elec power electronics converters applications and design complet

8/9/2019 ELEC Power Electronics Converters Applications and Design COMPLET

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Copyright © 2003by John Wiley & Sons, Inc.

Chapter 1 Introduction 1-2

Power Electronic Systems

• Block diagram

• Role of Power Electronics

• Reasons for growth


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Linear Power Supply

• Series transistor as an adjustable resistor

• Low Efficiency

• Heavy and bulky


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Switch-Mode Power Supply

• Transistor as a switch• High Efficiency

• High-Frequency Transformer


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Basic Principle of Switch-Mode Synthesis

• Constant switching frequency• pulse width controls the average

• L-C filters the ripple


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Application in Adjustable Speed Drives

• Conventional drive wastes energy across the throttling

valve to adjust flow rate

• Using power electronics, motor-pump speed is adjusted

efficiently to deliver the required flow rate


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Scope and Applications


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Power Processor as a Combination of

Converters

• Most practical topologies require an energy

storage element, which also decouples the input

and the output side converters


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Power Flow through Converters

• Converter is a general term

• An ac/dc converter is shown here• Rectifier Mode of operation when power from ac to dc

• Inverter Mode of operation when power from ac to dc


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AC Motor Drive

• Converter 1 rectifies line-frequency ac into dc

• Capacitor acts as a filter; stores energy; decouples• Converter 2 synthesizes low-frequency ac to motor

• Polarity of dc-bus voltage remains unchanged

– ideally suited for transistors of converter 2


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Matrix Converter

• Very general structure

• Would benefit from bi-directional and bi-polarity switches

• Being considered for use in specific applications


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Copyright © 2003by John Wiley & Sons, Inc. Chapter 1 Introduction 1-12

Interdisciplinary Nature of Power Electronics


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Copyright © 2003by John Wiley & Sons, Inc. Chapter 2 Power SemiconductorSwitches: An Overview2-1

Chapter 2 Overview of Power

Semiconductor Devices


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Diodes

• On and off states controlled by the power circuit


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Thyristors

• Semi-controlled device

• Latches ON by a gate-current pulse if forward biased

• Turns-off if current tries to reverse


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Copyright © 2003by John Wiley & Sons, Inc. Chapter 2 Power SemiconductorSwitches: An Overview 2-6

Generic Switch Symbol

• Idealized switch symbol

• When on, current can flow only in the direction of the arrow

• Instantaneous switching from one state to the other

• Zero voltage drop in on-state

• Infinite voltage and current handling capabilities

Switching Characteristics (linearized)


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Switching Characteristics (linearized)

Switching Power Loss is

proportional to:

• switching frequency• turn-on and turn-off times

Bi l J ti T i t (BJT)


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Bipolar Junction Transistors (BJT)

• Used commonly in the past• Now used in specific applications

• Replaced by MOSFETs and IGBTs

V i C fi ti f BJT


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Various Configurations of BJTs

MOSFET


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MOSFETs

• Easy to control by the gate• Optimal for low-voltage operation at high switching frequencies

• On-state resistance a concern at higher voltage ratings

Gate Turn Off Thyristors (GTO)


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Gate-Turn-Off Thyristors (GTO)

• Slow switching speeds

• Used at very high power levels

• Require elaborate gate control circuitry


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IGBT


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IGBT

MCT


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MCT

Comparison of Controllable Switches


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Chapter 2 Power SemiconductorSwitches: An Overview 2-15

Comparison of Controllable Switches

Summary of Device Capabilities


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Chapter 2 Power SemiconductorSwitches: An Overview 2-16

Summary of Device Capabilities


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Chapter 3 Basic Electrical andMagnetic Circuit Concepts 3-1

Chapter 3

Review of Basic Electrical andMagnetic Circuit Concepts


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Sinusoidal Steady State


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Three-Phase Circuit

Steady State in Power Electronics


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Copyright © 2003

by John Wiley & Sons, Inc.Chapter 3 Basic Electrical and

Magnetic Circuit Concepts 3-5

Steady State in Power Electronics

F i A l i


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Fourier Analysis

Di t ti i th I t C t


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Distortion in the Input Current

• Voltage is assumed to be sinusoidal• Subscript “1” refers to the fundamental

• The angle is between the voltage and the current fundamental

Phasor Representation


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Phasor Representation

Response of L and C


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Response of L and C

Inductor Voltage and Current in


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Copyright © 2003

by John Wiley & Sons, Inc.

