PWM Dc-to-Dc Power Conversion
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PWM Dc-to-Dc Power Conversion
Pul
sew
idth
Mod
ulat
ed D
c-to
-DC
Pow
er C
onve
rsio
n
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Head Lamp Drive Circuit in Automobile● Energy Source and Load
- Source:
- Load:
● Conventional Resistive Solution
- Control low:
- Ohmic loss at:
Dc-
to-D
c P
ow
er
Con
vers
ion
Controller
xR OI
BV oROV
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Problem of Resistive Solution
● Assumptions:
- Ploss : - Efficiency : ● Consequence of poor efficiency
Dc-
to-D
c P
ow
er
Con
vers
ion
Controller
xR OI
BV 60 W@ 12 VOV
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Dc-to-Dc Power Conversion as Alternative Solution
● Control law:
● No power loss in circuit:
Dc-
to-D
c P
ow
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Con
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Controller
a
Switch network
BV
Xv
BV
onT
sT
Ov
p
Ov
Xv
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● Power conversion: Changing electrical energy/power from one form to another form using electronics devices Examples:
● Power electronics: Electronic engineering that deals with all types of power conversions while questing the
● Dc-to-Dc power conversion: Process of changing the voltage level of a dc source to another value
Dc-to-Dc Power ConversionD
c-to
-Dc
Po
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onve
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Classification of Power Conversion
AC
Converters
Inverters
Cyclo-
converters
AC DC
DCRectifiers
Dc-
to-D
c P
ow
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Con
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ion
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● Dc source with non-ideal characteristics - Standalone dc source: - Rectified ac source:
Dc-to-Dc Power Conversion System
● Load as dynamic current sink with non-resistive impedance - Electric equipment: non-resistive load impedance
Dc-
to-D
c P
ow
er
Con
vers
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Dcsource
Power stageLoad
Controller
Dc-to-dc converter
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Dc-to-Dc Power Conversion System
● Dc-to-dc converter as voltage source• Function of dc-to-dc converter:
• Elements of dc-to-dc converter - Power stage: semiconductor switch
- Controller: processors, ICs, and discrete components
μ
Dc-
to-D
c P
ow
er
Con
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Dcsource
Power stageLoad
Controller
Dc-to-dc converter
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Features and Issues of PWM Dc-to-Dc Converter
● Power stage components - Semiconductors: high frequency switching - Inductors and capacitors: periodic voltage/current excitation - Transformers: periodic voltage/current excitation
● Power stage configurations - Accommodation of input voltage and load current requirements - Very large or very small voltage conversion ratio - Galvanic isolation between source and load ● Dynamic modeling and analysis - Closed-loop feedback control: stability - Dynamic modeling to accommodate conventional analysis technique
● Dynamic performance and controller design - Static and dynamic performance - Dynamic performance: stability, transfer functions, transient responses - Feedback controller design for optimal dynamic performance
Dc-
to-D
c P
ow
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Con
vers
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POWER ELECTRONICS: 2012 Fall
● General Information Office: IT3-314 Office Hour: Fri 9:00-12:00 AM Phone: 950-6603, Home Page: http://m80.knu.ac.kr/~SMPC/
● Course Objective: As an introductory course in power electronics, the class will address basic principles, analysis techniques, and applications of modern power electronics with a strong emphasis on switchmode dc-to-dc power conversions. The students would learn methods of solving various power electronics problems using their knowledge about electronics, circuit theories, and control theories.
● Text: Byungcho Choi, “Fundamentals of Switchmode Dc-to-Dc Power Conversions. 2nd Edition, 2010, Young Publishing http://w w w.bandinlunis.com /front/product/detailProduct.do?prodId= 3196848 Reference: R.W. Erickson, “Fundamentals of Power Electronics,” 1997. D. W. Hart, “Introduction to Power Electronics,” 1997, Prentice-Hall P. T. Krein, “Elements of Power Electronics,” 1998, Oxford
Tentative Course Outline
Topic Major Contents WeekChapter 1: Basics of Power Electronics
Introduction to power electronics Semiconductor switches and switching circuits Energy storage/transfer devices and switching circuits
3 weeks
Chapter 2: Step-down Dc-to-Dc Power Conversion Circuit:
Buck Converter
Basic principles of buck converter Time-domain analysis of buck converter Discontinuous-conduction mode of operation Closed-loop control of buck converter
3 week
Chapter 3: Dc-to-Dc Power Converter Circuits
Step-up dc-to-dc converter Buck/boost converter
1 week
Midterm TestChapter 3: Dc-to-Dc Power
Converter Circuits Flyback converters Bridge-type converters Forward converters
2 weeks
Chapters 4, 5, and 6: Modeling, Control Design and Analysis of PWM Converters
Average modeling of PWM converters Small-signal modeling of PWM converters Small-signal analysis of PWM dc-to-dc converters Compensation design and closed-loop analysis
4 weeks
Final Exam
Grading Policy: Midterm Test: 42%, Final Exam: 42%, Homework: 16%
Honor System: Students should develop their own solutions to homework problems. Late homework will not be accepted with no exceptions.
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