three wheeled electric vehicle

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1. INTRODUCTIONAn electric vehicle (EV), also referred to as an electric drive vehicle, uses one or moreelectric motors ortraction motors forpropulsion. Three main types of electric vehicles exist,those that are directly powered from an external power station, those that are powered bystored electricity originally from an external power source, and those that are powered by anon-board electrical generator, such as an internal combustion engine.

1.1 BATTERYIn electricity, a battery is a device consisting of one or more electrochemical cells thatconvert stored chemical energy into electrical energy. There are two types of batteries:

primary batteries (disposable batteries), which are designed to be used once and discarded,and secondary batteries (rechargeable batteries), which are designed to be recharged and used

multiple times.

1.2 ELECTRIC MOTORBrushless DC electric motor (BLDC motors, BL motors) also known aselectronically commutated motors (ECMs, EC motors) are synchronous motorswhich are powered by a DC electric source via an integrated inverter/switching

power supply, which produces an AC electric signal to drive the motor.

1.3 ELECTRONIC SPEED CONTROLLERAn electronic speed control or ESC is an electronic circuit with the purpose to vary anelectric motor's speed, its direction and possibly also to act as a dynamic brake. ESCs areoften used on electrically powered radio controlled models, with the variety most often usedforbrushless motors essentially providing an electronically-generated three phase electric

powerlow voltage source of energy for the motor.

1.4 MATERIAL OF THE FRAMEWrought iron is an alloy with a very low carbon content in contrast to cast iron, and hasfibrous inclusions , known as slag. This is what gives it a grainresembling wood, which isvisible when it is etched or bent to the point of failure. Wrought iron is tough, malleable,ductile, and easily welded.
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2. POWER SUPPLY2.1 BATTERY

In electricity, a battery is a device consisting of one or more electrochemical cells thatconvert stored chemical energy into electrical energy. Since the invention of the first battery(or "voltaic pile") in 1800 by Alessandro Volta and especially since the technically improvedDaniell cell in 1836, batteries have become a common power source for many household andindustrial applications. According to a 2005 estimate, the worldwide battery industrygenerates US$48 billion in sales each year,with 6% annual growth.

There are two types of batteries: primary batteries (disposable batteries), which are designedto be used once and discarded, and secondary batteries (rechargeable batteries), which aredesigned to be recharged and used multiple times. Batteries come in many sizes, from

miniature cells used to power hearing aids and wristwatches to battery banks the size ofrooms that provide standby power for telephone exchanges and computer data centres.

FI G 1 - ELECTROCHEM ICAL CELL

A battery is a device that converts chemical energy directly to electrical energy. It consists ofa number of voltaic cells; each voltaic cell consists of two half-cells connected in series by aconductive electrolyte containing anions and cations. One half-cell includes electrolyte andthe electrode to which anions (negatively charged ions) migrate, i.e., the anode or negativeelectrode; the other half-cell includes electrolyte and the electrode to which cations(positively charged ions) migrate, i.e., the cathode or positive electrode. In the redox reactionthat powers the battery, cations are reduced (electrons are added) at the cathode, while anionsare oxidized (electrons are removed) at the anode.The electrodes do not touch each other butare electrically connected by the electrolyte. Some cells use two half-cells with differentelectrolytes. A separator between half-cells allows ions to flow, but prevents mixing of theelectrolytes.


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Each half-cell has an electromotive force (or emf), determined by its ability to drive electriccurrent from the interior to the exterior of the cell. The net emf of the cell is the difference

between the emfs of its half-cells, as first recognized by Volta. Therefore, if the electrodes

have emfs and , then the net emf is ; in other words, the net emf is thedifference between the reduction potentials of the half-reactions.

The electrical driving force or across the terminals of a cell is known as the terminalvoltage (difference) and is measured in volts. The terminal voltage of a cell that is neithercharging nor discharging is called the open-circuit voltage and equals the emf of the cell.Because of internal resistance, the terminal voltage of a cell that is discharging is smaller inmagnitude than the open-circuit voltage and the terminal voltage of a cell that is chargingexceeds the open-circuit voltage.An ideal cell has negligible internal resistance, so it wouldmaintain a constant terminal voltage of until exhausted, then dropping to zero. If such a cellmaintained 1.5 volts and stored a charge of one coulomb then on complete discharge it would

perform 1.5 joule of work. In actual cells, the internal resistance increases under discharge,and the open circuit voltage also decreases under discharge. If the voltage and resistance are

plotted against time, the resulting graphs typically are a curve; the shape of the curve variesaccording to the chemistry and internal arrangement employed.

As stated above, the voltage developed across a cell's terminals depends on the energy releaseof the chemical reactions of its electrodes and electrolyte. Alkaline and zinccarbon cellshave different chemistries but approximately the same emf of 1.5 volts; likewise NiCd and

NiMH cells have different chemistries, but approximately the same emf of 1.2 volts. On theother hand the high electrochemical potential changes in the reactions of lithium compoundsgive lithium cells emfs of 3 volts or more.

FIG 2 -TYPES OF BATTERY CELLS


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2.1.1 PRIMARY BATTERIESPrimary batteries can produce current immediately on assembly. Disposable batteries areintended to be used once and discarded. These are most commonly used in portable devicesthat have low current drain, are used only intermittently, or are used well away from an

alternative power source, such as in alarm and communication circuits where other electricpower is only intermittently available. Disposable primary cells cannot be reliably recharged,since the chemical reactions are not easily reversible and active materials may not return totheir original forms. Battery manufacturers recommend against attempting to recharge

primary cell.

Common types of disposable batteries include zinc-carbon batteries and alkaline batteries Ingeneral, these have higher energy densities than rechargeable batteries, but disposable

batteries do not fare well under high-drain applications with loads under 75 ohms (75 .).

2.1.2

SECONDARY BATTERIES

Secondary batteries must be charged before use; they are usually assembled with activematerials in the discharged state. Rechargeable batteries orsecondary cells can be recharged

by applying electric current, which reverses the chemical reactions that occur during its use.Devices to supply the appropriate current are called chargers or rechargers.

The oldest form of rechargeable battery is the leadacid battery. This battery is notable inthat it contains a liquid in an unsealed container, requiring that the battery be kept upright andthe area be well ventilated to ensure safe dispersal of the hydrogen gas produced by these

batteries during overcharging. The leadacid battery is also very heavy for the amount of

electrical energy it can supply. Despite this, its low manufacturing cost and its high surgecurrent levels make its use common where a large capacity (over approximately 10 Ah) isrequired or where the weight and ease of handling are not concerns.

A common form of the leadacid battery is the modern car battery, which can, in general,deliver a peak current of 450 amperes. An improved type of liquid electrolyte battery is thesealed valve regulated leadacid battery (VRLA battery), popular in the automotive industryas a replacement for the leadacid wet cell. The VRLA battery uses an immobilized sulfuricacid electrolyte, reducing the chance of leakage and extending shelf life.VRLA batteries havethe electrolyte immobilized, usually by one of two means:

Gel batteries(or "gel cell") contain a semi-solid electrolyte to prevent spillage. Absorbed Glass Mat (AGM) batteries absorb the electrolyte in a special fiberglass

matting.

Other portable rechargeable batteries include several "dry cell" types, which are sealed unitsand are, therefore, useful in appliances such as mobile phones and laptop computers. Cells ofthis type (in order of increasing power density and cost) include nickelcadmium (NiCd),nickelzinc (NiZn), nickel metal hydride (NiMH), and lithium-ion (Li-ion) cells. By far, Li-ion has the highest share of the dry cell rechargeable market. Meanwhile, NiMH has replaced

NiCd in most applications due to its higher capacity, but NiCd remains in use in power tools,two-way radios, and medical equipment. NiZn is a new technology that is not yet well

established commercially.
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Recent developments include batteries with embedded electronics such as USBCELL, whichallows charging an AA cell through a USB connector, and smart batterypacks with state-of-charge monitors and battery protection circuits to prevent damage on over-discharge. lowself-discharge (LSD) allows secondary cells to be precharged prior to shipping.

2.2 BATTERY CELL TYPESThere are many general types of electrochemical cells, according to chemical processesapplied and design chosen. The variation includes galvanic cells, electrolytic cells, fuel cells,

flow cells and voltaic piles.

