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SOLAR BASED FAN WITH TAGGED SPEED SELECTION FOR RURAL PEOPLE

CHAPTER 1INTRODUCTION

Fig 1: Solar Fan

This project is designed keeping the problem of rural area people in mind. Basically the power shortage is frequent in rural areas, especially in summer, also, now a days the current charges are getting increased. To avoid all these problems we implemented this project with the help of renewable energy resources i.e. the sunlight

In this project the solar panel is used to charge the re-chargeable battery which is the heart of the project. The regulator followed by the battery sets the voltage level constantly i.e.12V. The fan is working with the voltage of 12V.

This project is easy to implement and less cost. It is durable and reliable. With the help of this project we can over-come the problem faced by the rural people because of the power shortage.

In this project battery is recharged from two supply voltages. One from house hold supply and another from solar panels. So in this way we have two phases of supplies are available for charging the battery.

V.K .R , V.N.B & A.G.K COLLEGE OF ENGINEERING


CHAPTER 2BLOCK DIAGRAM

all

To all sections

Fig 2: Block diagram


Control Switch Array

DC Motor(Fan)

Solar Panel Unidirectional flow circuit

Rechargeable Battery

Step down T/F

Bridge Rectifier

Filter Circuit

Regulator


2.1 EXPLANATION OF BLOCK DIAGRAM:

Solar rechargeable fans become necessary for a common man. Especially, in summer,

the power shortage is more. To overcome from the difficulties caused by power shortage this

innovative project is designed. This project is designed for 12V motor.

The battery also can be charged through 230V house hold supply. This charge circuit

uses regulated 12V, 750mA power supply. 7812 three terminal voltage regulator is used for

voltage regulation. Bridge type full wave rectifier is used to rectify the ac out put of

secondary of 230/18V step down transformer.

A rechargeable lead acid battery of 12V is used to power the circuit. A solar panel is

connected to the battery for charging the battery by means of solar energy. A PN junction

diode is used to control the charge current for unidirectional flow.

In this project Control switch array is used in between rechargeable battery and DC

fan. It controls the speed operation of a fan. By using this control switch array.

To run a fan we are using the DC motor. This motor can run with rechargeable

battery. It can be controlled by control switch array.



CHAPTER 3

SCHEMATIC DIAGRAM

Fig 3: Schematic Diagram



3.1 WORKING PROCEDURE

A rechargeable lead acid battery of 12V is used to power the circuit.

A solar panel is connected to the battery for charging the battery by means of solar

energy.

A PN junction diode is used to control the charge current for unidirectional flow.

The battery also can be charged through 230V house hold supply.

This charge circuit uses regulated 12V, 750mA power supply.

7812 three terminal voltage regulator is used for voltage regulation.

Bridge type full wave rectifier is used to rectify the ac output of secondary of

230/18V step down transformer.



EXPLANATION OF EACH BLOCK



CHAPTER 4

POWER SUPPLY DESIGN

Fig 4.1: Power supply design

Input ac supply gives the voltage of 230 volts to the transformer.

Transformer converts the voltage 230V to 12V.

The AC voltage is converted into DC voltage by the full wave bridge type rectifier.

The AC ripples presented in the output of full wave rectifier are eliminated by the

filter circuit.

For producing the constant output voltage of 12V, regulator is used.


INPUT AC SUPPLY

TRANSFORMER

FULL WAVE

BRIDGE TYPE

RECTIFIER

FILTER CIRCUIT

VOLTAGE REGULATO

R


4.1 POWER SUPPLY

The input to the circuit is applied from the regulated power supply. The a.c. input i.e.,

230V from the mains supply is step down by the transformer to 12V and is fed to a rectifier.

The output obtained from the rectifier is a pulsating d.c voltage. So in order to get a pure d.c

voltage, the output voltage from the rectifier is fed to a filter to remove any a.c components

present even after rectification. Now, this voltage is given to a voltage regulator to obtain a

pure constant dc voltage.

