Hybrid Power System

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Implementation of a Hybrid Power System Prototype using Solar and
Wind Energy




A Thesis Submitted

By

Islam, Md. Mahmudul 08-10472-1
Chowdhury, Md. Kawsar 08-09950-1
Rahman, Mahabubur Md. 07-09728-3
Ali, Shaiyan Moon A-Moon Ibne 08-10453-1





Under the supervision of
Chowdhury Akram Hossain
Lecturer
Faculty of Engineering
American International University- Bangladesh




Department of Electrical and Electronic Engineering
Faculty of Engineering
American International University- Bangladesh


Summer Semester 2010-2011

October 2011


































































































































































i

Implementation of a Hybrid Power System Prototype using
Solar and Wind Energy



A Thesis submitted to the Electrical and Electronic Engineering Department of the Engineering
Faculty, American International University - Bangladesh (AIUB) in partial fulfillment of the
requirements for the degree of Bachelor of Science in Electrical and Electronic Engineering.




1. Islam, Md. Mahmudul 08-10472-1
2. Chowdhury, Md. Kawsar 08-09950-1
3. Rahman, Mahabubur Md. 07-09728-3
4. Ali, Shaiyan Moon A-Moon Ibne 08-10453-1












Department of Electrical and Electronic Engineering
Faculty of Engineering
American International University- Bangladesh


Summer Semester 2010-2011

October 2011
































































































































































ii

Declaration



This is to certify that this project and thesis is our original work. No part of this work has been
submitted elsewhere partially or fully for the award of any other degree or diploma. Any material
reproduced in this thesis has been properly acknowledged.



___________________________
1. Islam, Md. Mahmudul
ID: 08-10472-1
Dept: EEE




___________________________
2. Chowdhury, Md. Kawsar
ID: 08-09950-1
Dept: EEE



___________________________

3. Rahman, Mahabubur Md.
ID: 07-09728-3
Dept: EEE




___________________________

4. Ali, Shaiyan Moon A-Moon Ibne
ID: 08-10453-1
Dept: EEE
































































































































































iii

Approval

The Project titled Implementation of a Hybrid Power System Prototype using Solar and Wind
Energy has been submitted to the following respected members of the Board of Examiners of
the Faculty of Engineering in partial fulfillment of the requirements for the degree of Bachelor of
Science in Electrical and Electronic Engineering on October 2011 by the following students and
has been accepted as satisfactory.


i. Islam, Md. Mahmudul 08-10472-1

ii. Chowdhury, Md. Kawsar 08-09950-1

iii. Rahman, Mahabubur Md. 07-09728-3

iv. Ali, Shaiyan Moon A-Moon Ibne 08-10453-1




___________________________ __________________________

Chowdhury Akram Hossain Mohammad Nasir Uddin
Supervisor External Supervisor
Lecturer, Faculty of Engineering Assistant Professor, Faculty of Engineering
American International University- American International University-
Bangladesh (AIUB) Bangladesh (AIUB)







____________________________ ___________________________

Prof. Dr. ABM Siddique Hossain Dr. Carmen Z. Lamagna
Dean, Faculty of Engineering Vice Chancellor
American International University- American International University-
Bangladesh (AIUB) Bangladesh (AIUB)
































































































































































iv

Acknowledgements



We are heartily thankful to our supervisor, Chowdhury Akram Hossain, Lecturer, Faculty of
Engineering, whose encouragement, supervision and support from the preliminary to the
concluding level gave us the courage to finish our work successfully. We would also like to
express our gratitude towards our External Supervisor Mohammad Nasir Uddin, Assistant
Professor, Faculty of Engineering for his presence during our presentation and for the various
advices that he gave us for future development of the project. We also thank Prof. Dr. ABM
Siddique Hossain, Dean, Faculty of Engineering, and our respected Vice Chancellor, Dr. Carmen
Z. Lamagna, for giving us the opportunity to carry out a thesis of our choice. In the reference
section of this book, we have mentioned the names and authors of the papers and information
sources without which this project would not have been possible, and our gratitude reaches out to
all those authors.

The Faculty of Engineering of American International University- Bangladesh has provided us
with the knowledge and assistance that constructed the foundation required in us to initiate and
follow through a project such as this, and for that we are most grateful to all the teachers,
officers, and staff of the EEE Department.


















































































































































































v


Abstract



The demand of power continues to rise day by day. Renewable energies available in nature can
definitely contribute as a solution towards this problem. In this project it has been shown that it is
possible to combine more than one or more source and generate power. The project uses energy
from light and wind to generate electricity. In coastal areas, especially those countries where it is
difficult to meet the increasing demand of electricity, the wind speed is sufficient most of the
time for the generation of electricity. In addition, the availability of sunlight definitely is another
option. In this project, the best source is chosen among the two whenever both of them are
available. The prototype was successfully able to charge a 4.5V battery and run a load along with
the charging process at the same time. A mobile phone was also connected for testing purpose,
and was successfully charged. This particular prototype can be thought of as a portable system,
and can be used for charging devices or run devices that require similar voltage during traveling.

















































































































































































Contents


Chapter 1 Introduction 1
1.1 History of Renwable Energy 1

Chapter 2 Renewable Energy 3
2.1 Introduction 4
2.2 Importance of renewable energy
2.3 Sources of renewable energy 5

Chapter 3 Solar Power 7
3.1 Solar energy 7
3.2 Solar Power 8
3.3 Photovoltaic Effect 8
3.4 Solar cell 8
3.5 Equivalent circuit of a solar cell 10
3.6 Material used in solar cells 10
3.7 Solar cell efficiency 11
3.8 The suns intensity 12
3.9 Temperature 13
3.10 Series resistance 14

Chapter 4 Wind Power 16
4.1 History 16
4.2 Nature of Wind 16
4.3 Windmill Basics 17
4.4 Components of a Wind Turbine Generator 18
4.5 Connection of Wind Energy Plants to the Grid 19
4.6 Wind Power generating system 19
4.7 Advantages of Wind Power 20
4.8 Disadvantages of Wind Power 21
































































































































































Chapter 5 Transistors 22
5.1 Definition 22
5.2 Transistors used in the Project 23
5.3 Images and Pin Configuration 23

Chapter 6 Operational Amplifier 25
6.1 Definition 25
6.2 Circuit notation 25
6.3 Operation 26
6.4 Op-Amp Characteristics 27
6.5 Internal Circuitry of the 741 type Op-Amp 29
6.6 Application 30

Chapter 7 Boost Converter 31
7.1 Introduction 31
7.2 Application 31
7.3 Circuit Analysis 32
7.4 Continuous Mode 33
7.5 Discontinuous Mode 36


Chapter 8 Microcontroller Atmega-16 38
8.1 Features 38
8.2 Pin Configuration and Pin description 38
8.3 NEXTSAPIENS 40
8.4 Softwares used for Coding 41
8.5 Programming 43

Chapter 9 Hybrid Operation 45
9.1 Intoruction 45
9.2 Circuit Diagram and Operation 46
































































































































































9.3 Four Main Operations 51
9.4 Charging of battery and feeding current to load using solar energy 52
9.5 Charging of battery and feeding current to load using solar energy 52
9.6 Current fed to the load directly from renewable source 54
9.7 Current fed to the load directly from battery 55
9.8 Experimental Analysis 55

Chapter 10 Discussion and Conclusion 57
10.1 Discussions 57
10.2 Suggestions for future work 58
10.3 Conclusion 59

Reference 60
DATASHEET 61


































































































































































1

Chapter 1
Introduction
1.1 History of Renewable Energy
Modern renewable energy technology dates from the second half of the 20th century
however the use of renewable resources for energy dates from when early humans learned to
control use of fire.
Besides burning wood and other flammable materials, our ancestors in ancient times took
advantage of the majority of the natural resources we know today: water, wind, sun and even
geothermal heat.
The power of the sun has been known and used already in ancient times which we can see at
the oculus at the top of famous Pantheon in Rome, Italy, which was built in the first half of
the 2nd century AD. Until the early 20th century when electrical lighting became the
predominant interior lighting, sunlight was the only source of light besides candles, torches,
oil lamps and after the industrial revolution in the second half of the 18th century - kerosene
lamps.
Sunlight has been used for making fire which is clearly indicated the writings of Lucian of
Samosa in the 2nd century AD who wrote that during the Siege of Syracuse (3rd century BC)
Archimedes repelled the Roman attack with a burning-glass. In addition to solar power,
sources of energy used were wind and water.
Since ancient times wind was used for propelling ships and to turn windmills whilst rivers
have turned water wheels for millennia, the Romans even used geothermal water for heating.
Until the middle of the 18th century and the discovery of fossil fuels, renewable sources were
the only sources of energy available to man.
































































































































































2

Excessive use of fossil fuels has caused global climate change which has became obvious in
the last few decades and has forced people and governments throughout the world to
seriously reconsider the replacement of fossil fuels with renewable energy sources.



































































































































































3

Chapter 2
Renewable Energy
2.1 Introduction
Renewable energy uses energy sources that are continuously available in nature such as- the
sun, wind, water, the Earth`s heat and plants. Renewable Energy technologies turn these fuels
into usable forms of energy. Till now fossil fuels are used as the main source of energy. But
there is a limited supply of these fuels, and they are being used much more rapidly than they
are created. So the amount of coal, oil and natural gas is decreasing day by day but demand
of energy is increasing. Also usage of fossil fuels has negative impact on nature. Nuclear
power came as an alternative, but it is very expensive and it has safety concerns and waste
disposal problem. Under all these circumstances renewable energy is the best option for
producing energy safely.