Chapter 3 Basic Electrical and


Inductor Voltage and Current in

Steady State

• Volt-seconds over T equal zero.

Capacitor Voltage and Current


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Capacitor Voltage and Current

in Steady State

• Amp-seconds

over T equal zero.

Ampere’s Law


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pe e s a

• Direction of magnetic field due to currents

• Ampere’s Law: Magnetic field along a path

Direction of Magnetic Field


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g

B-H Relationship; Saturation


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p;

• Definition of permeability

Continuity of Flux Lines


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y

1 2 3 0φ φ φ+ + =


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Analogy between Electrical and


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Magnetic Variables

Analogy between Equations in


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Magnetic Circuit Concepts3-18

Electrical and Magnetic Circuits

Magnetic Circuit and its


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Electrical Analog


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Inductance L


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• Inductance relates flux-linkage to current

Analysis of a Transformer


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Transformer Equivalent Circuit


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Including the Core Losses


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Transformer Core

Characteristic


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Characteristic

Chapter 4

Computer Simulation


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Chapter 4 Computer Simulation of Power

Electronic Converters & Systems4-1

Computer Simulation

System to be Simulated


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y

• Challenges in modeling power electronic systems

Large-Signal System Simulation


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• Simplest component models

Small-Signal Linearized Model for

Controller Design


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Electronic Converters & Systems

4-4

Controller Design

• System linearized around the steady-state point

Closed-Loop Operation: Large Disturbances


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4-5

• Simplest component models

• Nonlinearities, Limits, etc. are included

Modeling of Switching Operation


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4-6

• Detailed device models

• Just a few switching cycles are studied

Modeling of a Simple Converter


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4-7

• Input voltage takes on two discrete values

Trapezoidal Method of Integration


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4-8

• The area shown above represents the integral

A Simple Example


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4-9

• The input voltage takes on two discrete values

Modeling using PSpice


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4-10

• Schematic approach

is far superior

PSpice-based Simulation


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4-11

• Simulation results

Simulation using MATLAB


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4-12

MATLAB-based Simulation


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4-13

• Simulation results

Chapter 5

Diode Rectifiers


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Chapter 5 Line-Frequency Diode

Rectifiers

5-1

Diode Rectifier Block Diagram


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Rectifiers

5-2

• Uncontrolled utility interface (ac to dc)

A Simple Circuit


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Rectifiers

5-3

• Resistive load

A Simple Circuit (R-L Load)


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Rectifiers

5-4

• Current continues to flows for a while even after the input

voltage has gone negative

A Simple Circuit (Load has a dc back-emf)


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Rectifiers

5-5

• Current begins to flow when the input voltage exceeds the dc back-emf

• Current continues to flows for a while even after the input voltage has

gone below the dc back-emf

Single-Phase Diode Rectifier Bridge


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Rectifiers

5-6

• Large capacitor at the dc output for filtering and energy

storage

Diode-Rectifier Bridge Analysis


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Rectifiers

5-7

• Two simple (idealized) cases to begin with

Redrawing Diode-Rectifier Bridge


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Rectifiers

5-8

• Two groups, each with two diodes

Waveforms with a

purely resistive load

and a purely dc current


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Rectifiers

5-9

at the output

• In both cases, the dc-side

voltage waveform is the same


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Diode-Rectifier Bridge Analysis with AC-

Side Inductance


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Rectifiers

5-11

• Output current is assumed to be purely dc

Understanding Current Commutation


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Rectifiers

5-12

• Assuming inductance in this circuit to be zero

Understanding Current Commutation (cont.)