4.2 TRANSFORMER:

Usually, DC voltages are required to operate various electronic equipment and these

voltages are 5V, 9V or 12V. But these voltages cannot be obtained directly. Thus the a.c

input available at the mains supply i.e., 230V is to be brought down to the required voltage

level. This is done by a transformer. Thus, a step down transformer is employed to decrease

the voltage to a required level.



Fig 4.2: Transformer

4.3 RECTIFIER:

The output from the transformer is fed to the rectifier. It converts A.C. into

pulsating D.C. The rectifier may be a half wave or a full wave rectifier. In this project, a

bridge rectifier is used because of its merits like good stability and full wave rectification.

Fig 4.3: Rectifier

The Bridge rectifier is a circuit, which converts an ac voltage to dc voltage using both

half cycles of the input ac voltage. The Bridge rectifier circuit is shown in the figure. The

circuit has four diodes connected to form a bridge. The ac input voltage is applied to the

diagonally opposite ends of the bridge. The load resistance is connected between the other

two ends of the bridge.

For the positive half cycle of the input ac voltage, diodes D1 and D3 conduct, whereas

diodes D2 and D4 remain in the OFF state. The conducting diodes will be in series with the

load resistance RL and hence the load current flows through RL.



For the negative half cycle of the input ac voltage, diodes D2 and D4 conduct

whereas, D1 and D3 remain OFF. The conducting diodes D2 and D4 will be in series with the

load resistance RL and hence the current flows through RL in the same direction as in the

previous half cycle. Thus a bi-directional wave is converted into a unidirectional wave



Fig 4.3.1: Bridge rectifier output

4.4 FILTER



Capacitive filter is used in this project. It removes the ripples from the output of

rectifier and smoothens the D.C. Output received from this filter is constant until the mains

voltage and load is maintained constant. However, if either of the two is varied, D.C. voltage

received at this point changes. Therefore a regulator is applied at the output stage.

Fig 4.4: Capacitor Filter.

Capacitor is a electronic component which stores the energy in the form of electric

field. The capacitor is allows the only ac components and rejects the dc components so from

the properties of the capacitor, here we use the capacitor filter.



4.5 VOLTAGE REGULATOR

As the name itself implies, it regulates the input applied to it. A voltage regulator is an

electrical regulator designed to automatically maintain a constant voltage level. In this

project, power supply of 5V and 12V are required. In order to obtain these voltage levels,

7805 and 7812 voltage regulators are to be used. The first number 78 represents positive

supply and the numbers 05, 12 represent the required output voltage levels. The L78xx series

of three-terminal positive regulators is available in TO-220, TO-220FP, TO-3, D2PAK and

DPAK packages and several fixed output voltages, making it useful in a wide range of

applications. These regulators can provide local on-card regulation, eliminating the

distribution problems associated with single point regulation. Each type employs internal

current limiting, thermal shut-down and safe area protection, making it essentially

indestructible. If adequate heat sinking is provided, they can deliver over 1 A output current.

Although designed primarily as fixed voltage regulators, these devices can be used with

external components to obtain adjustable voltage and currents.

Fig 4.5: Voltage

Regulator PIN & INTERNAL diagrams.



CHAPTER 5

CONTROL SWITCH ARRAY

A group of four switches are used at the transmitter end for the robot movement. To

move the robot in forward, backward, left direction we require these control switch Array.

For this operation we are using push button (4 leg push button). A pushbutton is a simple

switch mechanism which permits user generated changes in the state of a circuit. Pushbutton

usually comes with four legs. Anyway, as you can see from the picture below, legs are

always connected in groups of two. When the pushbutton is pressed all the 4 legs are

connected. This kind of 4 switches are connected on pcb .

Fig 5: Control switch array.



