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SOLAR TRACKING

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF

Bachelor of Technology In

Electronics and Telecommunication

By

SUJIT MOHAPATRA SUKANTA GOUDO SUKRITI SRIVASTAVA Roll No: 116098 Roll No:116099 Roll No:116100

SUMIT KUMAR SRIVASTAVA SUSHOBHAN BEHERAMALI

Roll No:116101 Roll No:116102

SUSHREE SUBHADARSHINI ACHARYA Roll No:116102

Under the Guidance of Prof. JIBANANDA MISHRA

Department of Electronics and Telecommunication Engineering Orissa Engineering College

Orissa-752050

2014

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ORISSA ENGINEERING COLLEGE BHUBANESWAR

CERTIFICATE

This is to certify that the thesis titled “Solar Tracking” submitted by Sujit

Mohapatra, Sukanta Goudo, Sukriti Srivastava, Sumit Kumar Srivastava,

Sushobhan Beheramali, Sushree Subhadarshini Acharya in partial fulfillment of

the requirements for the award of Bachelor of Technology degree in Electronics &

Telecommunication Engineering during session 2014-2015 at Orissa Engineering

College, Bhubaneswar is an authentic work by them under my supervision and

guidance.

Prof. Jibananda Mishra Dept.of Electronics and

Telecommunication Engg.

Orissa Engineering College

Prof. Sunil Bisoi

H.O.D. Dept.of Electronics

and Telecommunication Engg.

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Acknowledgement

I would like to express my gratitude to my thesis guide Prof. Jibananda Mishra for his

guidance, advice and constant support throughout my thesis work. I would like to thank him

for being my advisor here at Orissa Engineering College, Bhubaneswar.

I would like to thank all faculty members and staff of the Department of Electronics

and Telecommunication Engineering, O.E.C. Bhubaneswar for their generous help in various

ways for the completion of this thesis. I would like to thank all my friends and especially my classmates for all the thoughtful

and mind stimulating discussions we had, which prompted us to think beyond the obvious.

I’ve enjoyed their companionship so much during my stay at OEC, Bhubaneswar.

I am especially indebted to my parents for their love, sacrifice, and support. They are

my first teachers after I came to this world and have set great examples for me about how to

live, study, and work.

. SUJIT MOHAPATRA

Roll No: 116098

SUKANTA GOUDO

Roll No: 116099

SUKRITI SRIVASTAVA Roll No:116100

SUMIT KUMAR SRIVASTAVA Roll No:116101

SUSHOBHAN BEHERAMALI Roll No:116102

SUSHREE SUBHADARSHINI ACHARYA Roll No:116103

Dept of ENTC,OEC, Bhubaneswar

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CONTENTS

CHAPTER 1. INTRODUCTION

1.1 Embedded Systems

1.2 Objective of project

CHAPTER2. DESCRIPTION OF HARDWARE COMPONENTS

2.1 ATmega8

2.2 TRANSFORMER

2.3 BRIDGE RECTIFIER

2.4 REGULATOR IC

2.5 SOLAR TRACKER

2.6 METHODS OF SOLAR TRACKER MOUNT

2.7 METHODS OF DRIVE

2.8 SENSORS

2.9 MOTOR

2.10 MICROCONTROLLER

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CHAPTER 3. CIRCUITS AND THEIR OPERATION

3.1 Technology of Solar Panel

3.2 Evolution of Solar Tracker

CHAPTER 4. SOFTWARE DEVELOPMENT

4.1 Flowchart

CHAPTER 5. RESULTS & CONCLUSION

REFERENCES

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ABSTRACT

This is a power generating method from sunlight. This method of power generation is simple and is taken from

natural resource. This need only maximum sunlight to generate power. This project helps for power generation by

setting the equipment to get maximum sunlight automatically. This system is tracking for maximum intensity of

light. When there is decrease in intensity of light, this system automatically changes its direction to get maximum

intensity of light. Here we are using two sensors in two directions to sense the direction of maximum intensity of

light. The difference between the outputs of the sensors is given to the micro controller unit. Here we are using the

microcontroller for tracking sunlight. It will process the input voltage from the comparison circuit and control the

direction in which the motor has to be rotated so that it will receive maximum intensity of light from the sun. The

power generated from this process is then stored in a lead acid battery and is made to charge an emergency light

and is made to glow with the help of solar panel .

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CHAPTER 1

INTRODUCTION

1.1 EMBEDDED SYSTEMS

Embedded systems are designed to do some specific task, rather than be a general-purpose

computer for multiple tasks. Some also have real time performance constraints that must be met, for

reason such as safety and usability; others may have low or no performance requirements, allowing

the system hardware to be simplified to reduce costs.

