Solartrackingsystem Report 130603013827 Phpapp01

8/16/2019 Solartrackingsystem Report 130603013827 Phpapp01

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1. INTRODUCTION

One of the most promising renewable energy sources characterized by a huge potential of conversion into

electrical power is the solar energy. The conversion of solar radiation into electrical energy by Photo-Voltaic

(PV) effect is a very promising technology being clean silent and reliable with very small maintenance

costs and small ecological impact. The interest in the Photo Voltaic conversion systems is visibly reflected

by the e!ponential increase of sales in this mar"et segment with a strong growth pro#ection for the ne!t

decades. $ccording to recent mar"et research reports carried out by %uropean Photovoltaic &ndustry

$ssociation (%P&$) the total installed power of PV conversion e'uipment increased from about * in

+,,up to nearly + * in +,,.

The continuous evolution of the technology determined a sustained increase of the conversion efficiency of

PV panels but nonetheless the most part of the commercial panels have efficiencies no more than +,/. $

constant research preoccupation of the technical community involved in the solar energy harnessing

technology refers to various solutions to increase the PV panel0s conversion efficiency. $mong PV efficiency

improving solutions we can mention1 solar trac"ing optimization of solar cells geometry enhancement of

light trapping capability use of new materials etc. The output power produced by the PV panels depends

strongly on the incident light radiation.

The continuous modification of the sun-earth relative position determines a continuously changing of

incident radiation on a fi!ed PV panel. The point of ma!imum received energy is reached when the direction

of solar radiation is perpendicular on the panel surface. Thus an increase of the output energy of a given PV

panel can be obtained by mounting the panel on a solar trac"ing device that follows the sun tra#ectory.

2nli"e the classical fi!ed PV panels the mobile ones driven by solar trac"ers are "ept under optimum

insolation for all positions of the 3un boosting thus the PV conversion efficiency of the system. The output

energy of PV panels e'uipped with solar trac"ers may increase with tens of percents especially during the

summer when the energy harnessed from the sun is more important. Photo-Voltaic or PV cells "nown

commonly as solar cells convert the energy from sunlight into 45 electricity. PVs offer added advantagesover other renewable energy sources in that they give off no noise and re'uire practically no maintenance. $

trac"ing system must be able to follow the sun with a certain degree of accuracy return the collector to its

original position at the end of the day and also trac" during periods of cloud over.

The ma#or components of this system are as follows.

• 6ight dependent resistor

• 7icrocontroller.

•Output mechanical transducer (stepper motor)

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1.1 Background

$ 3olar Trac"er is a device onto which solar panels are fitted which trac"s the motion of the sun across the

s"y ensuring that the ma!imum amount of sunlight stri"es the panels throughout the day. The 3olar Trac"er

will attempt to navigate to the best angle of e!posure of light from the sun. This report aims to let the reader

understand the pro#ect wor" which & have done. $ brief introduction to 3olar Panel and 3olar Trac"er is

e!plained in the 6iterature 8esearch section. 9asically the 3olar Trac"er is divided into two main categories

hardware and software. &t is further subdivided into si! main functionalities1 7ethod of Trac"er 7ount

4rives 3ensors 8T5 7otors and Power 3upply of the 3olar Trac"er is also e!plained and e!plored. The

reader would then be brief with some analysis and perceptions of the information.

9y using solar arrays a series of solar cells electrically connected a 45 voltage is generated which can be

physically used on a load. 3olar arrays or panels are being used increasingly as efficiencies reach higher

levels and are especially popular in remote areas where placement of electricity lines is not economically

viable. This alternative power source is continuously achieving greater popularity especially since the

realisation of fossil fuels shortcomings. 8enewable energy in the form of electricity has been in use to some

degree as long as :; or ,, years ago. 3ources such as 3olar *ind in the morning and the

evening. $t such an angle the light gathering ability of the cell is essentially zero resulting in no output. $s

the day progresses to midday the angle of incidence approaches ,> causing a steady increase in power until

at the point where the light incident on the panel is completely perpendicular and ma!imum power is

achieved. $s the day continues toward dus" the reverse happens and the increasing angle causes the power

to decrease again toward minimum again. ?rom this bac"ground we see the need to maintain the ma!imum

power output from the panel by maintaining an angle of incidence as close to ,> as possible. 9y tilting the

solar panel to continuously face the sun this can be achieved. This process of sensing and following the

position of the sun is "nown as 3olar Trac"ing. &t was resolved that real-time trac"ing would be necessary to

follow the sun effectively so that no e!ternal data would be re'uired in operation.



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2. Literature Research

This chapter aims to provide a brief "nowledge of 3olar Panel 3olar Trac"er and the components which

made up 3olar Trac"er.

2.1 Technology of olar !anel

3olar panels are devices that convert light into electricity. They are called solar after the sun because the sun

is the most powerful source of the light available for use. They are sometimes called photovoltaic which

means @light-electricity@. 3olar cells or PV cells rely on the photovoltaic effect to absorb the energy of the

sun and cause current to flow between two oppositely charge layers. $ solar panel is a collection of solar

cells. $lthough each solar cell provides a relatively small amount of power many solar cells spread over a

large area can provide enough power to be useful. To get the most power solar panels have to be pointed

directly at the 3un. The development of solar cell technology begins with A research of ?rench physicist

$ntoine-5esar 9ec'uerel.


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the Borthern


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$. !ro%ect Descri&tion

$.1 Block Diagra'

Fig 3.1 Block Diagram of Project

$.2 che'atic Diagra'

?ig .+ 3chematic 4iagram of Pro#ect



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$.$ !RINT"D CIRCUIT BO(RD

$lmost all circuits encountered on electronic e'uipment (computers TV radio industrial control e'uipment

etc.) are mounted on printed circuit boards. 5lose inspection of a P59 reveals that it contains a series of

copper trac"s printed on one or both sides of a fiber glass board. The copper trac"s form the wiring pattern

re'uired to lin" the circuit devices according to a given circuit diagram.


