maglev - seminar report by rohan

A Seminar Report on MAGLEV by ROHAN SHARMA

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CONTENTSCONTENTSCONTENTSCONTENTS

SR. NO. TOPIC PAGE NO.

1 Introduction 2

2 Historical Background 5

3 Maglev Methods 8

4 Working of Maglev vehicle 9

5 Propulsion Force 9

6 Linear Motor Principle 10

7 Propulsion of Maglev 12

8 Levitating Force 13

9 Lateral Guiding Force 18

10 Braking & Control 19

11 Varying Maglev Speed 20

12 Maglev in INDIA 21

13 Conclusion 22

14 References 23


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INTRODUCTIONINTRODUCTIONINTRODUCTIONINTRODUCTION

Magnetic levitation, maglev, or magnetic suspension is a

method by which an object is suspended above another

object with no support other than magnetic field .The

electromagnetic force is used to counteract the effects of the

gravitational force.

A substance which is diamagnetic repels a magnetic field.

Earnshaw's theorem does not apply to diamagnets; they

behave in the opposite manner of a typical magnet due to

their relative permeability of µr < 1. All materials have

diamagnetic properties, but the effect is very weak, and

usually overcome by the

object's paramagnetic or

ferromagnetic properties,

which act in the opposite

manner. Any material in which

the diamagnetic component is

strongest will be repelled by a

magnet, though this force is

not usually very large. Diamagnetic levitation can be used to

levitate very light pieces of pyrolytic graphite or bismuth

above a moderately strong permanent magnet. As water is

predominantly diamagnetic, this technique has been used to


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levitate water droplets and even live animals, such as a

grasshopper and a frog.

The minimum criteria for diamagnetic levitation is

Where:

• χ is the magnetic susceptibility

• ρ is the density of the material

• g is the local gravitational acceleration (-9.8

m/s2 on Earth)

• µ0 is the permeability of free space

• B is the magnetic field

• is the rate of change of the magnetic field

along the vertical axis.

Assuming ideal conditions along the z-direction of solenoid

magnet:

• Water levitates at

• Graphite at


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A live frog levitating inside a 32 mm diameter vertical

bore in a magnetic field of about 16 Tesla at the

Nijmegen High Field Magnet Laboratory

Levitating Pyrolytic Carbon


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HISTORHISTORHISTORHISTORICAL BACKICAL BACKICAL BACKICAL BACKGROUNDGROUNDGROUNDGROUND

Approximately 25 years ago, scientists became interested in

developing a train that would combine high-speed with a

smooth ride and quiet operation. They developed the

"Maglev", or magnetic levitation train. This vehicle rides on a

cushion created by the electromagnetic repulsion between a

series of on-board magnets and another embedded in the

trackway below the train. Thus, this train does not run on

wheels. As a result, the ride is very smooth and there is no

metal-to-metal contact to generate noise and steel dust.

Keeping this kind of Maglev train airborne and in smooth

motion requires advanced, extremely accurate feedback

circuits and very strict engineering tolerances. The other

type of Maglev uses super-conducting coils embedded in the

guideway and electromagnets in the train cars to establish

the levitation.

Two American scientists at Lawrence Livermore National

Laboratories have developed a new system called Indutrack

which employs the use of passive permanent magnets, just

like the ones on your kitchen refrigerator, only larger. In

preliminary tests, Indutrack trains have higher lifting

efficiency. Another big advantage of Indutrack is that it does

not require the incorporation of superconductive coils in the

guideway or in the bottom of the car. These coils require an


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extremely expensive, high maintenance, ultra-low

temperature helium cooling systems. The new system

consists of a series of passive magnets, called Halbach

arrays, attached under the vehicle. The guide-way, which

replaces the track or conventional subway and railroad

trains, has metallic magnetic-inductive coils embedded in its

surface. For each pound of the Halbach passive magnets, 50

pounds of vehicle/payload can be lifted.