Wireless communication has become an important feature for commercial

products and a popular research topic within the last ten years. There are now more mobile phone

subscriptions than wired-line subscriptions. Lately, one area of commercial interest has been low-

cost, low-power, and short-distance wireless communication used for \personal wireless networks."

Technology advancements are providing smaller and more cost effective devices for integrating

computational processing, wireless communication, and a host of other functionalities. These

embedded communications devices will be integrated into applications ranging from homeland

security to industry automation and monitoring. They will also enable custom tailored engineering

solutions, creating a revolutionary way of disseminating and processing information. With new

technologies and devices come new business activities, and the need for employees in these

technological areas. Engineers who have knowledge of embedded systems and wireless

communications will be in high demand. Unfortunately, there are few adorable environments

available for development and classroom use, so students often do not learn about these technologies

during hands-on lab exercises. The communication mediums were twisted pair, optical fiber,

infrared, and generally wireless radio.

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1.2 OBJECTIVE OF THE PROJECT:

AIM:

This is a power generating method from sunlight. This method of power generation is simple and is

taken from natural resource. This need only maximum sunlight to generate power. This project helps for power

generation by setting the equipment to get maximum sunlight automatically. This system is tracking for maximum

intensity of light. When there is decrease in intensity of light, this system automatically changes its direction to get

maximum intensity of light. Here we are using two sensors in two directions to sense the direction of maximum

intensity of light. The difference between the outputs of the sensors is given to the micro controller unit. Here we

are using the microcontroller for tracking sunlight. It will process the input voltage from the comparison circuit

and control the direction in which the motor has to be rotated so that it will receive maximum intensity of light

from the sun. The power generated from this process is then stored in a lead acid battery and is made to charge an

emergency light and is made to glow with the help of solar panel .

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BLOCK DIAGRAM

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CHAPTER 2: DESCRIPTION OF HARDWARE COMPONENT

2.1 Atmega8

The ATmega8 provides the following features: 8 Kbytes of In-System

Programmable Flash with Read-While-Write capabilities, 512 bytes of EEPROM, 1 Kbyte

of SRAM, 23 general purpose I/O lines, 32 general purpose working registers, three

flexible Timer/Counters with compare modes, internal and external interrupts, a serial

programmable USART, a byte oriented Two wire Serial Interface, a 6-channel ADC

(eight channels in TQFP and QFN/MLF packages) with 10-bit accuracy, a programmable

Watchdog Timer with Internal Oscillator, an SPI serial port, and five software selectable

power saving modes. The Idle mode stops the CPU while allowing the SRAM,

Timer/Counters, SPI port, and interrupt system to continue functioning. The Power down

mode saves the register contents but freezes the Oscillator, disabling all other chip

functions until the next Interrupt or Hardware Reset. In Power-save mode, the

asynchronous timer continues to run, allowing the user to maintain a timer base while the

rest of the device is sleeping. The ADC Noise Reduction mode stops the CPU and all I/O

modules except asynchronous timer and ADC, to minimize switching noise during ADC

conversions. In Standby mode, the crystal/resonator Oscillator is running while the rest

of the device is sleeping. This allows very fast start-up combined with low-power

consumption.

The device is manufactured using Atmel’s high density non-volatile

memory technology. The Flash Program memory can be reprogrammed In-

System through an SPI serial interface, by a conventional non-volatile memory

programmer, or by an On-chip boot program running on the AVR core. The

boot program can use any interface to download the application program in the

Application Flash memory. Software in the Boot Flash Section will continue

to run while the Application Flash Section is updated, providing true Read-

While-Write operation. By combining an 8-bit RISC CPU with In-System

Self-Programmable Flash on a monolithic chip, the Atmel ATmega8 is a

powerful microcontroller that provides a highly-flexible and cost-effective

solution to many embedded control applications.

The ATmega8 is supported with a full suite of program and system

development tools, including C compilers, macro assemblers, program

debugger/simulators, In-Circuit Emulators, and evaluation kits.

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Pin diagram

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Internal architecture:

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Features

• High-performance, Low-power Atmel®AVR® 8-bit Microcontroller • Advanced RISC Architecture

- 130 Powerful Instructions - Most Single-clock Cycle Execution - 32 × 8 General Purpose Working Registers - Fully Static Operation - Up to 16MIPS Throughput at 16MHz - On-chip 2-cycle Multiplier

• High Endurance Non-volatile Memory segments - 8Kbytes of In-System Self-programmable Flash program memory - 512Bytes EEPROM - 1Kbyte Internal SRAM - Write/Erase Cycles: 10,000 Flash/100,000 EEPROM - Data retention: 20 years at 85°C/100 years at 25°C(1)

- Optional Boot Code Section with Independent Lock Bits In-System Programming by On-chip Boot Program True Read-While-Write Operation

- Programming Lock for Software Security

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• Peripheral Features - Two 8-bit Timer/Counters with Separate Prescaler, one Compare Mode - One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture

