SOLAR BASED
CHAPTER 1 INTRODUCTION
Solar Fan 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.
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CHAPTER 2 BLOCK DIAGRAM
DC Motor (Fan)
Control Switch Array
Step down T/F
Rechargeable Battery
Unidirectional flow allTo all circuit sections
Solar Panel
Bridge Rectifier
Filter Circuit
Regulator
Fig 2: Block diagram Block diagram
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2.1 EXPLANATION EXPLANATION OF BLOCK DIAGRAM: 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 desi gned 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.
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CHAPTER 3 SCHEMATIC DIAGRAM
Fig 3: Schematic Diagram
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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.
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EXPLANATION OF EACH BLOCK
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CHAPTER 4 POWER SUPPLY DESIGN
INPUT AC SUPPLY
TRANSFORMER
VOLTAGE REGULATOR
FULL WAVE BRIDGE TYPE RECTIFIER
FILTER CIRCUIT
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.
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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
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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 R L and hence the load current flows through R L. 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 se ries with the load resistance R L and hence the current flows through R L in the same direction as in the previous half cycle. Thus a bi-directional wave is converted into a unidirectional wave
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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.
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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.
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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.
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SOLAR BASED
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
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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
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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.
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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.
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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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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 (Liion), 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.
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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.
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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 overch arging.
Fig 7.2.2: A Solar-powered Charger for Rechargeable Batteries
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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:
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.
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SOLAR BASED
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.
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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 “cumulativelycompounded” 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.
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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.
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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
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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 t hrough 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 currentcarrying 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.
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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
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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:
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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
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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:
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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
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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.
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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 .
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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.
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CHAPTER 11 CONCLUSION & FUTURE SCOPE This project presents the “SOLAR BASED FAN
WITH
TAGGED SPEED SELECTION FOR
R URAL 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.
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