CHAPTER 6

SOLAR PANEL

Fig 6: Solar Panel

6.1 SOLAR PANEL

A solar panel (photovoltaic module or photovoltaic panel) is a packaged

interconnected assembly of solar cells, also known as photovoltaic cells. The solar panel can

be used as a component of a larger photovoltaic system to generate and supply electricity in

commercial and residential applications. Because a single solar panel can only produce a

limited amount of power, many installations contain several panels. A photovoltaic system

typically includes an array of solar panels, an inverter, may contain a battery and

interconnection wiring.

Solar panels use light energy (photons) from the sun to generate electricity through

the photovoltaic effect. The structural (load carrying) member of a module can either be the

top layer or the back layer. The majority of modules use wafer-based crystalline silicon cells

or thin-film cells based on cadmium telluride or silicon. The conducting wires that take the



current off the panels may contain silver, copper or other conductive (but generally not

magnetic) transition metals.

The cells must be connected electrically to one another and to the rest of the system. Cells

must also be protected from mechanical damage and moisture. Most solar panels are rigid,

but semi-flexible ones are available, based on thin-film cells.

Electrical connections are made in series to achieve a desired output voltage and/or in

parallel to provide a desired current capability.

Separate diodes may be needed to avoid reverse currents, in case of partial or total

shading, and at night. The p-n junctions of mono-crystalline silicon cells may have adequate

reverse current characteristics that these are not necessary. Reverse currents waste power and

can also lead to overheating of shaded cells. Solar cells become less efficient at higher

temperatures and installers try to provide good ventilation behind solar panels.

Some recent solar panel designs include concentrators in which light is focused by

lenses or mirrors onto an array of smaller cells. This enables the use of cells with a high cost

per unit area (such as gallium arsenide) in a cost-effective way.[citation needed].

Depending on construction, photovoltaic panels can produce electricity from a range

of frequencies of light, but usually cannot cover the entire solar range (specifically,

ultraviolet, infrared and low or diffused light). Hence much of the incident sunlight energy is

wasted by solar panels, and they can give far higher efficiencies if illuminated with

monochromatic light. Therefore another design concept is to split the light into different

wavelength ranges and direct the beams onto different cells tuned to those ranges. This has

been projected to be capable of raising efficiency by 50%. The use of infrared photovoltaic

cells has also been proposed to increase efficiencies, and perhaps produce power at night.

[citation needed].

Sunlight conversion rates (solar panel efficiencies) can vary from 5-18% in

commercial products, typically lower than the efficiencies of their cells in isolation. Panels

with conversion rates around 18% are in development incorporating innovations such as

power generation on the front and back sides. The Energy Density of a solar panel is the

efficiency described in terms of peak power output per unit of surface area, commonly



expressed in units of Watts per square foot (W/ft2). The most efficient mass-produced solar

panels have energy density values of greater than 13 W/ft2.

Fig 6.1: Outer view of solar panel.



Fig 6.1.1: Conversion of Solar Energy

The solar panel diagram above shows how solar energy is converted into electricity through

the use of a silicon cell.

In the diagram above, you can see how a solar panel converts sunlight into energy to

provide electricity for a range of appliances.

This energy can be used for heating, through the use of solar hot water panels, or

electricity through the use of regular solar cells.

6.2 THE THEORY BEHIND THE SOLAR PANEL DIAGRAM

As you can see from the above diagram of a solar panel, photons are contained within

the sun’s rays and beam down to earth.

Once these photons reach the solar panel, they are absorbed by the silicon material,

and this allows electrons to be knocked off their orbit.

As the electrons are knocked off their orbit, they become free electrons and are able to

pick up a current, resulting in the flow of electricity to external sources.

New technologies are making renewable energy devices much more efficient and a

viable contender for electricity production from fossil fuels.

6.3 THE USE OF ELECTRICITY FROM SOLAR PANELS

As the solar panel diagram shows, you can see how power is sourced out to various

locations, this depends on how you plan to use the energy harnessed by a solar cell.