2.2.1 WET CELLA wet cell battery has a liquid electrolyte. Other names are flooded cell, since the liquidcovers all internal parts, orvented cell, since gases produced during operation can escape to

the air. Wet cells were a precursor to dry cells and are commonly used as a learning tool forelectrochemistry. It is often built with common laboratory supplies, such as beakers, fordemonstrations of how electrochemical cells work. A particular type of wet cell known as aconcentration cell is important in understanding corrosion. Wet cells may be primary cells(non-rechargeable) or secondary cells (rechargeable). Originally, all practical primary

batteries such as the Daniell cell were built as open-topped glass jar wet cells. Other primarywet cells are the Leclanche cell, Grove cell,Bunsen cell, Chromic acid cell, Clark cell, andWeston cell. The Leclanche cell chemistry was adapted to the first dry cells. Wet cells arestill used in automobile batteries and in industry for standby power for switchgear,telecommunication or large uninterruptible power supplies, but in many places batteries withgel cells have been used instead. These applications commonly use leadacid or nickel

cadmium cells.

2.2.2 DRY CELL"Dry cell" redirects here. For the heavy metal band, see Dry Cell (band).

A dry cellhas the electrolyte immobilized as a paste, with only enough moisture in it to allowcurrent to flow. Unlike a wet cell, a dry cell can operate in any orientation without spilling as

it contains no free liquid, making it suitable for portable equipment. By comparison, the firstwet cells were typically fragile glass containers with lead rods hanging from the open top,and needed careful handling to avoid spillage. Leadacid batteries did not achieve the safetyand portability of the dry cell until the development of the gel battery.

A common dry cell battery is the zinccarbon battery, using a cell sometimes called the dryLeclanch cell, with a nominal voltage of 1.5 volts, the same as the alkaline battery (since

both use the same zincmanganese dioxide combination).
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FIG 3 - LI NE ART DRAWING OF A DRY CELL

1. BRASS CAP,2. PLASTIC SEAL,3. EXPANSION SPACE,4. POROUS CARDBOARD,

5. ZINC CAN,6. CARBON ROD,7. CHEMICAL MIXTURE.

A standard dry cell comprises a zinc anode (negative pole), usually in the form of acylindrical pot, with a carbon cathode (positive pole) in the form of a central rod. Theelectrolyte is ammonium chloride in the form of a paste next to the zinc anode. Theremaining space between the electrolyte and carbon cathode is taken up by a second pasteconsisting of ammonium chloride and manganese dioxide, the latter acting as a depolariser.In some more modern types of so-called 'high-power' batteries (with much lower capacity

than standard alkaline batteries), the ammonium chloride is replaced by zinc chloride.

2.3 MOLTEN SALTMolten salt batteries are primary or secondary batteries that use a molten salt as electrolyte.Theirenergy density and power density give them potential for use in electric vehicles, butthey operate at high temperatures and must be well insulated to retain heat.
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2.4 RESERVEA reserve battery is stored in unassembled form and is activated, ready-charged, when itsinternal parts are assembled, e.g. by adding electrolyte; it can be stored unactivated for a long

period of time. For example, a battery for an electronic fuze might be activated by the impact

of firing a gun, breaking a capsule of electrolyte to activate the battery and power the fuze'scircuits. Reserve batteries are usually designed for a short service life (seconds or minutes)after long storage (years). A water-activated battery for oceanographic instruments or militaryapplications becomes activated on immersion in water.

2.5 BATTERY CELL PERFORMANCEA battery's characteristics may vary over load cycle, over charge cycle, and over lifetime dueto many factors including internal chemistry, current drain, and temperature.

A battery's capacity is the amount of electric charge it can store. The more electrolyte andelectrode material there is in the cell the greater the capacity of the cell. A small cell has lesscapacity than a larger cell with the same chemistry, and they develop the same open-circuitvoltage.

Because of the chemical reactions within the cells, the capacity of a battery depends on thedischarge conditions such as the magnitude of the current (which may vary with time), theallowable terminal voltage of the battery, temperature, and other factors. The availablecapacity of a battery depends upon the rate at which it is discharged. If a battery is dischargedat a relatively high rate, the available capacity will be lower than expected.

The capacity printed on a battery is usually the product of 20 hours multiplied by the constantcurrent that a new battery can supply for 20 hours at 68 F (20 C), down to a specifiedterminal voltage per cell. A battery rated at 100 Ah will deliver 5 A over a 20-hour period atroom temperature. However, if discharged at 50 A, it will have a lower capacity.

FIG 4 - CAPACITY AND DISCHARGING
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The relationship between current, discharge time, and capacity for a lead acid battery isapproximated (over a certain range of current values) by Peukert's law:

where

is the capacity when discharged at a rate of 1 amp.

is the current drawn from battery (A).

is the amount of time (in hours) that a battery can sustain.

is a constant around 1.3.

For low values ofIinternal self-discharge must be included.

Internal energy losses and limited rate of diffusion of ions through the electrolyte cause theefficiency of a real battery to vary at different discharge rates. When

discharging at low rate, the battery's energy is delivered more efficiently than at higherdischarge rates, but if the rate is very low, it will partly self-discharge during the long time ofoperation, again lowering its efficiency.

Installing batteries with different Ah ratings will not affect the operation of a device (except

for the time it will work for) rated for a specific voltage unless the load limits of the batteryare exceeded. High-drain loads such as digital cameras can result in delivery of less totalenergy, as happens with alkaline batteries. For example, a battery rated at 2000 mAh for a 10-or 20-hour discharge would not sustain a current of 1 A for a full two hours as its statedcapacity implies.

2.6 BATTERY LIFETIME

2.6.1 PRIMARY BATTERIESDisposable (or "primary") batteries typically lose 8 to 20 percent of their original chargeevery year at room temperature (2030C). This is known as the "self discharge" rate, and isdue to non-current-producing "side" chemical reactions which occur within the cell even if noload is applied. The rate of the side reactions is reduced if the batteries are stored at lowertemperature, although some batteries can be damaged by freezing. High or low workingtemperatures may reduce battery performance. This will affect the initial voltage of the

battery. For an AA alkaline battery, this initial voltage is approximately normally distributedaround 1.6 volts.In contrast to most of today's batteries, the Zamboni pile, invented in 1812,can have a very long service life without refurbishment or recharge, although it suppliescurrent only in the nanoamp range. The Oxford Electric Bell has been ringing almost

continuously since 1840 on its original pair of batteries, thought to be Zamboni piles.Discharging performance of all batteries drops at low temperature.
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2.6.2 SECONDARY BATTERIESStorage life of secondary batteries is limited by chemical reactions that occur between the

battery parts and the electrolyte; these are called "side reactions". Internal parts may corrodeand fail, or the active materials may be slowly converted to inactive forms. Since the active

material on the battery plates changes chemical composition on each charge and dischargecycle, active material may be lost due to physical changes of volume; this may limit the cyclelife of the battery.

Old chemistry rechargeable batteries self-discharge more rapidly than disposable alkalinebatteries, especially nickel-based batteries; a freshly charged nickel cadmium (NiCd) batteryloses 10% of its charge in the first 24 hours, and thereafter discharges at a rate of about 10% amonth. However, newer low self-discharge nickel metal hydride (NiMH) batteries andmodern lithium designs have reduced the self-discharge rate to a relatively low level (but still

poorer than for primary batteries). Most nickel-based batteries are partially discharged whenpurchased, and must be charged before first use. Newer NiMH batteries are ready to be usedwhen purchased, and have only 15% discharge in a year.

FIG 5 - RECHARGEABLE BATTERIES

Although rechargeable batteries have their energy content restored by charging, somedeterioration occurs on each chargedischarge cycle. Low-capacity NiMH batteries (17002000 mAh) can be charged for about 1000 cycles, whereas high-capacity NiMH batteries(above 2500 mAh) can be charged for about 500 cycles. NiCd batteries tend to be rated for1000 cycles before their internal resistance permanently increases beyond usable values.

Under normal circumstances, a fast charge, rather than a slow overnight charge, will shortenbattery lifespan. Also, if the overnight charger is not "smart" and cannot detect when thebattery is fully charged, then overcharging is likely, which also damages the battery.Degradation usually occurs because electrolyte migrates away from the electrodes or becauseactive material falls off the electrodes. NiCd batteries suffer the drawback that they should befully discharged before recharge. Without full discharge, crystals may build up on theelectrodes, thus decreasing the active surface area and increasing internal resistance. Thisdecreases battery capacity and causes the "memory effect". These electrode crystals can also

penetrate the electrolyte separator, thereby causing shorts. NiMH, although similar inchemistry, does not suffer from memory effect to quite this extent. A battery does notsuddenly stop working; its capacity gradually decreases over its lifetime, until it can no

longer hold sufficient charge.
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Automotive leadacid rechargeable batteries have a much harder life. Because of vibration,shock, heat, cold, and sulfation of their lead plates, few automotive batteries last beyond sixyears of regular use. Automotive starting (SLI: Starting, Lighting, Ignition) batteries havemany thin plates to provide as much current as possible in a reasonably small package. Ingeneral, the thicker the plates, the longer the life of the battery. They are typically drained

only a small amount before recharge. Care should be taken to avoid deep discharging astarting battery, since each charge and discharge cycle causes active material to be shed fromthe plates.