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Chapter 5 Line-Frequency DiodeRectifiers

5-13

• Inductance in this circuit is included

Current Commutation Waveforms


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5-14

• Shows the volt-seconds needed to commutate current

Current Commutation in Full-Bridge Rectifier


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5-15

• Shows the necessary volt-seconds

Understanding Current Commutation


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5-16

• Note the current loops for analysis

Rectifier with a dc-

side voltage


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5-17

DC-Side Voltage and Current Relationship


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5-18

• Zero current corresponds to dc voltage equal to the peak of

the input ac voltage

Effect of DC-Side Current on

THD, PF and DPF


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5-19

• Very high THD at low current values

Crest Factor versus the Current Loading


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5-20

• The Crest Factor is very high at low values of current

Diode-Rectifier with a Capacitor Filter


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5-21

• Power electronics load is represented by an equivalent load

resistance

Diode Rectifier Bridge


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5-22

• Equivalent circuit for analysis on one-half cycle basis

Diode-Bridge Rectifier: Waveforms


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5-23

• Analysis using MATLAB


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Line-Voltage Distortion


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5-26

• PCC is the point of common coupling

Line-Voltage Distortion


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5-27

• Distortion in voltage supplied to other loads

Voltage Doubler Rectifier


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5-28

• In 115-V position, one capacitor at-a-time is charged from the

input.


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Current in A Three-Phase, Four-Wire

System


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5-30

• The current in the neutral wire can be very high

Three-Phase, Full-Bridge Rectifier


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5-31

• Commonly used

Three-Phase, Full-Bridge Rectifier: Redrawn


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5-32

• Two groups with three diodes each

Three-Phase, Full-Bridge Rectifier Waveforms


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5-33

• Output current is

assumed to be dc

Three-Phase, Full-Bridge Rectifier: Input

Line-Current


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5-34

• Assuming output current to be purely dc and zero ac-side

inductance



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5-35

• Including the ac-side inductance

3-Phase Rectifier: Current Commutation


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5-36

• output

current is

assumed to bepurely dc

Rectifier with a Large Filter Capacitor


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5-37

• Output voltage is assumed to be purely dc



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5-38

• THD, PF and DPF as functions of load current

Crest Factor versus the Current Loading


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5-39

• The Crest Factor is very high at low values of current

Three-Phase Rectifier Waveforms


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5-40

• PSpice-based analysis


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Primitive circuits

with thyristors


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Chapter 6 Thyristor Converters 6-3

Thyristor Triggering


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• ICs available

Full-Bridge Thyristor Converters


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• Single-phase and three-phase


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1-Phase Thyristor Converter Waveforms


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• Assuming zero ac-side inductance

Average DC Output Voltage


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• Assuming zero ac-side inductance

Input Line-Current Waveforms


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• Harmonics, power and reactive power

1-Phase Thyristor Converter


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• Finite ac-side inductance; constant dc output

current

Thyristor Converter Waveforms


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• Finite ac-side inductance

Thyristor Converter: Discontinuous Mode


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• This mode can occur in a dc-drive at light loads



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• PSpice-based simulation

Thyristor Converter Waveforms:

Discontinuous Conduction Mode


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• PSpice-based simulation

DC Voltage versus Load Current


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• Various values of delay angle

Thyristor Converters: Inverter Mode


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• Assuming the ac-side inductance to be zero


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Thyristor Converters: Inverter Mode


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• Waveforms at start-up

3-Phase Thyristor Converters


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• Two groups of three thyristors each

3-Phase Thyristor Converter Waveforms


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• Zero ac-side inductance; purely dc current

DC-side voltage

waveforms

assuming zero ac-

side inductance


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Input line-current

waveforms

assuming zero ac-

side inductance


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Three-Phase Thyristor Converter


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• AC-side inductance is included

Current Commutation Waveforms


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• Constant dc-side current

Input Line-Current Waveform


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Input Line-Current Harmonics


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Input Line-Current Harmonics


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• Typical and idealized

Three-Phase Thyristor Converter


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• Realistic load



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• Realistic load; continuous-conduction mode



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• Realistic load; discontinuous-conduction mode

Thyristor Inverter


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• Constant dc current

Thyristor Inverter Waveforms


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Thyristor Inverter


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• Family of curves at various values of delay angle

Thyristor Inverter Operation


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• Importance of extinction angle

Thyristor Converters: Voltage Notching


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• Importance of external ac-side inductance

Limits on Notching and Distortion


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• Guidelines

Thyristor Converter Representation


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• Functional block diagram


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Block Diagram of DC-DC Converters


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Chapter 7 DC-DC Switch-ModeConverters