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?ig .D 3ingle sided P59

Dou,le+sided !CB

4ouble-sided P59s have copper trac"s on both sides of the board. The trac" layout is designed so as not to

allow shorts from one side to another if it is re'uired to lin" points between the two sides electrical

connections are made by small interconnecting holes which are plated with copper during manufacture.

?ig .; 4ouble sided P59

-ulti+layer !CB

&n multi-layer P59s each side contains several layers of trac" patterns which are insulated from one another.

These layers are laminated under heat and high pressure. $ multi-layer P59 is shown in ?igure .E

?ig .E 7ulti layered P59

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2) -(IN/ ( !CB

P59Cs commonly available on the mar"et are not particular circuits but are available as copper clad boards.

&n other words the whole area of one or both sides of the board is coated with copper. The user then draws

his trac" layout on the copper surface according to his circuit diagram. Be!t the untraced copper area

removed by a process called etching.


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• 2ltra-violet e!posure unit

Track layout design

2sing the same principles outlined in section a trac" layout is drawn to scale on the transparency using the

white boardC mar"er. &t may be useful to insert graph paper below the transparent sheet for accurate

dimensioning of the layout.

!hoto+etching

The principle behind photo-etching is to place the transparency over the copper clad and to e!pose it to 2V

radiation hence leaving the trac" regions intact and softening unused areas. ?irst the protective plastic film

is removed from the board. The traced transparency is then placed over the board being careful to ensure

that the copper side of the design faces upwards. The combination is ne!t placed in a 2V e!posure unit with

the transparency facing the fluorescent tubes inside the unit. $t the trac" regions 2V radiation is prevented

from reaching the board and hence the photo sensitive remains hardened in these regions. $fter an e!posure

of about ; minutes the board can be removed. The P59 is then placed in a solution of caustic soda which

dissolves away any unhardened photo-sensitive area. $fter a few minutes of development time the trac"

layout is apparent. The board is finally removed and rinsed in cold water.

inal etching

$fter having allowed the trac"s to harden for about half an hour the unmar"ed copper area is etched byferric chloride solution.

$) The folloing &oints should ,e noted*

• &t is a good idea to draft the trac" layout on graph paper before drawing the final layout on the copper

clad.

• 2se an etch resist pen to draw the trac" layout on the copper clad (the latter must be cleaned

initially).• The following lead spacing can be used as a rule of thumb1 allow , mm for a =D * resistor A mm

for a signal diode D mm for 6%4Cs and ceramic capacitors. The lead spacing may also be measured

before drawing.

• Terminals for the power supply input leads must also be included on the layout.

• The arrangement of components must be well planned so as to minimize the amount of cooper clad

board re'uired.

• $llow the in" to dry before etching.

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3) "tching

The copper clad is now ready to be etched. &f the etchant is available in powder form it needs to be mi!ed

with water in anon-corrodible container. $ powder to water ratio of +1; by mass is about right. %tching time

may vary between , to as long as , minutes depending on the concentration and temperature of the

etchant. The process can be accelerated by warming the solution and by fre'uently agitating the etching bath.

The ferric chloride solution gradually dissolves any untraced copper area. *hen etching is complete only

the trac" layout remains on the board. The latter is then removed the bath and rinsed with clean water. The

etch resist in" is finally rubbed away with a P59 eraser or with very fine grain sand paper.

-aking a !CB out of a &hoto+resist co&&er clad ,oard

The photo-resist board consists of a single or double sided copper clad coated with a light-sensitive and the

latter is protected with a plastic which should be removed before use. &ts advantage over the plain copper

clad board is that the trac" layout does not need to be drawn directly on the board.

The use of etch+resist transfers

The use of pens to design trac" layouts may not give neat result even when using a ruler. ?or instance it

may be difficult to draw trac"s with the same line *idth or to draw well aligned terminals for &5Cs and

discrete devices %tch-resist P59 symbols and trac"s are available for direct transfer to the copper clad or tothe transparency. Transfer is by rubbing down the relevant symbol with a soft pencil.

1#info4eee | Information For Electrical & Electronics Engineering


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3. Co'&onents Descri&tion

3.1 olar Tracker

3olar Trac"er is basically a device onto which solar panels are fitted which trac"s the motion of the sun

across the s"y ensuring that the ma!imum amount of sunlight stri"es the panels throughout the day. $fter finding the sunlight the trac"er will try to navigate through the path ensuring the best sunlight is detected.

The design of the 3olar Trac"er re'uires many components. The design and construction of it could be

divided into si! main parts that would need to wor" together harmoniously to achieve a smooth run for the

3olar Trac"er each with their main function. They are1

• 7ethods of Trac"er 7ount

• 7ethods of 4rives

• 3ensor and 3ensor 5ontroller

• 7otor and 7otor 5ontroller

• Trac"er 3olving $lgorithm

• 4ata $c'uisition=&nterface 5ard

3.2-ethods of Tracker -ount

1. ingle a4is solar trackers

3ingle a!is solar trac"ers can either have a horizontal or a vertical a!le. The horizontal type is used in

tropical regions where the sun gets very high at noon but the days are short. The vertical type is used in high

latitudes where the sun does not get very high but summer days can be very long. The single a!is trac"ing

system is the simplest solution and the most common one used.

2. Dou,le a4is solar trackers

4ouble a!is solar trac"ers have both a horizontal and a vertical a!le and so can trac" the 3unCs apparent

motion e!actly anywhere in the *orld. This type of system is used to control astronomical telescopes and so

there is plenty of software available to automatically predict and trac" the motion of the sun across the s"y.

9y trac"ing the sun the efficiency of the solar panels can be increased by ,-D,/.The dual a!is trac"ing

system is also used for concentrating a solar reflector toward the concentrator on heliostat systems.

3.$ -ethods of Dri#e

1. (cti#e Trackers

$ctive Trac"ers use motors and gear trains to direct the trac"er as commanded by a controller responding

to the solar direction. 6ight-sensing trac"ers typically have two photo sensors such as photodiodes



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configured differentially so that they output a null when receiving the same light flu!. 7echanically they

should be omnidirectional and are aimed , degrees apart. This will cause the steepest part of their cosine

transfer functions to balance at the steepest part which translates into ma!imum sensitivity.