Figure 2.1: global energy sources
































































































































































4

2.2 Importance of renewable energy
The main source of energy is oil. Different researches brought out that in 150 years, half of
the global oil reserve that took hundreds of millions of years to produce has been used by
mankind. Recent data indicate that global oil production has been constant since 2005 and
possibly is the early indicator that we are at the peak.















Figure 2.2: The growing gap between oil production and new oil fields finds

Due to excessive use, amount of other fuels like natural gas, coal is also decreasing rapidly.

More than 90% of greenhouse gas emissions come from the combustion of fossil fuels.
Combustion of fossil fuels also produces other air pollutants, such as nitrogen oxides, sulfur
dioxide, volatile organic compounds and heavy metals. Combustion of fossil fuels generates
sulfuric, carbonic, and nitric acids, which fall to Earth as acid rain, impacting both natural
areas and environment. Monuments and sculptures made from marble and limestone are
































































































































































5

particularly vulnerable, as the acids dissolve calcium carbonate. Fossil fuels also contain
radioactive materials like uranium and thorium.

The principal risks associated with nuclear power arise from health effects of radiation. This
radiation consists of subatomic particles traveling at or near the velocity of light 186,000
miles per second. They can penetrate deep inside the human body where they can damage
biological cells and thereby initiate a cancer. The radioactive waste products from the nuclear
industry must be isolated from contact with people for very long time periods. This high level
waste will be converted to a rock-like form and emplaced in the natural habitat of rocks, deep
underground. The average lifetime of a rock in that environment is one billion years. If the
waste behaves like other rock, it is easily shown that the waste generated by one nuclear
power plant will eventually, over millions of years cause one death from 50 years of
operation. Moreover the recent tsunami in Japan once again proved that nuclear power is not
safe at all.

On the other hand, there is infinite supply of renewable energy sources, they are not harmful
to the environment and also provides safety.

So, due to shortage of fossil fuels, pollution and safety reasons it is essential to find out an
alternative energy source for the future generation. That`s why the concept of renewable
energy is very important. Scientists and engineers all over the world are researching on
renewable energy.


2.3 Sources of renewable energy
Various sources of renewable energy are:
• Solar energy.
• Wind power.
• Hydropower.
































































































































































6

• Biomass.
• Bio-fuel.
• Geothermal energy.
In recent time, engineers and scientists are looking for a possibility to genrate energy from
sound.

































































































































































7

Chapter 3
Solar Power
3.1 Solar energy
Solar Energy is the energy from the Sun .The Earth receives an incredible supply of solar
energy. The sun is a fusion reactor that has been burning over 4 billion years. It provides
enough energy in one minute to supply the world's energy needs for one year. In one day, it
provides more energy than our current population would consume in 27 years. In fact, the
amount of solar radiation striking the earth over a three-day period is equivalent to the energy
stored in all fossil energy sources.










Figure 3.1: Solar Radiation

































































































































































8

Solar energy is a free resource. The ability to use solar power for heating water was the first
discovery to use solar energy. Producing electricity from solar energy was later discovered.

3.2 Solar Power
The concept of solar power is based on photovoltaic effect, so before discussing about solar
power it is needed to learn about photovoltaic effect.

3.3 Photovoltaic Effect
Photovoltaic effect is the creation of voltage in a material with exposure of light. It is quite
similar to photoelectric effect, but the operation is different. Instead of ejecting electrons, in
photovoltaic effect the generated electrons are transferred between different bands.
When a photovoltaic (PV) cell is exposed to the sun`s thermal radiation, it absorbs the
thermal energy and converts it directly into DC electrical energy. The size of the PV cell and
the DC voltage and energy it can deliver are small. A number of these cells are mounted on a
plate and connected in series and parallel. These plates together form a solar array. These
arrays require sizeable exposed area and reasonably clear skies to deliver useable quantities
of electrical energy. Exploiting solar energy and converting it into an electrical form has been
under intense development for a long time. The main advantage of PV cell is that it
consumes no fuel. No fuel consumption results no pollution.

3.4 Solar cell

Semiconductors are used to make solar cell. In semiconductors, the filled band (valence
band) and the band in which electrons are free to move (conduction band) are separated by a
potential difference of about 1 volt. Hence, light coming in can push an electron from the
valence band into the conduction band if it has energy of about 1 electron volt (1 eV). The
































































































































































9

electron in the conduction band is free to move. If it is kept from recombining, it can give up
its energy in an external circuit before coming back to the material.









Figure 3.2: Energy Diagram

When light shines, electrons are liberated in the p-type region and holes produced in the n-
type region; this lowers the potential energy barrier at the junction. A current flows and
establishes an external potential difference.











Figure 3.3: Inside a Photovoltaic System
Solar cells act in a way similar to the diode, so that current can flow in only one direction
when the cell is exposed to light.

































































































































































10

3.5 Equivalent circuit of a solar cell









Figure 3.4: Simple equivalent circuit for a solar cell

The solar cell can be seen as a current generator which generates the current (density) J
sc
.
The dark current flows in the opposite direction and is caused by a potential between the +
and - terminals. In addition there might be two resistances, one in series (R
s
) and one in
parallel (R
p
). The series resistance is caused by the fact that a solar cell is not a perfect
conductor. The parallel resistance is caused by leakage of current from one terminal to the
other due to poor insulation. In an ideal solar cell, R
s
= 0 and R
p
= ·.

3.6 Material used in solar cells
The most popular choice for solar cells is silicon (Si), with a band gap of 1.1 eV,production
cell efficiencies of about 12 % and a maximum efficiency of about15%, and gallium
arsenide, with a band gap of 1.4 eV and a maximum efficiency of about 22%. The maximum
theoretical efficiency for a single cell is 33%. For multiple cells, the theoretical maximum is
68%. Both of these materials must be grown as single crystals under very precisely
controlled conditions to minimize imperfections, which can cause recombination.
The material gallium arsenide (GaAs) is also very popular for solar cells. Gallium and
arsenic are exactly one atomic higher and lower than silicon, so the system has many
similarities to a silicon-based semiconductor. It is less friable than silicon, more resistant to
































































































































































11

radiation damage, and so is the material of choice in space-based solar cells. Doping this
material with atoms from nearby columns in the periodic table changes the properties a bit.
Additionally, only very thin films of gallium arsenide need be used since it is so effective at
absorbing light. About half the energy in sunlight is unusable by most PV cells because this
energy is below the band gap, and so can`t free an electron from the valence to the
conduction band, or because it carries excess energy, which must be transferred to the cell
as thermal energy, heating up the cell.











Figure 3.5: different properties of silicon, gallium arsenide, and aluminum gallium arsenide

3.7 Solar cell efficiency
The efficiency of a solar cell depends on many factors. It is therefore possible that a single
solar cells performance varies widely depending on its location. This presents the industry
with a problem. The power of a solar cell is expressed in wattpeak (Wp), which represents its
efficiency under laboratory conditions. These conditions are set at a temperature of 25°C, a
light travel distance of 1.5 air mass and a light intensity of 1 kw/m2. This theoretical limit is
almost never reached.


































































































































































12

3.8 The suns intensity
The first factor is probably the most obvious. The brighter the sunlight, the more there is for
the solar cell to convert. It is for this reason that a solar cell performs best during spring and
summer; in fall and winter the sunlight is less intense and thus less able to kick loose` the
electrons from their parent atoms. This mainly reduces the flow of current; the voltage is
usually not that much affected. It is also due to this factor, that a solar cell will be able to
deliver more energy in the sunnier areas. The map below is the so-called insolation map for
the United States. It displays the average amount of kilowatt-hours received per day. Since a
solar cell`s performance is measured at an intensity of 1 kw/m2, the insolation can also be
read as the average amount of daily hours of sunshine. The definition of 'one hour of
sunshine¨ is chosen to match the laboratory conditions of the solar cell specifications (1
kW/m2).
