There are two types of Maglev's: ones that use like magnets

which repel each other and ones that use opposing magnets

that attract with each other. Ones that use repelling

magnets' are called Superconducting Maglev's. The magnets

allow the train to float. Electromagnetic Maglevs use

opposing magnets.

Superconducting Maglevs use very cold temperature

magnets in order to make electricity without any opposition.

The magnets are then put on the bottom of the train. When

the train moves, it forms currents from the magnets in the

aluminum sheets placed in the guideway. Because of the

repelling force, the vehicle rises. Also in the guideway,

separate electric currents pass through which push the train

forward.

Electromagnetic Maglev's go under the guideway. They use

opposing magnets that attract with each other. This allows


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the Maglev to pull upward towards the guideway. Like the

superconducting Maglev's, separate currents make magnetic

fields shift which allows the train to move forward. These

Maglev's travel about 3/8's of an inch away from the

guideway. In order for the magnets from not hitting the

guideway, the lifting current must keep being fixed.

The main parts of the Maglev:

Guide way and guide rails - keep the train to on track

Landing wheels; levitation coils - run along the base of the

guide way (used in superconducting maglevs)

Emergency landing wheel; superconducting magnets and

propulsion coils - run along the base of guide way (used in

electromagnetic maglev's), and a linear induction motor -

moves and brakes the vehicle on the track.


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MAGLEV METHODSMAGLEV METHODSMAGLEV METHODSMAGLEV METHODS

• Repulsion between like poles of permanent magnets or

electromagnets.

• Repulsion between a magnet and a metallic conductor

induced by relative motion.

• Repulsion between a metallic conductor and an AC

electromagnet.

• Repulsion between a magnetic field and a diamagnetic

substance.

• Repulsion between a magnet and a superconductor.

• Attraction between unlike poles of permanent magnets or

electromagnets.

• Attraction between the open core of an electromagnetic

solenoid and a piece of iron or a magnet.

• Attraction between a permanent magnet or electromagnet

and a piece of iron.

• Attraction between an electromagnet and a piece of iron or a

magnet, with sensors and active control of the current to the

electromagnet used to maintain some distance between

them.

• Repulsion between an electromagnet and a magnet, with

sensors and active control of the current to the

electromagnet used to maintain some distance between

them.


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WORKING OWORKING OWORKING OWORKING OF MAGLEV VEHICLEF MAGLEV VEHICLEF MAGLEV VEHICLEF MAGLEV VEHICLE

Basically the construction depends on

3 different working forces.

� PROPULSION FORCE

� LEVITATING FORCE

� LATERAL GUIDING FORCE

1.1.1.1. PROPULSION FORCEPROPULSION FORCEPROPULSION FORCEPROPULSION FORCE

This is a horizontal force which causes the movement of

train. It requires 3 parameters.

• Large electric power supply

• Metal coil lining, a guide way or track.

• Large magnet attached under the vehicle.


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PRINCIPLE OF LINEAR MOTORPRINCIPLE OF LINEAR MOTORPRINCIPLE OF LINEAR MOTORPRINCIPLE OF LINEAR MOTOR Its principle is similar to induction motor having linear stator

and flat rotor. The 3-phase supply applied to the stator

produces a constant speed magnetic wave, which further

produces a repulsive force.

A linear motor or linear induction motor is essentially a

multi-phase alternating current (AC) electric motor that has

had its stator "unrolled" so that instead of producing a

torque (rotation) it produces a linear force along its length.

The most common mode of operation is as a Lorentz-type

actuator, in which the applied force is linearly proportional to

the current and the magnetic field (F = qv × B).