FI G 6 - AN ANALOG CAMCORDER BATTERY [LI THI UM ION]

"Deep-cycle" leadacid batteries such as those used in electric golf carts have much thickerplates to aid their longevity. The main benefit of the leadacid battery is its low cost; themain drawbacks are its large size and weight for a given capacity and voltage. Leadacid

batteries should never be discharged to below 20% of their full capacity, because internalresistance will cause heat and damage when they are recharged. Deep-cycle leadacidsystems often use a low-charge warning light or a low-charge power cut-off switch to preventthe type of damage that will shorten the battery's life.

2.7 EXTENDING BATTERY LIFEBattery life can be extended by storing the batteries at a low temperature, as in a refrigeratororfreezer, which slows the chemical reactions in the battery. Such storage can extend the lifeof alkaline batteries by about 5%; rechargeable batteries can hold their charge much longer,depending upon type. To reach their maximum voltage, batteries must be returned to roomtemperature; discharging an alkaline battery at 250 mA at 0C is only half as efficient as it isat 20C. Alkaline battery manufacturers such as Duracell do not recommend refrigerating

batteries.
http://en.wikipedia.org/wiki/Automotive_batteryhttp://en.wikipedia.org/wiki/Lead%E2%80%93acidhttp://en.wikipedia.org/wiki/Lead%E2%80%93acidhttp://en.wikipedia.org/wiki/Lead%E2%80%93acidhttp://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery#Sulfationhttp://en.wikipedia.org/wiki/Automotive_batteryhttp://en.wikipedia.org/wiki/Charge_and_discharge_cyclehttp://en.wikipedia.org/wiki/Refrigeratorhttp://en.wikipedia.org/wiki/Freezerhttp://en.wikipedia.org/wiki/Duracellhttp://en.wikipedia.org/wiki/File:2011-04-04_18-35-26_267.jpghttp://en.wikipedia.org/wiki/Duracellhttp://en.wikipedia.org/wiki/Freezerhttp://en.wikipedia.org/wiki/Refrigeratorhttp://en.wikipedia.org/wiki/Charge_and_discharge_cyclehttp://en.wikipedia.org/wiki/Automotive_batteryhttp://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery#Sulfationhttp://en.wikipedia.org/wiki/Lead%E2%80%93acidhttp://en.wikipedia.org/wiki/Automotive_battery


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2.8 EXPLOSIONA battery explosion is caused by the misuse or malfunction of a battery, such as attempting torecharge a primary (non-rechargeable) battery, or short circuiting a battery. Car batteries aremost likely to explode when a short-circuit generates very large currents. Car batteries

liberate hydrogen, which is very explosive, when they are overcharged (because ofelectrolysis of the water in the electrolyte). The amount of overcharging is usually very smalland generates little hydrogen, which dissipates quickly. However, when "jumping" a car

battery, the high current can cause the rapid release of large volumes of hydrogen, which canbe ignited explosively by a nearby spark, for example, when disconnecting a jumper cable.

When a battery is recharged at an excessive rate, an explosive gas mixture of hydrogen andoxygen may be produced faster than it can escape from within the walls of the battery,leading to pressure build-up and the possibility of bursting of the battery case. In extremecases, the battery acid may spray violently from the casing of the battery and cause injury.Overcharging that is, attempting to charge a battery beyond its electrical capacity can alsolead to a battery explosion, in addition to leakage or irreversible damage. It may also causedamage to the charger or device in which the overcharged battery is later used. In addition,disposing of a battery in fire may cause an explosion as steam builds up within the sealedcase of the battery.

2.9 LEAKAGEMany battery chemicals are corrosive, poisonous, or both. If leakage occurs, eitherspontaneously or through accident, the chemicals released may be dangerous. For example,disposable batteries often use a zinc "can" both as a reactant and as the container to hold the

other reagents. If this kind of battery is run all the way down, or if it is recharged afterrunning down too far, the reagents can emerge through the cardboard and plastic that formthe remainder of the container. The active chemical leakage can then damage the equipmentthat the batteries were inserted into. For this reason, many electronic device manufacturersrecommend removing the batteries from devices that will not be used for extended periods oftime.

FI G 7 - LEAKED ALKAL INE BATTERY
http://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Electrolysishttp://en.wikipedia.org/wiki/File:LeakedBattery_2701a.jpghttp://en.wikipedia.org/wiki/Electrolysishttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Short_circuit


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2.10 ENVIRONMENTAL CONCERNSThe widespread use of batteries has created many environmental concerns, such as toxicmetal pollution. Battery manufacture consumes resources and often involves hazardouschemicals. Used batteries also contribute to electronic waste. Some areas now have battery

recycling services available to recover some of the materials from used batteries. Batteriesmay be harmful or fatal if swallowed. Recycling or proper disposal prevents dangerouselements (such as lead, mercury, and cadmium) found in some types of batteries fromentering the environment. In the United States, Americans purchase nearly three billion

batteries annually, and about 179,000 tons of those end up in landfills across the country.

In the United States, the Mercury-Containing and Rechargeable Battery Management Act of1996 banned the sale of mercury-containing batteries, enacted uniform labeling requirementsfor rechargeable batteries, and required that rechargeable batteries be easily removable.California, and New York City prohibit the disposal of rechargeable batteries in solid waste,and along with Maine require recycling of cell phones. The rechargeable battery industry hasnationwide recycling programs in the United States and Canada, with dropoff points at localretailers. The Battery Directive of the European Union has similar requirements, in additionto requiring increased recycling of batteries, and promoting research on improved batteryrecycling methods. In accordance with this directive all batteries to be sold within the EUmust be marked with the "collection symbol" (A crossed out wheeled bin). This must cover atleast 3% of the surface of prismatic batteries and 1.5% of the surface of cylindrical batteries.All packaging must be marked likewise.

2.11 INGESTIONSmall button cells can be swallowed, particularly by young children. While in the digestivetract the battery's electrical discharge may lead to tissue damage; such damage is occasionallyserious and very rarely even leads to death. Ingested disk batteries do not usually cause

problems unless they become lodged in the gastrointestinal (GI) tract. The most commonplace disk batteries become lodged, resulting in clinical sequelae, is the esophagus. Batteriesthat successfully traverse the esophagus are unlikely to lodge at any other location. Thelikelihood that a disk battery will lodge in the esophagus is a function of the patient's age andthe size of the battery. Disk batteries of 16 mm have become lodged in the esophagi of 2children younger than 1 year. Older children do not have problems with batteries smaller than

2123 mm. Liquefaction necrosis may occur because sodium hydroxide is generated by thecurrent produced by the battery (usually at the anode). Perforation has occurred as rapidly as6 hours after ingestion.
http://en.wikipedia.org/wiki/Electronic_wastehttp://en.wikipedia.org/wiki/Electronic_wastehttp://en.wikipedia.org/wiki/Recyclinghttp://en.wikipedia.org/wiki/Swallowinghttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Mercury_%28element%29http://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Mercury-Containing_and_Rechargeable_Battery_Management_Acthttp://en.wikipedia.org/wiki/Battery_Directivehttp://en.wikipedia.org/wiki/Button_cellhttp://en.wikipedia.org/wiki/Button_cellhttp://en.wikipedia.org/wiki/Battery_Directivehttp://en.wikipedia.org/wiki/Mercury-Containing_and_Rechargeable_Battery_Management_Acthttp://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Mercury_%28element%29http://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Swallowinghttp://en.wikipedia.org/wiki/Recyclinghttp://en.wikipedia.org/wiki/Electronic_wastehttp://en.wikipedia.org/wiki/Electronic_waste


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2.12 BATTERY CHEMISTRY2.12.1PRIMARY BATTERY CHEMISTRIES

Chemistry

Nominal

Cell

Voltage

Specific

Energy

[MJ/kg]

Elaboration

Zincchloride 1.5 Also known as "heavy duty", inexpensive.