Figure 3.6: insolation map


































































































































































13













Figure 3.7: Daily Insolation Curve

3.9 Temperature
Contrary to popular belief, the efficiency of a solar cell decreases with increasing
temperature. The reason for this is that a higher temperature increases the conductivity of the
semiconductor. This balances out the charge within the material, reducing the magnitude of
the electric field at the junction. This in turn inhibits charge separation, which lowers the
voltage across the cell. It should be noted that a higher temperature increases the mobility of
electrons, which causes the flow of current to increase slightly. This increase is however
minor and insignificant compared to the decrease in voltage.






































































































































































14













Figure 3.8: effect of temperature on solar cell
This figure displays the response of a solar cell to varying temperature. The current increases
slightly, whilst the voltage decreases rapidly. The result is a lower overall power yield
(P=V*I).

The listed power of a solar cell is the power measured under ideal laboratory conditions,
which prescribe a temperature of 25 °C (77 °F). However, on a typical hot summer day, it is
not uncommon for a solar cell to reach a temperature of 70 °C (158 °F). A general rule of
thumb is that the efficiency of a solar cell decreases with 0.5% for every 1 °C (1.8 °F) above
25 °C (77 °F). This means that on a hot summer day, the efficiency of a solar cell could drop
as much as 25%. It is therefore extremely important to keep solar panels well ventilated.


3.10 Series resistance
When tying solar cells together, it is important to keep series resistance of the circuit to a
minimum. Resistance directly influences both voltage and current, and an increasing
resistance will cause the voltage-current curve of the solar cell to move away from the
maximum power point (MPP). At this point, a solar cell produces maximum output (through
































































































































































15

the equation P=V*I) and it is thus advantageous to maintain this point. Since the material in a
solar cell acts as a resistor to current flow, it is often advisable to limit the amount of serially
connected solar cells. By wiring individual serial batches` of solar cells in parallel can be
overcome














Figure 3.9: Effect of series resistance in solar cell

This figure displays the effect of series resistance on a solar cell`s output voltage and current.
By increasing series resistance, the solar cell moves away from the maximum power point.

































































































































































16

Chapter 4
Wind Power
4.1 History
Wind power has been utilized by mankind since historical times. Windmills have been
getting increasing attention on account of wind energy being available 'free¨ of cost and also
on account of being the most nonpolluting source of electricity. On the electricity front, it
started with a wind turbine driving an electricity generator, mainly an induction motor, which
is universally available. The output ratings were minuscule, a few hundred watts. Today, it is
entering into the club of megawatt-scale electricity producers. Krieger`s Flak, an island
located in the Baltic Sea between Sweden, Denmark, and Germany, is expected to fully
commission its wind farm rated at 630 MW by 2010.
The latest rates of growth are striking. In Europe, wind farm installations grew at a rate of
38% during 2007, compared to 19% during 2006. By 2007, total installed wind power
capacity there stood at 67 GW. Germany, Denmark, and Portugal were prominent. In the
United States, total wind farm capacity stood at 11 GW in 2007. It is growing fast in China,
India, and many other countries.
Yet, total contribution by wind energy to production of world electricity energy at the
beginning of 2006 has been very minuscule, 0.7% of the total of 17,500 TW -hr. It has its
drawbacks by its very nature.


4.2 Nature of Wind
Wind may blow steadily during certain periods, varying by day, season, location, and so on.
Let us say the velocities fall within some zones. The wind may die down, falling to almost
nil. Then it may rise from a very low speed. There may be a wind lull, when the wind dies
out and then raises in short bursts. A wind gust is the opposite phenomenon to a wind lull. A
































































































































































17

very strong wind is a storm. This nature of wind makes it an unreliable source of power due
to its variability and uncertainty.

4.3 Windmill Basics
The idea behind generating electricity from wind is quite simple. Wind is the manifestation
of the kinetic energy of air molecules in the atmosphere. In order to use this kinetic energy
for other purposes, all that one has to do is to have the wind hit a surface that is allowed to
move. This will cause the kinetic energy of the wind to be converted to the kinetic energy of
the moving object. Anyone who has ever been outside on a very windy days understands
these concepts. The hard part about generating electricity from wind is doing it cheaply. To
do this, a more fundamental knowledge about wind energy is needed
Let us imagine air that is moving through an area A with a velocity v as shown in following
figure. It is known that the kinetic energy of an individual air molecule is given by the
formula 1/2 mv
2
.

Now consider a large system of air molecules, which means looking at a volume of particles.
In a time At, the mass of the air that will flow through the area A is given by m = p A v At,
where p is the density of the air. Put these two formulae together, the kinetic energy of the air
that passes through an area A in a time At is given by the formula 1/2 p A v
3
At. Since the
energy per unit time is equal to the power, the power in the wind moving through the area A
is given by

P = K.E./At = 1/2 p A v
3





Figure 4.1: Diagram of wind tube
































































































































































18

In 1919, a German physicist by the name of Albert Betz

showed that the maximum amount of
power that one can get from the wind is only 59% of that given by the formula above. In
actuality, less than this maximum amount is getable. Therefore, the formula for the power
from a wind turbine is written as,
P = 1/2 Cp A v
3
Where, the factor C depends on the actual design of the windmill. The factors that affect the
constant C are many and complicated.

4.4 Components of A Wind Turbine Generator:
The following figure shows the components of a wind turbine generator. These are mainly:
1. The rotor blades, whose pitch is adjustable as per wind velocity so as to catch maximum
wind energy,

2. The gear box which adjusts the rpm of the rotor of the generator as closely as possible to
the grid synchronous frequency.

3. The generator, which converts mechanical input into an electrical output.












Figure 4.2: a wind turbine generator
































































































































































19

4.5 Connection of Wind Energy Plants to the Grid
In the early days of wind electricity generation, the plant sizes were small. With an induction
generator, there was no problem of synchronizing with grid frequency. External capacitors
took care of voltages; when there was a disturbance in the grid leading to low voltages at the
point of connection, the wind plants were disconnected and stayed disconnected until the grid
disturbance was cleared. Today, wind plant sizes have increased. Should a wind plant get
disconnected due to a grid disturbance, it could aggravate the situation. A grid code for
interconnection has evolved. The mean features of the grid codes are:

1. Accurate power control at a PF of ±0.95 has to be maintained at the point of connection.
2. Accurate plant models must be submitted.
3. SCADA data must be supplied as agreed with the system operator.


4.6 Wind Power generating system
A small DC motor has been used for this purpose. The fact that a motor can be used as a
generator has been applied here. The motor used in this project looks somewhat like the one
shown below in the picture:






Figure 4.3: A small DC motor
































































































































































20

This motor is a DC motor consisting of a brush. The brushed DC electric motor generates
torque directly from DC power supplied to the motor by using internal commutation,
stationary magnets (permanent or electromagnets), and rotating electrical magnets.
Like all electric motors or generators, torque is produced by the principle of Lorentz Force,
which states that any current-carrying conductor placed within an external magnetic field
experiences a torque or force known as Lorentz force. Advantages of a brushed DC motor
include low initial cost, high reliability, and simple control of motor speed. Disadvantages
are high maintenance and low life-span for high intensity uses. Maintenance involves
regularly replacing the brushes and springs which carry the electric current, as well as
cleaning or replacing the commutator. These components are necessary for transferring
electrical power from outside the motor to the spinning wire windings of the rotor inside the
motor. For the required operation of this project, a small fan consisting of three blades is
connected to the shaft of the motor. By applying sufficient wind from a suitable source, s
small table fan for example, the blades can be made to rotate which creates a potential
difference across the ends of the motor.

4.7 Advantages of Wind Power
1. The wind is free and with modern technology it can be captured efficiently.
2. Once the wind turbine is built it doesn`t cause green house effect.
3. Although wind turbines can be very tall each takes up only a small plot of land. This
means that the land below can still be used. This is especially the case in agricultural areas as
farming can still continue.
4. Remote areas that are not connected to the electricity power grid can use wind turbines to
produce their own supply.
5. Wind turbines have a role to play in both the developed and third world.
































































































































































21

6. Wind turbines are available in a range of sizes which means a vast range of people and
businesses can use them. Single households to small towns and villages can make good use
of range of wind turbines available today.

4.8 Disadvantages of Wind Power
1. The electricity produced will not be constant since wind speed varies everywhere through
out the world. At times there won`t be any production of electricity.