Many designs have been put forward for linear motors,

falling into two major categories, low-acceleration and high-


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acceleration linear motors. Low-acceleration linear motors

are suitable for maglev trains and other ground-based

transportation applications. High-acceleration linear motors

are normally quite short, and are designed to accelerate an

object up to a very high speed and then release the object,

like roller coasters. They are usually used for studies of

hypervelocity collisions, as weapons, or as mass drivers for

spacecraft propulsion. The high-acceleration motors are

usually of the linear induction design (LIM) with an active

three-phase winding on one side of the air-gap and a

passive conductor plate on the other side. The low-

acceleration, high speed and high power motors are usually

of the linear synchronous design (LSM), with an active

winding on one side of the air-gap and an array of alternate-

pole magnets on the other side. These magnets can be

permanent magnets or energized magnets. The Transrapid

Shanghai motor is an LSM.


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Maglev vehicles are propelled primarily by one of Maglev vehicles are propelled primarily by one of Maglev vehicles are propelled primarily by one of Maglev vehicles are propelled primarily by one of the following three options:the following three options:the following three options:the following three options:

1.A linear synchronous motor (LSM) in which coils in the

guideway are excited by a three phase winding to produce a

traveling wave at the speed desired; Trans Rapid in

Germany employs such a system.

2. A Linear Induction Motor (LIM) in which an electromagnet

underneath the vehicle induces current in an aluminum

sheet on the guideway.

3. A reluctance motor is employed in which active coils on

the vehicle are pulsed at the proper time to realize thrust.


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2. LEVITATING FORCELEVITATING FORCELEVITATING FORCELEVITATING FORCE

The levitating force is the upward thrust which lifts the

vehicle in the air.

There are 3 types of levitating systems

1. EDS system

2. EMS system

3. INDUCTRACK system

Levitating force is produced due to the eddy current in the

conducting ladder by the electromagnetic interaction. At low

speed the force due to induced poles cancel each other. At

high speed a repulsive force is taken place as the magnet is

shifted over a particular pole.


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I. EDS SYSTEM:

In EDS both the rail and the train exert a magnetic field, and

the train is levitated by the repulsive force between these

magnetic fields.

At slow speeds, the current induced in these coils and the

resultant magnetic flux is not large enough to support the

weight of the train. For this reason the train must have

wheels or some other form of landing gear to support the

train until it reaches a speed that can sustain levitation.

Onboard magnets and large margin between rail and train

enable highest recorded train speeds (581 km/h).This

system is inherently stable. Magnetic shielding for

suppression of strong magnetic fields and wheels for travel

at low speed are required. It can’t produce the propulsion

force. So, LIM system is required.


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II. EMS SYSTEM: Maglev concepts using electro -magnetic suspension employ

attractive forces. Magnetic fields inside and outside the

vehicle are insignificant; proven, commercially available

technology that can attain very high speeds (500 km/h); no

wheels or secondary propulsion system needed.

The separation between the vehicle and the guideway must

be constantly monitored and corrected by computer systems

to avoid collision due to the unstable nature of

electromagnetic attraction.


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III. INDUCTRACK SYSTEM:

The inductrack guide way would contain two rows of tightly

packed levitation coils, which would act as the rails. Each of

these “rails” would be lined by two Halbach arrays carried

underneath the maglev vehicle: one positioned directly

above the “rail” and one along the inner side of the “rail”.

The Halbach arrays above the coils would provide levitation

while the Halbach arrays on the sides would provide lateral

guidance that keeps the train in a fixed position on the

track.

The track is actually an array of electrically-shorted circuits

containing insulated wire. In one design, these circuits are

aligned like rungs in a ladder. As the train moves, a

magnetic field repels the magnets, causing the train to

levitate.


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There are two inductrack designs, Inductrack I and II.

Inductrack I is designed for high speeds, while inductrack II

is suited for slow speeds. Inductrack trains could levitate

higher with greater stability. As long as it’s moving a few

miles per hour, an inductrack train will levitate nearly an

inch above the track. A greater gap above the track means

that the train would not require complex sensingsystems to

maintain stability. Permanent magnets had not been used

before because scientists thought that they would not create

enough levitating force. The inductrack design bypasses this

problem by arranging the magnets in a Halbach array. The

magnets are configured so that the intensity of the magnetic

field concentrates above the array instead of below it which

generates higher magnetic field.