Lithium

(lithiummanganese

dioxide)

LiMnO2

3.0 0.83-1.01

Expensive.

Only used in high-drain devices or for long shelf

life due to very low rate of self discharge.'Lithium' alone usually refers to this type of

chemistry.

Lithium (lithiumiron

disulfide) LiFeS21.5

Expensive.

Used in 'plus' or 'extra' batteries.

Mercury oxide 1.35High drain and constant voltage. Banned in most

countries because of health concerns.

Zinccarbon 1.5 0.13 Inexpensive.

Alkaline

(zincmanganese dioxide)1.5 0.4-0.59

Moderate energy density.

Good for high and low drain uses.

Nickel oxyhydroxide (zinc

manganese dioxide / nickel

oxyhydroxide)

1.7Moderate energy density.

Good for high drain uses

Zincair 1.351.65 1.59 Mostly used in hearing aids.

Lithium

(lithiumcopper oxide)

LiCuO

1.7No longer manufactured.

Replaced by silver oxide (IEC-type "SR") batteries.

Silver-oxide (silverzinc) 1.55 0.47Very expensive.

Only used commercially in 'button' cells.
http://en.wikipedia.org/wiki/Zinc%E2%80%93chloride_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93chloride_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93chloride_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93chloride_batteryhttp://en.wikipedia.org/wiki/Lithium_batteryhttp://en.wikipedia.org/wiki/Lithium_batteryhttp://en.wikipedia.org/wiki/Mercury_batteryhttp://en.wikipedia.org/wiki/Mercury_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93carbon_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93carbon_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93carbon_batteryhttp://en.wikipedia.org/wiki/Alkaline_batteryhttp://en.wikipedia.org/wiki/Nickel_oxyhydroxide_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93air_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93air_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93air_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93air_batteryhttp://en.wikipedia.org/wiki/Lithium_batteryhttp://en.wikipedia.org/wiki/International_Electrotechnical_Commissionhttp://en.wikipedia.org/wiki/Silver-oxide_batteryhttp://en.wikipedia.org/wiki/Silver-oxide_batteryhttp://en.wikipedia.org/wiki/International_Electrotechnical_Commissionhttp://en.wikipedia.org/wiki/Lithium_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93air_batteryhttp://en.wikipedia.org/wiki/Nickel_oxyhydroxide_batteryhttp://en.wikipedia.org/wiki/Alkaline_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93carbon_batteryhttp://en.wikipedia.org/wiki/Mercury_batteryhttp://en.wikipedia.org/wiki/Lithium_batteryhttp://en.wikipedia.org/wiki/Lithium_batteryhttp://en.wikipedia.org/wiki/Zinc%E2%80%93chloride_battery


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2.12.2RECHARGEABLE BATTERY CHEMISTRIES

ChemistryCell

Voltage

Specific

Energy

[MJ/kg]

Comments

NiCd 1.2 0.14

Inexpensive.High/low drain, moderate energy density.Can withstand very high discharge rates with virtually no loss ofcapacity.Moderate rate of self discharge.Environmental hazard due to Cadmiumuse now virtually

prohibited in Europe.

Leadacid 2.1 0.14

Moderately expensive.Moderate energy density.Moderate rate of self discharge.Higher discharge rates result in considerable loss of capacity.

Environmental hazard due to Lead.Common useAutomobile batteries

NiMH 1.2 0.36

Inexpensive.Performs better than alkaline batteries in higher drain devices.Traditional chemistry has high energy density, but also a high rate ofself-discharge.

Newer chemistry has low self-discharge rate, but also a ~25% lowerenergy density.Used in some cars.

NiZn 1.6 0.36

Moderately inexpensive.High drain device suitable.Low self-discharge rate.Voltage closer to alkaline primary cells than other secondary cells.

No toxic components.Newly introduced to the market (2009). Has not yet established atrack record.Limited size availability.

AgZn1.861.5

0.46

Smaller volume than equivalent Li-ion.Historically extremely expensive.Very high energy density.Very high drain capable.Reactions are not fully understood.Terminal voltage very stable but suddenly drops to 1.5 volts at 70-80% charge (believed to be

due to presence of both argentous and argentic oxide in positive plate- one is consumed first).

Lithium ion 3.6 0.46

Very expensive.Very high energy density.

Not usually available in "common" battery sizes.Very common in laptop computers, moderate to high-end digitalcameras, camcorders and cellphones.Very low rate of self discharge.Terminal voltage unstable (varies from 4.2 to 3.0 volts duringdischarge).Volatile: Chance of explosion if short circuited, allowed to overheat,or not manufactured with rigorous quality standards.
http://en.wikipedia.org/wiki/Nickel%E2%80%93cadmium_batteryhttp://en.wikipedia.org/wiki/Nickel%E2%80%93cadmium_batteryhttp://en.wikipedia.org/wiki/Lead%E2%80%93acid_batteryhttp://en.wikipedia.org/wiki/Lead%E2%80%93acid_batteryhttp://en.wikipedia.org/wiki/Lead%E2%80%93acid_batteryhttp://en.wikipedia.org/wiki/Lead%E2%80%93acid_batteryhttp://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_batteryhttp://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_batteryhttp://en.wikipedia.org/wiki/Low_self-discharge_NiMH_batteryhttp://en.wikipedia.org/wiki/Nickel%E2%80%93zinc_batteryhttp://en.wikipedia.org/wiki/Nickel%E2%80%93zinc_batteryhttp://en.wikipedia.org/wiki/Silver-zinc_batteryhttp://en.wikipedia.org/wiki/Silver-zinc_batteryhttp://en.wikipedia.org/wiki/Lithium-ion_batteryhttp://en.wikipedia.org/wiki/Lithium-ion_batteryhttp://en.wikipedia.org/wiki/Lithium-ion_batteryhttp://en.wikipedia.org/wiki/Silver-zinc_batteryhttp://en.wikipedia.org/wiki/Nickel%E2%80%93zinc_batteryhttp://en.wikipedia.org/wiki/Low_self-discharge_NiMH_batteryhttp://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_batteryhttp://en.wikipedia.org/wiki/Lead%E2%80%93acid_batteryhttp://en.wikipedia.org/wiki/Nickel%E2%80%93cadmium_battery


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2.12.3SPECIFICATIONSNumber of sets of battery used = 2

Number of batteries in each set = 4

BATTERY

TYPE

MODEL

NUMBER

VOLTS

(in V)

RATING

AT

30 C

MAX. OVERALL DIMENSIONS

(in mm)(TOLRENCE=+3mm)

LENGTH WIDTH HEIGHT

EXIDEELECTRICA

12EC25L 12 20Ah(C2) 180 80 170


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FI G 8 - INTERNAL DIAGRAM OF BATTERY

FI G 9VIEW OF POSITIVE PLATE


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2.13. SCHEMATIC DIAGRAM OF BATTERY

FI G 10SCHEMATIC DI AGRAM OF BATTERY


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3. ELECTRIC MOTOR

FI G 11ELECTRIC MOTOR

Brushless DC electric motor (BLDC motors, BL motors) also known as electronicallycommutated motors (ECMs, EC motors) are synchronous motors which are powered by a DCelectric source via an integrated inverter/switching power supply, which produces an ACelectric signal to drive the motor (AC, alternating current, does not imply a sinusoidalwaveform but rather a bi-directional current with no restriction on waveform); additionalsensors and electronics control the inverter output amplitude and waveform (and therefore

percent of DC bus usage/efficiency) and frequency (i.e. rotor speed).

The motor part of a brushless motor is often a permanent magnet synchronous motor, but canalso be a switched reluctance motor, orinduction motor.

Brushless motors may be described as stepper motors; however, the termstepper motortendsto be used for motors that are designed specifically to be operated in a mode where they arefrequently stopped with the rotor in a defined angular position. This page describes moregeneral brushless motor principles, though there is overlap.