2. !assi#e Trackers

Passive Trac"ers use a low boiling point compressed gas fluid that is driven to one side or the other by solar

heat creating gas pressure to cause the trac"er to move in response to an imbalance.

3.3 ensors

$ sensor is a device that measures a physical 'uantity and converts it into a signal which can be read by an

observer or by an instrument.

1. Light De&endent Resistor

6ight 4ependent 8esistor is made of a high-resistance semiconductor. &t can also be referred to as a

photoconductor. &f light falling on the device is of the high enough fre'uency photons absorbed by the

semiconductor give bound electrons enough energy to #ump into the conduction band. The resulting free

electron conducts electricity thereby lowering resistance.


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2. !hotodiode

Photodiode is a light sensor which has a high speed and high sensitive silicon P&B photodiode in a

miniature flat plastic pac"age. $ photodiode is designed to be responsive to optical input. 4ue to its water

clear epo!y the device is sensitive to visible and infrared radiation. The large active area combined with a

flat case gives a high sensitivity at a wide viewing angle. Photodiodes can be used in either zero bias or

reverse bias. &n zero bias light falling on the diode causes a voltage to develop across the device leading to

a current in the forward bias direction. This is called the photovoltaic effect and is the basis for solar cells -

in fact a solar cell is #ust a large number of big cheap photodiodes. 4iodes usually have e!tremely high

resistance when reverse biased. This resistance is reduced when light of an appropriate fre'uency shines on

the #unction.


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This application note describes how to implement an e!act linear speed controller for stepper motors. The

stepper motor is an electromagnetic device that converts digital pulses into mechanical shaft rotation. 7any

advantages are achieved using this "ind of motors such as higher simplicity since no brushes or contacts are

present low cost high reliability high tor'ue at low speeds and high accuracy of motion. 7any systemswith stepper motors need to control the acceleration=deceleration when changing the speed. This application

note presents a driver with a demo application capable of controlling acceleration as well as position and

speed.

?ig D. 3tepper 7otors

Theory

te&&er 'otor

This application note covers the theory about linear speed ramp stepper motor control as well as the

realization of the controller itself. &t is assumed that the reader is familiar with basic stepper motor operation

but a summary of the most relevant topics will be given.

Bi&olar #s. Uni&olar ste&&er 'otors

The two common types of stepper motors are the bipolar motor and the 2nipolar motor. The bipolar and

unipolar motors are similar e!cept that the 2nipolar has a centre tap on each winding as shown in ?igure D.D



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?ig D.D 9ipolar and 2nipolar stepper 7otor

Uni&olar ste&&er 'otor

3tepper motors are very accurate motors that are commonly used in computer dis" drives printers and

cloc"s. 2nli"e dc motors which spin round freely when power is applied stepper motors re'uire that their

power supply be continuously pulsed in specific patterns. ?or each pulse the stepper motor moves around

one step often ; degrees giving +D steps in a full revolution.There are two main types of stepper motors -

2nipolar and 9ipolar. 2nipolar motors usually have four coils which are switched on and off in a particular

se'uence. 9ipolar motors have two coils in which the current flow is reversed in a similar se'uence. %ach of

the four coils in a 2nipolar stepper motor must be switched on and off in a certain order to ma"e the motor

turn. 7any microprocessor systems use four output lines to control the stepper motor each output line

controlling the power to one of the coils. $s the stepper motor operates at ;V the standard transistor circuit

is re'uired to switch each coil. $s the coils create a bac" emf when switched off a suppression diode on

each coil is also re'uired. The table below show the four different steps re'uired to ma"e the motor turn.

Table D. 2nipolar stepper motor operation

te& Coil 1 Coil 2 Coil $ Coil 3

, ,

+ , ,

, ,

D , ,

, ,

6oo" carefully at the table D. and notice that a pattern is visible. 5oil + is always the opposite or logical

BOT of coil . The same applies for coils and D. &t is therefore possible to cut down the number of

microcontroller pins re'uired to #ust two by the use of two additional BOT gates. ?ortunately the 4arlington



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driver &5 26B+,, can be used to provide both the BOT and 4arlington driver circuits. &t also contains the

bac" emf suppression diodes so no e!ternal diodes are re'uired.

Bi&olar te&&er 'otor

The bipolar stepper motor has two coils that must be controlled so that the current flows in different

directions through the coils in a certain order. The changing magnetic fields that these coils create cause the

rotor of the motor to move around in steps.

The bipolar motor needs current to be driven in both directions through the windings and a full bridge

driver is needed as shown in ?igure D.; (a). The centre tap on the 2nipolar motor allows a simpler driving

circuit shown in ?igure D.; (b) limiting the current flow to one direction. The main drawbac" with the

2nipolar motor is the limited capability to energize all windings at any time resulting in a lower tor'ue

compared to the bipolar motor. The 2nipolar stepper motor can be used as a bipolar motor by disconnectingthe centre tap.

(a) (b)

?ig D.; 9ipolar and 2nipolar drivers with 7O3 transistors

I'&le'entation

$ wor"ing implementation written in 5 is included with this application note. ?ull documentation of the

source code and compilation information is found by opening the Greadme.html0 file included with the source

code. The demo application demonstrates linear speed control of a stepper motor. The user can control the

stepper motor speed profile by issuing different commands using the serial port and the $V8 will drive the

connected stepper motor accordingly. The demo application is divided in three ma#or bloc"s as shown in the



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bloc" diagram in ?igure D.E. There is one file for each bloc" and also a file for 2$8T routines used by the

main routine.

?ig D.E 9loc" diagram of demo application

7ain c has a menu and a command interface giving the user control of the stepper motor by a terminal

connected to the serial line. 3peed controller c calculates the needed data and generates step pulses to ma"e

the stepper motor follow the desired speed profile. 3mdriver.c counts the steps and outputs the correct

signals to control the stepper motor.

Ti'er interru&t

The timer interrupt generates the step pulses calls the function 3tep 5ounter ( ) and is only running when the

stepper motor is moving. The timer interrupt will operate in four different states according to the speed

profile shown in ?igure D.: and this behaviour is realized with a state machine in the timer interrupt shown

in ?igure D.A.

