Transcript Introduction to Power Electronics Students Version

POWER ELECTRONICS
CIRCUITS, DEVICES, AND
APPLICATIONS
Eng.Mohammed Alsumady
Relationship of Power Electronics
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POWER ELECTRONICS TECHNOLOGY
• As the technology for the power semiconductor devices and integrated
circuit develops, the potential for applications of power electronics become
wider. There are already many power semiconductor devices that are
commercially available, however, the development in this direction is continuing.
• The power semiconductor devices or power electronic converter fall
generally into four categories :
-AC to DC Converter (Controlled Rectifier)
-DC to DC Converter (DC Chopper)
-AC to AC Converter (AC voltage regulator)
-DC to AC Converter (Inverter)
•
The design of power electronics converter circuits requires design the
power and control circuits. The voltage and current harmonics that are generated
by the power converters can be reduced or minimized with a proper choice of the
control strategy.
Power Electronics Application
• Power Electronics defined as the application of solidstate (devices) electronics for the control and
conversion of electric power.
• Power electronics have already found an important
place in modern technology and are now used in a
great variety of high-power product, including heat
controls, light controls, electric motor control, power
supplies, vehicle propulsion system and high voltage
direct current (HVDC) systems.
POWER ELECTRONIC SWITCHING
DEVICES
1.Uncontrolled turn on and off (Power Diode)
2.Controlled turn on uncontrolled turn off (Thyristors)
3.Controlled turn on and off characteristic (Power Transistor, BJT,
MOSFET, GTO, IGBT)
4.Continuous gate signal requirement (BJT, MOSFET, IGBT)
5.Pulse gate requirement (SCR(Silicon-Controlled Rectifier) , GTO)
6.Bidirectional current capability (TRIAC)
7.Undirectionalcurrent capability (SCR, GTO, BJT, MOSFET,
IGBT)
Diagram Block of Converters
•
Diode Rectifiers. A diode rectifier circuit converts AC voltage into a fixed DC
voltage. The input voltage to rectifier could be either single phase or three phase.
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AC to DC Converters. An AC to DC converter circuit can convert AC
voltage into a DC voltage. The DC output voltage can be controlled by varying
the firing angle of the thyristors. The AC input voltage could be a single phase or
three phase.
•
AC to AC Converters. This converters can convert from a fixed ac input voltage
into variable AC output voltage. The output voltage is controlled by varying
firing angle of TRIAC. These type converters are known as AC voltage
regulators.
•
DC to DC Converters . These converters can converte a fixed DC input voltage
into variable DC voltage or vice versa. The DC output voltage is controlled by
varying of duty cycle.
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Examples of
Some
Applications
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History of Power Electronics
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Types of Power Devices
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General Purposes Diodes
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Thyristors
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GTOs
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Power Ratings of Devices
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Ratings of Power Devices
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Devices Symbols and Characteristics
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Devices Symbols and Characteristics
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Applications of Power Devices
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Control Characteristics of Devices
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Control Characteristics of Devices
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Switching Characteristics
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Ideal Characteristics
Ideal
Characteristics
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Voltage and Current Waveforms
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Diode Rectifiers
Vo ( average ) 
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2Vm

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Ac-dc Converter
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AC to DC Converters
-Single phase, half wave AC to DC converter
Input voltage
Output average voltage :
rms value of Output voltage :
Waveform of single-phase, half wave AC to DC converter α
AC-DC Converter
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Vo ( average) 
Vrms
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Vm

(1  cos  )
Vm 1
sin 2

((   ) 
)
2
2 
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1. AC to DC Converters
-Single phase, Full wave AC to DC converter
The average output voltage can be found from :
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AC to DC Converters
Single phase, Full wave AC to DC converter
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3 Phase Half-Wave Uncontrolled Rectifier with
Inductive Load
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3 Phase Half-Wave Uncontrolled
Rectifier with Inductive Load
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Three Phase Controlled Rectifier with Resistive
Load
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Three Phase Controlled Rectifier with Inductive
Load
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3 Phase Half-Wave Controlled Rectifier
With Inductive Load
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AC to DC Converters
-Three-phase, Half wave AC to DC converter with
inductive load
If the phase voltage is : van= Vm Sin(wt). The
average output voltage for a continuous load current is :
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AC to DC Converters
-Three-phase, Half wave AC to DC converter
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AC-AC Converter
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Vo ( rms )
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Vm  1 
sin 2  

       2 
2 

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IGBT in DC-DC Converter
Vo ( average )   VS
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DC-AC Converter
Vo1( rms  fundamental ) 
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4Vs
 2
 0.90VS
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UPS System
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RMS Values of Waveforms
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RMS Values of Waveforms
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Power Converter System
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Drive System
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Smart Power System
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Summary
• Power electronics uses low power electronics
(ICs, microprocessors, controllers ), and
switching power devices for power converter
and/or processing from one form of power to
another.
• The characteristics of the power devices play
a major role in the speed and effectiveness of
the power conversion.
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