Two key performance parameters of brushless DC motors are the Motor constants Kv andKm (which are numerically equal in SI units.)
http://en.wikipedia.org/wiki/Synchronous_motorhttp://en.wikipedia.org/wiki/Inverter_%28electrical%29http://en.wikipedia.org/wiki/Permanent_magnet_synchronous_motorhttp://en.wikipedia.org/wiki/Switched_reluctance_motorhttp://en.wikipedia.org/wiki/Induction_motorhttp://en.wikipedia.org/wiki/Stepper_motorshttp://en.wikipedia.org/wiki/Motor_constantshttp://en.wikipedia.org/wiki/Motor_constantshttp://en.wikipedia.org/wiki/Stepper_motorshttp://en.wikipedia.org/wiki/Induction_motorhttp://en.wikipedia.org/wiki/Switched_reluctance_motorhttp://en.wikipedia.org/wiki/Permanent_magnet_synchronous_motorhttp://en.wikipedia.org/wiki/Inverter_%28electrical%29http://en.wikipedia.org/wiki/Synchronous_motor


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3.1 BRUSHLESS vs BRUSHED MOTORSBrushed DC motors have been in commercial use since 1886.Brushless motors on the otherhand did not become commercially viable until 1962.

Brushed DC motors develop a maximum torque when stationary, linearly decreasing asvelocity increases. Some limitations of brushed motors can be overcome by brushless motors,they include higher efficiency and a lower susceptibility of the commutator assembly tomechanical wear. These benefits come at the cost of potentially less rugged, more complex,and more expensive control electronics.

A typical brushless motor has permanent magnets which rotate and a fixed armature,eliminating problems associated with connecting current to the moving armature. Anelectronic controller replaces the brush/commutator assembly of the brushed DC motor,which continually switches the phase to the windings to keep the motor turning. The

controller performs similar timed power distribution by using a solid-state circuit rather thanthe brush/commutator system.

Brushless motors offer several advantages over brushed DC motors, including more torqueper weight, more torque perwatt (increased efficiency), increased reliability, reduced noise,longer lifetime (nobrush and commutator erosion), elimination of ionizing sparks from thecommutator, and overall reduction ofelectromagnetic interference (EMI). With no windingson the rotor, they are not subjected to centrifugal forces, and because the windings aresupported by the housing, they can be cooled by conduction, requiring no airflow inside themotor for cooling. This in turn means that the motor's internals can be entirely enclosed and

protected from dirt or other foreign matter.

Brushless motor commutation can be implemented in software using a microcontroller orcomputer, or may alternatively be implemented in analogue hardware or digital firmwareusing an FPGA. Use of an FPGA provides greater flexibility and capabilities not availablewith brushed DC motors including speed limiting, "micro stepped" operation for slow and/orfine motion control and a holding torque when stationary.

The maximum power that can be applied to a brushless motor is limited almost exclusivelyby heat; too much of which weakens the magnets, and may damage the winding's insulation.A brushless motor's main disadvantage is higher cost, which arises from two issues. First,

brushless motors require complex electronic speed controllers (ESCs) to run. Brushed DC

motors can be regulated by a comparatively simple controller, such as a rheostat (variableresistor). However, this reduces efficiency because power is wasted in the rheostat. Second,some practical uses have not been well developed in the commercial sector. For example, inthe radio control (RC) hobby arena, brushless motors are often hand-wound while brushedmotors are usually machine-wound.

Brushless motors are more efficient at converting electricity into mechanical power thanbrushed motors. This improvement is largely due to motor's velocity being determined by thefrequency at which the electricity is switched, not the voltage. Additional gains are due to theabsence of brushes, alleviating loss due to friction. The enhanced efficiency is greatest in theno-load and low-load region of the motor's performance curve. Under high mechanical loads,

brushless motors and high-quality brushed motors are comparable in efficiency.
http://en.wikipedia.org/wiki/Brushed_DC_motorhttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Armature_%28electrical_engineering%29http://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Brush_%28electric%29http://en.wikipedia.org/wiki/Electromagnetic_interferencehttp://en.wikipedia.org/wiki/FPGAhttp://en.wikipedia.org/wiki/Electronic_speed_controlhttp://en.wikipedia.org/wiki/Potentiometer#Rheostathttp://en.wikipedia.org/wiki/Potentiometer#Rheostathttp://en.wikipedia.org/wiki/Electronic_speed_controlhttp://en.wikipedia.org/wiki/FPGAhttp://en.wikipedia.org/wiki/Electromagnetic_interferencehttp://en.wikipedia.org/wiki/Brush_%28electric%29http://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Armature_%28electrical_engineering%29http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Brushed_DC_motor


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Environments and requirements in which manufacturers use brushless-type DC motorsinclude maintenance-free operation, high speeds, and operation where sparking is hazardous(i.e. explosive environments), or could affect electronically sensitive equipment.

3.2 MOTOR CONTROL POWER SUPPLIESTypical brushless motors are permanent magnet synchronous AC motors, combined withsensor electronics (detecting rotor position) and an AC signal generator (Inverter) driven by aDC supply. Typical brushless inverters use a switched power supply pulse width modulationto generate an AC drive signal. Various terms are used to refer to the inverters/electroniccontrol systems, including "Vector Drives", and "VVVF drives" (variable voltage variablefrequency).

3.3 APPLICATIONSThe four poles on the stator of a two-phase brushless motor. This is part of a computer

cooling fan; the rotor has been removed.

FI G 12

FOUR POLE MOTOR WINDI NG

Brushless motors fulfill many functions originally performed by brushed DC motors, but costand control complexity prevents brushless motors from replacing brushed motors completelyin the lowest-cost areas. Nevertheless, brushless motors have come to dominate manyapplications, particularly devices such as computer hard drives and CD/DVD players. Smallcooling fans in electronic equipment are powered exclusively by brushless motors. They can

be found in cordless power tools where the increased efficiency of the motor leads to longerperiods of use before the battery needs to be charged. Low speed, low power brushless

motors are used in direct-drive turntables forgramophone records.
http://en.wikipedia.org/wiki/Hard_diskhttp://en.wikipedia.org/wiki/Direct-drive_turntablehttp://en.wikipedia.org/wiki/Gramophone_recordhttp://en.wikipedia.org/wiki/Gramophone_recordhttp://en.wikipedia.org/wiki/File:Poles.jpghttp://en.wikipedia.org/wiki/Gramophone_recordhttp://en.wikipedia.org/wiki/Direct-drive_turntablehttp://en.wikipedia.org/wiki/Hard_disk


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3.4 TRANSPORTHigh power brushless motors are found in electric vehicles and hybrid vehicles. These motorsare essentially AC synchronous motors with permanent magnet rotors.The Segway Scooterand Vectrix Maxi-Scooter use brushless technology.A number of electric bicycles use

brushless motors that are sometimes built into the wheel hub itself, with the stator fixedsolidly to the axle and the magnets attached to and rotating with the wheel.

3.5 HEATING AND VENTILATIONSThere is a trend in the HVAC and refrigeration industries to use brushless motors instead ofvarious types ofAC motors. The most significant reason to switch to a brushless motor is thedramatic reduction in power required to operate them versus a typical AC motor. Whileshaded-pole and permanent split capacitormotors once dominated as the fan motor of choice,many fans are now run using a brushless motor. Some fans use brushless motors also in order

to increase overall system efficiency.

In addition to the brushless motor's higher efficiency, certain HVAC systems (especiallythose featuring variable-speed and/or load modulation) use brushless motors because the

built-in microprocessor allows for programmability, better control over airflow, and serialcommunication.

3.6 INDUSTRIAL ENGINEERINGThe application of brushless DC motors within industrial engineering primarily focuses onmanufacturing engineering or industrial automation design. In manufacturing, brushless

motors are primarily used formotion control, positioning oractuation systems.

