Ch2slides

Ch2slides - Chapter 2 Principles of Steady-State Converter...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Fundamentals of Power Electronics Chapter 2: Principles of steady-state converter analysis 1 Chapter 2 Principles of Steady-State Converter Analysis 2.1. Introduction 2.2. Inductor volt-second balance, capacitor charge balance, and the small ripple approximation 2.3. Boost converter example 2.4. Cuk converter example 2.5. Estimating the ripple in converters containing two- pole low-pass filters 2.6. Summary of key points
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Fundamentals of Power Electronics Chapter 2: Principles of steady-state converter analysis 2 2.1 Introduction Buck converter SPDT switch changes dc component Switch output voltage waveform complement D : D = 1 - D Duty cycle D: 0 D 1 + R + v ( t ) 1 2 + v s ( t ) V g v s ( t ) V g DT s D ' T s 0 t 0 DT s T s Switch position: 12 1
Background image of page 2
Fundamentals of Power Electronics Chapter 2: Principles of steady-state converter analysis 3 Dc component of switch output voltage v s = 1 T s v s ( t ) dt 0 T s v s = 1 T s ( DT s V g )= DV g Fourier analysis: Dc component = average value v s ( t ) V g 0 t 0 DT s T s v s = DV g area = DT s V g
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Fundamentals of Power Electronics Chapter 2: Principles of steady-state converter analysis 4 Insertion of low-pass filter to remove switching harmonics and pass only dc component v v s = DV g + L CR + v ( t ) 1 2 + v s ( t ) V g V g 0 0 D V 1
Background image of page 4
Fundamentals of Power Electronics Chapter 2: Principles of steady-state converter analysis 5 Three basic dc-dc converters Buck Boost Buck-boost M ( D ) D 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 D 0 1 2 3 4 5 0 0.2 0.4 0.6 0.8 1 D –5 –4 –3 –2 –1 0 0 0.2 0.4 0.6 0.8 1 (a) (b) (c) + L CR + v 1 2 + L + v 1 2 + L + v 12 M ( D )= D M ( D 1 1– D M ( D D D i L ( t ) V g i L ( t ) V g i L ( t ) V g
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Fundamentals of Power Electronics Chapter 2: Principles of steady-state converter analysis 6 Objectives of this chapter ! Develop techniques for easily determining output voltage of an arbitrary converter circuit ! Derive the principles of inductor volt-second balance and capacitor charge (amp-second) balance ! Introduce the key small ripple approximation ! Develop simple methods for selecting filter element values ! Illustrate via examples
Background image of page 6
Fundamentals of Power Electronics Chapter 2: Principles of steady-state converter analysis 7 2.2. Inductor volt-second balance, capacitor charge balance, and the small ripple approximation Buck converter containing practical low-pass filter Actual output voltage waveform v ( t )= V + v ripple ( t ) Actual output voltage waveform, buck converter + L CR + v ( t ) 1 2 i L ( t ) + v L ( t ) i C ( t ) V g v ( t ) t 0 V Actual waveform v ( t ) = V + v ripple ( t ) dc component V
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Fundamentals of Power Electronics Chapter 2: Principles of steady-state converter analysis 8 The small ripple approximation In a well-designed converter, the output voltage ripple is small. Hence, the waveforms can be easily determined by ignoring the ripple: v ( t ) V v ( t )= V + v ripple ( t ) v ( t ) t 0 V Actual waveform v ( t ) = V + v ripple ( t ) dc component V v ripple < V
Background image of page 8
Fundamentals of Power Electronics Chapter 2: Principles of steady-state converter analysis 9 Buck converter analysis: inductor current waveform original converter switch in position 2 switch in position 1 + L
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 45

Ch2slides - Chapter 2 Principles of Steady-State Converter...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online