2. Wind turbines are noisy. Each one can generate the same level of noise as a family car
traveling at 70 mph.

3. Another of the disadvantages is that they can be damaged in thunderstorms, partially
because of their tall, thin shape. The website of the National Lightning Safety Institute
indicates that most damage to wind turbines is caused by lightening. This is more of a
problem in warmer parts of the world, where they are frequent.

4. Pollution is caused to some extent by the turbines.

5. Large wind farms are needed to provide entire communities with enough electricity. For
example, the largest single turbine available today can only provide enough electricity for
475 homes, when running at full capacity.





































































































































































22

Chapter 5
Transistors
5.1 Definition
The transistor, invented by three scientists at the Bell Laboratories in 1947, rapidly replaced
the vacuum tube as an electronic signal regulator. A transistor regulates current or voltage
flow and acts as a switch or gate for electronic signals. A transistor consists of three layers of
a semiconductor material, each capable of carrying a current. A semiconductor is a material
such as germanium and silicon that conducts
Electricity in a "semi-enthusiastic" way, it's somewhere between a real conductor such as
copper and an insulator (like the plastic wrapped around wires).
The semiconductor material is given special properties by a chemical process called doping.
The doping results in a material that either adds extra electrons to the material (which is then
called N-type for the extra negative charge carriers) or creates "holes" in the material's crystal
structure (which is then called P-type because it results in more positive charge carriers). The
transistor's three-layer structure contains an N-type semiconductor layer sandwiched between
P-type layers (a PNP configuration) or a P-type layer between N-type layers (an NPN
configuration).
A small change in the current or voltage at the inner semiconductor layer (which acts as the
control electrode) produces a large, rapid change in the current passing through the entire
component. The component can thus act as a switch, opening and closing an electronic gate
many times per second. Today's computers use circuitry made with complementary metal
oxide semiconductor (CMOS) technology. CMOS uses two complementary transistors per
gate (one with N-type material; the other with P-type material). When one transistor is
maintaining a logic state, it requires almost no power.
































































































































































23

Transistors are the basic elements in integrated circuits (ICs), which consist of very large
numbers of transistors interconnected with circuitry and baked into a single silicon microchip
or "chip."

5.2 Transistors used in Project
The two type of transistors used in our project are MOSFET and BJT. The full form
MOSFET is metal-oxide semiconductor field-effect transistor, whereas, the full form of BJT
is bipolar-junction-transistor.
The MOSFET used is the Power MOSFET IRF540N.
The BJT used is 2N3055 NPN transistor.
Both these transistors have been used for switching purpose. The BJT has been used in a
boost converter circuit because it is a current controlled and also provides faster switching
time. Using a MOSFET in that case wouldn`t provide the desired result.


5.3 Image and Pin Configuration





Figure 5.1: Image of 2N3055

Pin Configuration is quite simple. There is no pin for collector; the case itself acts as the
collector pin. The base is where the pulse has to be applied to ensure the flow of current from
collector to emitter.


































































































































































24









Figure 5.2: Image of IRF540N

The pin marked 1, 2 and 3 are the gate, drain and source pin respectively. Here, pulse has to
be applied to the gate terminal to ensure that switching is possible.

















































































































































































25

Chapter 6
Operational Amplifier
6.1 Introduction
Op-Amp is a kind of electrical device which is used as a DC coupled high voltage electric
amplifier which have different input and one output. Op-Amp is basically used for creating a
high voltage in the output whatever the input is given. An op-amp can create hundred or
thousand time larger output than the voltage difference between the input terminals.
Operational amplifiers are important electrical components for a wide range of electronic
circuits. Op-Amp was used for the first time in the analog computer. They were used in
many linear, non-linear and frequency-dependent circuits in analog computer. Its popularity
and importance increase for the characteristics of the final op-amp circuits with negative
feedback (such as their gain) are set by external components with a slightly dependence on
temperature changes.
Op-Amp is a differential amplifier. The difference which makes op-amp more efficient from
the other differential amplifier is those amplifier mostly have two output where op-amp is
only one output. The instrumentation amplifier (basically built from three op-amps), the
isolation amplifier (similar to the instrumentation amplifier, but with tolerance to common-
mode voltages that would destroy an ordinary op-amp), and negative feedback amplifier
(usually built from one or more op-amps and have a resistive feedback network).

6.2 Circuit notation




Figure 6.1: Circuit diagram symbol for an op-amp
































































































































































26

The circuit symbol for an op-amp is shown to the right, where:
• Vs
+
: positive power supply
• Vs
-
: negative power supply
• V
+
: non-inverting input
• V
-
: inverting input
• V
out
: output.
To provide additional power for amplification of the signal. Often these pins are left out of
the diagram for clarity, and the power configuration is described or assumed from the circuit.

6.3 Operation








Figure 6.2: An op-amp without negative feedback (a comparator)

The amplifiers differential input have +V input and a V input and ideally the op-amp
amplifies the difference in voltage between this two, these are called the differential input
voltage. The output voltage is calculated by the equation given below:
V
out
= (V
+
- V
-
).A
OL

Where,
A
OL
= open-loop gain of the amplifier.
V
+
= voltage at the non-inverting terminal
V
-
= voltage at the inverting terminal
































































































































































27

The amount of A
OL
is naturally very large; therefore even a slightly small difference between
V
+
and V
-
drives the amplifier output just about to the supply voltage. This is called
saturation of the amplifier. And the saturation can`t be controlled by the manufacturing
process. And this is a very vital draw back for the op-amp because for this we can`t use an
operational amplifier just as a differential amplifier.

6.4 Op-Amp characteristic
Ideal Op-Amps: An ideal op-amp is usually considered to have the following properties:
1. Infinite voltage range available at the output (v
out
) (in practice the voltages available from
the output are limited by the supply voltages V
s-
and V
s+
). The power supply sources are
called rails.
2. Infinite open-loop gain (when doing theoretical analysis, a limit may be taken as open loop
gain A
OL
goes to infinity).
3. Infinite input impedance (so, in the diagram, R
in
=·, and zero current flows from V
+
to V
-
).
4. Zero output impedance (i.e., R
out
= 0, so that output voltage does not vary with output
current).
5. Zero input current (i.e., there is assumed to be no leakage or bias current into the device).
6. Zero input offset voltage (i.e., when the input terminals are shorted so that V
+
= V
-
, the
output is a virtual ground or v
out
= 0).
7. Infinite bandwidth (i.e., the frequency magnitude response is considered to be flat
everywhere with zero phase shift).
8. Infinite slew rate (i.e., the rate of change of the output voltage is unbounded) and power
bandwidth (full output voltage and current available at all frequencies).
9. Zero noise.
































































































































































28

These ideals can be summarized by the two rules:
1. The inputs draw no current
2. The output attempts to do whatever is necessary to make the voltage difference between
the inputs zero.
In practice, none of these ideals can be perfectly realized, and different shortcomings and
compromises have to be accepted. Depending on the parameters of interest, a real op-amp
may be designed to take account of some of the non-infinite or non-zero parameters using the
same resistors and capacitors in the op-amp design. The designer can then include the effects
of these unwanted, but real, effects into the overall performance of the final circuit. Some
parameters may turn out to have a effect which is very negligible on the final design while
others represent actual limitations of the final performance, that must be evaluated.














Figure 6.3: An equivalent circuit of an operational amplifier that models some resistive non-
ideal parameters.
































































































































































29

6.5 Internal circuitry of 741 type op-amp:













Figure 6.4: A component level diagram of the common 741 op-amp. Dotted lines outline:
current mirrors (red); differential amplifier (blue); class A gain stage (magenta); voltage
level shifter (green); output stage (cyan).
Though designs differ between products and manufacturers, all op-amps have basically the
same internal structure, which consists of three stages:
1. Differential amplifier provides low noise amplification, high input impedance,
usually a differential output.
2. Voltage amplifier provides high voltage gain, a single-pole frequency roll-off,
usually single-ended output.
3. Output amplifier provides high current driving capability, low output impedance,
current limiting and short circuit protection circuitry.
IC op-amps as implemented in practice are quite complex integrated circuits. A typical
example is the ubiquitous 741 op-amp designed by Dave Fullagar in Fairchild Semiconductor
after the remarkable Widlar LM301. Thus the basic architecture of the 741 is identical to that
of the 301.
































































































































































30

6.6 Application:
In this project, the operational amplifier amplifies any voltage from the two renewable
sources. Two resistors of 1K and 10K have been used, while the two inputs are connected to
the positive input terminal of the operational amplifier. Since the ratio between the two
resistors is 10 so we get an amplification which is 11 times that of the input. The operation is
chosen such that, if the voltage of either of the input is at least 1.5V then it goes to the input
of the amplifier. Depending on the efficiency, either of solar or wind is chosen when both are
available.