?ig D.: Operating states for different speed profile parts



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?ig D.A 3tate machine for timer interrupt

*hen the application starts or when the stepper motor is stopped the state-machine remains in the state

3TOP. *hen setup calculations are done a new state is set and the timer interrupt is enabled. *hen moving

more than one step the state-machine goes to $55%6. &f moving only step the state is changed to 4%5%6.

*hen the state is changed to $55%6 the application accelerates the stepper motor until either the desiredspeed is reached and the state is changed to 82B or deceleration must start changing the state to 4%5%6.

*hen the state is set to 82B the stepper motor is "ept at constant speed until deceleration must start then

the state is changed to 4%5%6.&t will stay in 4%5%6 and decelerate until the speed reaches zero desired

number of steps. The state is then changed to 3TOP.

3.6 -icrocontroller

$ microcontroller is a single chip that contains the processor non-volatile memory for the program volatile

memory for input and output a cloc" and an &=O control unit also called a computer on a chip billions of

microcontroller units are embedded each year in a myriad of products from toys to appliances to

automobiles. ?or e!ample a single vehicle can use :, or more microcontrollers. The following picture

describes a general bloc" diagram of microcontroller.

eatures


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• %!tensive On-chip 4ebug 3upport

• Programming of ?lash %%P8O7 ?uses and 6oc" 9its through the JT$ &nterface

Peripheral ?eatures

• Two A-bit Timer=5ounters with 3eparate Prescalers and 5ompare 7odes

• One E-bit Timer=5ounter with 3eparate Prescalers 5ompare 7ode and 5apture

7ode

• 8eal Time 5ounter with 3eparate Oscillator

• ?our P*7 5hannels

• A-channel ,-bit $45

A 3ingle-ended 5hannels

: 4ifferential 5hannels in TK?P Pac"age Only

+ 4ifferential 5hannels with Programmable ain at ! ,! or +,,!

•

9yte-oriented Two-wire 3erial &nterface• Programmable 3erial 23$8T

• 7aster=3lave 3P& 3erial &nterface

• Programmable *atchdog Timer with 3eparate On-chip Oscillator

• On-chip $nalog 5omparator

3pecial 7icrocontroller ?eatures

• Power-on 8eset and Programmable 9rown-out 4etection

• &nternal 5alibrated 85 Oscillator

• %!ternal and &nternal &nterrupt 3ources

• 3i! 3leep 7odes1 &dle $45 Boise 8eduction Power-save Power-down 3tandby

and %!tended 3tandby

&=O and Pac"ages

• + Programmable &=O 6ines

• D,-pin P4&P DD-lead TK?P and DD-pad K?B=76?

Operating Voltages

• +.: - ;.;V for $TmegaE6

• D.; - ;.;V for $TmegaE

3peed rades

• , - A 7


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The $TmegaE is a low-power high-performance advance 8&35A-bit microcontroller with +I bytes of in-

system programmable ?lash memory. The on-chip ?lash allows the program memory to be reprogrammed

in-system or by a conventional non-volatile memory programmer. 9y combining a versatile A-bit 5P2 with

in-system programmable ?lash on a monolithic chip the $tmel $TmegaE is a powerful microcontroller

which provides a highly fle!ible and cost-effective solution to many embedded control applications. The

$TmegaE provides the following standard features1+I bytes of ?lash ,+D byte of %%P8O7 +I9

&BT%8B$6 3 8$7 + &=O lines *atch dog timer two data pointers two E-bit timer=counters a si!-

vector two-level interrupt architecture a full duple! serial port on-chip oscillatorA-channel , bit $45 and

cloc" circuitry. &n addition the $TmegaE is designed with static logic for operation down to zero fre'uency

and supports two software selectable power saving modes. The &dle 7ode stops the 5P2 while allowing the

8$7 timer=counters serial port and interrupt system to continue functioning. The Power-down mode saves

the 8$7 con-tents but freezes the oscillator disabling all other chip functions until the ne!t interrupt.

?ig D. Pin diagram of $TmegaE

O#er#ie+

The $TmegaE is a low-power 57O3 A-bit microcontroller based on the $V8 enhanced 8&35 architecture.

9y e!ecuting powerful instructions in a single cloc" cycle the $TmegaE achieves throughputs approaching

7&P3 per 7


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7CC 4igital supply voltage

/ND round

!ort ( 8!(9 + !(:) Port $ serves as the analog inputs to the $=4 5onverter. Port $ also serves as an A-bit

bi-directional &=O port if the $=4 5onverter is not used. Port pin scan provide internal pull-up resistors. The

Port $ output buffers have symmetrical drive characteristics with both high sin" and source capability. *hen

pins P$, to P$:are used as inputs and are e!ternally pulled low they will source current if the internal pull-

up resistors are activated. The Port $ pins are tri-stated when a reset condition becomes active even if the

cloc" is not running.

!ort B 8!B9 + !B:) Port 9 is an A-bit bi-directional &=O port with internal pull-up resistors. The Port 9

output buffers have symmetrical drive characteristics with both high sin" and source capability. $s inputs

Port 9 pins that are e!ternally pulled low will source current if the pull-up resistors are activated. The Port 9

pins are tri-stated when a reset condition becomes active even if the cloc" is not running.

!ort C 8!C9 + !C:) Port 5 is an A-bit bi-directional &=O port with internal pull-up resistors. The Port 5



pins are tri-stated when a reset condition becomes active even if the cloc" is not running. &f the JT$

interface is enabled; the pull-up resistors on pins P5; (T4&) P5 (T73) and P5+ (T5I) will be activated

even if a reset occurs.

!ort D 8!D9 + !D:) Port 4 is an A-bit bi-directional &=O port with internal pull-up resistors. The Port 4



pins are tri-stated when a reset condition becomes active even if the cloc" is not running.

R""T 8eset &nput. $ low level on this pin for longer than the minimum pulse length will generate a reset

even if the cloc" is not running.


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(R" $8%? is the analog reference pin for the $=4 5onverter.