Possible uses of solar electricity could be to incorporate the current into an existing

power supply, provide a separate power supply dependent upon the solar panel, to charge

solar batteries for the storage of solar electricity, or even to sell back to the national grid.

Solar panels can even be used to heat water in different designs. Some home

swimming pools also use solar energy to heat the water, however this can usually be a very

expensive option.

Solar energy has a huge advantage for providing electricity in remote locations due to the

simple running requirements (i.e. no fossil fuels need to be transported the location).

A remote solar panel system can provide electricity for vital tasks where the laying of

electricity cable is not practical, a working example of this is on satellites



CHAPTER 7

RECHARGEABLE BATTERY

Fig 7: Rechargeable Battery

7.1 RECHARGEABLE BATTERY

A rechargeable battery or storage battery is a group of one or more electrochemical

cells. They are known as secondary cells because their electrochemical reactions are

electrically reversible. Rechargeable batteries come in many different shapes and sizes,

ranging anything from a button cell to megawatt systems connected to stabilize an electrical

distribution network. Several different combinations of chemicals are commonly used,



including: lead-acid, nickel cadmium (NiCd), nickel metal hydride (NiMH), lithium ion (Li-

ion), and lithium ion polymer (Li-ion polymer).

Rechargeable batteries have lower total cost of use and environmental impact than

disposable batteries. Some rechargeable battery types are available in the same sizes as

disposable types.

Rechargeable batteries are used for automobile starters, portable consumer

devices, light vehicles (such as motorized wheelchairs, golf carts, electric bicycles, and

electric forklifts), tools, and uninterruptible power supplies. Emerging applications in hybrid

electric vehicles and electric vehicles are driving the technology to reduce cost and weight

and increase lifetime.

Normally, new rechargeable batteries have to be charged before use; newer low

self-discharge batteries hold their charge for many months, and are supplied charged to about

70% of their rated capacity.

Grid energy storage applications use rechargeable batteries for load leveling,

where they store electric energy for use during peak load periods, and for renewable energy

uses, such as storing power generated from photovoltaic arrays during the day to be used at

night. By charging batteries during periods of low demand and returning energy to the grid

during periods of high electrical demand, load-leveling helps eliminate the need for

expensive peaking power plants and helps amortize the cost of generators over more hours of

operation.

The US National Electrical Manufacturers Association has estimated that U.S.

demands for rechargeable batteries is growing twice as fast as demand for non rechargeable.

7.2 CHARGING AND DISCHARGING

During charging, the positive active material is oxidized, producing electrons, and the

negative material is reduced, consuming electrons. These electrons constitute the current flow

in the external circuit. The electrolyte may serve as a simple buffer for ion flow between

the electrodes, as in lithium-ion and nickel-cadmium cells, or it may be an active participant

in the electrochemical reaction, as in lead-acid cells.


http://en.wikipedia.org/wiki/Lead-acid_battery

http://en.wikipedia.org/wiki/Electrochemical

http://en.wikipedia.org/wiki/Nickel-cadmium_battery

http://en.wikipedia.org/wiki/Lithium-ion_battery

http://en.wikipedia.org/wiki/Electrode

http://en.wikipedia.org/wiki/Ion

http://en.wikipedia.org/wiki/Electrolyte

http://en.wikipedia.org/wiki/Electrical_network

http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Redox

http://en.wikipedia.org/wiki/Electron

http://en.wikipedia.org/wiki/Oxidized


Fig7.2: Charging Of a Secondary Cell Battery

Fig 7.2.1: Battery Charge

The energy used to charge rechargeable batteries usually comes from a battery

charger using AC mains electricity. Chargers take from a few minutes (rapid chargers) to

several hours to charge a battery. Most batteries are capable of being charged far faster than

simple battery chargers are capable of; there are chargers that can charge consumer sizes of

NiMH batteries in 15 minutes. Fast charges must have multiple ways of detecting full charge

