magnetic levitation train by shaheen galgali_seminar report final

MAGNETIC LEVITATION

SECAB I.E.T. VIJAYPUR DEPT. OF EEE

CHAPTER 1: INTRODUCTION

Magnetic levitation (maglev) systems are electromechanical device that suspend

ferromagnetic material using electromagnetism. Magnetic levitation technology is used in

high speed trains, in which the train is lifted from the guideway by a magnetic field.

Propulsion is by means of a moving magnetic field. Magnetic levitation systems have

received much attention as a mean of eliminating Coulomb friction due to mechanical

contact. They are becoming popular in two different kinds of realization: high-speed

motion and precision engineering industry.

Levitation bearing has been used from the beginning in rotating machinery to

support rotors without friction low energy consumption, high rotational speed, no

lubrication and greater reliability. It also allows a simpler and safer mechanical design as

in the case of pumps used in nuclear installations where fluid leakage avoidance is of

primary importance. The most famous application is high speed ground transportation

systems: Japanese “Maglev” and German “Transrapid”, shown in Fig. 1, are very fast

trains with linear motor.

Fig.1: German “Transrapid”

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There are different categories of magnetic levitation in which research and

development efforts are being made. Based on the basic principle, magnetic levitation

may broadly be classified into two types, electrodynamics levitation and electromagnetic

levitation. The electrodynamics system actuates through repulsive forces. Most of such

systems utilize superconducting magnets to generate the forces. One of the main

constraints of the superconducting repulsion principle is that it cannot provide suspension

force below some critical speed. The electrodynamics levitation system (EDLS) is

inherently stable, but at high speed it possess stability problem due to negative damping.

So some kind of passive damper is required in electro-dynamically levitated vehicle to

maintain stability at high speed.

In electromagnetic levitation system (EMLS), the levitation is produced due to the

attractive force between electromagnets and ferromagnetic object. In electromagnetic

levitation (attraction system), the electromagnets are driven either by AC or DC source.

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CHAPTER 2: MAGNETIC LEVITATION TRAIN

Magnetic levitation is method by which an object is suspended in air with no support

other than magnetic field. Maglev can create frictionless, efficient, far-out sounding

technology. If a Maglev wants to use this force to levitate, it needs a strong magnetic field

in its wagons. We could use normal magnets, but their magnetic power is limited. The

most efficient way to produce the most powerful magnetic field we know of today, with a

reasonable energy cost, is the use superconducting coil. For efficiency reasons, the

superconducting coils are placed on the sides of the wagons (four on each side), these

coils are made with conventional superconductors that require very low temperatures, a

few kelvins above absolute zero: they are hence always surrounded with liquid helium.

Magnetically levitated train is a highly modern vehicle. Maglev vehicles use noncontact

magnetic levitation, guidance, and propulsion systems and have no wheels, axles, and

transmission. Contrary to traditional railroad vehicles, there is no direct physical contact

between maglev vehicle and its guide-way. These vehicles move along magnetic fields

that are established between the vehicle and its guide-way. Conditions of no mechanical

contact and no friction provided by such technology make it feasible to reach higher

speeds of travel attributed to such train.

Maglev trains can be conveniently considered as a solution for transportation

needs of the current time as well as future needs of the world. . The levitation coils are

installed on the sidewalls of the guide-way. When the on-board superconducting magnets

pass at a high speed about several centimeters below the center of these coils, an electric

current is induced within the coils, which then act as electromagnets temporarily. As a

result, there are forces which push the superconducting magnet upwards and ones which

pull them upwards simultaneously, thereby levitating the maglev vehicle. The levitation

coils facing each other are connected under the guidway, constituting a loop.

When a running maglev vehicle, that is a superconducting magnet, displaces

laterally, an electric current is induced in the loop, resulting in a repulsive force acting on

the levitation coils of the side near the car and an attractive force acting on the levitation

coils of the side farther apart from the car. Thus, a running car is always located at the

center of the guideway. A repulsive force and an attractive force induced between the

magnets are used to propel the vehicle (superconducting magnet). The propulsion coils

located on the sidewalls on both sides of the guideway are energized by a three-phase

alternating current from a substation, creating a shifting magnetic field on the guideway.