(lternate unctions of !ort (

Port $ has an alternate function as analog input for the $45 as shown in Table D.+. &f some Port $ pins are

configured as outputs it is essential that these do not switch when a conversion is in progress. This might

corrupt the result of the conversion.

Table D.+ Port $ Pins $lternate ?unctions

!ort !in (lternate unction

P$: $45: ($45 input channel :)

P$E $45E ($45 input channel E)

P$; $45; ($45 input channel ;)

P$D $45D ($45 input channel D)

P$ $45 ($45 input channel )

P$+ $45+ ($45 input channel +)

P$ $45 ($45 input channel )

P$, $45, ($45 input channel ,)

The alternate pin configuration of Port 9 is as follows1

= C > !ort B; Bit 9

35I1 7aster 5loc" output 3lave 5loc" input pin for 3P& channel. *hen the 3P& is enabled as a 3lave this

pin is configured as an input regardless of the setting of 449:. *hen the 3P& is enabled as a 7aster the

data direction of this pin is controlled by 449:. *hen the pin is forced by the 3P& to be an input the pull-up

can still be controlled by the PO8T9: bit.

= -IO > !ort B; Bit 6

7&3O1 7aster 4ata input 3lave 4ata output pin for 3P& channel. *hen the 3P& is enabled as a 7aster this

pin is configured as an input regardless of the setting of 449E. *hen the 3P& is enabled as a 3lave the data

direction of this pin is controlled by 449E. *hen the pin is forced by the 3P& to be an input the pull-up can

still be controlled by the PO8T9E bit.

= -OI > !ort B; Bit 5

7O3&1 3P& 7aster 4ata output 3lave 4ata input for 3P& channel. *hen the 3P& is enabled as a 3lave this

pin is configured as an input regardless of the setting of 449;. *hen the 3P& is enabled as a 7aster the

data direction of this pin is controlled by 449;. *hen the pin is forced by the 3P& to be an input the pull-up

can still be controlled by the PO8T9; bit.

= > !ort B; Bit 3



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331 3lave 3elect input. *hen the 3P& is enabled as a 3lave this pin is configured as an input regardless of

the setting of 449D. $s a 3lave the 3P& is activated when this pin is driven low. *hen the 3P& is enabled as

a 7aster the data direction of this pin is controlled by 449D. *hen the pin is forced by the 3P& to be an

input the pull-up can still be controlled by the PO8T9D bit.

= (IN1?OC: > !ort B; Bit $

$&B $nalog 5omparator Begative &nput 5onfigure the port pin as input with the internal pull-up switched

off to avoid the digital port function from interfering with the function of the analog comparator. O5,

Output 5ompare 7atch output1 The P9 pin can serve as an e!ternal output for the Timer=5ounter ,

5ompare 7atch. The P9 pin has to be configured as an output to serve this function. The O5, pin is also

the output pin for the P*7 mode timer function.

= (IN:?INT2 > !ort B; Bit 2

$&B, $nalog 5omparator Positive input 5onfigure the port pin as input with the internal pull-up switched

off to avoid the digital port function from interfering with the function of the $nalog 5omparator. &BT+

%!ternal &nterrupt 3ource +1 The P9+ pin can serve as an e!ternal interrupt source to the 752.

= T1 > !ort B; Bit 1

T Timer=5ounter 5ounter 3ource.

= T:? !ort B; Bit :

T, Timer=5ounter , 5ounter 3ource 5I 23$8T %!ternal 5loc". The 4ata 4irection 8egister 449,

controls whether the cloc" is output 449, set or input 449, cleared. The 5I pin is active only when the

23$8T operates in 3ynchronous mode.

The alternate pin configuration of Port 5 is as follows1= TOC2 > !ort C; Bit 9

TO35+ Timer Oscillator pin +1 *hen the $3+ bit in $338 is set one to enable asynchronous cloc"ing of

Timer=5ounter+ pin P5: is disconnected from the port and becomes the inverting output of the Oscillator

amplifier. &n this mode a 5rystal Oscillator is connected to this pin and the pin cannot be used as an &=O pin.

= TOC1 > !ort C; Bit 6



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TO35 Timer Oscillator pin 1 *hen the $3+ bit in $338 is set one to enable asynchronous cloc"ing of

Timer=5ounter+ pin P5E is disconnected from the port and becomes the input of the inverting Oscillator

amplifier. &n this mode a 5rystal Oscillator is connected to this pin and the pin cannot be used as an &=O pin.

= TDI > !ort C; Bit 5

T4& JT$ Test 4ata &n1 3erial input data to be shifted in to the &nstruction 8egister or 4ata 8egister. *hen

the JT$ interface is enabled this pin cannot be used as an &=O pin.

= TDO > !ort C; Bit 3

T4O JT$ Test 4ata Out1 3erial output data from &nstruction 8egister or 4ata 8egister. *hen the JT$

interface is enabled this pin cannot be used as an &=O pin. The T4, pin is tri-stated unless T$P states that

shifts out data are entered.

= T- > !ort C; Bit $

T73 JT$ Test 7ode 3elect1 This pin is used for navigating through the T$P-controller state machine.

*hen the JT$ interface is enabled this pin cannot be used as an &=O pin.

= TC > !ort C; Bit 2

T5I JT$ Test 5loc"1 JT$ operation is synchronous to T5I. *hen the JT$ interface is enabled this

pin cannot be used as an &=O pin.

D( > !ort C; Bit 1

34$ Two-wire 3erial &nterface 4ata1 *hen the T*%B bit in T*58 is set one to enable the Two-wire

3erial &nterface pin P5 is disconnected from the port and becomes the 3erial 4ata &=O pin for the Two-wire

3erial &nterface. &n this mode there is a spi"e filter on the pin to suppress spi"es shorter than ;, ns on the

input signal and the pin is driven by an open drain driver with slew-rate limitation. *hen this pin is used by

the Two-wire 3erial &nterface the pull-up can still be controlled by the PO8T5 bit.