Mode - Real Time Counter with Separate Oscillator - Three PWM Channels - 8-channel ADC in TQFP and QFN/MLF package

Eight Channels 10-bit Accuracy - 6-channel ADC in PDIP package

Six Channels 10-bit Accuracy - Byte-oriented Two-wire Serial Interface - Programmable Serial USART - Master/Slave SPI Serial Interface - Programmable Watchdog Timer with Separate On-chip Oscillator - On-chip Analog Comparator

• Special Microcontroller Features - Power-on Reset and Programmable Brown-out Detection - Internal Calibrated RC Oscillator - External and Internal Interrupt Sources - Five Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, and

Standby • I/O and Packages

- 23 Programmable I/O Lines - 28-lead PDIP, 32-lead TQFP, and 32-pad QFN/MLF

• Operating Voltages - 2.7V - 5.5V (ATmega8L) - 4.5V - 5.5V (ATmega8)

• Speed Grades - 0 - 8MHz (ATmega8L) - 0 - 16MHz (ATmega8)

• Power Consumption at 4Mhz, 3V, 25°C - Active: 3.6mA - Idle Mode: 1.0mA - Power-down Mode: 0.5µA

Atmel

AVR

CPU

Core

Introduction This section discusses the Atmel®AVR® core architecture in general. The main

function of the CPU core is to ensure correct program execution. The CPU must

therefore be able to access memories, perform calculations, control peripherals, and

handle interrupts.

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Architectural BLOCK DIAGRAM OF AVR MCU ARCHITECTURE

Overview

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2.2 TRANSFORMER:

A transformer is a device that transfers electrical energy from one circuit to another through inductively

coupled conductors - the transformer's coils or windings. Except for air-core transformers, the conductors are

commonly wound around a single iron-rich core, or around separate but magnetically coupled cores. A

varying current in the first or primary winding creates a varying magnetic field in the core of the transformer.

This varying magnetic field induces a varying electromotive force or voltage in the secondary winding. This

effect is called mutual induction.

Transformer

If 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 VS, of an ideal transformer, is scaled from the primary VP by a factor equal to the

ratio of the number of turns of wire in their respective windings:

𝐍𝐬

𝐍𝐩

= 𝐕𝐬

𝐕𝐩

By appropriate selection of the numbers of turns, a transformer thus allows an alternating voltage to be

stepped up - by making NS more than NP or stepped down, by making it.

BASIC PARTS OF A TRANSFORMER

In its most basic form a transformer consists of:

A primary coil or winding.

A secondary coil or winding.

A core that supports the coils or windings.

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Refer to the transformer circuit in figure as you read the following explanation: The primary winding is

connected to a 50-hertz ac voltage source. The magnetic field builds up and collapses about the primary

winding. The expanding 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.

THE COMPONENTS OF A TRANSFORMER

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

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

air-core transformer. Transformers used at low frequencies, such as 50 hertz and 400 hertz, require a core of

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

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

are: The core, which provides a path for the magnetic lines of flux. 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.

2.3 BRIDGE RECTIFIER

A bridge rectifier makes 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 operation

According to the conventional model of current flow originally established by Benjamin Franklin and still

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

to the negative pole. In actuality, free electrons in a conductor nearly always flow from the negative to the

positive pole. In the vast majority of applications, however, the actual direction of current flow is irrelevant.

Therefore, in the discussion below the conventional model is retained. In 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.

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Bridge rectifier

When 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.

In each case, the upper right output remains positive and lower right output negative. Since this is true

whether the input is AC or DC, this circuit not only produces a DC output from an AC input, it can also

provide what is sometimes called "reverse polarity protection". That is, it permits normal functioning of DC-

powered equipment when batteries have been installed backwards, or when the leads from a DC power

source have been reversed, and protects the equipment from potential damage caused by reverse polarity.

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

components. Since about 1950, 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.

Output smoothing

For many applications, especially with single phase AC where the full-wave bridge serves to convert an AC

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

of fixed polarity but continuously varying or pulsating magnitude.

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Bridge rectifier in parallel capacitor at the output

The function of this capacitor, known as a reservoir capacitor is to lessen the variation in the rectified AC

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

impedance path to the AC component of the output, reducing the AC voltage across, and AC current through,

the resistive load. In 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.

Increases of voltage correspondingly store excess 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 AC power source is removed.

If supplying a dangerous voltage, a practical circuit should include a reliable way to safely discharge the

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

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. Because a bleeder sets a minimum current drain, the

regulation of the circuit, defined as percentage voltage change from minimum to maximum load, is

improved. However in many cases the improvement is of in significant magnitude. capacitor and the load

resistance have a typical time constant τ = RC where C and R are the capacitance and load resistance

respectively. As long as the load resistor is large enough so that this time constant is much longer than the

time of one ripple cycle, the above configuration will produce a smoothed DC voltage across the load.