(voltage, temperature, etc.) to stop charging before onset of harmful overcharging.


http://en.wikipedia.org/wiki/Mains_electricity

http://en.wikipedia.org/wiki/Battery_charger


http://en.wikipedia.org/wiki/File:Secondary_Cell_Diagram.svg

http://en.wikipedia.org/wiki/File:Charger.jpg


Fig 7.2.2: A Solar-powered Charger for Rechargeable Batteries

Rechargeable multi-cell batteries are susceptible to cell damage due to reverse

charging if they are fully discharged. Fully integrated battery chargers that optimize the

charging current are available.

Attempting to recharge non-rechargeable batteries with unsuitable equipment may

cause battery explosion Flow batteries, used for specialized applications, are recharged by

replacing the electrolyte liquid.

Battery manufacturers' technical notes often refer to VPC; this is volts per cell, and

refers to the individual secondary cells that make up the battery. For example, to charge a 12

V battery (containing 6 cells of 2 V each) at 2.3 VPC requires a voltage of 13.8 V across the

battery's terminals.

Non-rechargeable alkaline and zinc-carbon cells output 1.5V when new, but this

voltage gradually drops with use. Most NiMH AA and AAA batteries rate their cells at 1.2 V,

and can usually be used in equipment designed to use alkaline batteries up to an end-point of

0.9 to 1.2V

7.3 REVERSE CHARGING

Subjecting a discharged cell to a current in the direction which tends to discharge it

further, rather than charge it, is called reverse charging; this damages cells. Reverse charging

can occur under a number of circumstances, the two most common being:


http://en.wikipedia.org/wiki/Electrochemical_cell

http://en.wikipedia.org/wiki/Volt

http://en.wikipedia.org/wiki/Flow_battery

http://en.wikipedia.org/wiki/Battery_explosion#Explosion


http://en.wikipedia.org/wiki/Rechargeable_battery#Reverse_charging

http://en.wikipedia.org/wiki/Rechargeable_battery#Reverse_charging

http://en.wikipedia.org/wiki/File:Solar_AA_charger_01_Pengo.jpg


When a battery or cell is connected to a charging circuit the wrong way round.

When a battery made of several cells connected in series is deeply discharged.

When one cell completely discharges ahead of the rest, the live cells will apply a reverse

current to the discharged cell ("cell reversal"). This can happen even to a "weak" cell that is

not fully discharged. If the battery drain current is high enough, the weak cell's internal

resistance can experience a reverse voltage that is greater than the cell's remaining internal

forward voltage. This results in the reversal of the weak cell's polarity while the current is

flowing through the cells. This can significantly shorten the life of the affected cell and

therefore of the battery. The higher the discharge rate of the battery needs to be, the better

matched the cells should be, both in kind of cell and state of charge. In some extreme cases,

the reversed cell can begin to emit smoke or catch fire.

CHAPTER 8

DC MOTOR

Fig 8: DC Motor



8.1 DC MOTOR

A DC motor is an electric motor that runs on direct current (DC) electricity. A motor

is a electrical device which converts electrical energy into mechanical energy. A motor

working on the direct current supply is known as DC MOTOR.

8.2 DC MOTOR CONNECTIONS

Figure shows schematically the different methods of connecting the field and

armature circuits in a DC Motor. The circular symbol represents the armature circuit, and

the squares at the side of the circle represent the brush commutator system. The direction of

the arrows indicates the direction of the magnetic fields.

Fig 8.2: Motor Connections



Externally –Excited DC-Motor:

This type of DC motor is constructed such that the field is not connected to the

armature. This type of DC motor is not normally used.

Shunt DC Motor

The motor is called “shunt” Motor because the field id parallel, or “shunts” the

armature.

Series DC Motor

The motor field windings for a series motor are in series with the armature.