= CL > !ort C; Bit :

356 Two-wire 3erial &nterface 5loc"1 *hen the T*%B bit in T*58 is set one to enable the Two-wire

3erial &nterface pin P5, is disconnected from the port and becomes the 3erial 5loc" &=O pin for the Two-

wire 3erial &nterface. &n this mode there is a spi"e filter on the pin to suppress spi"es shorter than ;, ns on

the input signal and the pin is driven by an open drain driver with slew-rate limitation. *hen this pin is used

by the Two-wire 3erial &nterface the pull-up can still be controlled by the PO8T 5, bit.

3.9 LCD Dis&lay



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$ 6i'uid 5rystal 4isplay is an electronic device that can be used to show numbers or te!t. There are two

main types of 654 display numeric display and alphanumeric te!t displays. The display is made up of a

number of shaped Gcrystals0. &n numeric displays these crystals are shaped into Gbars0 and in alphanumeric

displays the crystals are simply arranged into patterns of Gdots0. %ach crystal has an individual electrical

connection so that each crystal can be controlled independently. *hen the crystal is Goff0 i.e. when no current

is passed through the crystal the crystal reflect the same amount of light as the bac"ground material and so

the crystals cannot be seen.


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?ig D. Transformer

&f a load is connected to the secondary circuit electric charge will flow in the secondary winding of the

transformer and transfer energy from the primary circuit to the load connected in the secondary circuit. The

secondary induced voltage V3 of an ideal transformer is scaled from the primary VP by a factor e'ual to the

ratio of the number of turns of wire in their respective windings1

N s

N p=

V s

V p

9y appropriate selection of the numbers of turns a transformer thus allows an alternating voltage to be

stepped up - by ma"ing B3 more than BP or stepped down by ma"ing it.

B(IC !(RT O ( TR(NOR-"R

&n its most basic form a transformer consists of1

• $ primary coil or winding.

• $ secondary coil or winding.

• $ core that supports the coils or windings.

8efer to the transformer circuit in figure as you read the following e!planation1 The primary winding is

connected to a ;,-hertz ac voltage source. The magnetic field builds up and collapses about the primary

winding. The e!panding and contracting magnetic field around the primary winding cuts the secondary

winding and induces an alternating voltage into the winding. This voltage causes alternating current to flow

through the load. The voltage may be stepped up or down depending on the design of the primary and

secondary windings.

TA" CO-!ON"NT O ( TR(NOR-"R

Two coils of wire are wound on some type of core material. &n some cases the coils of wire are wound on a

cylindrical or rectangular cardboard form. &n effect the core material is air and the transformer is called an



27/40

air-core transformer. Transformers used at low fre'uencies such as ;, hertz and D,, hertz re'uire a core of

low-reluctance magnetic material usually iron. This type of transformer is called an iron-core transformer.

7ost power transformers are of the iron-core type. The principle parts of a transformer and their functions

are1 The core which provides a path for the magnetic lines of flu!. The Primary winding this receives

energy from the ac source. The secondary winding this receives energy from the primary winding and

delivers it to the load. The enclosure this protects the above components from dirt moisture and mechanical

damage.

3.BRID/" R"CTII"R

$ bridge rectifier ma"es use of four diodes in a bridge arrangement to achieve full-wave rectification. This is

a widely used configuration both with individual diodes wired as shown and with single component bridges

where the diode bridge is wired internally.

Basic o&eration

$ccording to the conventional model of current flow originally established by 9en#amin ?ran"lin and still

followed by most engineers today current is assumed to flow through electrical conductors from the positive

to the negative pole. &n actuality free electrons in a conductor nearly always flow from the negative to the

positive pole. &n the vast ma#ority of applications however the actual direction of current flow is irrelevant.

Therefore in the discussion below the conventional model is retained. &n the diagrams below when the input

connected to the left corner of the diamond is positive and the input connected to the right corner is

negative current flows from the upper supply terminal to the right along the red(positive) path to the output

and returns to the lower supply terminal via the blue (negative) path.

?ig D.+ 9ridge rectifier

*hen the input connected to the left corner is negative and the input connected to the right corner is

positive current flows from the lower supply terminal to the right along the red path to the output and

returns to the upper supply terminal via the blue path.



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&n each case the upper right output remains positive and lower right output negative. 3ince this is true

whether the input is $5 or 45 this circuit not only produces a 45 output from an $5 input it can also

provide what is sometimes called @reverse polarity protection@. That is it permits normal functioning of 45-

powered e'uipment when batteries have been installed bac"wards or when the leads from a 45 power

source have been reversed and protects the e'uipment from potential damage caused by reverse polarity.

Prior to availability of integrated electronics such a bridge rectifier was always constructed from discrete

components. 3ince about ;, a single four terminal component containing the four diodes connected in the

bridge configuration became a standard commercial component and is now available with various voltage

and current ratings.

Out&ut s'oothing

?or many applications especially with single phase $5 where the full-wave bridge serves to convert an $5

input into a 45 output the addition of a capacitor may be desired because the bridge alone supplies an

output of fi!ed polarity but continuously varying or pulsating magnitude.

?ig D. 9ridge rectifier in parallel capacitor at the output

The function of this capacitor "nown as a reservoir capacitor is to lessen the variation in the rectified $5

output voltage waveform from the bridge. One e!planation of smoothing is that the capacitor provides a low

impedance path to the $5 component of the output reducing the $5 voltage across and $5 current through

the resistive load. &n less technical terms any drop in the output voltage and current of the bridge tends to be

cancelled by loss of charge in the capacitor. This charge flows out as additional current through the load.

Thus the change of load current and voltage is reduced relative to what would occur without the capacitor.

&ncreases of voltage correspondingly store e!cess charge in the capacitor thus moderating the change in

output voltage = current. The simplified circuit shown has a well-deserved reputation for being dangerous

because in some applications the capacitor can retain a lethal charge after the $5 power source is removed.

&f supplying a dangerous voltage a practical circuit should include a reliable way to safely discharge the

capacitor. &f the normal load cannot be guaranteed to perform this function perhaps because it can be

2!info4eee | Information For Electrical & Electronics Engineering


29/40

disconnected the circuit should include a bleeder resistor connected as close as practical across the

capacitor. This resistor should consume a current large enough to discharge the capacitor in a reasonable

time but small enough to minimize unnecessary power waste. 9ecause a bleeder sets a minimum current

drain the regulation of the circuit defined as percentage voltage change from minimum to ma!imum load is

improved.


