flexible electrhhhic power converter - ismail b mohamad - tk7872.r35.i85 2006

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FLEXIBLE ELECTRIC POWE R CONVERTER

ISMAIL BIN MOHAMAD

This Report Is Submitted In Partial Fulfillment O f Requirements For

The Bachelor s D egree In Electrical Engineering (Industrial Pow er)

Fakulti Kejuruteraan Elektrik

Kolej Universiti Teknikal Kebangsaan Malaysia

APRIL 2 6



BSTR CT

This project is called Flexible Electric Power Converter. This project

describes a integration between 3 converter circuits which re AC to DC (rectifier),

D to AC (inverter), and DC to DC (chopper). All of them will be working in a

single housing and able to do the power conversion simultaneously or separately.The voltage level and frequen y level can be controlled at the circuit itself. There are

a few switching methods that will be used prior to each circuit. Switching method

that will be used for all converter is Pulse Width Modulator (PWh4). Problems like

output can e eliminated by using capacitor which is the simplest filteration method.

The overall design including the housing is expected to be small and portable so it

can be relocated anywhere without problem. This device is intended to be use for

normal or home usage and not for industrial use.



BSTR K

Projek ini dikenali sebagai Penukar Kuasa Elektrik Bolehubah. la

menerangkan gabungan antara litar pengubah iaitu pengubah voltan ulang alik

kepada voltan terus dan pengubah voltan terus kepada voltan terus. Kedua dua litar

pengubah ini akan bekerja dalam satu perumah dan mampu menjalankan peranan

untuk menjadi pengubah voltan secara serentak ataupun satu demi satu. bukan pada

masa yang sama). Magnitud voltan keluaran boleh dikawal pada litar pengubah itu

sendiri. Tugas menjalankan projek ini adalah untuk merekabentuk litar yang paling

sesuai di mana ianya akan menggunakan komponen yang betul untuk menjalankan

fungsi tertentu, mampu bekerja secara berterusan d n mampu memberi bekalan

kepada beban. Terdapat beberapa cam kawalan penukar yang akan digunakan untuk

setiap litar. Masalah seperti riak gelombang pada gelombang keluaran boleh diatasi

dengan mengunakan kapasitor. Rekaan keseluruhan termasuk perurnah litar

diharapkan kecil d n mudah alih supaya senang dibawa ke mana man a oleh

pengguna tanpa sebarang masalah. Sasaran kegunaan pengubah ini hanyalah untuk

penggunaan biasa dan bukan untuk kegunaan industri. Keluaran untuk setiap litar

difokuskan kepada saiz voltan yang biasa digunakan.



CH PTER 1

INTRODUCTION

1 1 Introduction to the Project

This project with title flexible electric power converter is meant to e se

human life in the spect of using electrical appliances because the differences of the

electrical source in terms of types of voltage that might be incompatible with the

types of voltage needed by the electrical appliances itself. Even though it might not

be suit with certain loads because of bigger power rating due to the transformer that

is used is mted at smaller amps, it is hoped that it could match the objective of the

converter.

1 2 Project Background

The difference of voltage types which alternating current (AC) and direct

current (DC), voltage level which re root mean squ re (RMS) and dc (direct

current) between the main supply or source (electricity) and the load could bring

difficulties to connect both of them t each ends [I ] Normally this can be solved by

using electric power converter which b sed on the voltage type a t the input terminal

and output terminal.



Nonetheless, it is needed to use a new method or replacement of this normal

converter when the source and the load are not suitable anymore which each other

and can lead to non-relevancy. So, the alternative solution for this to prevent the

problem of noncompatibility between source and load isto

use flexible converter.

This electric power converter is a merging result of switching method like

full Pulse Width Modulator PWM) trigger transistor and Metal Oxide

Semiconductor Field-Effect Transistor (MOSFET). The electric power converter is

going to facilitate two operating modes that te controlled through knob built on the

electric power converter itself. The two operating modes are C toD rectifier) and

DC to D chopper). proper circuit design of the flexible electric power converter

is developed in this project, and a prototype of the flexible electric power converter

will be build in order to test out the performance of the developed circuit design.