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The on-board superconducting magnets are attracted and pushed by the shifting field,

propelling the maglev vehicle. There are two types of magnetic levitation as follows,

2.1 TYPES OF MAGNETIC LEVITATION TRAIN

Magnetic levitation Train can be based on several types follows as

2.1.1 Electromagnetic suspension

2.1.2 Electrodynamics suspension

2.1.1 Electromagnetic suspension

Electromagnetic suspension works like an active magnetic bearing. This

principle is sometimes called a servo-stabilization. Sensors measure the air-gap between

an electromagnet and guideway. Control system tries to keep it constant.

Servo-stabilization is able to hold the body in the required position, even if the

train standstill. Therefore no wheels are required for assuring of the main levitation

function. However some retainer wheels for safety purposes are usually employed. In

EMS system, the vehicle is levitated about 1 to 2 cm above the guideway using attractive

forces, the electromagnets on the vehicle interact with and are attracted to levitation rails

on the guideway. Electromagnets attached to the vehicle are directed up toward the

guideway, which levitates the vehicle above the guideway and keeps the vehicle levitated.

Control of allowed air gaps between the guideway and vehicle is achieved by using

highly advanced control systems. The electromagnet use feedback control to maintain

train at a constant distance from the track.

Fig. 2.1: Electromagnetic suspension

In EMS train levitate due to the attraction between the opposite poles of magnets one in

the guideway & the other in the undercarriage. The distance between the train & the

undercarriage must maintained 15mm. The train also remains suspended in air when it is

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not moving, Minor changing between the magnets and the train produces a varying force

and this force is very unstable do complex electronic Feedback system is Necessary to

maintain the accurate distance. The system varies the current in electromagnets & control

the magnetic force of attraction.

2.1.2 Electrodynamics Suspension

In Electrodynamics suspension the train is levitated by the repulsive force

between these magnetic fields. The magnetic field in the train is produced by either

electromagnets or by an array of permanent magnets. The repulsive force in the track is

created by an induced magnetic field in wires or other conducting strips in the track. In

EDS system, the vehicle is levitated about above the track using repulsive forces.

Fig 2.2 Electrodynamics suspension

In EDS both the track & the train exert a magnetic field & the train is levitate by

the repulsive force between these magnetic field

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CHAPTER 3: BASIC PRINPLES OF THE MAGNETIC

LEVITATION TRAIN & BLOCK DIAGRAM

Maglev trains have to perform the following functions to operate in high speed

1. Levitation

2. Propulsion

3. Lateral guidance

3.1 Levitation

The levitation coils are installed on the sidewalls of the guideway. When the on-

board superconducting magnets pass at a high speed about several centimeters below the

center of these coils, an electric current is induced within the coils, which then act as

electromagnets temporarily. As a result, there are forces which push the superconducting

magnet upwards and ones which pull them upwards simultaneously, thereby levitating the

maglev vehicle. The levitation coils facing each other are connected under the guideway,

constituting a loop.

When a running maglev vehicle, that is a superconducting magnet, displaces

laterally, an electric current is induced in the loop, resulting in a repulsive force acting on

the levitation coils of the side near the car and an attractive force acting on the levitation

coils of the side farther apart from the car. Thus, a running car is always located at the

center of the guideway. A repulsive force and an attractive force induced between the

magnets are used to propel the vehicle (superconducting magnet). The propulsion coils

located on the sidewalls on both sides of the guideway are energized by a three-phase

alternating current from a substation, creating a shifting magnetic field on the guideway.

The on-board superconducting magnets are attracted and pushed by the shifting field,

propelling the maglev vehicle.

Fig 3.1 shows principle of levitation

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3.2 Propulsion

The propulsion coils are active, which means they are supplied by a source of

energy: this makes sense; the train must accelerate and defeat air resistance. Since these

coils are made of metal, they consume energy. Nevertheless, they can be totally

controlled: when the direction and the intensity of the currents going through them are

controlled, the sign and the intensity of the created magnetic field are also controlled. To

make the Maglev accelerate, you only need to send an electric current in the propulsion

coils located in the beams upstream from the Maglev in order to attract it; and to send an

electric current in the coils downstream in order to push it. Attracted in the front and

pushed in the back, the Maglev accelerates. The engine of the Maglev is hence located in

the tracks! To slow down, we only need to invert the current, pushing the front of the

Maglev and attracting its back.

Furthermore, the wagons are equipped with air brakes in order to slow down

without consuming any energy. The propulsion coils located on the sidewalls on both

sides of the guideway are energized by a three-phase alternating current from a

substation, creating a shifting magnetic field on the guideway. The on-board

superconducting magnets are attracted and pushed by the shifting field, propelling the

maglev vehicle.