In some designs, a series resistor at the load side of the capacitor is added. The smoothing can then be

improved by adding additional stages of capacitor–resistor pairs, often done only for sub-supplies to critical

high-gain circuits that tend to be sensitive to supply voltage noise. The idealized waveforms shown above are

seen for both voltage and current when the load on the bridge is resistive. When the load includes a

smoothing capacitor, both the voltage and the current waveforms will be greatly changed. While the voltage

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is smoothed, as described above, current will flow through the bridge only during the time when the input

voltage is greater than the capacitor voltage. For example, if the load draws an average current of n Amps,

and the diodes conduct for 10% of the time, the average diode current during conduction must be 10n Amps.

This non-sinusoidal current leads to harmonic distortion and a poor power factor in the AC supply. In a

practical circuit, when a capacitor is directly connected to the output of abridge, the bridge diodes must be

sized to withstand the current surge that occurs when the power is turned on at the peak of the AC voltage

and the capacitor is fully discharged. Sometimes a small series resistor is included before the capacitor to

limit this current, though in most applications the power supply transformer's resistance is already sufficient.

Output can also be smoothed using a choke and second capacitor. The choke tends to keep the current rather

than the voltage more constant. Due to the relatively high cost of an effective choke compared to a resistor

and capacitor this is not employed in modern equipment.

2.4 REGULATOR IC

It is a three pin IC used as a voltage regulator. It converts unregulated DC current into regulated DC current.

First pin is used for input, second for ground and third pin gives the rectified and filtered output. It has an

inbuilt filtering circuit which removes the ripples present in the rectified DC obtained from full bridge

rectifier circuit.

MCT7805CT voltage regulator

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Normally we get fixed output by connecting the voltage regulator at the output of the filtered DC see in

above diagram. It can also be used in circuits to get a low DC voltage from a high DC voltage for example

we use 7805 to get 5V from 12V. There are two types of voltage regulators 1. fixed voltage regulators 78xx,

79xx 2. Variable voltage regulators in fixed voltage regulators there is another classification 1. + ve voltage

regulators 2.–vevoltage regulators positive voltage regulators this include 78xx voltage regulators. The most

commonly used ones are 7805 and 7812. 7805 gives fixed 5V DC voltage if input voltage is in 7.5V, 20V.

7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage regulator

ICs. The voltage source in a circuit may have fluctuations and would not give the fixed voltage output. The

voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx indicates the fixed

output voltage it is designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable

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

2.5 Solar Tracker

Solar Tracker is basically a device onto which solar panels are fitted which tracks the motion of the sun

across the sky ensuring that the maximum amount of sunlight strikes the panels throughout the day. After

finding the sunlight, the tracker will try to navigate through the path ensuring the best sunlight is detected.

The design of the Solar Tracker requires many components. The design and construction of it could be

divided into six main parts that would need to work together harmoniously to achieve a smooth run for the

Solar Tracker, each with their main function. They are:

Methods of Tracker Mount

Methods of Drives

Sensor and Sensor Controller

Motor and Motor Controller

Tracker Solving Algorithm

Data Acquisition/Interface Card

2.6 Methods of Tracker Mount

1. Single axis solar trackers

Single axis solar trackers can either have a horizontal or a vertical axle. 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 axis tracking

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

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2. Double axis solar trackers

Double axis solar trackers have both a horizontal and a vertical axle and so can track the Sun's apparent

motion exactly anywhere in the World. This type of system is used to control astronomical telescopes, and so

there is plenty of software available to automatically predict and track the motion of the sun across the sky.

By tracking the sun, the efficiency of the solar panels can be increased by 30-40%.The dual axis tracking

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

2.7 Methods of Drive

1. Active Trackers

Active Trackers use motors and gear trains to direct the tracker as commanded by a controller responding

to the solar direction. Light-sensing trackers typically have two photo sensors, such as photodiodes,

configured differentially so that they output a null when receiving the same light flux. Mechanically, they

should be omnidirectional and are aimed 90 degrees apart. This will cause the steepest part of their cosine

transfer functions to balance at the steepest part, which translates into maximum sensitivity.

2. Passive Trackers

Passive Trackers 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 tracker to move in response to an imbalance.

2.8 Sensors

A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an

observer or by an instrument.

1. Light Dependent Resistor

Light Dependent Resistor is made of a high-resistance semiconductor. It can also be referred to as a

photoconductor. If light falling on the device is of the high enough frequency, photons absorbed by the

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

electron conducts electricity, thereby lowering resistance. Hence, Light Dependent Resistors is very useful in

light sensor circuits. LDR is very high-resistance, sometimes as high as 10MΩ, when they are illuminated

with light resistance drops dramatically.