It is expected that both circuit will be integrated into one or perhaps will be

separated, (depends on the complexity of the design) Socket design for input and

output should be universal which supports almost all male socket design of the

market today. The voltage will e controlled on the device itself

1 3 OaTE TIVESAND THE S OPE OF PROJE T

This project only covers about converter circuit design for small applications

like normal chopper, and rectifier. Normally for home and light usage which draws

only low and moderate power. In conjunction with that, the input and output socket

for both D and C will be designed to support normal electrical appliances. So,

pin input and output socket will be preferred. This project it s not expected to support

any industrial purpose because of some limitations and constraints. For instance,



continuous and large power delivery won t e guaranteed because the limitation of

budget.

For rectifier, the input voltage range is planned to e around 110 240Vac

and output voltage range is around 5 12Vdc.

The scope of this project is to develop a multi purpose converter that will

perform the following task:

1. The chopper input voltage is variable which would e 0 to 12Vdc and so

does the output voltage.

2. The rectifier would be able to receive 240Vac from normal 3 pin electric

socket at home and convert to 3 types of common Vdc output that is

normally used:

a) Variable Vdc output ranging from 24Vb) Fixed 12Vdc output which consists of positive and negative

voltage.

c) Fixed 5Vdc output.

3. Able to feed small loads but the continuous supply power won t e

guaranteed.



1 4 PROJECT B SIC REQUIREMENT

Multiple tools as below are needed to complete the schematic design and

hardware for the converters.

1. Circuit design and simulation

Multisim is a circuit simulation software that incorporates advanced

schematic capture capabilities integrated with f i l l analogldigital

SPICE simulation. It offers a single easy-to-use graphical interfacefor all design and analysis needs.

Easily Applicable Graphical Layout Editor or EAGLE as its

abbreviation. EAGLE is mainly used by me to transfer the schematic

circuit to PC layout

2. Breadboard and components for early phase of the project

The schematics circuitry will be applied to breadboard with all

components that are needed.

For bigger schematics circuitry etching based circuit method will be

proceeded.

No protoboard will be used for all circuit because two times job will

be t costly.

3. Multimeter and Oscilloscope for testing

For each increment or decrement for each input voltage and the result

of the output voltage. The value of each can be observed by using

multimeter.



To see the waveform for output C voltage, oscilloscope will be used.

The output waveform can show how smooth the output voltage will

be.

1 5 roject Significant

This project could deliver a few benefits which are providing solution for

Electric power conversion for almost electrical utility that covers domestic use. The

power supply is restricted to single phase only. Other than that, it also provides an

alternative to those expensive power converters that s available in the market today.

Even though this is an amateur project, this might be considered as a starting point.

Any mistakes or error can be reduced by repeating a few steps that will lead to

improvement from time to time. The power converter is not promised to be as good

as the one that is proven to be the best seller. Since it is not meant to be

commercialized and will never be scrutinized by S R M or any related authority, the

normal usage for consumer s load is not promised. This is because there are a lot of

things that should be done to the design to ensure its reliability and stability. Due to

time constraints, the detailed process for this project won t be settled. But at least it

could be a more economical way for those who can t afford such expensive

converter.



1 6 xpected esults

The final result is expected to be a flexible electric power converter which

is able to support three operating modes which is AC to D rectifier) andD o D

(chopper). Even electricity source and the load have difference in terms of voltage

type t is hoped that this dev ice will connect both of it together.

Switching method that will be use for each converter is PWM in conjunction

to trigger MOSFET or IGBT switch. It s understood that both of them do haveadvantages and disadvantages of their own. So smart choice should be done while

designing and sim ulating which is the current step right now.

The targe t user for this device is only home application only. Continuous and

non-fluctuated power delivery is the most important thing in this project.



CH PTER

LITER TUREREVIEW

2 1 ntroduction

Literature review and project methodology are two crucial steps for the

completion of this project. A literature review is an account of what has been

published on a topic by accredited scholars and researchers. The purpose is to

understand what knowledge and ideas have been established on a topic and what

their strengths and weaknesses are. The first step of doing literature review is

focusing on problem formulation where a topic or field is being examined. Second

step is literature search where the aim is to find materials relevant to the subject

being explored. Third step is data evaluation where one has to determine which

literature makes a significant contribution to the understanding of the topic. Finally

analysis and interpretation where one has to discuss the findings and conclusions of

pertinent literature.

The result later will be come in handy as a supportive reference for the

project title. It is also a result of the compilation of a series of material from all kind

of sources. The sources can e from all kinds of reading materials which include

books ournals technical reports projectlresearch papers and etc. For this project



the materials have been used re reference books, thesis s, projectlresearch papers,

and technical reports from the library, internet and organizational journals such s of

EEE The details of the literature study and the project methodology is under the

two sections below. All the reference that been use re approved by international

bodies.