Fig 3.2 shows of principle propulsion

3.3 Lateral Guidance

The track along which the train moves is called the guide way. Both the guide way

as well as the train’s undercarriage also have magnets which repel each other. Thus the

train is said to levitate about 0.39 inches on top of the guide way. After the levitat ion is

complete, enough power has to be produced so as to move the train through the guide

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way. This power is given to the coils within the guide way, which in turn produces

magnetic fields, which pulls and pushes the train through the guide way.

Fig 3.3 shows principle of lateral guidance

The current that is given to the electric coils of the guide way will be alternating in

nature. Thus the polarity of the coils will be changing in period. Thus the change causes a

pull force for the train in the front and to add to this force, the magnetic field behind the

train adds more forward thrust.

3.4 BLOCK DIAGRAM OF MAGNETIC LEVITATION TRAIN

Fig. 3.4: Block diagram of maglev train

Fig.3.1 shows the block diagram of maglev train. Here the 3ø AC Power (variable) is

being fed to a controller (variable frequency). The frequency will decide the speed of the

train. The overall MAGLEV system is made up of two subsystems: propulsion and

levitation.

http://www.circuitstoday.com/wp-content/uploads/2010/12/MAGLEV-Track.gif

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CHAPTER 4: WORKING OF MAGLEV TRAIN

Fig. 4.1: Working principle of maglev train

Fig. 4.2: Magnetic field & forces acting on the track

The train will be floating about 10mm above the magnetic guiding track. The train

will be propelled to move by the guide way itself. Thus, there is no need of any engine

inside the train. The detailed working of MAGLEV train is shown in the figure below.

The train is propelled by the changing in magnetic fields. As soon as the train starts to

move, the magnetic field changes sections by switching method and thus the train is again

pulled forward. The whole guide way is run by electromagnets so as to provide the

magnetic effect.

https://en.wikipedia.org/wiki/File:Railgun-1.svg

MAGNETIC LEVITATION


In a traditional DC electric motor, a central core of tightly wrapped magnetic

material (known as the rotor) spins at high speed between the fixed poles of a magnet

(known as the stator) when an electric current is applied. In an AC induction motor,

electromagnets positioned around the edge of the motor are used to generate a rotating

magnetic field in the central space between them. This "induces" (produces) electric

currents in a rotor, causing it to spin. In an electric car, DC or AC motors like these are

used to drive gears and wheels and convert rotational motion into motion in a straight

line.

A linear motor is effectively an AC induction motor that has been cut open and

unwrapped. The "stator" is laid out in the form of a track of flat coils made from

aluminum or copper and is known as the "primary" of a linear motor. The "rotor" takes

the form of a moving platform known as the "secondary." When the current is switched

on, the secondary glides past the primary supported and propelled by a magnetic field.

Linear motors have a number of advantages over ordinary motors. Most

obviously, there are no moving parts to go wrong. As the platform rides above the track

on a cushion of air, there is no loss of energy to friction or vibration (but because the air-

gap is greater in a linear motor, more power is required and the efficiency is lower). The

lack of an intermediate gearbox to convert rotational motion into straight-line motion

saves energy. Finally, as both acceleration and braking are achieved through

electromagnetism, linear motors are much quieter than ordinary motors.

4.1 Superconducting Magnets Principle

The main problem with linear motors has been the cost and difficulty of

developing suitable electromagnets. Enormously powerful electromagnets are required to

levitate (lift) and move something as big as a train, and these typically consume

substantial amounts of electric power. Linear motors often now use superconducting

magnets to solve this problem.

If electromagnets are cooled to low temperatures using liquid helium or nitrogen

their electrical resistance disappears almost entirely, which reduces power consumption

considerably. This helpful effect, known as superconductivity, has been the subject of

intense research since the mid 1980s and makes large-scale linear motors that much more

viable.

http://www.explainthatstuff.com/induction-motors.html

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CHAPTER 5: APPLICATIONS & BENEFITS OF MAGLEV

TECHNOLOGY

5.1 Applications

1. Aerospace Engineering(space craft, Rocket)

2. Nuclear Engineering(centrifuge)

3. Military Weapon Engineering(Rocket, Gun)

4. Civil Engineering & Building Facilities

5. Biomedical Engineering(Heart pump)

6. Chemical Engineering(Analyzing Foods and Beverages)

7. Electrical Engineering(Magnet, etc)

8. Architectural Engineering & Household Appliances

9. Automotive Engineering(car etc)

5.2 Advantages

1. The foremost advantage of maglev trains is the fact that it doesn't have moving parts as

conventional trains do, and therefore, the wear and tear of parts is minimal, and that

reduces the maintenance cost by a significant extent.