7-2

• Functional block diagram

Stepping Down a DC Voltage


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7-3

• A simple approach that shows the evolution

Pulse-Width Modulation inDC-DC Converters


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7-4

• Role of PWM

Step-Down DC-DC Converter


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7-5

• Pulsating input to

the low-pass filter

Step-Down DC-DC Converter: Waveforms


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7-6

• Steady state; inductor current flows continuously


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Step-Down DC-DC Converter:Discontinuous Conduction Mode


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7-8

• Steady state; inductor current discontinuous

Step-Down DC-DC Converter: Limits of

Cont./Discont. Conduction


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7-9

• The duty-ratio of 0.5 has the highest value of the

critical current

Step-Down DC-DC Converter: Limits of



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7-10

• Output voltage is kept constant

Step-Down Conv.: Output Voltage Ripple


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7-11

• ESR is assumed to be zero

Step-Up DC-DC Converter


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7-12

• Output voltage must be greater than the input


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Step-Up DC-DC Converter: Limits of



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7-14

• The output voltage is held constant

Step-Up DC-DC Converter: Discont.

Conduction


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7-15

• Occurs at light loads


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Step-Up DC-DC Converter: Effect of

Parasitics


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7-17

• The duty-ratio is generally limited before theparasitic effects become significant

Step-Up DC-DC Converter Output Ripple


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7-18


Step-Down/Up DC-DC Converter


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7-19

• The output voltage can be higher or lower thanthe input voltage

Step-Up DC-DC Converter: Waveforms


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7-20

• Continuation conduction mode


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Step-Up DC-DC Converter:

Discontinuous Conduction Mode


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7-22

• This occurs at light loads


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Step-Up DC-DC Converter: Effect of

Parasitics


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7-24

• The duty-ratio is limited to avoid these parasiticeffects from becoming significant

Step-Up DC-DC Converter:Output Voltage Ripple


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7-25


Cuk DC-DC Converter


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7-26

• The output voltage can be higher or lower than

the input voltage

Cuk DC-DC Converter: Waveforms

• The capacitor

voltage is assumed

constant


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7-27

Converter for DC-Motor Drives


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7-28

• Four quadrant operation is possible

Converter Waveforms

• Bi-polar voltage switching


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7-29

Converter Waveforms

• Uni polar voltage switching


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7-30

• Uni-polar voltage switching

Output Ripple in Converters for DC-MotorDrives


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7-31

• bi-polar and uni-polar voltage switching

Switch Utilization in DC-DC Converters


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7-32

• It varies significantly in various converters

Equivalent Circuits in DC-DC Converters


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7-33

• replacing inductors and capacitors by current

and voltage sources, respectively

Reversing the Power Flow in DC-DC Conv.


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7-34

• For power flow from right to left, the input

current direction should also reverse

Chapter 8

Switch-Mode DC-AC Inverters


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Chapter 8 Switch-Mode DC-Sinusoidal AC Inverters

8-1

• converters for ac motor drives anduninterruptible power supplies

Switch-Mode DC-AC Inverter


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8-2

• Block diagram of a motor drive where the powerflow is unidirectional



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8-3

• Block diagram of a motor drive where the powerflow can be bi-directional



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8-4

• Four quadrants of operation

One Leg of a Switch-Mode DC-AC Inverter


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8-5

• The mid-point shown is fictitious

Synthesis of a Sinusoidal Output by PWM


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8-6

Details of a Switching Time Period


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8-7

• Control voltage can be assumed constant duringa switching time-period

Harmonics in the DC-AC Inverter OutputVoltage


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8-8

• Harmonics appear around the carrier frequency

and its multiples

Harmonics due to Over-modulation


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8-9

• These are harmonics of the fundamental

frequency

Output voltage Fundamental as a Functionof the Modulation Index


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8-10

• Shows the linear and the over-modulationregions; square-wave operation in the limit


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Half-Bridge Inverter


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8-12

• Capacitors provide the mid-point

Single-Phase Full-Bridge DC-AC Inverter


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8-13

• Consists of two inverter legs

PWM to Synthesize Sinusoidal Output


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8-14

• The dotted curve is the desired output; also the

fundamental frequency

Analysis assuming Fictitious Filters


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8-15

• Small fictitious filters eliminate the switching-

frequency related ripple


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Output Waveforms:Uni-polar Voltage