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?ig D.D 75T:A,;5T voltage regulator

Bormally we get fi!ed output by connecting the voltage regulator at the output of the filtered 45 see in

above diagram. &t can also be used in circuits to get a low 45 voltage from a high 45 voltage for e!ample

we use :A,; to get ;V from +V. There are two types of voltage regulators . fi!ed voltage regulators :A!!

:!! +. Variable voltage regulators in fi!ed voltage regulators there is another classification . S ve voltage

regulators +.Hvevoltage regulators positive voltage regulators this include :A!! voltage regulators. The most

commonly used ones are :A,; and :A+. :A,; gives fi!ed ;V 45 voltage if input voltage is in :.;V +,V.

:A,; is a voltage regulator integrated circuit. &t is a member of :A!! series of fi!ed linear voltage regulator

&5s. The voltage source in a circuit may have fluctuations and would not give the fi!ed voltage output. The

voltage regulator &5 maintains the output voltage at a constant value. The !! in :A!! indicates the fi!ed

output voltage it is designed to provide. :A,; provides S;V regulated power supply. 5apacitors of suitable

values can be connected at input and output pins depending upon the respective voltage levels.

3.11 The Ca&acitor ilter

The simple capacitor filter is the most basic type of power supply filter. The application of the simple

capacitor filter is very limited. &t is sometimes used on e!tremely high-voltage low current power supplies

for cathode ray and similar electron tubes which re'uire very little load current from the supply. The

capacitor filter is also used where the power-supply ripple fre'uency is not critical this fre'uency can be

relatively high. The capacitor 5 shown in figure D.; is a simple filter connected across the output of the

rectifier in parallel with the load.

3#info4eee | Information For Electrical & Electronics Engineering


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?ig D.; ?ull wave rectifier with a capacitor filter

*hen this filter is used the 85 charge time of the filter capacitor 5 must be short and the 85 discharge

time must be long to eliminate ripple action. &n other words the capacitor must charge up fast preferably

with no discharge a tall. 9etter filtering also results when the input fre'uency is high therefore the full-

wave rectifier output is easier to filter than that of the half-wave rectifier because of its higher fre'uency. ?or

you to have a better understanding of the effect that filtering has on % avg a comparison of a rectifier circuit

with a filter and one without a filter is illustrated in figure D.E and figure D.:. The output waveforms in

figure D.E represent the unfiltered and figure D.: represents filtered outputs of the half-wave rectifier

circuit. 5urrent pulses flow through the load resistance 86 each time a diode conducts. The dashed line

indicates the average value of output voltage. ?or the half-wave rectifier %avg is less than half of the pea"

output voltage. This value is still much less than that of the applied voltage. *ith no capacitor connected

across the output of the rectifier circuit the waveform in figure D.E has a large pulsating component

compared with the average or dc component. *hen a capacitor is connected across the output figure D.:

the average value of output voltage %avg is increased due to the filtering action of capacitor 5

UNILT"R"D

?ig D.E


32/40

ILT"R"D

?ig D.:


33/40

the discharge period gradually decreases until the time of the ne!t half cycle of rectifier operation. Ieep in

mind that for good filtering the filter capacitor should charge up as fast as possible and discharge as little as

possible as shown in ?igure D.A and figure D..

!OITI7" A(L+CCL"

?ig D.A 5apacitor filter circuit

N"/(TI7" A(L+CCL"

?ig D. 5apacitor filter circuit

3ince practical values of 5 and 86 ensure a more or less gradual decrease of the discharge voltage a

substantial charge remains on the capacitor at the time of the ne!t half cycle of operation. $s a result no

current can flow through the diode until the rising ac input voltage at the anode of the diode e!ceeds the

voltage on the charge remaining on 5. The charge on 5 is the cathode potential of the diode. *hen the

potential on the anode e!ceeds the potential on the cathode the charge on 5 the diode again conducts and

5 begins to charge to appro!imately the pea" value of the applied voltage. $fter the capacitor has charged

to its pea" value the diode will cut off and the capacitor will start to discharge. 3ince the fall of the ac input

voltage on the anode is considerably more rapid than the decrease on the capacitor voltage the cathode

'uic"ly become more positive than the anode and the diode ceases to conduct. Operation of the simple

capacitor filter using a full-wave rectifier is basically the same as that discussed for the half-wave rectifier.



34/40

8eferring to figure you should notice that because one of the diodes is always conducting on alternation the

filter capacitor charges and discharges during each half cycle. Bote that each diode conducts only for that

portion of time when the pea" secondary voltage is greater than the charge across the capacitor.

?ig D.+, ?ull-wave rectifier with capacitor filter

$nother thing to "eep in mind is that the ripple component % r of the output voltage is an ac voltage and the

average output voltage %avg is the dc component of the output. 3ince the filter capacitor offers relatively low

impedance to ac the ma#ority of the ac component flows through the filter capacitor. The ac component is

therefore bypassed around the load resistance and the entire dc component % avg flows through the load

resistance. This statement can be clarified by using the formula for 5 in a half wave and full-wave rectifier.

?irst you must establish some values for the circuit. $s you can see from the calculations by doubling thefre'uency of the rectifier you reduce the impedance of the capacitor by one-half. This allows the ac

component to pass through the capacitor more easily. $s a result a full wave rectifier output is much easier

to filter than that of a half-wave rectifier. 8emember the smaller the 5 of the filter capacitor with respect to

the load resistance the better the filtering action.

c R1

2 π fC

3ince the largest possible capacitor will provide the best filtering. 8emember also that the load resistance is

an important consideration. &f load resistance is made small the load current increases and the average value

of output voltage %avg decreases. The 85 discharge time constant is a direct function of the value of the

load resistance therefore the rate of capacitor voltage discharge is a direct function of the current through the

load. The greater load current the more rapid the discharge of the capacitor and the lower the average value

of output voltage. ?or this reason the simple capacitive filter is seldom used with rectifier circuits that must

supply a relatively large load current. 2sing the simple capacitive filter in con#unction with a full-wave or

bridge rectifier provides improved filtering because the increased ripple fre'uency decreases the capacitive

reactance of the filter capacitor.



