PWM Dc-to-Dc Power Conversion

2

Head Lamp Drive Circuit in Automobile

● Energy Source and Load - Source: - Load: ● Conventional Resistive Solution

R x I O



V B V O



R o

Controller - Control low: - Ohmic loss at: 2 2

3 ● Assumptions:

Problem of Resistive Solution

R x I O



V B V O

 60 W @ 12 V Controller -

P

loss : - Efficiency : ● Consequence of poor efficiency 3 3

4

Dc-to-Dc Power Conversion as Alternative Solution

4

V B

Switch network

a



p

v X

 

v O

 Controller

V B v O v X T on T s

● Control law: ● No power loss in circuit : 4

5 5

Dc-to-Dc Power Conversion

● 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 5

6

AC Cyclo converters AC Classification of Power Conversion Rectifiers Inverters DC DC Converters

6 6

7

Dc-to-Dc Power Conversion System

Dc source Power stage Controller Dc-to-dc converter ● Dc source with non-ideal characteristics - Standalone dc source: - Rectified ac source: ● Load as dynamic current sink with non-resistive impedance - Electric equipment: non-resistive load impedance Load 7 7

8

Dc-to-Dc Power Conversion System

Dc source Power stage Controller Dc-to-dc converter ● Dc-to-dc converter as voltage source • Function of dc-to-dc converter: • Elements of dc-to-dc converter - Power stage: semiconductor switch Load 8 8

9

Features and Issues of PWM Dc-to-Dc Converter

9 ● 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 9

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.

2 nd Edition, 2010, Young Publishing http://www.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

Chapter 1: Basics of

Power Electronics

Chapter 2: Step-down Dc-to-D

c Power Conversion Circuit: Buck Converter

Chapter 3: Dc-to-Dc Power Co

nverter Circuits

Chapter 3: Dc-to-Dc Power Co

nverter Circuits

Chapters 4, 5, and 6: Modeling

, Control Design and Analysis of PWM Converters

   Major Contents Introduction to power electronics Semiconductor switches and switching circuits Energy storage/transfer devices and switching circuits              Basic principles of buck converter Time-domain analysis of buck converter Discontinuous-conduction mode of operation Closed-loop control of buck converter Step-up dc-to-dc converter Buck/boost converter

Midterm Test

Flyback converters Bridge-type converters Forward 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

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.

Week 3 weeks 3 week 1 week 2 weeks 4 weeks