Compounded DC Motor

A compounded DC motor is constructed so that it contains both a shunt and a series

field. This particular schematic shows in a above diagram fig 8.2 “cumulatively-

compounded” DC motor because the shunt and series fields are aiding one another.

Compound DC Motor

Compound DC motor is also called a “differentially – compounded” DC motor

because the shunt and series field oppose one another.

8.3 BRUSHED DC MOTOR

The brushed DC motor generates torque directly from DC power supplied to the

motor by using internal commutation, stationary permanent magnets, and rotating electrical

magnets.It works on 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.



Fig 8.3: Brushed DC motor

8.4 BRUSHLESS DC MOTOR

Brushless DC motors use a rotating permanent magnet in the rotor, and stationary

electrical magnets on the motor housing. A motor controller converts DC to AC. This design

is simpler than that of brushed motors because it eliminates the complication of transferring

power from outside the motor to the spinning rotor. Advantages of brushless motors include

long life span, little or no maintenance, and high efficiency. Disadvantages include high

initial cost, and more complicated motor speed controllers.

8.5 TORQUE AND SPEED OF A DC MOTOR

The torque of an electric motor is independent of speed. It is rather a function of flux and

armature current. As shown in below fig 8.5

Fig 8.5: Torque Generation



8.6 CHARACTERISTICS OF DC MOTORS

DC motors respond to load changes in different ways, depending on the arrangement

of the windings.

Fig 8.6: Arrangement of DC Motor

8.7 SHUNT WOUND MOTOR

A shunt wound motor has a high-resistance field winding connected in parallel with

the armature. It responds to increased load by trying to maintain its speed and this leads to an

increase in armature current. This makes it unsuitable for widely-varying loads, which may

lead to overheating.

8.8 SERIES WOUND MOTOR

A series wound motor has a low-resistance field winding connected in series with the

armature. It responds to increased load by slowing down and this reduces the armature

current and minimizes the risk of overheating. Series wound motors were widely used as

traction motors in rail transport of every kind, but are being phased out in favor of AC

induction motors supplied through solid state inverters. The counter-emf aids the armature

resistance to limit the current through the armature. When power is first applied to a motor,

the armature does not rotate. At that instant the counter-emf is zero and the only factor

limiting the armature current is the armature resistance. Usually the armature resistance of a

motor is less than 1 Ω; therefore the current through the armature would be very large when



the power is applied. Therefore the need arises for an additional resistance in series with the

armature to limit the current until the motor rotation can build up the counter-emf. As the

motor rotation builds up, the resistance is gradually cut out.

8.9 PERMANENT MAGNET MOTOR

A permanent magnet DC motor is characterized by its locked rotor (stall) torque and

its no-load angular velocity (speed)

8.10 PRINCIPLES OF OPERATION

In any electric motor, operation is based on simple electromagnetism. A current-

carrying conductor generates a magnetic field; when this is then placed in an external

magnetic field, it will experience a force proportional to the current in the conductor, and to

the strength of the external magnetic field. As you are well aware of from playing with

magnets as a kid, opposite (North and South) polarities attract, while like polarities (North

and North, South and South) repel. The internal configuration of a DC motor is designed to

harness the magnetic interaction between a current-carrying conductor and an external

magnetic field to generate rotational motion.

Let's start by looking at a simple 2-pole DC electric motor (here red represents a magnet or

winding with a "North" polarization, while green represents a magnet or winding with a

"South" polarization).

Fig 8.10: Operation of Permanent Motor

Every DC motor has six basic parts -- axle, rotor (a.k.a., armature), stator,

commutator, field magnet(s), and brushes. In most common DC motors (and all that Beamers

will see), the external magnetic field is produced by high-strength permanent magnets. The

stator is the stationary part of the motor -- this includes the motor casing, as well as two or



more permanent magnet pole pieces. The rotor (together with the axle and attached

commutator) rotates with respect to the stator. The rotor consists of windings (generally on a

core), the windings being electrically connected to the commutator. The above diagram

shows a common motor layout -- with the rotor inside the stator (field) magnets.