35/40

3.12 Light "'itting Diode

$n 6%4 is a very simple electronics component which lights up when electricity flows through it. 3ince it is

a diode electricity can only flow one way. There is usually a flat section on the side of the 6%4 to mar" its

polarity1 this side should be connected to ground. This side usually also has a shorter leg. &n order to prevent

too much current flowing through an 6%4 and damaging it it should be connected in series with a resistor.

?ig D.+ 6ight %mitting 4iode

3.1$ Resistor

$ resistor is a component of a circuit that resists the flow of electrical current. &t has two terminals across

which electricity must pass and it is designed to drop the voltage of the current as it flows from one terminal

to the other. 8esistors are primarily used to create and maintain "nown safe currents within electrical

components. 8esistance is measured in ohms after OhmCs law. This law states that electrical resistance is

e'ual to the drop in voltage across the terminals of the resistor divided by the current being applied. $ high

ohm rating indicates a high resistance to current. This rating can be written in a number of different ways -

for e!ample A8 represents A ohms while AI represents A,,, ohms. 7aterials in general have a

characteristic behavior of opposing the flow of electric charge. This opposition is due to the collisions

between electrons that ma"e up the materials. This physical property or ability to resist current is "nown as

resistance and is represented by the symbol R. 8esistance is e!pressed in ohms which is symbolized by the

capital ree" letter omega.

The resistance of any material is dictated by four factors1

• 7aterial property-each material will oppose the flow of current differently.

• 6ength-the longer the length the more is the probability of collisions and hence the larger the

resistance.

• 5ross-sectional area-the larger the area A the easier it becomes for electrons to flow and hence the

lower the resistance.

• Temperature-typically for metals as temperature increases the resistance increases.

The amount of resistance offered by a resistor is determined by its physical construction. $ carbon

composition resistor has resistive carbon pac"ed into a ceramic cylinder while a carbon film resistor consists

of a similar ceramic tube but has conductive carbon film wrapped around the outside. 7etal film or metal



36/40

o!ide resistors are made much the same way but with metal instead of carbon. $ wire wound resistor made

with metal wire wrapped around clay plastic or fibre glass tubing offers resistance at higher power levels.

Those used for applications that must withstand high temperatures are typically made of materials such as

cermets a ceramic-metal composite or tantalum a rare metal so that they can endure the heat.

8esistors are coated with paint or enamel or covered in moulded plastic to protect them. 9ecause they are

often too small to be written on a standardized color-coding system is used to identify them. The first three

colors represent ohm value and a fourth indicates the tolerance or how close by percentage the resistor is to

its ohm value. This is important for two reasons1 the nature of its construction is imprecise and if used above

its ma!imum current the value can change or the unit itself can burn up. The circuit element used to model

the current-resisting behavior of a material is the resistor . ?or the purpose of constructing circuits resistors

shown in ?igure D.++ are usually made from metallic alloys and carbon compounds. The resistor is the

simplest passive element.

?ig D.++ from top to bottom1

1

4 *

1

2 * and -* resistors

T!" O R"IT"R

4ifferent types of resistors have been created to meet different re'uirements. 3ome resistors are shown in

?igure D.+. The primary functions of resistors are to limit current divide voltage and dissipate heat. $

resistor is either fi!ed or variable. 7ost resistors are of the fi!ed type that is their resistance remains

constant. The two common types of fi!ed resistors wire wound and composition are shown in ?igure D.+D.

*ire wound resistors are used when there is a need to dissipate a large amount of heat while the compositionresistors are used when large resistance is needed.



37/40

?ig D.+ 4ifferent types of resistors

(a) (b)

?ig D.+D ?i!ed resistors1 (a) wire wound type (b) 5arbon film type

R"ITOR COLOUR COD"

3ome resistors are physically large enough to have their values printed on them. Other resistors are too small

to have their values printed on them. ?or such small resistors color coding provides a way of determining the

value of resistance. $s shown in ?igure D.+; the color coding consists of three four or five bands of color

around the resistor.

?ig D.+; 5olor coding



38/40

The first three bands specify the value of the resistance. 9ands $ and 9 represent the first and second digits

of the resistance value and 5 is usually given as a power of , as shown in figure D.+;. &f present the fourth

band 4 indicates the tolerance percentage. ?or e!ample a ; percent tolerance indicates that the actual value

of the resistance is within U ; of the color-coded value. *hen the fourth band is absent the tolerance is ta"en

by default to be U +, percent. The fifth band % if present is used to indicate a reliability factor which is a

3tatistical indication of the e!pected number of components that will fail to have the indicated resistance

after wor"ing for ,,, hours. $s shown in ?igure D.+; the statement 9ig 9oys 8ace Our Woung irls 9ut

Violet enerally *insX can serve as a memory aid in remembering the color code.

5. CONCLUION

?rom the design of e!perimental set up with 7icro 5ontroller 9ased 3olar Trac"ing 3ystem 2sing 3tepper

7otor &f we compare Trac"ing by the use of 648 with ?i!ed 3olar Panel 3ystem we found that the

efficiency of 7icro 5ontroller 9ased 3olar Trac"ing 3ystem is improved by ,-D;/ and it was found that

all the parts of the e!perimental setup are giving good results. The re'uired Power is used to run the motor

by using 3tep-4own T=? by using ++,V $5. 7oreover this trac"ing system does trac" the sun in a

continuous manner. $nd this system is more efficient and cost effective in long run. ?rom the results it isfound that by automatic trac"ing system there is , / gain in increase of efficiency when compared with

non-trac"ing system. The solar trac"er can be still enhanced additional features li"e rain protection and wind

protection which can be done as future wor".

3!info4eee | Information For Electrical & Electronics Engineering


39/40

6. R""R"NC"

YZ 8iz" J. and 5hai"o W. 3olar Trac"ing 3ystem1 7ore %fficient 2se of 3olar PanelsX *orld $cademy of

3cience %ngineering and Technology D +,,A.

Y+Z ?ilfil $hmed Basir 7ohussen 4eia


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