Figure 6.5: An op-amp with negative feedback (a non-inverting amplifier)













































































































































































31

Chapter 7
Boost Converter
7.1 Introduction
A boost converter (step-up converter) is a power converter with an output DC voltage greater
than its input DC voltage. It is a class of switching mode power supply (SWPS) containing at
least two semiconductor switches (a diode and a transistor) and at least one energy storage
element. Filters made of capacitors (sometimes in combination with inductors) are normally
added to the output of the converter to reduce output voltage ripple.
A boost converter is a dc-dc converter with an output voltage greater than the source voltage.
A boost converter is sometimes called a step-up converter since it 'steps up¨ the source
voltage. Since power (P = VI) must be conserved, the output current is lower than the source
current.

7.2 Applications
Battery powered systems often stack cells in series to achieve higher voltage. However,
sufficient stacking of cells is not possible in many high voltage applications due to lack of
space. Boost converters can increase the voltage and reduce the number of cells. Two
battery-powered applications that use boost converters are hybrid electric vehicles (HEV)
and lighting systems.
The NHW20 model Toyota Prius HEV uses a 500 V motor. Without a boost converter, the
Prius would need nearly 417 cells to power the motor. However, a Prius actually uses only
168 cells and boosts the battery voltage from 202 V to 500 V. Boost converters also power
devices at smaller scale applications, such as portable lighting systems. A white LED
typically requires 3.3 V to emit light, and a boost converter can step up the voltage from a
single 1.5 V alkaline cell to power the lamp. Boost converters can also produce higher
































































































































































32

voltages to operate cold cathode fluorescent tubes (CCFL) in devices such as LCD backlights
and some flashlights.
A boost converter is used as the voltage increase mechanism in the circuit known as the
'Joule thief'. This circuit topology is used with low power battery applications, and is aimed
at the ability of a boost converter to 'steal' the remaining energy in a battery. This energy
would otherwise be wasted since the low voltage of a nearly depleted battery makes it
unusable for a normal load. This energy would otherwise remain untapped because many
applications do not allow enough current to flow through a load when voltage decreases. This
voltage decrease occurs as batteries become depleted, and is a characteristic of the ubiquitous
alkaline battery. Since (P = V
2
/ R) as well, and R tends to be stable, power available to the
load goes down significantly as voltage decreases.

7.3 Circuit Analysis
Operating Principle: The key principle that drives the boost converter is the tendency of an
inductor to resist changes in current. When being charged it acts as a load and absorbs energy
(somewhat like a resistor; it is to be noticed that base pulse of the transistor which has been
used as the switch should be less than millisecond to reduce the chance to damage the
inductor); when being discharged it acts as an energy source (somewhat like a battery). The
voltage it produces during the discharge phase is related to the rate of change of current, and
not to the original charging voltage, thus allowing different input and output voltages.





Figure 7.1: Boost converter schematic


































































































































































33









Figure 7.2: The two configurations of a boost converter, depending on the state of the switch
S.
The basic principle of a Boost converter consists of 2 distinct states
• In the On-state, the switch S is closed, resulting in an increase in the inductor current;
• In the Off-state, the switch is open and the only path offered to inductor current is
through the diode D, the capacitor C and the load R. This result in transferring the
energy accumulated during the On-state into the capacitor.
• The input current is the same as the inductor current as can be seen in figure 2. So it is
not discontinuous as in the buck converter and the requirements on the input filter are
relaxed compared to a buck converter.

7.4 Continuous mode







Figure 7.4: Waveforms of current and voltage in a boost converter operating in continuous
mode
































































































































































34

When a boost converter operates in continuous mode, the current through the inductor (I
L
)
never falls to zero. Figure shows the typical waveforms of currents and voltages in a
converter operating in this mode. The output voltage can be calculated as follows, in the case
of an ideal converter (i.e. using components with an ideal behavior) operating in steady
conditions:
During the On-state, the switch S is closed, which makes the input voltage appear across the
inductor, which causes a change in current (I
L
) flowing through the inductor during a time
period (t) by the formula:

At the end of the On-state, the increase of I
L
is therefore:

D is the duty cycle. It represents the fraction of the commutation period T during which the
switch is on. Therefore D ranges between 0 (S is never on) and 1 (S is always on).
During the Off-state, the switch S is open, so the inductor current flows through the load. If
we consider zero voltage drop in the diode, and a capacitor large enough for its voltage to
remain constant, the evolution of I
L
is:

Therefore, the variation of I
L
during the Off-period is:

As we consider that the converter operates in steady-state conditions, the amount of energy
stored in each of its components has to be the same at the beginning and at the end of a
commutation cycle. In particular, the energy stored in the inductor is given by:


L
V
o
-V
i



=
di

dt

L

=
AI
t


At

V
i


L

L

AI
Lon



=
1

L
V
i
dt


=
}

DT
0
DT
V
i
L

L

=
AI
Loff


(V
i
- V
o
) (1-D)T

L

=

}

T
DT
(V
i
- V
o
) oT

L

E

=

0.5L I
L
2

































































































































































35


= AI
Lon



+

AI
Loff



0
So, the inductor current has to be the same at the start and end of the commutation cycle.
This means the overall change in the current (the sum of the changes) is zero:

Substituting AI
Lon
and AI
Loff
by their expressions yields:

This can be written as:

This in turns reveals the duty cycle to be:

From the above expression it can be seen that the output voltage is always higher than the
input voltage (as the duty cycle goes from 0 to 1), and that it increases with D, theoretically
to infinity as D approaches 1. This is why this converter is sometimes referred to as a step-up
converter.









AI
Lon



+

AI
Loff



=

=
V
i
DT

L
(V
i
- V
o
) (1-D)T

L

0

=
V
o


V
i


1

(1-D)


= D
V
o


V
i



1

-
































































































































































36

7.5 Discontinuous mode









Figure 7.4: Waveforms of current and voltage in a boost converter operating in
discontinuous mode
In some cases, the amount of energy required by the load is small enough to be transferred in
a time smaller than the whole commutation period. In this case, the current through the
inductor falls to zero during part of the period. The only difference in the principle described
above is that the inductor is completely discharged at the end of the commutation cycle (see
waveforms in figure 4). Although slight, the difference has a strong effect on the output
voltage equation. It can be calculated as follows:
As the inductor current at the beginning of the cycle is zero, its maximum value I
LMAX
(at t =
DT) is

During the off-period, I
L
falls to zero after oT:

Using the two previous equations, o is:


I
Lmax


=
V
i
DT

L

I
Lmax


+
(V
i
- V
o
) oT

L

=

0

o

=
V
i
D

(V
i
- V
o
)
































































































































































37

The load current I
o
is equal to the average diode current (I
D
). As can be seen on figure 4, the
diode current is equal to the inductor current during the off-state. Therefore the output
current can be written as:

Replacing I
max
and o by their respective expressions yields:
Therefore, the output voltage gain can be written as follows:

Compared to the expression of the output voltage for the continuous mode, this expression is
much more complicated. Furthermore, in discontinuous operation, the output voltage gain not
only depends on the duty cycle, but also on the inductor value, the input voltage, the
switching frequency, and the output current.















I
o


=

I
D

I
Lmax

o
2

L

=

I
o


=

*
V
i
DT

2L
V
i
D

(V
i
- V
o
)

=
V
i
2

D
2
T

2L(V
i
- V
o
)

=

1

+
V
i
2

D
2
T

2LI
o

V
o


V
i


































































































































































38

Chapter 8
Microcontroller ATmega-16
8.1 Features
The following are some of the common features of the microcontroller used in this project.
1. Advanced RISC Architecture.
2. Up to 16 MIPS Throughput at 16 MHz.
3. 16K Bytes of In-System Self-Programmable Flash.
4. 512 Bytes EEPROM.
5. 1K Byte Internal SRAM.
6. 32 Programmable I/O Lines.
7. In-System Programming by On-chip Boot Program.
8. 8-channel, 10-bit ADC.
9. Two 8-bit Timer/Counters with Separate Prescalers and Com.
10. One 16-bit Timer/Counter with Separate Prescaler, Compare.
11. Four PWM Channels.
12. Programmable Serial USART.
13. Master/Slave SPI Serial Interface.
14. Byte-oriented Two-wire Serial Interface.
15. Programmable Watchdog Timer with Separate On-chip Oscill.
16. External and Internal Interrupt Sources.