The inductrack II design incorporates two Halbach arrays to

generate a stronger magnetic field at lower speeds. Dr.

Richard post at the Livermore National Laboratory in

California came up with this concept in response to safety

and cost concerns. The prototype tests caught the attention

of NASA, which awarded a contract to Dr.post and his team

to explore the possibility of using the inductrack system to

launch satellites into orbit.


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3.3.3.3. LATERAL GUIDING FORCELATERAL GUIDING FORCELATERAL GUIDING FORCELATERAL GUIDING FORCE Guidance or steering refers to the

sideward forces that are required to

make the vehicle follow the

guideway. The necessary forces are

supplied in an exactly analogous

fashion to the suspension forces,

either attractive or repulsive. The

same magnets on board the vehicle,

which supply lift, can be used

concurrently for guidance or separate

guidance magnets can be used.

It requires the following arrangements:

• Guideway levitating coil

• Moving magnet


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BRAKING & CONTROL OF MAGLEV TRAINSBRAKING & CONTROL OF MAGLEV TRAINSBRAKING & CONTROL OF MAGLEV TRAINSBRAKING & CONTROL OF MAGLEV TRAINS

GENERALY TWO TYPES OF BREAKING ARE USED

• AERODYNOMIC BREAKING

• ELECTOMAGNETIC BREAKING

Yamanashi Superconducting MagnetYamanashi Superconducting MagnetYamanashi Superconducting MagnetYamanashi Superconducting Magnet


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Varying Maglev SpeedVarying Maglev SpeedVarying Maglev SpeedVarying Maglev Speed

The Maglev’s speed can vary from standstill to full operating

speed by simply adjusting the frequency of the alternating

current. To bring the train to a full stop, the direction of the

travelling field is reversed. Even during braking, there isn't

any mechanical contact between the stator and the rotor.


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MAGLEV in INDIAMAGLEV in INDIAMAGLEV in INDIAMAGLEV in INDIA

Mumbai – Delhi: A maglev line project was presented to

India's railways minister Lalu Prasad Yadav by an American

company. If approved, this line would serve between the

cities of Mumbai and Delhi, the Prime Minister Manmohan

Singh said that if the line project is successful the Indian

government would build lines between other cities and also

between Mumbai centre and Chattrapati Shivaji

International Airport.

Maharashtra has also approved feasibility study for Maglev

train between Mumbai, which is commercial capital of India

and state govt capital and Nagpur, which is second capital of

the state and about 1000 km away. It plans to connect

developed area of Mumbai and Pune with Nagpur via

underdeveloped hinterland via Ahmednagar, Beed, Latur,

Nanded and Yavatmal.


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CONCLUSIONCONCLUSIONCONCLUSIONCONCLUSION

It’s no longer science fiction, maglev trains are the new way

of transportation in the near future, just some obstacles are

in the way, but with some researches nothing is impossible.

With no engine, no wheels, no pollution, new source of

energy, floating on air, the concept has token tens of years

to develop, just recently it’s true capacities has been

realized. Competing planes with speed, boats with efficiency,

traditional trains with safety, and cars with comfort, it seems

like it isn't a fair fight....

Advantages

1. Quicker and efficient transport

2. No noise

3. Comfortable, smooth ride due to very little friction

4. Safe and cost-effective

5. Less consumption of natural resources

6. Environment-friendly as no gas is emitted

Disadvantage

1. Highly Expensive

2. Complex control system

3. No overlap or junction can done


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REFERENCESREFERENCESREFERENCESREFERENCES

• Principles of Electrical Machines

• www.wikipedia.org

• www.howstuffworks.com

• www.google.co.in

maglev - seminar report by rohan

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