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A Light Dependent Resistor is a resistor that changes in value according to the light falling on it. A

commonly used device, the ORP-12, has a high resistance in the dark, and a low resistance in the light.

Connecting the LDR to the microcontroller is very straight forward, but some software ‘calibrating’ is

required. It should be remembered that the LDR response is not linear, and so the readings will not change in

exactly the same way as with a potentiometer. In general there is a larger resistance change at brighter light

levels. This can be compensated for in the software by using a smaller range at darker light levels.

Fig 4.1 Light Dependent Resistor

2. Photodiode

Photodiode is a light sensor which has a high speed and high sensitive silicon PIN photodiode in a

miniature flat plastic package. A photodiode is designed to be responsive to optical input. Due to its water

clear epoxy 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. In 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 just a large number of big, cheap photodiodes. Diodes usually have extremely high resistance

when reverse biased. This resistance is reduced when light of an appropriate frequency shines on the

junction. Hence, a reverse biased diode can be used as a detector by monitoring the current running through

it. Circuits based on this effect are more sensitive to light than ones based on the photovoltaic effect.

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different type of photo diodes

2.9 Motor

Motor is use to drive the Solar Tracker to the best angle of exposure of light. For this section, we are using

stepper motor.

Stepper Motor

Features

Linear speed control of stepper motor

Control of acceleration, deceleration, max speed and number of steps to move

Driven by one timer interrupt

Full - or half-stepping driving mode

Supports all AVR devices with 16bit timer

Introduction

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

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

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

present, low cost, high reliability, high torque at low speeds, and high accuracy of motion. Many systems

with 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.

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Fig 4.3 Stepper Motors

Theory

Stepper motor

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

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

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

Bipolar vs. Unipolar stepper motors

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

unipolar motors are similar, except that the Unipolar has a centre tap on each winding as shown in Figure 4.4

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Fig 4.4 Bipolar and Unipolar stepper Motor

Unipolar stepper motor

Stepper motors are very accurate motors that are commonly used in computer disk drives, printers and

clocks. Unlike dc motors, which spin round freely when power is applied, stepper motors require that their

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

step often 15 degrees giving 24 steps in a full revolution.There are two main types of stepper motors -

Unipolar and Bipolar. Unipolar motors usually have four coils which are switched on and off in a particular

sequence. Bipolar motors have two coils in which the current flow is reversed in a similar sequence. Each of

the four coils in a Unipolar stepper motor must be switched on and off in a certain order to make the motor

turn. Many microprocessor systems use four output lines to control the stepper motor, each output line

controlling the power to one of the coils. As the stepper motor operates at 5V, the standard transistor circuit

is required to switch each coil. As the coils create a back emf when switched off, a suppression diode on each

coil is also required. The table below show the four different steps required to make the motor turn.

Table 4.1 Unipolar stepper motor operation

Step Coil 1 Coil 2 Coil 3 Coil 4

1 1 0 1 0

2 1 0 0 1

3 0 1 0 1

4 0 1 1 0

1 1 0 1 0

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Look carefully at the table 4.1 and notice that a pattern is visible. Coil 2 is always the opposite or logical

NOT of coil 1. The same applies for coils 3 and 4. It is therefore possible to cut down the number of

microcontroller pins required to just two by the use of two additional NOT gates. Fortunately the Darlington

driver IC ULN2003 can be used to provide both the NOT and Darlington driver circuits. It also contains the

back emf suppression diodes so no external diodes are required.

Bipolar Stepper motor

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 Figure 4.5 (a). The centre tap on the Unipolar motor allows a simpler driving circuit

shown in Figure 4.5 (b), limiting the current flow to one direction. The main drawback with the Unipolar

motor is the limited capability to energize all windings at any time, resulting in a lower torque compared to

the bipolar motor. The Unipolar stepper motor can be used as a bipolar motor by disconnecting the centre

tap.

(a) (b)

Fig - Bipolar and Unipolar drivers with MOS transistors

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Implementation

A working implementation written in C is included with this application note. Full documentation of the

source code and compilation information is found by opening the ‘readme.html’ 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 AVR will drive the

connected stepper motor accordingly. The demo application is divided in three major blocks, as shown in the

block diagram in Figure 4.6. There is one file for each block and also a file for UART routines used by the

main routine.

Fig 4.6 Block diagram of demo application

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

connected to the serial line. Speed controller c calculates the needed data and generates step pulses to make

the stepper motor follow the desired speed profile. Smdriver.c counts the steps and outputs the correct signals

to control the stepper motor.

Timer interrupt

The timer interrupt generates the step pulses calls the function Step Counter ( ) 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 Figure 4.7 and this behaviour is realized with a state machine in the timer interrupt shown in

Figure 4.8.