8.2 Pin Configuration and Pin Descriptions
The pin descriptions are as follows:
VCC: Digital supply voltage. (+5V)

GND: Ground. (0 V) Note there are 2 ground Pins.

Port A (PA7 - PA0): Port A serves as the analog inputs to the A/D Converter. Port A also
serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used. When pins PA0 to
































































































































































39

PA7 are used as inputs and are externally pulled low, they will source current if the internal
pull-up resistors are activated. The Port A pins are tri-stated when a reset condition becomes
active, even if the clock is not running.

Port B (PB7 PB0): Port B is an 8-bit bi-directional I/O port with internal pull-up resistors
(selected for each bit). Port B also serves the functions of various special features of the
Atmega16.

Port C (PC7 PC0): Port C is an 8-bit bi-directional I/O port with internal pull-up resistors
(selected for each bit). Port C also serves the functions of the JTAG interface and other
special features of the ATmega16. If the JTAG interface is enabled, the pull-up resistors on
pins PC5(TDI), PC3(TMS) and PC2(TCK) will be activated even if a reset occurs.
Port D (PD7 - PD0): Port D is an 8-bit bi-directional I/O port with internal pull-up resistors
(selected for each bit). Port D also serves the functions of various special features of the
Atmega16.

RESET: Reset Input. A low level on this pin for longer than the minimum pulse length will
generate a reset, even if the clock is not running.

XTAL1: External oscillator pin 1

XTAL2: External oscillator pin 2

AVCC: AVCC is the supply voltage pin for Port A and the A/D Converter. It should be
externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be
connected to VCC through a low-pass filter.

AREF: AREF is the analog reference pin for the A/D Converter.



































































































































































40













Figure. Atmega16 Pin Configurations

8.3 NEXTSAPIENS
The burner used for the microcontroller used in this project is NEXTSAPIENS. The features
are as follows:

1. 40 Pin Atmel ATmega16/32 microcontroller with internal system clock up to 8 MHz and
externally up to 16 MHz

2. 16/32 KB FlashRAM memory for programs.

3. 1/2 KB of SRAM .

4. 512/1024 Bytes of EEPROM.

5. One 6x1 Pin SPI Relimate Header.

6. Eight 3x1 Pin Relimate header inputs for 8 analog sensors.

PA0(ADC0)
PA1(ADC1)
PA2(ADC2)
PA3(ADC3)
PA4(ADC4)
PA5(ADC5)
PA6(ADC6)
PA7(ADC7)
AREF
GND
AVCC
PC7(TOSC2)
PC6(TOSC1)
PC5(TD1)
PC4(TD0)
PC3(TMS)
PC2(TCK)
PC1(SDA)
PC0(SCL)
PD7(OC2)



(XCK/T0)PB0
(T1)PB1
(INT2/AIN0)PB2
(OC0/AIN1)PB3
(SS`)PB4
(MOSI)PB5
(MISO)PB6
(SCK)PB7
RESET`
VCC
GND
XTAL2
XTAL1
(RXD)PD0
(TXD)PD1
(INT0)PD2
(INT1)PD3
(OC1B)PD4
(OC1A)PD5
(ICP1)PD6


40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21




1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20



































































































































































41

7. One 16 Pin header to connect 16*2 alphanumeric LCD.

8. Two onboard L293D drivers for motors (upto 600 mA per channel)..

9. Dual 7805 Voltage regulator.

10. Dual power input options (Through molex connector or through DC Jack).

11. Two programmable Micro-Switches.

12. Two programmable LEDs.

13. Two DPDT switches (one for power on/off and one for reset).

14. MAX 232 Level shifter for RS232 communication.

15. One 3x1 Pin relimate header for RS2332 communication.

17. Four 8 Pin berg stick headers (male) from each port of ATmega16/32.

18.Wide input power range from 7 volts to 24 volts at 1.5-2 Amps.

19. Board size of 6 x 3 inches, designed for educational and hobby purpose, on high quality
PCB.


8.4 Software used for Coding

The software used for coding is BASCOM AVR. It is the original Windows BASIC
COMPILER for the AVR family. It is designed to run on W95/W98/NT/W2000/XP.

The following are some the key benefits of using this software:
· Structured BASIC with labels.
· Structured programming with IF-THEN-ELSE-END IF, DO-LOOP, WHILE-WEND,
SELECT- CASE.
· Fast machine code instead of interpreted code.
· Variables and labels can be as long as 32 characters.
































































































































































42

· Bit, Byte, Integer, Word, Long, Single and String variables.
· Compiled programs work with all AVR microprocessors that have internal memory.
· Statements are highly compatible with Microsoft`s VB/QB. Special commands for
LCD-displays, I2C chips and 1WIRE chips, PC keyboard, matrix keyboard, RC5
reception.
· AT keyboard support, send IR remote code, SPI protocol master & slave, graphical
LCD support.
· Local variables, user functions, library support.
· Integrated terminal emulator with download option.
· Integrated simulator for testing. Or use AVR Studio and toggle between the BASIC
code and object/asm code.
· Integrated ISP programmer (application note AVR910.ASM).
· Many Integrated programmers like the STK200, STK300, STK500, SE, Hotchip, and
Futurelec.
· Editor with statement highlighting.
· Context sensitive help.
· Perfectly matches the DT006 Simm-Stick
· DEMO version compiles 2KB of code.
· Well suited for the AT90S2313.
· Ideal tool for your first steps into Micro's.
· Support for TCP/IP.






































































































































































43

8.5 Programming
The following code has been used in this project:
$regfile "m32def.dat"
$crystal = 1000000

Config Lcd = 16 * 2
Config Lcdpin = Pin , Db4 = Portb.4 , Db5 = Portb.5 , Db6 = Portb.6 , Db7 = Portb.7 , E =
Portb.3 , Rs = Portb.2

Config Adc = Single , Prescaler = Auto , Reference = Avcc
Start Adc

Config Timer1 = Pwm , Pwm = 8 , Prescale = 1 , Compare A Pwm = Clear Down , Compare
B Pwm = Clear Down
Start Timer1

Config Porta = Input
Config Portd.0 = Output
Config Portd.1 = Output
Config Portd.2 = Output
Config Portc.0 = Output
Config Portc.1 = Output
Dim A As Integer
Dim B As Integer
Dim C As Integer
Start Adc
Do
Reset Portc.1
Waitus 10.305
Reset Portc.0
Waitms .1
A = Getadc(0)

Lcd A
Lcd " "
B = Getadc(1)
Lcd B
Lcd " "
C = Getadc(2)
Lcd C
































































































































































44

Cls

If A > 300 And B > 300 Then
Set Portd.1
Reset Portd.0
Elseif A > 300 And B < 300 Then
Set Portd.0
Reset Portd.1
Elseif A < 300 And B > 300 Then
Set Portd.1
Reset Portd.0
Elseif A < 300 And B < 300 Then
Reset Portd.0
Reset Portd.1
End If

If A > 300 And B > 300 And C > 1000 Then
Reset Portd.2
Elseif A > 300 And B > 300 And C < 1000 Then
Set Portd.2
End If
If A > 300 And B < 300 And C > 1000 Then
Reset Portd.2
Elseif A > 300 And B < 300 And C < 1000 Then
Set Portd.2
End If

If A < 300 And B > 300 And C > 1000 Then
Reset Portd.2
Elseif A < 300 And B > 300 And C < 1000 Then Set Portd.2
End If

If A < 300 And B < 300 Then
Set Portd.2
End If
Set Portc.1
Waitus 10.305
Set Portc.0
Waitms .1
Loop

To develop an understanding of this code on can go through the BASCOM AVR tutorial
which is available online and can be downloaded very easily.

































































































































































45

Chapter 9
Hybrid Operation
9.1 Introduction
The circuit consists of three project boards, a solar panel, a small fan connected to the shaft
of a DC motor which acts as the wind turbine, few MOSFETs, one operational amplifier, a
microcontroller, a boost converter, two buck converters and some other necessary
components such as resistors, capacitors and inductors. The basic idea of this project is to
utilize the best source among the two and use it to charge a battery and supply current to a
load. For efficient performance it has been ensured that when the battery is fully charged,
current is fed directly from one of the sources to the load. When none of the sources are
available but the battery has been charged to some extent for use then current is fed from the
battery to the load. All these operations have been performed by the microcontroller. The
picture below gives an idea of the project as a whole.