2 2 Facts and Finding

After doing a few research and information seeking, there are a few literature

review that been done by several engineers where their paperwork is quire useful to

be treat s a guideline for this project.

2 2 1 PC Based Integrated Power Converter

This paper was done by Ikis Rohadikisno and Martin Roekman from Fakultas

Teknik Universitas Indonesia, s a part of their project. For this design, it is observed

that they were using the integrated form of push pull inverter, full wave inverter and

half wave rectifier to generate 4 operating modes of AC/DC, DC/DC, DC/AC or

AC/AC. All three circuit are working together so all 4 modes can be used at the same

time. In other words, each circuit is dependant to each other. To control voltage level

and frequency, special software is developed and can be controlled through

computer. There is a microcontroller in between computer and the converter circuit

to achieve a connection between those two. So, there are 3 major section in this

project which are electric circuitry, microcontroller design and software

development.



Figure 2 1: PC based Integrated Power Converter

This kind of project can be considered as hlly computerized. The operation

of this project is simplified in the block diagram shown above. All four converters

re depends on the push pull inverter and the push pull inverter s operation is

controlled by pulse that is generated by microcontroller. The basic operation of the

microcontroller is 16-bit digital divider. It will process the received signals from

personal computer to 3 digital counters respectively. The sequence of the counter is

determined by the value of desired output whether AC output or D output.

In conclusion, the aim of PC based Integrated Power Converter is to connect

as much as possible between two different source and load even thought there re

differences in matter of frequency or typ of voltage. Integration of three typ of

converters in elementary will create a scheme where it will work it four different

conversion mode at a time. The digital triggering control is defined by setting the

value of alpha for firing angle method in switching scheme and controlling the

frequency by using computer.



There are a few things obtained from this research paper where the idea of

creating a flexible electric power converter by using different circuits is done.

These circuits are not meant to control specified mode of conversion but the

manipulation of digital controller enable the circuits to do four function of

conversion mode one at a time. So h m his paper it generate an idea of using one

type of switching mode that can be use for all conversion method where quite

beneficial in the process o f this project.

2 2 2 Dc Ripple arrent Reduction Method On Single Phase PWM Voltage

Source onverter

This paperwork which were proposed by Toshihisa Shimim Yasuhiro

Fujioka Gunji Kirnura h m Tokyo Metropolitan University introduces a single

phase PWM voltage source converter and related control method that can produce

not only a sinusoidal input current but also zero-ripple output current The main

circuit of this converter is composed of a conventional single phase PWM voltage

source converter and a ripple reduction circuit. The ripple reduction circuit is

composed of an additional switching leg an inductor and a switching leg that is

shared with the PW M converter.

The input current control is achieved by the conventional high-frequency

PWM current control technique. On the other hand D ipple reduction control is

associated with some difficulties because one of the switching legs in the ripple

reducing portion is shared with the PWM converter portion. In order to reduce the

D ripple current the inductor current at the ripple reducing portion must be

maintained to the adequate value which is deeply influenced by the modulation

factor on the PW M converter. The effectiveness of this circuit was confined by these

researchers experimentally and by simulation. The converter is useful for D power

supplies particularly in the case in which batteries are connected to the D ine.



The generation of harmonics and their subsequent propagation into utility

lines is a topic of increasing concern for power supply authorities. To reduce

harmonics in power lines, unity power factor PWM converters are used. However,

single-phase PWM converters have serious defects including low fkquency ripple

current which appears on the DC output increases in proportion to the input current

into the PWM converter, resulting in low frequency ripple voltage in the DC output

Therefore, a very large capacitor or a passive L C filter circuit is generally

connected to the DC ine in order to reduce low fkquency ripple voltage.

This proposed scheme does not covers the whole aspect of a converter but the

method that is used for reducing DC ipple current is quite important in the task of

designing chopper circuit. Smooth output waveform fkom DC DC onverter ensures

that the power output will be delivered constantly to match with the load needs. Even

the ripple is not fully eliminated; it is reduced at quite satisfying level. The usage of

thisDC ipple reduction really helps PWM to maintain theD output level.

2.2.3 A Single Stage Single Switch Power Factor Corrected ACIDC Converter

This title were proposed by M Daniele, P. Jain , and G. Joos fkom

Department of Electrical and Computer Engineering, Concordia University, Canada.