Fig 4.7 Operating states for different speed profile parts

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Fig 4.8 State machine for timer interrupt

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

STOP. When setup calculations are done, a new state is set and the timer interrupt is enabled. When moving

more than one step the state-machine goes to ACCEL. If moving only 1 step, the state is changed to DECEL.

When the state is changed to ACCEL, the application accelerates the stepper motor until either the desired

speed is reached and the state is changed to RUN, or deceleration must start, changing the state to DECEL.

When the state is set to RUN, the stepper motor is kept at constant speed until deceleration must start, then

the state is changed to DECEL.It will stay in DECEL and decelerate until the speed reaches zero desired

number of steps. The state is then changed to STOP.

2.10 Microcontroller

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

memory for input and output, a clock and an I/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.

For example, a single vehicle can use 70 or more microcontrollers. The following picture describes a general

block diagram of microcontroller.

Features

High-performance, Low-power AVR 8-bit Microcontroller

Advanced RISC Architecture

131 Powerful Instructions – Most Single-clock Cycle Execution

32 x 8 General Purpose Working Registers

Fully Static Operation

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Up to 16 MIPS Throughput at 16 MHz

On-chip 2-cycle Multiplier

High Endurance Non-volatile Memory segments

16K Bytes of In-System Self-programmable Flash program memory

512 Bytes EEPROM

1K Byte Internal SRAM

Write/Erase Cycles: 10,000 Flash/100,000 EEPROM

Data retention: 20 years at 85°C/100 years at 25°C

Optional Boot Code Section with Independent Lock Bits

In-System Programming by On-chip Boot Program

True Read-While-Write Operation

Programming Lock for Software Security

JTAG Interface

Boundary-scan Capabilities According to the JTAG Standard

Extensive On-chip Debug Support

Programming of Flash, EEPROM, Fuses, and Lock Bits through the JTAG Interface

Peripheral Features

Two 8-bit Timer/Counters with Separate Prescalers and Compare Modes

One 16-bit Timer/Counter with Separate Prescalers, Compare Mode, and Capture

Mode

Real Time Counter with Separate Oscillator

Four PWM Channels

8-channel, 10-bit ADC

8 Single-ended Channels

7 Differential Channels in TQFP Package Only

2 Differential Channels with Programmable Gain at 1x, 10x, or 200x

Byte-oriented Two-wire Serial Interface

Programmable Serial USART

Master/Slave SPI Serial Interface

Programmable Watchdog Timer with Separate On-chip Oscillator

On-chip Analog Comparator

Special Microcontroller Features

Power-on Reset and Programmable Brown-out Detection

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Internal Calibrated RC Oscillator

External and Internal Interrupt Sources

Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, Standby

and Extended Standby

I/O and Packages

32 Programmable I/O Lines

40-pin PDIP, 44-lead TQFP, and 44-pad QFN/MLF

Operating Voltages

2.7 - 5.5V for ATmega16L

4.5 - 5.5V for ATmega16

Speed Grades

0 - 8 MHz for ATmega16L

0 - 16 MHz for ATmega16

Power Consumption @ 1 MHz, 3V, and 25°C for ATmega16L

Active: 1.1 mA

Idle Mode: 0.35 mA

Power-down Mode: < 1 μA

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CHAPTER 3 :CIRCUITS AND THEIR OPERATION

3.1 Technology of Solar Panel

Solar 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". Solar 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. A solar panel is a collection of solar

cells. Although 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 Sun. The development of solar cell technology begins with 1839 research of French physicist

Antoine-Cesar Becquerel. He observed the photovoltaic effect while experimenting with a solid electrode in

an electrolyte solution. After that he saw a voltage developed when light fell upon the electrode.

According to Encyclopaedia Britannica the first genuine for solar panel was built around 1883 by Charles

Fritts. He used junctions formed by coating selenium (a semiconductor) with an extremely thin layer of gold.

Crystalline silicon and gallium arsenide are typical choices of materials for solar panels. Gallium arsenide

crystals are grown especially for photovoltaic use, but silicon crystals are available in less-expensive standard

ingots, which are produced mainly for consumption in the microelectronics industry. Norway’s Renewable

Energy Corporation has confirmed that it will build a solar manufacturing plant in Singapore by 2010 - the

largest in the world. This plant will be able to produce products that can generate up to 1.5 Giga watts of

energy every year. That is enough to power several million households at any one time. Last year the world

as a whole produced products that could generate just 2 GW in total.

