONVERRERS ON UTILITY SYSTEM

LINE VOLTAGE HARMONIC DISTORTION

POOR LINE POWER FACTOR

EMI

LINE AND EQUIPMENT HARMONIC CURRENT LOADING

COMMUNICATION INTERFERENCE

METER INACCURACY

SPURIOUS LINE RESONANCE

IEEE-519 STANDARD – HARMONIC DISTORTION CONTROL AT COMMON ENTRY POINT

IEC-1000 STANDARD – CONTROLS HARMONIC DISTORTION OF INDIVIDUAL EQUIPMENT