Switching

• Harmoniccomponents around


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8-17

components around

the switching

frequency are absent

DC-Side Current in a Single-Phase Inverter


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8-18

• Uni-polar voltage switching

Sinusoidal Synthesis by Voltage Shift


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8-19

• Phase shift allows voltage cancellation tosynthesize a 1-Phase sinusoidal output

Single-Phase Inverter


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8-20

• Analysis at the fundamental frequency

Square-Wave and PWM Operation


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8-21

• PWM results in much smaller ripple current


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Three-Phase Inverter


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8-23

• Three inverter legs; capacitor mid-point isfictitious

Three-Phase

PWM

Waveforms


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8-24

Three-Phase Inverter Harmonics


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8-25

Three-Phase Inverter Output


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8-26

• Linear and over-modulation ranges

Three-Phase Inverter: Square-Wave Mode


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8-27

• Harmonics are of the fundamental frequency

Three-Phase Inverter: FundamentalFrequency


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8-28

• Analysis at the fundamental frequency can bedone using phasors


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DC-Side Current in a Three-Phase Inverter


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8-30

• The current consists of a dc component and the

switching-frequency related harmonics


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PWM Operation


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8-32

• devices conducting are indicated

Short-Circuit States in PWM Operation


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8-33

• top group or the bottom group results in short

circuiting three terminals

Effect of BlankingTime

• Results in


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8-34

Results in

nonlinearity

Effect of Blanking Time


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8-35

• Voltage jump when the current reverses direction

Effect of Blanking Time


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8-36

• Effect on the output voltage


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Tolerance-Band Current Control


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8-38

• Results in a variable frequency operation

Fixed-Frequency Operation


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8-39

• Better control is possible using dq analysis

Transition from Inverter to Rectifier Mode


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8-40

• Can analyze based on the fundamental-

frequency components

Summary of DC-AC Inverters


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8-41

• Functional representation in a block-diagram form

Chapter 9Zero-Voltage or Zero-Current Switchings


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Chapter 9 Resonant Converters 9-1

• converters for soft switching

One Inverter Leg


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• The output current can be positive or negative

Hard Switching Waveforms


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• The output current can be positive or negative

Turn-on and Turn-off Snubbers


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• Turn-off snubbers are used

Switching Trajectories


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• Comparison of Hard versus soft switching

Undamped Series-Resonant Circuit


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• The waveforms shown include initial conditions

Series-Resonant Circuit withCapacitor-Parallel Load


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• The waveforms shown include initial conditions

Impedance of a Series-Resonant Circuit


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• The impedance is capacitive below theresonance frequency

Undamped Parallel-Resonant Circuit


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• Excited by a current source

Impedance of a Parallel-Resonant Circuit


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• The impedance is inductive at below the

resonant frequency

Series Load Resonant (SLR) Converter


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• The transformer is ignored in this equivalentcircuit

SLR Converter Waveforms


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• The operating frequency is below one-half theresonance frequency



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• The operating frequency is in between one-half theresonance frequency and the resonance frequency



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• The operating frequency is above the resonancefrequency

Lossless Snubbers in SLR Converters


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SLR Converter Characteristics


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• Output Current as a function of operatingfrequency for various values of the output voltage

SLR Converter Control

• The operating frequency is varied to regulate

the output voltage


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Parallel Load Resonant (PLR) Converter

• The transformer is ignored in this equivalent


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• The transformer is ignored in this equivalent

circuit

PLR Converter Waveforms

• The current is in a discontinuous conduction


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• The current is in a discontinuous conduction

mode


Th ti f i b l th


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• The operating frequency is below the resonance

frequency



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PLR Converter Characteristics


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• Output voltage as a function of operatingfrequency for various values of the output current

Hybrid-Resonant DC-DC Converter


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• Combination of series and parallel resonance

Parallel-Resonant Current-Source Converter

• Basic circuit to illustrate the operating principle


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at the fundamental frequency

Parallel-Resonant Current-Source Converter


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• Using thyristors; for induction heating

Class-E Converters

Optimum mode


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Class-E Converters

Non-Optimum

mode


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Resonant Switch Converters

Classifications


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ZCS Resonant-Switch Converter

• Waveforms; voltage is regulated by varying the


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switching frequency

ZCS Resonant-Switch Converter

• A practical circuit


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ZVS Resonant-Switch Converter

• Serious limitations


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ZVS Resonant-Switch Converter

• Waveforms


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MOSFET Internal Capacitances

