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SOLAR BASED FAN WITH TAGGED SPEED SELECTION FOR
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SOLAR BASED FAN WITH TAGGED SPEED SELECTION FOR RURAL PEOPLE
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INDEX
1. ABSTRACT
2. BLOCK DIAGRAM
3. POWER SUPPLY
4. Solar Panel
5. Rechargeable Battery
6. Astable multivibrator
7. Transistor Driver circuit
8. H-Bridge
9. DC Motor
10. CONCLUSION
11. REFERENCES
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ABSTRACT
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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.
This 555 timer based PWM controller features almost 0 to 100% pulse width regulation using a
variable potentiometer, while keeping the oscillator frequency relatively stable. This project is
designed to operate the motor with a frequency of about 170 to 200 Hz. Any 555 chip will do,
CMOS is fine as well.
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 out put of secondary of
230/18V step down transformer.
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Block Diagram
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Control Switch
Array
Driver Circuit
DC Motor
(Fan)
Solar Panel
Step
down
T/F
Unidirectional
flow circuit
Bridge
Rectifier
Filter
Circuit
Rechargeable
Battery
Regulator
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INTRODUCTION TO PROJECT
A solar fan is a mechanical fan powered by solar panels. The solar panels are either mounted on
the device or are installed independently. Solar fans mostly do not require secondary power
sources other than solar power, as most of them are used for cooling purposes during day time.
Some types are also used for heating purposes. It runs the fastest when it is the hottest outside
providing savings on air conditioning costs
Applications
Solar fans are mostly applied for residential cooling purposes and in some cases, for industrial
applications.
Solar-powered attic fan
When airflow in the attic is low and when the sealing between the building and the attic is
ruptured, solar-powered attic fans will provide airflow from the building into the attic. This
action reduces the dampness in the building and saves energy. By installing a solar fan in the
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attic, the whole house is cooled as it creates a draft, draws in hot air and pushes it out. It provides
good circulation of air when the cool outside air is being drawn into the house through windows.
Solar-powered gable fan
It is similar to the solar-powered attic fan, except that its installation is a little different. Attic
fans are installed on the roof, whereas gable fans are installed in the gables, as the name
suggests. They are typically smaller in size but are more powerful than the solar attic fans. They
are mostly installed in places like garages or barns and other storage places where moisture is
usually present. These types of fans are generally installed on intake grills to provide ventilation.
Vents are usually installed high on the gable close to the ridge and are also coupled with soffit or
roof vents for well-balanced intake and exhaust air avenues. The airflow depends upon the level
of sunlight when there is more sunlight, the airflow will be more resulting in enhanced cooling. It
is also capable of lowering the air conditioning costs by cooling the attic.
As of February 2009, there have been plans of installing solar fans on the roof of Honolulu's
airport in addition to the ones existing and in the mansion of Indiana governor. The Indiana State
Senate was expected to pass a bill giving tax credits to homeowners with solar fans.
Advantages
A solar fan is more environmentally friendly.
Though initially the installation may be costlier, in the long term it would turn out to be
cheaper owing to the fact that it does not use power from the utility grid and may provide savings
up to 30 percent on air conditioning costs.
Risk of electric accidents are eliminated as there are no electric cords attached to the solar fan.
Another great benefit of having a cordless appliance is that it has much more mobility
compared to conventional fans
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Working procedure:
In this project total four switches are used for controlling the fan at different speed.

If switch 1 is pressed the speed range is very low.

If switch 2 is pressed the speed range is low.

If switch 3 is pressed the speed range is high.

