POWER ELECTRONICS withPULSEWIDTH MODULATEDDC-TO-DC POWER CONVERSION

by BYUNGCHO CHOI

POWER ELECTRONICS

● General InformationOffice: IT3-314 Office Hour: Fri 9:00-12:00 AMPhone: 950-6603, Home Page: http://m80.knu.ac.kr/~SMPC/Email: bchoi@ee.knu.ac.krPSpice Lab: Sep 30th – Oct 6th IT2-114 7:00-9:00 PMClass Changes: Nov 1st week Æ Nov 7th (sat) 1:30 PM- (ELEC2) 4:00 PM- (ELEC3)

Nov 14th (sat) 1:30 PM- (ELEC2) 4:00 PM- (ELEC3) ● 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 variouspower electronics problems using their knowledge about electronics, circuit theories, and control theories.

● Text: Byungcho Choi, “Pulsewidth Modulated Dc-to-Dc Power Conversion:Circuits, Dynamics, and Control Designs, 2013, Wiley.

y Grading Policy:Midterm Test: 40%, Final Exam: 40%,Homework and Project: 20%

y Honor System:Students should develop their own solutions to homeworkproblems.Late homework will not be accepted with no exceptions.

Tentative Course Outline

Topic Major Contents WeeksChapter 1: PWM Dc-to-Dc Power

ConversionChapter 2: Power Stage

Components

y Introduction to PWM dc-to-dc power conversiony Semiconductor switches and switching circuitsy Energy storage/transfer devices and switching circuitsy Switch circuits in practice

2 weeks

Chapter 3: Buck Converter y Basic principles of buck convertery Time-domain analysis of buck convertery Discontinuous-conduction mode of operationy Closed-loop control of buck converter

2 weeks

Chapter 4: Dc-to-Dc Power Converter Circuits

y Boost convertery Buck/boost convertery Flyback convertery Isolated converter topologies

2 weeks

Midterm TestChapter 5: Modeling PWM Dc-to-

Dc ConvertersChapter 6: Power Stage Transfer

Functions

y Averaging power stage dynamicsy Linearizing averaged power stage dynamicsy Bode plot for transfer functionsy Power stage dynamics of three basic converters

3 weeks

Chapter 7: Dynamic Performance of PWM Dc-to-Dc Converters

Chapter 8: Closed-Loop Performance and Feedback Design

yFrequency-domain performance of dc-to-dc convertersyTime-domain performance of dc-to-dc convertersy Stability of dc-to-dc convertersy Compensation design and closed-loop analysis

4 weeks

Final Exam

PULSEWIDTH MODULATEDDC-TO-DC POWER CONVERSIONCircuits, Dynamics, and Control Designs

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Contents in BriefPart One : Circuits for Dc-to-Dc Conversion

Chapter 1: PWM Dc-to-Dc Power ConversionChapter 2: Power Stage ComponentsChapter 3: Buck ConverterChapter 4: Dc-to-Dc Power Converter Circuits

Part Two: Modeling, Dynamics, and Design of PWM Dc-to-Dc Converters Chapter 5: Modeling PWM Dc-to-Dc ConvertersChapter 6: Power Stage Transfer FunctionsChapter 7: Dynamic Performance of PWM Dc-to-Dc ConvertersChapter 8: Closed-Loop Performance and Feedback CompensationChapter 9: Practical Considerations in Modeling, Analysis, and Design of

PWM Converters

Part Three : Current Mode Control

Chapter 10: Current Mode Control-Functional Basics and Classical Analysis

Chapter 11: Current Mode Control-Sampling Effects and New Control Design

Procedures

PWM Dc-to-Dc Power Conversion

Pulsewidth Modulated Dc-to-Dc Power Conversion. By Byungcho ChoiCopyright © 2013 IEEE, Published by John Wiley & Sons, Inc

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Chapter Outline

1) PWM Dc-to-Dc Power Conversion

Dc-to-Dc Power Conversion

PWM Technique

2) Dc-to-Dc Power Conversion System

3) Features and Issues of PWM Dc-to-Dc Converter

8

88

Electric Bulb Drive CircuitPW

M D

c-to

-Dc

Pow

er C

onve

rsio

n

Energy source and loadSource: battery with variable output voltage Load: electric bulb

•

( V V)

V ( V)B

O

V

V

= -=

18 30

12 12

Conventional resistive solution·

Control law: = = VoO B

x o

RV V

R R+12

= ==

Ohmic loss at : ( )

x loss in out O B O O

O B O

R P P P I V I V

I V V

- --

Controller

xR IO

VB RoV

+

-

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9

99

Problem of Resistive Solution

Efficiency evaluationAssumptions

Battery voltage: Bulb: 60 W power at voltage level and

Efficiency:

V

V V / A

( ) ( ) W

.

B

O O

loss O B O

out out

in out loss

V

V I

P I V V

P Pη

P P P

·

== = =

= - = - =

= = = =+ +

30

12 12 60 12 5

5 30 12 90

600 4

60 90

Consequence of poor efficiencyHeat generation Requirement of coolingsystem

Increase in weight and size of bulb drive circuit

·

PW

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c-to

-Dc

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Controller

xR IO

VB RoV

+

-

O

10

1010

SPDT Switch

Single-pole double-throw (SPDT) switch contains one pole which is always connected to one of the two contacts: the throw a and the throw p.

·

PW

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-Dc

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 SPDT switch is usually implemented using MOSFET-diode pair.·

11

1111

Dc-to-Dc Power Conversion as Alternative Solution

Control law: average( ) { ( )} ( ) VonO O X X B

s

Tv t V v t v t V

T· » = = = = 12

No power loss in circuit %η· = 100

Two steps in dc-to-dc power conversion i) conversionof dc voltage into a pulse waveform ii) filtering of the pulse waveform into another dc voltage

·

PW

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c-to

-Dc

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Controller

VB

vX

VB

onT

offT

vO

p

v

+

-

X

0V 0 V

v

+

-

O oR

oR v

+

-

O

onT

sT

12

1212

Pulsewidth Modulation for Output Voltage Regulation

BV = 24 V

sT μ=10 s

30 V

onT

μ

5 s

�24 V

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Ov

Xv

sT μ=10 s

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sT μ=10 s

sT μ=10 s

onT

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5 s

onT

μ

4 s

Ov

Control law: Von onB B

s s

T TV V

T T

¢¢· = = 12

Output remains constant in spite of input voltage variationOutput voltage regulation using pulsewidth modulation(PWM) scheme

·

PW

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13

1313

PWM Dc-to-Dc Converter

Power conversion: changing electrical energy/power from one form to anotherformusing electric devices

·

Power electronics: electronic engineering that deals with all types of powerconversions

·whilequesting the maximum possible conversion

efficiency

Dc-to-dc power conversion: process of changing the voltage level of a dc source to another value·

PWMdc-to-dc power converter: dc-to-dc conversion circuit operating under thePWM technique

·

PW

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c-to

-Dc

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