3.2 Evolution of Solar Tracker

Since the sun moves across the sky throughout the day, in order to receive the best angle of exposure to

sunlight for collection energy. A tracking mechanism is often incorporated into the solar arrays to keep the

array pointed towards the sun. A solar tracker is a device onto which solar panels are fitted which tracks the

motion of the sun across the sky ensuring that the maximum amount of sunlight strikes the panels throughout

the day. When compare to the price of the PV solar panels, the cost of a solar tracker is relatively low. Most

photovoltaic solar panels are fitted in a fixed location- for example on the sloping roof of a house, or on

framework fixed to the ground. Since the sun moves across the sky though the day, this is far from an ideal

solution. Solar panels are usually set up to be in full direct sunshine at the middle of the day facing South in

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the Northern Hemisphere, or North in the Southern Hemisphere. Therefore morning and evening sunlight hits

the panels at an acute angle reducing the total amount of electricity which can be generated each day.

Fig - Sun’s apparent motion

During the day the sun appears to move across the sky from left to right and up and down above the

horizon from sunrise to noon to sunset. Figure 2.1 shows the schematic above of the Sun's apparent

motion as seen from the Northern Hemisphere. To keep up with other green energies, the solar cell

market has to be as efficient as possible in order not to lose market shares on the global energy

marketplace. The end-user will prefer the tracking solution rather than a fixed ground system to increase

their earnings because:

The efficiency increases by 30-40%.

The space requirement for a solar park is reduced, and they keep the same output.

The return of the investment timeline is reduced.

The tracking system amortizes itself within 4 years.

In terms of cost per Watt of the completed solar system, it is usually cheaper to use a solar

tracker and less solar panels where space and planning permit.

A good solar tracker can typically lead to an increase in electricity generation capacity of 30-

50%.

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3.3 Project Description

3.3.1 Block Diagram

Block Diagram of Project

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3.3.2 Schematic Diagram

Schematic Diagram of Project

3.3.3 PRINTED CIRCUIT BOARD

Almost all circuits encountered on electronic equipment (computers, TV, radio, industrial control equipment,

etc.) are mounted on printed circuit boards. Close inspection of a PCB reveals that it contains a series of

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

required to link the circuit devices according to a given circuit diagram. Hence, to construct a circuit the

necessity of connecting insulated wires between components is eliminated, resulting in a cleaner arrangement

and providing mechanical support for components. Moreover, the copper tracks are highly conductive and

the whole PCB can be easily reproduced for mass production with increased reliability.

1) Types of PCB

PCB's can be divided into three main categories:

Single-sided

Double-sided

Multi-layered.

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Single-sided PCB

A single-sided PCB contains copper tracks on one side of the board only, as shown in Figure 3.3. Holes are

drilled at appropriate points on the track-so that each component can be inserted from the non-copper side of

the board, as shown in Figure 3.4. Each pin is then soldered to the copper track.

Printed circuit board

Single sided PCB Double-sided PCB

Double-sided PCBs have copper tracks on both sides of the board. The track layout is designed so as not to

allow shorts from one side to another, if it is required to link points between the two sides, electrical

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

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Double sided PCB Multi-layer PCB

In multi-layer PCBs, each side contains several layers of track patterns which are insulated from one another.

These layers are laminated under heat and high pressure. A multi-layer PCB is shown in Figure 3.6

Multi layered PCB 2) MAKING A PCB

PCB's commonly available on the market are not particular circuits, but are available as copper clad boards.

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

his track layout on the copper surface, according to his circuit diagram. Next, the untraced copper area

removed by a process called etching. Here, the unused copper area is dissolved away by an etching solution

and only the required copper tracks remain. The board is then cleaned and drilled at points where each device

is to be inserted. Finally, each component is soldered to the board.

The etching process depends on whether board is of plain or photo-resist type. These are treated separately in

the following section.

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a) Making a PCB out of a plain copper clad board

Equipment required

The following items are required:

A single-sided copper clad board.

Ferric chloride solution, which is the etching liquid.

An etch-resist pen is with its ink resisting to ferric chloride.

A PCB eraser.

Track layout design

The first step is to draw the track layout on the plain copper clad board, according to the circuit to be

implemented which turns on an LED when the push-button is pressed. The lines joining different

components will form the track layout on the PCB. Each component is inserted from the non-copper side of

the board and its leads appear on the copper side. For example, when viewing the component side, the base

of the BC109 transistor appears to the right of the collector, while from the track side, it appears at the left of

the collector.

b) Making a PCB out of a photo resist board

Equipment required

Photo-resist board

Ferric chloride solution as etchant

A white board marker

Transparent polyester film for use as drafting sheet

Sodium hydroxide solution as developer

Ultra-violet exposure unit

Track layout design

Using the same principles outlined in section a track layout is drawn to scale on the transparency using the

white board' marker. It may be useful to insert graph paper below the transparent sheet for accurate

dimensioning of the layout.