If switch 4 is pressed the speed range is very high.
The speed will be varies depends upon the resistance values connected in series with dc
motor i.e., fan. If resistance value decreases the speed will be increases and vice versa.
The speed of the motor is controlled using control switches through transistor driver
circuit. In this the transistor will be in the on state but the output voltage given to the dc motor
varies according to the switch we select.
Solar panel is nothing but photovoltaic cells. So in this panel it produced some energy.
The Solar panel output voltage is 5v dc voltage. By using that energy the battery will be
charged. We are placing a diode between solar panel and battery terminal to avoid unwanted
drain of battery nothing but a reverse charge protection. Apart the solar panel by using household
power we can charge the battery. The maximum rated charge is 1.2 AH.
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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 is connected on Pb.
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Solar panel
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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 semiflexible 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.
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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.
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The solar panel diagram below shows how solar energy is converted into electricity through the
use of a silicon cell.
The below image is not a solar panel wiring diagram, if you need access to a wiring plan,
you could consult a specialist electrician, or solar installer.
In the diagram below, 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.
The Theory behind the Solar Panel Diagram
As you can see from the above diagram of a solar panel, photons are contained within the
suns rays and beam down to earth.
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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.
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.
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Rechargeable battery
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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 have higher initial cost, but can be recharged very
cheaply and used many times.
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.
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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.
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.
Charging of a secondary cell battery.
Battery charger
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A solar-powered charger for rechargeable batteries
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.
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,
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and can usually be used in equipment designed to use alkaline batteries up to an end-point of 0.9
to 1.2V
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:

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.[3][4] 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.
In critical applications using Ni-Cad batteries, such as in aircraft, each cell is
individually discharged by connecting a load clip across the terminals of each cell, thereby
avoiding cell reversal, then charging the cells in series.
TRANSISTOR DRIVER CIRCUIT:
An SPDT relay consists of five pins, two for the magnetic coil, one as the common terminal and
the last pins as normally connected pin and normally closed pin. When the current flows through
this coil, the coil gets energized. Initially when the coil is not energized, there will be a
connection between the common terminal and normally closed pin. But when the coil is
energized, this connection breaks and a new connection between the common terminal and
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normally open pin will be established. Thus when there is an input from the microcontroller to
the relay, the relay will be switched on. Thus when the relay is on, it can drive the loads
connected between the common terminals and normally open pin. Thus the relay acts as an
isolation device.
Vcc
RELAY
GROUND
The operation of this circuit is as follows:
The transistor will be switched on when the base to emitter voltage is greater than 0.7V (cut-in
voltage). Thus when the voltage applied is (>0.7V), the transistor will be switched on and thus
the relay will be ON and the load will be operated.
When the voltage applied is (<0.7V) the transistor will be in off state and the relay will be OFF.
Thus the transistor acts like a current driver to operate the relay accordingly.
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DC Fan
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DC motor
A DC motor is an electric motor that runs on direct current (DC) electricity.
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.
Brushed
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.
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Brushed DC motor
Brushless
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.
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.
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Characteristics of DC motors
DC motors respond to load changes in different ways, depending on the arrangement of the
windings.
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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.
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.
Permanent magnet motor
A permanent magnet DC motor is characterized by its locked rotor (stall) torque and its no-load
angular velocity (speed).
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
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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).
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.
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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).
So since most small DC motors are of a three-pole design, let's tinker with the workings of one
via an interactive animation.
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
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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:
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.
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DC motor behavior
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.
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.
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 gear motor) 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:
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Since most small DC motors have 3 coils, the coils' current curves will overlay each other:
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 commentator’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):
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).
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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
(you'll only be able to filter out "spiky" transients this way, though -- you'll always see curves
like the ones above being imposed on your power). 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.
SOLAR BASED FAN WITH TAGGED SPEED SELECTION FOR RURAL PEOPLE
MP17
www.WineYard.in
Conclusion
The project “SOLAR BASED FAN
WITH
TAGGED SPEED SELECTION FOR RURAL PEOPLE” is
designed such that it can be installed on any surface. It is much easy and cost effective than
increasing the height of the wall. The project is easily expandable and can be used by people to
reduce power consumption.
SOLAR BASED FAN WITH TAGGED SPEED SELECTION FOR RURAL PEOPLE
MP17
www.WineYard.in
REFERENCES:
1. Wikipedia
2. Magazines
3. Electronics for you
4. Electrikindia
5. WWW.google.com
6. WWW.Electronic projects.com
SOLAR BASED FAN WITH TAGGED SPEED SELECTION FOR RURAL PEOPLE