The geometry of the brushes, commutator contacts, and rotor windings are such that

when power is applied, the polarities of the energized winding and the stator magnet(s) are

misaligned, and the rotor will rotate until it is almost aligned with the stator's field magnets.

As the rotor reaches alignment, the brushes move to the next commutator contacts, and

energize the next winding. Given our example two-pole motor, the rotation reverses the

direction of current through the rotor winding, leading to a "flip" of the rotor's magnetic field,

driving it to continue rotating.

In real life, though, DC motors will always have more than two poles (three is a very

common number). In particular, this avoids "dead spots" in the commutator. You can imagine

how with our example two-pole motor, if the rotor is exactly at the middle of its rotation

(perfectly aligned with the field magnets), it will get "stuck" there. Meanwhile, with a two-

pole motor, there is a moment where the commutator shorts out the power supply (i.e., both

brushes touch both commutator contacts simultaneously). This would be bad for the power

supply, waste energy, and damage motor components as well. Yet another disadvantage of

such a simple motor is that it would exhibit a high amount of torque "ripple" (the amount of

torque it could produce is cyclic with the position of the rotor).

Fig 8.10.1: Two-pole DC Motor

So since most small DC motors are of a three-pole design, let's tinker with the

workings of one via an interactive animation.



Fig 8.10.2: Three-pole DC Motor

You'll notice a few things from this -- namely, one pole is fully energized at a time

(but two others are "partially" energized). As each brush transitions from one commutator

contact to the next, one coil's field will rapidly collapse, as the next coil's field will rapidly

charge up (this occurs within a few microsecond). We'll see more about the effects of this

later, but in the meantime you can see that this is a direct result of the coil windings' series

wiring:

Fig 8.10.3: Three-pole DC Motor

The use of an iron core armature (as in the Mabuchi, above) is quite common, and has

a number of advantages. First off, the iron core provides a strong, rigid support for the

windings -- a particularly important consideration for high-torque motors. The core also

conducts heat away from the rotor windings, allowing the motor to be driven harder than

might otherwise be the case. Iron core construction is also relatively inexpensive compared

with other construction types.



But iron core construction also has several disadvantages. The iron armature has a

relatively high inertia which limits motor acceleration. This construction also results in high

winding inductances which limit brush and commutator life.

In small motors, an alternative design is often used which features a 'coreless'

armature winding. This design depends upon the coil wire itself for structural integrity. As a

result, the armature is hollow, and the permanent magnet can be mounted inside the rotor

coil. Coreless DC motors have much lower armature inductance than iron-core motors of

comparable size, extending brush and commutator life.

Fig 8.10.4: Internal Diagram of DC motor

8.11 DC MOTOR BEHAVIOR

8.11.1 HIGH-SPEED OUTPUT

This is the simplest trait to understand and treat -- most DC motors run at very high

output speeds (generally thousands or tens of thousands of RPM). While this is fine for some

BEAM bots (say, photo poppers or solar rollers), many BEAM bots (walkers, heads) require

lower speeds -- you must put gears on your DC motor's output for these applications.

8.12 BACK EMF

Just as putting voltage across a wire in a magnetic field can generate motion, moving

a wire through a magnetic field can generate voltage. This means that as a DC motor's rotor

spins, it generates voltage -- the output voltage is known as back EMF. Because of back

EMF, a spark is created at the commutator as a motor's brushes switch from contact to

contact. Meanwhile, back EMF can damage sensitive circuits when a motor is stopped

suddenly.

8.13 NOISE (RIPPLE) ON POWER LINES

A number of things will cause a DC motor to put noise on its power lines:

commutation noise (a function of brush / commutator design & construction), roughness in



bearings (via back EMF), and gearing roughness (via back EMF, if the motor is part of a

gearmotor) are three big contributors.