It describes a concept of single stage single switch isolated converter topology to

achieve a regulated dc output voltage having no low frequency components and a

high input power factor. The topology is derived fiom the basic forward converter,

but incorporates an additional transformer winding, an inductor, and a few diodes.

The proposed circuit by this trio inherently forces the input current to be

discontinuous and ac modulated to achieve high input power factor. Both duty cycle

and variable fkquency controls are used to regulate the output voltage and to

minimize dc capacitor voltage variations. Analysis of the converter is presented and

performance characteristics are given. Further, design guidelines to select critical



components of the circuit are presented. Finally, experimental results on a 50W, 110

Vac to 5 Vdc converter re given which confirm the high efficiency and high power

factor features of the proposed topology.

The focus of this paperwork is to do power factor correction where it

becomes mandatory on modern single phase power supply to meet more strict

requirement such as define in a few I standards. Previously, a few other

researchers have made the project of two stages power factor correction circuits. But,

it reduce the operation efficiency, producing low power output density and

increasing the cost as more components have to be used. In contrary, single stage

circuits also have its disadvantages. First, D output voltage contains a large low

fiequency voltage ripple component and second, the control and power circuits re

more complex.

In order to overcome this, they have decided to do a single stage single switch

isolated converter to achieve a regulated dc output voltage having no low fiequency

components and a high input power factor. It is actually a basic forward converter

but incorporates and addition transformer winding, an inductor, and three additional

diodes which naturally forces the input current to be discontinuous and ac modulated

so producing high power factor. As a result, they achieve an overall efficiency of

80 , input power factor at 0.96 which is considered as high and near to unity, and

low fiequency output voltage ripple component.

By referring to this study, it is understand that power factor correction is

important to get high efficiency and regulated output voltage for rectifier. Without a

doubt, it has been shown that the combination of PWM and variable fiequency

controls result in lower voltage stresses and higher no load to full-load efficiency.



CH PTER

PROJECT METHODOLOGY

3 1 Introduction

This project is begun right after the project title received from supervisor. At

first supervisor will sk he student to give a brief overview regarding to the selected

project title and the student must understand what he or she is going to do to carry on

the project. After the proposed project title have been approved by the supervisor,

research and literature studies will be camed out to get the clearer view on what

other people do and what we can gain from their knowledge in order to implement

the idea in this project. These s teps are done by referring to related reading materials

such s hesis, project paper, journals, and articles.

After sufficient information is gained and proper understanding about the

fbndernentals is well prepared the design and simulation process can be started.

There are two softwares that are considered to be used for simulation and design

which re Multisim and EAGLE Easily Applicable Graphical Layout Editor). Even

though OrC D Pspice is said to be the best electrical simulation software that is



available around, after quite sometime, I found some difficulties to use it due to the

fact that there are quite number of desired component that could not be found and the

simulation phase encountered errors quite often. That s why it is not chosen to be

used.Then, when both circuits have been designed and simulated, component

searching step will be started. The circuit must be finalized so there will be no

changes because once components are bought, it have to be used. Any changes will

resulting higher cost than expected. This is not good because budget allocation for

this project is quite limited. Even if the required component exists in the simulation

software, it is not guaranteed that the same component is available in the market.

This can be considered a big problem because if this happens, it might slow down the

flow of the project. This will be a domino effect where other steps will be affected

because the dependency o f the postponed step. If this problem is dragged to a quite

long period, it could be a big factor that contributes to the failure of the project.

Component installation step will be implemented after all equipments,

component and every required item are in hand. For starter breadboard will be used

as the base for each circuit so testing can be done fiom time to time to see whether

the components and the whole circuit can sustain in a long period. After achieving

satisfaction on the circuit performance, the drawn lines on the circuit will be

transferred to a blank etching board s etching process can be done as a final step.

Etching process will be explained in detail in chapter 5.

Etching process could require an intricate work details because any faults on

the copper lining will affect the whole circuit operation. Proper work is a must for

this step s it won t spoil the whole circuit. Then, drilling process for each

component s lead will be done on the etching board. Soldering job will be proceeded

for all the components. Finally, all connection among etched lines and components

will be checked. Then, input and output voltage testing will be conducted and the

results will be used for analysis.