Photo-etching

The principle behind photo-etching is to place the transparency over the copper clad and to expose it to UV

radiation, hence leaving the track regions intact and softening unused areas. First, the protective plastic film

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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 next placed in a UV exposure unit, with the

transparency facing the fluorescent tubes inside the unit. At the track regions, UV radiation is prevented from

reaching the board, and hence the photo sensitive remains hardened in these regions. After an exposure of

about 5 minutes the board can be removed. The PCB is then placed in a solution of caustic soda which

dissolves away any unhardened photo-sensitive area. After a few minutes of development time, the track

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

Final etching

After having allowed the tracks to harden for about half an hour, the unmarked copper area is etched by ferric

chloride solution.

3) The following points should be noted:

It is a good idea to draft the track layout on graph paper before drawing the final layout on the copper

clad.

Use an etch resist pen to draw the track layout on the copper clad (the latter must be cleaned initially).

The following lead spacing can be used as a rule of thumb: allow 10 mm for a 1/4 W resistor, 8 mm

for a signal diode, 4 mm for LED's 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 required.

Allow the ink to dry before etching.

4) Etching

The copper clad is now ready to be etched. If the etchant is available in powder form, it needs to be mixed

with water in anon-corrodible container. A powder to water ratio of 2:5 by mass is about right. Etching time

may vary between 10 to as long as 90 minutes, depending on the concentration and temperature of the

etchant. The process can be accelerated by warming the solution and by frequently agitating the etching bath.

The ferric chloride solution gradually dissolves any untraced copper area. When etching is complete, only the

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

resist ink is finally rubbed away with a PCB eraser, or with very fine grain sand paper.

Making a PCB out of a photo-resist copper clad board

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. Its advantage over the plain copper clad

board is that the track layout does not need to be drawn directly on the board.

The use of etch-resist transfers

The use of pens to design track layouts may not give neat result, even when using a ruler. For instance, it

may be difficult to draw tracks with the same line Width or to draw well aligned terminals for IC's and

discrete devices, Etch-resist PCB symbols and tracks are available for direct transfer to the copper clad or to

the transparency. Transfer is by rubbing down the relevant symbol with a soft pencil.

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CHAPTER 4: SOFTWARE DEVELOPMENT

4.1 FLOWCHART

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CHAPTER 5 : RESULTS & CONCLUSION

APPLICATIONS

Used in satellites as source of fuel.

Used in solar thermal collector to collect heat.

Used in water heaters.

Used in heat extinguishers.

Used in solar power plants.

Used in inverters[AC-DC].

Used in solar water pumps.

Advantages

The advantage of this unit is that to run the system it does not need computer.

Solar cells directly convert the solar radiation into electricity using photovoltaic effect without going through a

thermal process.

During the winter the sun has a low position, tracking angle from sunrise to sunset is shortened.

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Limitations

Using this system at a time we can control only one solar panel.

Higher hardware expenditure.

Weather condition can affect the system.

CONCLUSION

From the design of experimental set up with Micro Controller Based Solar Tracking System Using Stepper

Motor If we compare Tracking by the use of LDR with Fixed Solar Panel System we found that the

efficiency of Micro Controller Based Solar Tracking System is improved by 30-45% and it was found that all

the parts of the experimental setup are giving good results. The required Power is used to run the motor by

using Step-Down T/F by using 220V AC. Moreover, this tracking system does track the sun in a continuous

manner. And this system is more efficient and cost effective in long run. From the results it is found that, by

automatic tracking system, there is 30 % gain in increase of efficiency when compared with non-tracking

system. The solar tracker can be still enhanced additional features like rain protection and wind protection

which can be done as future work.

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REFERENCES

[1] Rizk J. and Chaiko Y. “Solar Tracking System: More Efficient Use of Solar Panels”, World Academy of

Science, Engineering and Technology 41 2008.

[2] Filfil Ahmed Nasir, Mohussen Deia Halboot, Dr. Zidan Khamis A. “Microcontroller-Based Sun Path

Tracking System”, Eng. & Tech. Journal, Vol. 29, No.7, 2011.

[3] Alimazidi Mohammad, Gillispie J, Mazidi, Rolin D. McKinlay, “The 8051 Microcontroller and

Embedded Systems”, An imprint of Pearson Education.

[4] Mehta V K, Mehta Rohit, “Principles of Electronics”, S. Chand & Company Ltd.

[5] Balagurusamy E, “Programming in ANSI C”, Tata McGraw-Hill Publishing Company Limited.

[6] Damm, J. Issue #17, June/July 1990. An active solar tracking system, Home Brew Magazine.

[7] Koyuncu B and Balasubramanian K, “A microprocessor controlled automatic sun tracker,” IEEE Trans.

Consumer Electron., vol. 37, no. 4,pp. 913-917, 1991.

[8] Konar A and Mandal A K, “Microprocessor based automatic sun tracker,” IEE Proc. Sci., Meas.

Technol., vol. 138, no. 4, pp. 237-241,1991.