Figure 9.1: Circuit Photo
































































































































































46

9.2 Circuit Diagram and Operation
It has been discussed earlier that the title hybrid` has been given since more than one source
of different type has been used for production of current. Let`s now try and look more deeply
into the circuit and understand the operation of purpose of it. The diagram below shows how
various components along with the two renewable sources are connected.






















Figure 9.2: Circuit Diagram of the Hybrid System

































































































































































47

Selection of the Source: The two sources are connected to the ADC of the microcontroller
and also to the input of the operational amplifier. The code of the microcontroller has been
set in such a way so that it allows the voltage from one of the sources to the operational
amplifier only when it is greater than around 1.47V. The purpose of IRF540N which is the n-
channel depletion type mosfet is to serve as switches in all parts of the circuit. In the
diagram, it can be seen two IRF540N is connected with the positive terminal of the solar
panel and wind turbine before they are connected to the positive input terminal of the
operational amplifier. This has been done for switching purpose. When the ADC of the
microcontroller reads a voltage greater than 1.47V it sends a pulse to the gate of the
corresponding MOSFET. For instance, if the voltage supplied by the solar panel is 1.5V
while the wind turbine is not rotating, than the microcontroller sends a 5V pulse to the gate of
the MOSFET which is connected to the positive terminal of the solar panel. When the pulse
has been provided, current flows from source to drain and thus that path has been shorted.
This is how switching is done.
The basic idea is to choose the most efficient source among the two. Whenever the word
efficient comes to mind, one would think of the source that provides greater voltage.
However, in this project one of the drawbacks of the solar panel is that the current provided
by it is quite less compared to that provided by the wind turbine system. Therefore, the code
has been set in a way so that the microcontroller chooses wind as the source of supply
whenever it provides a voltage greater than 1.47V. This will be explained in details later on.

Use of Adapter and LM7805: The use of adapter is to ensure the supply the supply of voltage
to the microcontroller and the biasing voltage to the operational amplifier. However, a 12V
DC adapter has been used, which is suitable for biasing of the Op-Amp but not suitable as the
V
cc
of the microcontroller. For this purpose the buck regulator LM7805 has been used which
regulates the voltage to 5V. It has also been used to regulate the output of the Op-Amp to 5V.

Operational Amplifier for step-up operation: Although boost converters are usually used for
step-up operation, in that could not be used. This is due to the fact the current provided by the
solar panel is very low. From the operation of boost converter we know that it can amplify a
DC voltage, but the output current decreases. A minimum current also needs to be provided
































































































































































48

as the input current to ensure that a boost converter works. Even though the boost converter
may work when the wind turbine is working as the source, but whenever the solar panel is
working the current is too low for the boost converter to work. Although, this problem could
have been solved by providing a pulse of smaller time period to the base of the transistor
used in the boost circuit, this couldn`t be done due to the limitation of our microcontroller.
A suitable and economic solution to this problem is the use of IC741 which is the operational
amplifier. Although, this is not a suitable solution when a system is to be designed for
producing high voltages, but for a prototype this turned out to be suitable solution.
The operation of the Op-Amp as a non-inverting amplifier has been applied to this problem.
One resistor of 1KO connected to the negative input terminal and one 10KO connected
between the output and negative input terminal ensured a gain of 11 times that of the input
voltage. The only problem of using Op-Amp is that current flowing is about 17mA and this
increases the time taken by the battery to store charge. Since the output provided by the Op-
Amp is a minimum of around 10V so a buck regulator has been used again to ensure that no
harm is done to the battery during the process of charging.

Use of Boost Converter: In most charging system, a Charger light for instance, during the
charging of the battery the load cannot be on. In this prototype system, the charging of
battery and the load being on happens simultaneously. This is mainly because of the use of
the boost regulator. It has been stated earlier that the use of boost regulator isn`t possible
because of the lack of the flow of current from the solar panel. So the question that comes to
mind is how come the boost regulator is coming to use now? Well, this can be explained
easily if we take a close look at a certain portion of the circuit.








































































































































































49

















Figure 9.3: A close look at the circuit













Figure 9.4: A closer look at the circuit board
































































































































































50

If we look at the current flowing, we get an idea of what is happening here. The LM7805 is
the regulator that regulates the output from the Op-Amp. This voltage is used for charging
the battery and also as the input of the boost regulator. As the battery starts to store charge, a
current tries to flow in the opposite direction. A diode placed right after the regulator stops
the current from flowing in the opposite direction and forces it to flow in the direction shown
in the diagram. The current marked IB is the current from the battery, and IR is the current
from the renewable source, these two currents are added together as IB+R and flows through
the boost converter circuit. Thus, it can be concluded that the current has been increased and
now the boost regulator works successfully. So, this is how the boost regulator has been
made to work using the current from both the rechargeable battery as well as the renewable
source. This also ensures that the charging of battery and the load remaining on happens at
the same time. From experimental analysis it has been found out that the regulated output of
the boost converter is in the range 13V-16V.

Various functions of ATMEGA32: The microcontroller uses BASCOM AVR code. The code
has been shown in of the earlier chapters. The various functions of the microcontroller will
now be discussed.
The first basic operation is to choose the most efficient source of the two. This has already
been discussed in the topic 'Selection of the Source¨. Three MOSFETs and one BJT have
been used in this project. Thus, another function of the microcontroller is to send pulses to
these transistors as per requirement.
Earlier in this chapter, it has been mentioned that there is a limitation of the microcontroller
ATMEGA32 which doesn`t allow us to reduce the time period of the pulses. The limitation is
that the microcontroller cannot send pulses in nanoseconds. Had this been possible, it would
have allowed the use of boost regulator in place of the Op-Amp.

Use of BJT: Although, MOSFET could have been used in the boost converter circuit, but
MOSFET is a voltage controlled device, whereas, BJT is a current controlled device. In
addition, the switching time of BJT is fast compared to that MOSFET, thus in this project
BJT was preferred to MOSFET in the boost converter circuit.

































































































































































51

9.3 Four Main Operations
The whole project had to be verified experimentally many times to ensure that all the
components were working successfully especially the microcontroller. Since, the practical
world always presents us with many factors which are neglected in the theoretical world, in
the initial stages there were many unexplainable errors. However, after repeating the analysis
many times we were successfully able to build a prototype whose operation has already been
described. Let`s now summarize the four main operations of our project with pictures and
data tables. These are the four main operations:
i) Charging of battery and feeding current to load using wind energy
ii) Charging of battery and feeding current to load using solar energy
iii) Current fed to the load directly from renewable source
iv) Current fed to the load directly from battery

9.4 Charging of battery using wind energy feeding current to load using
wind energy
When the voltage from the generator is greater than the voltage from the solar panel then the
battery is charged using wind power. However, in this project, the solar panel is a bit weak.
The solar panel is weak in a sense that it provides with less current compared to that of wind,
even if the voltage provided by it is comparable or greater than that of wind. Thus, whenever
sufficient wind energy is available the microcontroller chooses wind over solar. This
operation is fairly simple and can be done by connecting the positive terminal of the inputs to
ADC pins of the microcontroller. The microcontroller converts the analog voltage to a digital
value and compares the input from wind and solar. This operation goes on as long as
sufficient wind energy is available and battery needs to be charged. In addition, the load also
draws current from the wind power.


































































































































































52










Figure 9.5: Charging of battery using wind energy













Figure 9.6: A photo of the system utilizing wind energy

9.5 Charging of battery and feeding current to load using solar energy
Although, the microcontroller is supposed to perform this operation whenever the voltage
provided by the solar panel is higher than that provided by the wind, in practice the
Wind
Turbine
Battery Load
































































































































































53

Battery Load
Solar
Panel
microcontroller has been programmed such that it allows the charging of battery by solar
energy only when wind energy isn`t available in sufficient amount. This has been done to
ensure efficient performance since the solar panel is a bit weak when it comes to providing
current. The operation is similar to that mentioned in one of the pervious chapter. Once
again, the ADC pin comes into use and current is also fed to the load.








Figure 9.7: Charging of battery and feeding current to load using solar energy
















Figure 9.8: A photo of the system utilizing solar energy (wind turbine not rotating)
































































































































































54

9.6 Current fed to the load directly from renewable source
To ensure efficient performance of the system this operation has been added. It ensures that
when the battery is fully charged, the charging path is open so that the battery charging
process is stopped. Then the load only draws current from one of the source. Once again, this
is done by connecting the positive terminal of the battery to one of the ADC pins of the
microcontroller. Whenever, the microcontroller reads that the battery is fully charged it
disconnects the charging path by turning of the pulse that was going to the MOSFET.
However, it must be mentioned that once the battery charging path has been forced to be
open using the MOSFET as switch, the boost regulator no longer works. This is because of
the fact that during the charging process the battery contributes some of its current to the load
and this current is added to a portion of the current coming from the renewable energy. Thus,
when the charging process is stopped there is no longer a contribution of current by the
battery. So, the earlier problem of not having enough current causes the same problem again.
In this situation, one possible improvement that could have been made to this circuit was
connecting two renewable sources in series. However, this wasn`t done owing to the fact that
the solar panel has an opposing current flowing in situation when there is no light, which
meant that more MOSFETs had to be used.