3 2 lowChart

S T RT

LrnR AI1T RE REVIEW, RESEARCA ND PROBLEMMI LYSIS

FINDING SOLUTIONS FOR PROBLEMS

PROCEEDW Ta HARDWARE DESIGN USING SOFIWARE

SIMULATION ANDO

ANALYZING CIRCUITS

HARDWARE TESTING

CIRCUIT NDCOMPONENTS INSTALLATION

HARDWARE REALIZATION ND FINALIZATION



3 3 Project Schedule and ilestone

This section states the project schedule and milestone which would be the

main timehme guideline for the PSM project. Schedule date will be started fiom the

PSM 1 seminar and end by the submission of the finalized PSM 2 final report. The

section below section is the table of project milestone.

Deliverables

Topic

Suggestion

Form

Progress

Evaluation

Form PSM 1-

1

Project

Proposal

FormComponents

Application

Form

Item

1.

2.

3.

4.

5.

6

7.

8.

9.

End Date

13/7/05

28/7/05

4/8/05

4/8/05

11/8/05

11/8/05

2 1/9/05

2 1/9/05

Activity

PMS 1 seminar

compulsory)Project Topic and

Supervisor Confirmation

Project Topic Approval

by PSM committee

Submission of Progress

Evaluation Form PSM 1-

1

Research on Literature

Review of the Topic

Submission of Project

Proposal Form

Application of

Components Related to

the Project Opened

Research on Journals

Project Paper Thesies

and TechnicaVLab report

on the topic

Analysis Problem and

Establish Problem

Statement

Duration

Od

15d

2d

Od

7d

7d

41d

41d

Start Date

13/7/05

13/7/05

28/7/05

4/8/05

4/8/05

4/8/05

11/8/05

11/8/05



Table 3.1: Project Milestones PSM 1

ProgressEvaluationForm PSM 1-2SlidePresentation

Evaluation

ProgressPresentationSupervisor)

ProgressEvaluationForm PSM 1-

3ProgressPresentationSupervisor)

CourseWithdrawalFormProgressEvaluationForm PSM 1-4Present PSM1 FinalReportSupervisor)

PSM I Reportand PSMActivity og

ook

25/8/05

2 1/9/05

21 19/05

29/9/05

29/9/05

30/9/05

2011 0105

13/10/05

27110105

Od

7d

8d

Od

21d

Od

Od

14d

Od

10.

11.

12.

13.

14.

15.

16.

17.

18.

25/8/05

28/9/05

29/9/05

29/9/05

2011 0105

30/9/05

2011 0105

27110105

27110105

Submission of ProgressEvaluation Form PSM 12

PSM 1 Presentation andEvaluation

Circuit Design,Simulation and Analysis

Submission of ProgressEvaluation Form PSM 1-3

Circuit Design,Simulation and Analysis

Withdrawal from PSM 1Course


Producing PSM 1 FinalReport

Submission of PSM 1Final Report



Table 3.2 Project M ilestones PSM 2

ProgressEvaluationForm PSM2-1

ProgressEvaluationForm PSM2-2ProgressEvaluationForm PSM2 -3

CourseWithdrawal

FormEvaluation

bysupervisorSlides shoulde completed

and gonethroughSlide

PresentationEvaluationEvaluation

bysupervisorpanelCorrection

2 copiesverified bysupervisor

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

30.

3 1.

Od

96d

Od

Od

Od

Od

Od

Od

4d

3d

Od

Od

d

PMS 2 seminarcompulsory)

Component Wu rem en t ,

Hardware Development

and Modification


Start on frnal reportwritingSubmission of ProgressEvaluation Form PSM 2-2


Withdrawal from PSM 2Course


Preparation for PSM 2presentation

PSM 2 Presentation and

Evaluation


Collection of PSM 2Final ReportSubmission of FinalizedPSM 2 Final Report

0410 1106

27/12/05

23/01/06

2410 1106

20/02/06

20/03/06

17/03/06

29/03/06

0 1/04/06

05/04/06

12/04/06

19/04/06

04/05/06

0410 1106

3 1/03/06

23/01/06

2410 1106

20/02/06

20/03/06

17/03/06

29/03/06

04/04/06

07/04/06

12/04/06

19/04/06

04/05/06



3 4 roject Gantt hart

Table 3.3 Project Gantt Chart

PER NC NG N PROJEKPROJECT PLANNING

Senaraikan aktiviti-aktiviti utarna bagi projek yang dicad angkan . Nyatakan jangka m asa yang diperlukan bagi setiap aktiviti.List major activities involved in the proposedproject. Indicate duration of each activity to the related

ktiviti Projek

Project ActivitiesDiscussing the title of the project Flexible Electric Pow er Converter)

Literature Study

Circuit Design

Simulation

Constructing the con verter circuit

Integrating ll circuit design and d evice housing

Device T esting

Constructing the final device

Report writing and final presentation

month@ .