FI G 13DC MOTOR

Brushless motors are ideally suited for manufacturing applications because of their highpower density, good speed-torque characteristics, high efficiency and wide speed ranges andlow maintenance. The most common uses of brushless DC motors in industrial engineering

are linear motors. servomotors, actuators for industrial robots, extruder drive motors and feeddrives for CNC machine tools.
http://en.wikipedia.org/wiki/Electric_vehiclehttp://en.wikipedia.org/wiki/Hybrid_vehicleshttp://en.wikipedia.org/wiki/Segway_PThttp://en.wikipedia.org/wiki/Vectrixhttp://en.wikipedia.org/wiki/Electric_bicycleshttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Refrigerationhttp://en.wikipedia.org/wiki/AC_motorhttp://en.wikipedia.org/wiki/Shaded-polehttp://en.wikipedia.org/wiki/Permanent_split_capacitorhttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Industrial_engineeringhttp://en.wikipedia.org/wiki/Manufacturing_engineeringhttp://en.wikipedia.org/wiki/Automationhttp://en.wikipedia.org/wiki/Motion_controlhttp://en.wikipedia.org/wiki/Robot_end_effectorhttp://en.wikipedia.org/wiki/Linear_actuatorhttp://en.wikipedia.org/wiki/Linear_actuatorhttp://en.wikipedia.org/wiki/Robot_end_effectorhttp://en.wikipedia.org/wiki/Motion_controlhttp://en.wikipedia.org/wiki/Automationhttp://en.wikipedia.org/wiki/Manufacturing_engineeringhttp://en.wikipedia.org/wiki/Industrial_engineeringhttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Permanent_split_capacitorhttp://en.wikipedia.org/wiki/Shaded-polehttp://en.wikipedia.org/wiki/AC_motorhttp://en.wikipedia.org/wiki/Refrigerationhttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Electric_bicycleshttp://en.wikipedia.org/wiki/Vectrixhttp://en.wikipedia.org/wiki/Segway_PThttp://en.wikipedia.org/wiki/Hybrid_vehicleshttp://en.wikipedia.org/wiki/Electric_vehicle


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3.7 MOTION CONTROL SYSTEMSBrushless motors are commonly used as pump, fan and spindle drive s in adjustable orvariable speed applications. They can develop high torque with good speed response. Inaddition, they can be easily automated for remote control. Due to their construction, they

have good thermal characteristics and high energy efficiency. To obtain a variable speedresponse, brushless motors operate in an electromechanical system that includes an electronicmotor controllerand a rotor position feedback sensor.Brushless dc motors are widely used asservomotors for machine tool servo drives. Servomotors are used for mechanicaldisplacement, positioning or precision motion control. In the past DC stepper motors wereused as servomotors; however, since they are operate with open loop control, they typicallyexhibit torque pulsations. Brushless dc motors are more suitable as servomotors since their

precise motion is based upon a closed loop control system that provides tightly controlled andstable operation.

3.8

POSITIONING AND ACTUATION SYSTEMSBrushless motors are used in industrial positioning and actuation applications. For assemblyrobots,brushless stepperorservo motors are used to position a part for assembly or a tool fora manufacturing process, such as welding or painting. Brushless motors can also be used todrive linear actuators.

Actuators that produce linear motion are called linear motors. The advantage of linear motorsis that they can produce linear motion without the need of a transmission system, such as a

ball-and-lead screw, rack-and-pinion, cam, gears or belts, that would be necessary for rotarymotors. Transmission systems are known to introduce less responsiveness and reduced

accuracy. Direct drive, brushless DC linear motors consist of a slotted stator with magneticteeth and a moving actuator, which has permanent magnets and coil windings. To obtainlinear motion, a motor controller excites the coil windings in the actuator causing an

interaction of the magnetic fields resulting in linear motion.

3.9 MODEL ENGINEERING

FI G 14BRUSHLESS MOTOR.

Legal restrictions for the use of combustion engine driven model aircraft in some countries

have also supported the shift to high-power electric systems.
http://en.wikipedia.org/wiki/Motor_controllerhttp://en.wikipedia.org/wiki/Servo_motorhttp://en.wikipedia.org/wiki/Stepper_motorhttp://en.wikipedia.org/wiki/Open-loop_controllerhttp://en.wikipedia.org/wiki/Control_theoryhttp://en.wikipedia.org/wiki/Stepper_motorhttp://en.wikipedia.org/wiki/Stepper_motorhttp://en.wikipedia.org/wiki/Servo_motorhttp://en.wikipedia.org/wiki/Linear_motorhttp://en.wikipedia.org/wiki/Transmission_%28mechanics%29http://en.wikipedia.org/wiki/File:Brushless-Motor-DUM60.jpghttp://en.wikipedia.org/wiki/Transmission_%28mechanics%29http://en.wikipedia.org/wiki/Linear_motorhttp://en.wikipedia.org/wiki/Servo_motorhttp://en.wikipedia.org/wiki/Stepper_motorhttp://en.wikipedia.org/wiki/Control_theoryhttp://en.wikipedia.org/wiki/Open-loop_controllerhttp://en.wikipedia.org/wiki/Stepper_motorhttp://en.wikipedia.org/wiki/Servo_motorhttp://en.wikipedia.org/wiki/Motor_controller


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3.10 CONSTRUCTION AND OPERATING PRINCIPLESThis torque is at its maximum when the rotor starts to move, but it reduces as the two fieldsalign to each other. Thus, to preserve the torque or to build up the rotation, the magnetic field

generated by stator should keep switching. To catch up with the field generated by the stator,the rotor will keep rotating. Since the magnetic field of the stator and rotor both rotate at thesame frequency, they come under the category of synchronous motor.

This switching of the stator to build up the rotation is known as commutation. For 3-phasewindings, there are 6 steps in the commutation; i.e., 6 unique combinations in which motorwindings will be energized.

Driving circuitry and waveforms for the implementation of a BLDC motor will be discussedin the second part of this article.

3.11 TORQUE AND EFFICIENCYFor the study of electric motors, torque is a very important term. By definition, torque is thetendency of force to rotate an object about its axis.

Thus, to increase the torque, either force has to be increased which requires strongermagnets or more current or distance must be increased for which bigger magnets will berequired. Efficiency is critical for motor design because it determines the amount of powerconsumed. A higher efficiency motor will also require less material to generate the requiredtorque.

Where,

Having understood the above provided equations, it becomes important to understand thespeed vs. torque curve.

With an increase in speed, the torque reduces (considering the input power isconstant).

Maximum power can be delivered when the speed is half of the no load speed andtorque is half of the stall torque.


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FIG 15 - TORQUE SPEED GRAPH


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3.12 APPLICATIONSSingle speedFor single-speed applications, induction motors are more suitable, but if the

speed has to be maintained with the variation in load, then because of the flat speed-torquecurve of BLDC motor, BLDC motors are a good fit for such applications.

Adjustable speedBLDC motors become a more suitable fit for such applications because

variable speed induction motors will also need an additional controller, thus adding to system

cost. Brushed DC motors will also be a more expensive solution because of regular

maintenance.

Position controlPrecise control is not required applications like an induction cooker and

because of low maintenance; BLDC motors are a winner here too. However, for such

applications, BLDC motors use optical encoders, and complex controllers are required to

monitor torque, speed, and position.

Low noise applicationsBrushed DC motors are known for generating more EMI noise, so

BLDC is a better fit but controlling requirements for BLDC motors also generate EMI and

audible noise. This can, however, be addressed using Field-Oriented Control (FOC)

sinusoidal BLDC motor control.

3.13 LINEAR MOTORA linear motor is an electric motorthat has had its statorand rotor"unrolled" so that insteadof producing a torque (rotation) it produces a linearforce along its length. The most commonmode of operation is as a Lorentz-type actuator, in which the applied force is linearly

proportional to the current and the magnetic field .

Many designs have been put forward for linear motors, falling into two major categories,low-acceleration and high-acceleration linear motors. Low-acceleration linear motors aresuitable for maglev trains and other ground-based transportation applications. High-acceleration linear motors are normally rather short, and are designed to accelerate an objectto a very high speed, for example see the railgun.

High-acceleration motors are usually used for studies ofhypervelocity collisions, as weapons,or as mass drivers for spacecraft propulsion. They are usually of the AC linear inductionmotor (LIM) design with an active three-phase winding on one side of the air-gap and a

passive conductor plate on the other side. However, the direct current homopolarlinear motorrailgun is another high acceleration linear motor design. The low-acceleration, high speed andhigh power motors are usually of the linear synchronous motor (LSM) design, with anactive winding on one side of the air-gap and an array of alternate-pole magnets on the otherside. These magnets can be permanent magnets or energized magnets. The ShanghaiTransrapid motor is an LSM.
http://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Statorhttp://en.wikipedia.org/wiki/Rotor_%28electric%29http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Rotationhttp://en.wikipedia.org/wiki/Forcehttp://en.wikipedia.org/wiki/Lorentz_forcehttp://en.wikipedia.org/wiki/Linear_equationhttp://en.wikipedia.org/wiki/Linear_equationhttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Maglev_trainhttp://en.wikipedia.org/wiki/Railgunhttp://en.wikipedia.org/wiki/Hypervelocityhttp://en.wikipedia.org/wiki/Weaponhttp://en.wikipedia.org/wiki/Mass_driverhttp://en.wikipedia.org/wiki/Spacecraft_propulsionhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Homopolar_motorhttp://en.wikipedia.org/wiki/Railgunhttp://en.wikipedia.org/wiki/Shanghai_Transrapidhttp://en.wikipedia.org/wiki/Shanghai_Transrapidhttp://en.wikipedia.org/wiki/Shanghai_Transrapidhttp://en.wikipedia.org/wiki/Shanghai_Transrapidhttp://en.wikipedia.org/wiki/Railgunhttp://en.wikipedia.org/wiki/Homopolar_motorhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Spacecraft_propulsionhttp://en.wikipedia.org/wiki/Mass_driverhttp://en.wikipedia.org/wiki/Weaponhttp://en.wikipedia.org/wiki/Hypervelocityhttp://en.wikipedia.org/wiki/Railgunhttp://en.wikipedia.org/wiki/Maglev_trainhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Linear_equationhttp://en.wikipedia.org/wiki/Linear_equationhttp://en.wikipedia.org/wiki/Lorentz_forcehttp://en.wikipedia.org/wiki/Forcehttp://en.wikipedia.org/wiki/Rotationhttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Rotor_%28electric%29http://en.wikipedia.org/wiki/Statorhttp://en.wikipedia.org/wiki/Electric_motor