2. More importantly, there is no physical contact between the train and track, so there is

no rolling resistance. While electromagnetic drag and air friction do exist, that doesn't

hinder their ability to clock a speed in excess of 200 mph.

3. Absence of wheels also comes as a boon, as you don't have to deal with deafening

noise that is likely to come with them.

4. Maglevs also boast of being environment friendly, as they don't resort to internal

combustion engines.

5. These trains are weather proof, which means rain, snow, or severe cold don't really

hamper their performance.

6. Experts are of the opinion that these trains are a lot safe than their conventional

counterparts as they are equipped with state-of-the-art safety systems, which can keep

things in control even when the train is cruising at a high speed.

5.3 Disadvantages

The biggest problem with maglev trains is the high cost incurred on the initial setup .

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CHAPTER 6: IMPLEMENTED PROJECTS

In Germany, engineers are building an electromagnetic suspension (EMS) system,

called Transrapid. In this system, the bottom of the train wraps around a steel guideway.

Electromagnets attached to the train’s undercarriage are directed up toward the guideway,

which levitates the train about one-third of an inch (1 cm) above the guideway and keeps

the train levitated even when it’s not moving. Other guidance magnets embedded in the

trains body keep it stable during travel. Germany has demonstrated that the Transrapid

maglev train can reach 300 mph with people on board.

Japanese engineers are developing a competing version of Maglev trains that use

an electrodynamics suspension (EDS) system, which is based on the repelling force of

magnets. The key difference between Japanese and Germany Maglev trains is that the

Japanese trains use super-cooled superconducting electromagnets. These kinds of

electromagnets can conduct electricity even after the power supply has been shut off. In

the EMS system, which uses standard electromagnets, the coils only conduct electricity

when a power supply is present. By chilling the coils at frigid temperatures, Japanes

system saves energy.

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CHAPTER 8: FUTURE SCOPE IN INDIA

Maglev train from Pune (Pimple Saudagar) to Mumbai (Panvel) :

The Indian Ministry is currently in the process of reviewing a proposal to start a

Maglev train system in India. It has already been estimated that the cost to complete this

process would be over $30 Billion. The company who sent the proposals is a company

based in the United States. Although still at a preliminary stage if completed, the train

travel time between the two cities will be reduced to three hours, compared to an original

16 hours & fuel consumption of 0.2 million liters a day .

Mumbai to Delhi:

A maglev line project is proposed to 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 Centraland

Chhatrapati Shivaji International Airport.

Mumbai - Nagpur

The State of Maharashtra has also approved a feasibility study for a maglev train between

Mumbai (the commercial capital of India as well as the State government capital) and

Nagpur (the second State capital) about 1,000 km (620 mile) away. It plans to connect the

regions of Mumbai and Pune with Nagpur via less developed hinterland (via

Ahmednagar, Beed, Latur, Nanded and Yavatmal).

Chennai - Bangalore - Mysore

A maglev line project is proposed to serve between the cities of Chennai and Mysore via

Bangalore. The speed of Maglev will be 350 kmph and will take 30 mins from Chennai to

Mysore via Bangalore.

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CONCLUSION

Magnetic levitation is very promising technology for the high speed

transportation. MAGLEV trains make use of Electrodynamics and Electromagnetic

suspension for their propulsion. In this report two types of Maglev technologies i)

Electromagnetic suspension ii) Electrodynamics suspension are explained. It is found that

that EDS is Efficient, FAST, CHEAP and reliable.

The speed of the Maglev trains is 560 km/hr where as the conventional trains run

at a speed of 100 km/hr (Rajdhani).

A conventional train uses Diesel as fuel and emits lot of Green house gases (CO2,

NOX, etc) which is causing Global Warming and pollution.

There is no friction in Maglev trains, hence no losses due to friction. Therefore

Maglev trains are more efficient and less noisy than conventional trains.

Therefore MAGLEV trains are better than traditional trains because of their

construction and working principle.

.

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http://www.buzzle.com/articles/advantages-and-disadvantages-of-maglev-trains.html