Even without these avoidable factors, any electric motor will put noise on its power

lines by virtue of the fact that its current draw is not constant throughout its motion. Going

back to our example two-pole motor, its current draw will be a function of the angle between

its rotor coil and field magnets:

Fig 8.13: Rippler Waveforms

Since most small DC motors have 3 coils, the coils' current curves will overlay each other:

Fig 8.13.1: Rippler Waveforms for 3 Coils

Added together, this ideal motor's current will then look something like this:

Reality is a bit more complex than this, as even a high-quality motor will display a current

transient at each commutation transition. Since each coil has inductance (by definition) and

some capacitance, there will be a surge of current as the commutator's brushes first touch a

coil's contact, and another as the brushes leave the contact (here, there's a slight spark as the

coil's magnetic field collapses).

As a good example, consider an oscilloscope trace of the current through a Mabuchi

FF-030PN motor supplied with 2 V (1ms per horizontal division, 0.05 mA per vertical

division):



Fig 8.13.2: Oscilloscope Output Waveform

In this case, the peak-to-peak current ripple is approximately 0.29 mA, while the

average motor current is just under 31 mA. So under these conditions, the motor puts about

less than 1% of current ripple onto its power lines (and as you can see from the "clean" traces,

it outputs essentially no high-frequency current noise). Note that since this is a 3-pole motor,

and each coil is energized in both directions over the course of a rotor rotation, one revolution

of the rotor will correspond to six of the above curves (here, 6 x 2.4 ms = 0.0144 sec,

corresponding to a motor rotation rate of just fewer than 4200 RPM).

Motor power ripple can wreak havoc in Nv nets by destabilizing them inadvertently.

Fortunately, this can be mitigated by putting a small capacitor across the motor's power lines

On the flip side of this coin, motor power ripple can be put to good use -- as was shown

above, ripple frequency can be used to measure motor speed, and its destabilizing tendencies

can be used to reverse a motor without the need for discrete "back-up" sensors.



CHAPTER 9

ADVANTAGES

To Save Power

When the power is turned off then we get the power from the sun light so in

this way we can able to save the power.

Renewable Energy

Renewable energy means the energy which is again producing. In our project

sunlight is used for charging of the battery, so it is a renewable energy resource.



Less Cost Effective

All the components used for the solar fan design are less cost, only the solar

panels are expensive so by overall designation it is less cost effective.

Two way Power Supply

In this project tow way power supply is the main advantage .one is from by

using house hold voltage source and another is from solar panels which converts solar

energy into electrical energy .

CHAPTER 10

APPLICATIONS

In air transport :

It is mainly used in the air craft’s to run the fans fast in the plane. Such type of planes

is called “Electric air craft”.

In Home Applications

In home appliances like refrigerators, fan etc..,

In Field of Agriculture



In the field of agriculture to run a wind mills also we are using this type of solar cells.

Industrial applications

In industrial appliance we can use this solar fan for to run a generator in machines.

Air conditioning systems

In air conditioners the fan is used in inside the conditioner to get an cool air.

In land transport

In land transport also we can use this project to run a vehicle in side motor is used fro

this we can this project is very help full to that.

CHAPTER 11

CONCLUSION & FUTURE SCOPE



This project presents the “SOLAR BASED FAN WITH TAGGED SPEED SELECTION FOR

RURAL PEOPLE” is been designed and implemented with Driver Circuit in order to drive the

DC Fan with the reference of Solar Panels . Experimental work has been carried out

carefully. The result shows higher efficiency.

To provide more power to drive the motors we have to enhance with more number of

Solar panels.

CHAPTER 12

REFERENCES



1."Solar Thermal Panel Kozi". solarpanelsonline.org.

2.”Solar Fan Man Looks To Sun For Solutions”. abcnews.go.com

3.”Solar powered fans-get cool breeze for free from these solar fans”.solarpoweredfans.org.

4.”Benfits of using solar powered fans”. irevew.com


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