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3.14 TYPES

3.14.1INDUCTION MOTORIn this design, the force is produced by a moving linear magnetic field acting on conductorsin the field. Any conductor, be it a loop, a coil or simply a piece of plate metal, that is placedin this field will have eddy currents induced in it thus creating an opposing magnetic field, inaccordance with Lenz's law. The two opposing fields will repel each other, thus creatingmotion as the magnetic field sweeps through the metal.

FI G 16I NDUCTION MOTOR

3.14.2SYNCHRONOUS MOTORIn this design the rate of movement of the magnetic field is controlled, usually electronically,to track the motion of the rotor. For cost reasons synchronous linear motors rarely usecommutators, so the rotor often contains permanent magnets, or soft iron. Examples includecoilguns and the motors used on some maglev systems, as well as many other linear motors.A linear motor for trains running Toei Oedo line

FI G 17SYNCHRONOUS MOTOR
http://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Eddy_currenthttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Lenz%27s_lawhttp://en.wikipedia.org/wiki/Coilgunhttp://en.wikipedia.org/wiki/Maglevhttp://en.wikipedia.org/wiki/Maglevhttp://en.wikipedia.org/wiki/Coilgunhttp://en.wikipedia.org/wiki/Lenz%27s_lawhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Eddy_currenthttp://en.wikipedia.org/wiki/Magnetic_field


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3.14.3HOMOPOLARIn this design a large current is passed through a metal sabot across sliding contacts that arefed from two rails. The magnetic field this generates causes the metal to be projected alongthe rails.

3.14.4PIEZO ELECTRICPiezoelectric drive is often used to drive small linear motors.

3.15 OPERATIONAL CHARACTERISTICS OF BRUSHLESS DCMOTOR

Brushless dc motors are rapidly gaining popularity in the appliance, automotive, aerospace,

consumer, medical and industrial automation industries. As a result of the absence of

mechanical commutators and brushes and the permanent magnet rotor, brushless dc motors

have many advantages over the brush dc and induction motor. Some of the advantages of

brushless dc motors are:

High power density, low inertia and high torque to inertia ratio and high dynamicresponse due to the small size, low weight and high flux density neodymium-iron-

boron permanent magnet rotor.

High efficiency due to the low rotor losses as a result of the absence of currentcarrying conductors on the rotor and reduced friction and windage losses in the rotor.

Long operating life and high reliability due to the absence of brushes and metalliccommutators.

Clean operation due to the absence of brushes, resulting in no brush dust duringoperation and allowing for clean room applications.

Low audible noise operation due to the absence of brushes, commutators and smoothlow air resistance rotor.

High speed operation in excess of 80,000 rpm is possible, since these motors areelectronically commutated and are not subjected to the limitations of conventional

commutations.

Low thermal resistance since most of the machine losses occur in the stationary stator,thereby allowing heat dissipation by the process of direst conduction. In addition,

since the rotor losses are small, heat transfer to machine tools and work pieces when

these motors are utilized in machine tools is minimal, thereby reducing the effects of

heat on the machining operation.


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As a result of the above features, the brushless dc motor has been replacing other motors in

many industries. The household appliance industry has been one of the fastest growing end

product market for adjustable speed drives [7]. Brushless dc motors are now being used in

refrigeration compressors, washing machines, fans, food processing equipment and vacuum

cleaners in the household appliance industry. In the automotive industry, brushless dc motors

are being used in fuel pumps, air-condition blowers and engine cooling fans.

The exceptional features of brushless dc motors described above are responsible for their

widespread use in many industries, however, a review of the literature did not provide motor

operational characteristics based on the various phenomena occurring in the motor. Since the

operational characteristic of a motor is important for its control, modeling and deriving

optimum performance, this paper is focused on the determination of the energization

sequence of the motor, its effect on electromagnetic torque production and the utilization of

the torque production mechanism for the classification of the brushless dc motor.

3.16 DETERMINATION OF ENERGIZATION SEQUENCE FORBRUSHLESS DC MOTOR

Three-phase brushless dc motors are operated by energizing two of its three phase windings

at a time. However, for continuous operation of the motor in a particular direction of rotation,

the pair of windings to be energized is dependent on the rotor position. The dependence of

phase winding energization on rotor position lies in the fact that the rotor magnet of the motor

induces voltages in the phase windings during rotation, and efficient motor operation is

accomplished when the energized windings are experiencing their steady or non-varying back

emf. Hence, knowledge of the back emf of each phase winding as a function of rotor position

is necessary in the determination of the phase winding energization sequence.

The determination of phase winding back emf as a function of rotor position for a three-phasebrushless dc motor was obtained by operating the brushless dc machine in generator mode. In

this test, a brush dc motor was used as a prime mover to drive the three-phase, two-pole

brushless dc machine at constant speed in an anti-clockwise direction. The apparatus used is

shown in Fig. 1. The rotating flux of the two-pole brushless dc machine rotor induces

voltages in each phase winding. For a three wire star connected brushless dc machine, the star

point is not

accessible and the three resistors labeled R, in star connection were used to obtain machine

phase voltages from line to the star point n formed by the three resistors.


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FI G 18BLOCK DIAGRAM OF ENERGIZATION SEQUENCE

3.17 BRUSHLESS DC MACHINE OPERATED AS A GENERATORThe resulting generated phase voltages as functions of rotor position , relative to the stator

for the two-pole, three-phase brushless dc machine are shown in Fig. 2(a). These generated

phase voltages are trapezoidal in nature, having flat tops of 120 electrical degrees and

positive and negative slopes each of 60 electrical degrees. Their magnitudes for a particular

brushless dc machine are dependent on the speed of rotation of the machine.

The three generated phase voltages ean , ebn and ecn are displaced 120 electrical degrees from

each other and their variations are dependent on rotor position, since,

where, e is the generated voltage, is the flux linkage, is the rotor position and is the

angular velocity of the rotor. From Eq. (1), the generated voltage waveform is a function of

rotor position, thereby providing an indication of the rotor position at any time. The

waveforms of Fig. 2 reveal that for a two-pole machine, one electrical cycle of generated

waveform was completed in one mechanical revolution of the rotor. However, in the case of a

four-pole rotor, there would be two electrical cycles of generated voltage waveform for onemechanical revolution of the rotor. reveals that two phase voltages are of constant value for

60 electrical degrees and for a star connected stator as shown in Fig. 3, line voltage

waveforms can be drawn from two phase voltages. These line voltage generated waveforms

ebc , eca and eab are shown in Fig. 2(b). Since two phase windings of a star connected

brushless dc motor are experiencing a constant generated line voltage for 60 electrical

degrees, then efficient operation of the motor is obtained when the two energized windings

are experiencing theirconstant back emf.


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FI G 19PHASE DIAGRAM

Fig. 2 Brushless DC Motor Voltages (a) Generated Phase Voltages ean , ebn and ecn (b)

Generated Line Voltages ebc , eca and eab (c) Supply Line Voltages Vbc , Vca and Vab

Hence, the generated line voltage waveforms shown in Fig. 2(b), which are functions of rotor

position , are used to determine the sequence of energization of the motor windings for a

particular direction of rotation. Therefore, for anti-clockwise operation of the brushless dc

motor, using Fig. 2(b), and starting with rotor position at = 0, the winding pairs should be

energized in the sequence ac, bc, ba, ca, cb, ab and ac again, with each winding pair being

energized for 60 electrical degrees [8-9]. It must be noted that for clockwise operation of the

brushless dc motor, the sequence of energization of the winding pairs must be reversed and

would take the form ab, cb, ca, ba, bc and ac.