Figure 9.9: Current fed to the load directly from renewable source

Solar
Panel
Wind
Turbine
Load
































































































































































55

9.7 Current fed to the load directly from battery:
This particular operation comes into use when none of the sources are available. If the battery
is fully or sufficiently charged then the microcontroller sends pulse to one of the MOSFETs
which short a path connecting the battery and the load. This ensures that the load remains on
all the time.

9.8 Experimental Analysis
After practically testing the design several times we were successfully able to build a
prototype of a simple power system. Below are some of the readings that were noted during
the experiment.

Expt.
No.
Wind Turbine Solar
Panel
Source
Chosen
Boost Converter
output
Battery
Charging
Load

(i)

0V 2V Solar 14.5V On On
(ii) 4.5V X Wind 15 On On
(iii) 4.5V X Wind
Drop Across the
Load
Full(4.88V) On
(iv) 1V 2V Solar
Drop Across the
Load
Full(4.88V) On
(v) 0V 0V None 16V Off On
(vi) 0V 0V None 0V Off Off
Figure 9.10: Experimental Data
































































































































































56

It is important to note that in (iii) and (iv) when the battery is fully charged the boost
regulator doesn`t work due to the fact that the current provided isn`t high enough. Does the
voltage read is the drop across the load.
In (v) none of the sources are available; this is when the load is fed directly from the battery.
No charging of battery is possible in this case.
In (vi) none of the sources are available, the battery has run out of charge and thus the system
comes to a halt with both charging and load being off.




















































































































































































57

Chapter 10
Discussion and Conclusion
10.1 Discussions
This project presented some major difficulties one of which was the use of buck boost
converter. Although, ready made buck boost converters are available in markets at present,
but in our country these converters are not available neither are boost converters. Thus, the
decision to use operational amplifier which is the IC-741 was taken. This served for the boost
operation. LM7805 and LM7812 which regulates voltage to 5V and 12V respectively were
bought. For both LM7805 and LM7812 the input voltages to the chip must be greater than 5
and 12 volts respectively or else the circuit will not work.
The use of operational amplifier introduced one of the major drawbacks of this project which
is the fact that it doesn`t allow a great amount of current to flow through. Experimental
analysis shows that only a current of approximately 16mA could flow. This is a huge
problem since it increases the time taken by the battery to complete the charging process. In
addition, some loads that require higher current than 16mA could not be used properly in our
circuit. For example, an energy saving bulb that requires 12V and a current of 2A was
connected in our circuit but its brightness was minimum due to the lack of flow of current.
The use of diode is essential in the charging circuit which ensures that current doesn`t flow in
the opposite direction, that is, from battery towards the regulator. In similar situations, where
the flow of current in a particular direction was to be avoided, a diode was used.
The use of OPAMP forced the use of some extra voltage sources for biasing which increased
the cost of this particular circuit. A simple to this problem once again is the use of a boost
regulator.
Negative biasing was provided simply by connecting the positive terminal of the battery to
the ground and the negative terminal to the desired pin of IC 741.
The use of boost converter with the load connected across its output was possible mainly
because of the fact the battery while charging contributes some of its current along with the
































































































































































58

current coming from the regulated output of the Op-Amp. This also enabled the charging
process and load being on to be possible at the same time.

10.2 Suggestions for future work
Although this type of a system is not really suited to countries where the wind speed is not
sufficient, this particular prototype can be used in small applications. One particular
application that can be suggested for future work is the use of this circuit as a portable
charger for cell phone, or source of power for devices that require 5-12V. This would be
feasible when traveling in a car or fast moving vehicle where there`s always sufficient wind
and during daytime the possibility of solar power.
The second suggestion for future work is the possible use of a third source. Sound energy is
one possible source that can be used. The only problem with using sound energy is that it
produces very less voltage for a very loud sound. Experimental analysis shows that
piezoelectric crystals are materials capable of turning mechanical energy into electrical
energy. A prototype of a particular technology was able to convert sound of around 100
decibels - the equivalent of noisy traffic - to generate 50 mill volt of electricity. The
technology uses tiny strands of zinc oxide sandwiched between two electrodes. A sound
absorbing pad on top vibrates when sound waves hit it, causing the tiny zinc oxide wires to
compress and release. This movement generates an electrical current that can then be used to
charge a battery. In our project we tried using a microphone to generate electricity from a
sound source; however, very loud sound was required. We played loud music from the
speakers of a computer and held the microphone near the speaker. Approximately 30mV was
generated, this was later on amplified to about 3V using an operational amplifier, majority of
which was due to noise. So, the use of sound energy as the third source is definitely possible
but needs a lot of research to be done.
Another proposal for future work is probably is the most interesting of all. In recent times, in
our country the use of Electric Vehicle has been quite popular. It uses electricity with the
help of a battery system to start its engine. However, during the charging process of these
batteries they consume a huge amount of power from the grid. The prototype used in this
































































































































































59

project with a few changes to it can turn out to be a very suitable system for these types of
vehicles and can also save huge amount of power from the grid.

10.3 Conclusion
It`s very difficult to remove the losses from a power system. Thus, a better method of
improving things would be to try and utilize the energy that is being wasted. It`s not
necessary to use that waste energy and utilize it to generate voltage in huge amount; rather,
we can try and use them in many small applications. That way it`s possible to reduce
increasing demand of electricity from the National Grid.
With our prototype, we have successfully charged various mobile phones. The size of our
prototype is very small and easily portable. The output was boosted to around 16V. If some
improvements are made, then it can be utilized in the use of appliances that require voltages a
bit higher than 5V.

Many people might argue that the future of 'A Renewable World¨ is dark. But, from what
we have experienced after doing the project, the possibilities of utilizing renewable energy is
endless, useful and interesting.


































































































































































60

References:

[1] R. W. Erickson, D. Maksimovic, Fundamentals of Power Electronics, Kluwer Academic
Publishers, 2nd Edition, New York, USA, 2004.
[2] V. Vorpérian, 'Simplified Analysis of PWM Converters Using the Model of the PWM
Switch Part I: Continuous Conduction Mode¨, IEEE Transactions on Aerospace and
Electronics Systems, vol. 26, no. 3, pp. 490-496, May 1990.
[3] Jia-Ren Chang Chien,Kuo-Ching Tseng, and Bo-Yi Yan, 'Design of a hybrid battery
charger system fed by a wind-turbine and photovoltaic power generators¨, Department of
Electronic Engineering, National Kaohsiung First University of Science and Technology,
No.2, Jhuoyue Rd., Nanzih District, Kaohsiung City, 811 Taiwan (Received 29 December
2010; accepted 12 February 2011; published online 10 March 2011).
[4] B.J. Chalmers, A.M. Green, A.B.J. Reece, A.H. Al-Badi, 'Modeling and Simulation of
Torus Generator¨, Electric Power Application, vol. 144, issue 6, November 1997.
[5] Z. Guo, L. Chang, 'FEM Study of Permanent Magnet Synchronous Generators for Small
Wind Turbines¨ Canadian Conference on Electrical and Computer Engineering, pp. 641-644,
May 2005.
[6] I. Barbi, Eletrônica de Potência, Autor`s Editor, 6
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Edition, Florianópolis, 2006.
[7] I. Barbi, Projeto de Fontes Chaveadas, Autor`s Editor, 2
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[8] Wang, Z., 2-MOSFET Transistors with Extremely Low Distortion for Output Reaching
Supply Voltage, Electron. Lett., Vo1.26, pp.951-952, 1990.
[9] E. Koutroulis, K. Kalaitzakis, 'Design of a Maximum Power Tracking System for Wind-
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2, pp. 486-494, April 2006.
[10] H. M. Oliveira Filho, R. P. T. Bascopé, L. H. S. C. Barreto, F. L. M. Antunes, D. S.
Oliveira Jr., 'Control Design of Converters for Wind Energy Conversion Systems Applied to
Battery Charging¨, in Proc. of INDUSCON, vol. 8, 2008.




































































































































































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IRF540N (DATASHEET):













































































































































































































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2N3055(DATASHEET):













































































































































































































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LM78XX Series(DATASHEET):













































































































































































































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