2006

X X X

2005

X X X

X

X X X X X

X

X

J J S O N D J F M M J

X

X

X

X X X

X X X



CHAPTER

DESIGNING ND H RDW RE IMPLEMENTATION

4 1 Chopper

This part will explains on how the chopper is designed and includes a bit of

elaboration on how chopper circuit works.

4 1 1 Introduction

Chopper is a Dc to dc converter. It s a power electronic circuits that convert a

dc voltage to a different dc voltage level, often providing a regulated output buck

converter or stepdown switch mode power supply can also e called a switch mode

regulator. Popularity of a switch mode regulator is due to its fairly high efficiency

and compact size and a switch mode regulator is used in place of a linear voltage

regulator at relatively high output. Linear voltage regulators tend to e inefficient. [ ]



Since the power devices used in linear regulators have to dissipate a fairly

large amount of power, they have to be adequately cooled, by mounting them on

heatsinks and the heat is transferred from the heatsinks to the surrounding air either

by natural convection or by forced-air cooling. Heatsinks and provision for cooling

makes the regulator bulky and large. In applications where size and efficiency are

critical, linear voltage regulators cannot be used.

A switch mode regulator overcomes the drawbacks of linear regulators.

Switched power supplies are more efficient and they tend to have an efficiency of

80 or more. They can be packaged in a f'raction of the size of linear regulators.

Unlike linear regulators, switched power supplies can step up or step down the input

voltage.[4]

4 1 2 Linear Voltage Regulators

Before discussing switched-mode converters, it is usefil to understand the

motivation for an alternative to linear dc--dcconverters. One method of converting a

dc voltage to a lower dc voltage is the simple circuit shown below:

Figure 4 1 A Basic Linear Regulator

The output voltage is:



where the load current is controlled by the transistor. By adjusting the transistor base

current, the output voltage may be controlled over a range of to roughly Vs. The

base current can be adjusted to compensate for variations in the supply voltage or the

load, thus regulating the output. This type of circuit is called a linear dc-dc converter

or a liner regulator because the transistor operates in the linear region rather than in

the saturation or cutoff region [I]. The transistor, in effect, operates s a variable

resistance.

While this may be a simple way of convertinga dc supply voltage to a lower

dc voltage and regulating the output, the low efficiency of this circuit is a serious

drawback for power applications. The power absorbed by the load is VJL, and the

power absorbed by the transistor is VcJL, assuming a small base current. The power

loss in the transistor makes this circuit inefficient. For example, if the output voltage

is onequarter of the input voltage, the load resistor absorbs one-quarter of the power

source, which is an efficiency of 25 . The transistor absorbs the other 75 of the

power supplied by the source. Lower output voltages result in even lower

efflc iencies. [4]

4 1 3 asic Switching Converter

An efficient alternative to the linear regulator is the switching converter. In a

switching converter circuit, the transistor operates s an electronic switch by being

completely on or completely off saturation or cutoff for a BJT . This circuit is also

known as a dc chopper.

Assuming the switch is ideal. The output is the same as the input when the

switch is closed, and the output is zero when the switch is open. Periodic opening

and closing of the switch results in the pulse output [I]. The pulse and ideal circuit is

shown s below



Figure 4 2:

a A basic dc-dc switching converter b Switching equivalent

c Output Voltage

The dc component of the output is controlled by adjusting the duty ratioD

which is the fraction of the period that the switch is closed:

D =-

tonton of

where is the switching frequen y in hertz. The dc component of the output will be

less than or equal to the input for this circuit. [ ]



4 1 4 Switching ethod

A transistor made by International Rectifier is used The model is IRFP264

which is HEXFET power MOSFET The reason why IRFP264 is chosen due to its

special charac teristics like:

Dynamic dvldt Rating

Repetitive Avalanche Rated

Isolated Central Mounting Hole

Fast Switching

Ease of Paralleling

Simple Drive Requirements

Figure 4 3: Symbol of IRFP264 MOSFET transistor

TO 247AC

Figure 4 4: IRFP264 actual look

flexible electrhhhic power converter - ismail b mohamad - tk7872.r35.i85 2006

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