• These capacitances affect the MOSFET switching


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ZVS-CV DC-DC Converter

Th i d t t t di ti


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• The inductor current must reverse directionduring each switching cycle

ZVS-CV DC-DC Converter


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• One transition is shown

ZVS-CV Principle Applied to DC-AC Inverters

• Very large ripple in the output current


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Three-Phase ZVS-CV DC-AC Inverter

• Very large ripple in the output current


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Output Regulation by Voltage Control


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• Each pole operates at nearly 50% duty-ratio

ZVS-CV with Voltage Cancellation

• Commonly used


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Resonant DC-Link Inverter

• The dc-link voltageis made to oscillate


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Three-Phase Resonant DC-Link Inverter

• Modifications have been proposed


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High-Frequency-Link Inverter

• Basic principle for selecting integral half-cycles of the

high-frequency ac input


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high frequency ac input

High-Frequency-Link Inverter

• Low-frequency ac output is synthesized by selecting

integral half-cycles of the high-frequency ac input


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integral half cycles of the high frequency ac input


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Chapter 10

Switching DC Power Supplies

• One of the most important applications of power

electronics


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Chapter 10 SwitchingDC Power Supplies

10-1

e ect o cs

Linear Power Supplies

• Very poor efficiency and large weight and size


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10-2

y p y g g

Switching DC Power Supply: Block Diagram

• High efficiency and small weight and size


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10-3

g y g

Switching DC Power Supply: Multiple

Outputs

• In most applications, several dc voltages arerequired possibly electrically isolated from each other


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10-4

pp grequired, possibly electrically isolated from each other


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PWM to Regulate Output

• Basic principle is the same as discussed in Chapter 8


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10-6

Flyback Converter

• Derived from buck-boost; very power at small power

(> 50 W ) power levels


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10-7

Flyback Converter

• Switch on and off states (assuming incomplete core

demagnetization)


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10-8

Flyback Converter

• Switching waveforms (assuming incomplete coredemagnetization)


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10-9

g )

Other Flyback Converter Topologies

• Not commonly used


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10-10

C i ht © 2003

Forward Converter

• Derived from Buck; idealized to assume that the

transformer is ideal (not possible in practice)


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10-11

C i ht © 2003 Ch t 10 S it hi

Forward Converter:

in Practice

• Switching waveforms (assuming

incomplete core demagnetization)


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10-13


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10-15


Full-Bridge Converter

• Used at higher power levels (> 0.5kW

)


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10-16


Current-Source Converter

• More rugged (no shoot-through) but both switches

must not be open simultaneously


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10-17


Ferrite Core Material

• Several materials to choose from based on applications


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p gDC Power Supplies

10-18

Copyright © 2003 Chapter 10 Switching 10-19

Core Utilization in Various Converter

Topologies

• At high switching frequencies, core losses limitexcursion of flux density


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Copyright © 2003b J h Wil & S I

Chapter 10 Switching 10-20

Control to Regulate Voltage Output

• Linearized representation of the feedback controlsystem


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Copyright © 2003b J h Wil & S I

Chapter 10 SwitchingDC P S li

10-21

Forward Converter: An Example

• The switch and the diode are assumed to be ideal


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Copyright © 2003by John Wiley & Sons Inc

Chapter 10 SwitchingDC P S li

10-22

Forward Converter:Transfer Function Plots

• Example

considered earlier


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10-23

Flyback Converter:Transfer Function Plots

• An example


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10-24

Linearizing the PWM Block

• The transfer function is essentially a constant with

zero phase shift


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10-25

Gain of the PWM IC

• It is slope of the characteristic


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10-27

A General Amplifier for Error Compensation

• Can be implemented using a single op-amp


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10-28

Type-2 Error Amplifier

• Shows phase boost at the crossover frequency


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10-29

Voltage Feed-Forward

• Makes converter immune from input voltage

variations


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10-30

Voltage versus Current Mode Control

• Regulating the output voltage is the objective in both

modes of control


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10-32

Peak Current Mode Control

• Slope compensation is needed


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10-33

A Typical PWM Control IC

• Many safety control

functions are built in


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10-34

Current Limiting

• Two options are shown


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10-35

Implementing

ElectricalIsolation in the

Feedback Loop

• Two ways are shown

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