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FI G 20STAR CONNECTED BRUSHLESS DC MOTOR

Fig. 2(c) shows the line voltages for efficient motor operation, placing the supply voltages in

phase with the generated or back emf line values. The line supply voltages are greater than

the line back emf to ensure that electromagnetic torque is developed by the machine. The

development of the energization sequence for a three-phase brushless dc motor, as a function

of rotor position and hence back emf, for rotation in a particular direction has been lacking in

the literature. The material presented above can be used in the absence of the manufacturers

data to determine the energization sequence of a brushless dc motor.

3.18 TORQUE PRODUCTION AND OPERATION OF BLDCMUSING VECTOR ANALYSIS

The theory of vector analysis of a three-phase stator, justifying the existence and location of

vector currents and voltages and the equality of scalar and vector current magnitude. A cross

sectional view of a two-pole, three-phase brushless dc motor is shown in Fig. 4. The rotor

magnet is shown with a reduced diameter and hence an enlarged air-gap for illustration

purposes. The two-pole rotor is assumed to be rotating at a constant angular velocity

rad/sec in an anticlockwise direction. At the instant of observation in Fig. 4, its d -axis which

is defined as the centre of the south pole is at the position = 0, which corresponds to the

= 0 point on the horizontal axes of the waveforms in Fig. 2. At this rotor position = 0,

winding pairac would begin to experience their constant back emfEac due to the effect of the

rotor magnet on the stator windings as shown in Fig. 2(b). Hence, at this rotor position = 0,

winding pairac must be energized with a supply voltage ofVac volts to oppose the constant


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back emfEac present experienced by the windings. The magnitude of the supply voltage must

be greater than the constant back emf developed by the windings as shown in Fig. 2(c) and

sufficient to develop electromagnetic torque to sustain the rotor speed.

FIG 21 - STATOR AND ROTOR VECTORS FOR TWO-POLE,

BRUSHLESS DC MOTOR

The energization of stator winding pair ac with supply voltage V ac and the resulting phase

currents are shown in Fig. 5(a). The energization of winding pairac results in the currents iathrough winding aa'and ic through winding cc' respectively, where, ia = ic . These currents

establish stationary current vectors ia and ic along the positive magnetic axis of winding aa'

and negative magnetic axis of winding cc'respectively [10]. The vector addition of these two

stationary current vectors ira and i c , results in the resultant stationary current vector i ac as

shown in Fig. 4.


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FIG 22 - ENERGIZATION SEQUENCE OF TWO-POLE, THREE-PHASE

STATOR

At this rotor position = 0, the resultant stationary current vector iac , is displaced from the

rotor flux vector rm by an angle of 120 electrical degrees. The resultant stationary stator flux

vector rac , produced by current vector iac , establishes a magnetic south pole at the arrow

head

rm . The interaction of these flux vectors ac and m develops electromagnetic torque,

resulting in the rotor and its flux vector being pulled towards the resultant stationary stator

flux vector

rac , causing rotation of the motor in an anti-clockwise direction. The electromagnetic torque

Te developed by the machine is given by the cross product of peak flux linkage vector

rm =N

rm ) and current vectori

rac [11], hence,

Tre=mi ac= N(mi ac)

Tre =N| rm || irac | Sin k

The unit vector where, rmis the rotor flux vector, is the angle between vectors m and ira

whose direction is perpendicular to the plane in which m

indicates that the developed electromagnetic torque varies with the magnitude of the resultant

stationary current vectorirac and Sin, since,Nand m are constants.

The utilization of the developed energization sequence for the brushless dc motor, for rotor


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positions in the range 0 60 resulted in the electromagnetic torque equation presented

in Eq. (3). The electromagnetic torque developed by the motor produced anticlockwise

rotation, resulting in an increase in the angle from its 0 position . This increase in the angle

in an anticlockwise direction, results in a decrease of angle from its initial 120, thereby

increasing the electromagnetic torque developed by the motor, provided there is no decrease

in the magnitude of the resultant stationary current vector irac. When = 90, the developed

torque is maximum, but as decreases and reaches 60, the developed electromagnetic torque

decreases to the value when was 0. When > 60 in Fig. 2(b), the back emf in winding

pairac is no longer at its constant value for this speed of operation, and the electromagnetic

torque developed for < 60, would be less than the values obtained for 0 60 and 60

120. If winding pair acremains energized up to the point where = 120, the angle

between the vectors

rm and iracwould be = 0, and the electromagnetic torque developed using Eq. (3) would

be

zero. In addition to zero torque being developed at = 120, the rotor would be locked in this

zero torque position, since the north pole of the rotor magnet would be aligned with the south

pole produced by resultant stationary flux vector ac . Hence, for continuous torque

production

and rotation of the motor and efficient energy conversion from electrical to mechanical,

winding pairacmust not remain energized for > 60. Examination of Fig. 2(b), reveals that

at = 60, winding pairbc has just begun to experience its constant back emfEbc , hence,

winding aa'must be commutated and winding bb'brought into conduction with winding cc'.

That is, winding pairbc must be energized with Vbcat= 60 as shown in Figs. 2(c) and

5(b).

The energization of winding pairbc with supply voltage Vbc results in the current ib throughwinding bb'and ic through winding cc'. These currents establish stationary current vectors iband i

rc , along the positive magnetic axis of winding bb' and negative magnetic axis of

winding cc'respectively. The vector addition of these two current vectorsibandirc, results in

theresultant stationary current vectorirbcas shown in Fig. 4. At this rotor position = 60, the

resultant stationary current vectorirbc, is displaced from the rotor flux vector

rm by an angle

of 120 electrical degrees. The interaction of these vectors i bc and m develops

electromagnetic torque, resulting in the rotor and its flux vector being pulled towards the

resultant stationary stator flux vector rbc , causing rotation to continue in an anti-clockwise

direction. The process of

torque production continues until = 120 and a new winding pair ba is brought into

conduction as shown in Fig. 2(c).

Similarly, the energization of the other phase windings shown in Figs. 5(c) to (f), results inthe


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production of resultant stationary current vectors and iab respectively as shown

in Fig. 4. These resultant stationary current vectors occupy a fixed position in the stator. They

are displaced from each other by an angle of 60 electrical degrees and their magnitudes are

dependent on the current flowing in the phase windings.

The electromagnetic torque developed by the machine is not constant throughout each 60

movement of the rotor and is given by

T

r

e= m ir

xySin kr (4)

where, x is the phase winding terminal connected to the positive end of the supply voltage, y

is the other phase winding terminal connected to the negative end of the supply voltage and

is in the range 60 120. The electromagnetic torque developed by the motor for a fixed

stator winding current I for one revolution of the rotor and ignoring the electromagnetic

torque developed during commutation.

FI G 23ROTOR POSITION


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The events described above for efficient operation of the two-pole, three-phase brushless dc

motor, showing the range of rotor positions for a pair of windings to remain energized, the

corresponding back emf of the energized windings and the corresponding electromagnetic

torque developed are summarized in Table 1 below.

3.19 CLASSIFICATION OF BRUSHLESS DC MOTORElectric motors are classified into two main categories, namely brush dc and ac brushless

motors as shown in Fig. 7 and presented in [1]. Brush dc motors are made up of statorsconsisting of poles produced by permanent magnets or dc excited magnets, which give rise to

static magnetic fields across the rotor. The rotor of these brush dc motors consists of

windings connected to mechanical commutators to facilitate the application of a dc power

source. Current flow through these rotor windings takes place through carbon brushes which

make contact with the commutators, thereby producing a magnetic field and a current vector

which remains in a relatively fixed position relative to the stator. The relatively stationary

current vector of the rotor interacts with the stationary magnetic field of the stator,

developing electromagnetic torque given by the cross product of these two vectors. Fig. 8(a)


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shows the brush dc machine stationary flux.

linkage vectorNrs and the relatively stationary rotor current vector ir separated by an angle

. The electromagnetic torque developed by the machine is given by:

Te= N(i rs).

Three-phase ac machines are divided into two categories, synchronous and asynchronous.

The stators of synchronous and asynchronous ac machines are supplied with three-phase ac

voltages and the resulting three-phase ac currents produce a rotating current vector and

magnetic field, both of which are of constant magnitude and rotate at the angular velocity of

the supply voltage.

FIG 24 - CLASSIF ICATION OF ELECTRIC MOTOR


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The difference betwee

three wheeled electric vehicle

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