MAGNETIC LEVITATION PRECAP…..

1. Introduction

2. Summary

3. Theorem related to its principle

4. Uses and its Practical Application in MAGNETIC BEARING….

Prepared By:13BEE110 SHETHNA VASAV

13BBEE111 SHINGALA TUSHAR

Guided by:Prof. Hormaz Amrolia

Magnetic Levitation Magnetic levitation is the use of magnetic fields to levitate a (usually) metallic object.

Manipulating magnetic fields and controlling their forces can levitate an object.

Using either Ferromagnetism or Diamagnetism object can be levitated.

A superconductor is perfectly diamagnetic and electromagnets can exhibit varying levels of ferromagnetism.

Most important application of Magnetic Levitation is Trans-rapid magnetic lift trains.

As a means of eliminating friction or

physical contact

Frictionless bearings

High speed Ground

Transportation

Areas of Attraction

Maglev Train MAGLEV = MAGnetic + LEVitation

History of Maglev Train• In the 1960s in Britain Eric Laithwaite developed a functional maglev train. His maglev had 1.6 km of track and was in detail tested. His research was stopped in 1973 because lack of money and his progress was not enough. In the 1970s, Germany and Japan also began research and after some failures both nations developed mature technologies in the 1990’s.

Basic Principle of Maglev Trains

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

1.Leviation

2.Propulsion

3.Guidance

Types of Maglev Trains

Based on the technique used for Levitation the are two types of Maglev trains

1. Electromagnetic Suspension -Attractive

2. Electrodynamic Suspension -repulsive

EMS Technique In the EMS-attractive system, the electromagnets which do the work of levitation are attached on the top side of a casing that extends below and then curves back up to the rail that is in

the center of the track.

Gap Sensor This attractive force is controlled by a gap sensor that measures the distance between the rails and electromagnets.

EDS Technique Electrodynamic Suspension uses Superconductors for levitation, propulsion and lateral guidance.

Pros and Cons of Different

TechnologiesTECHNOLOGY PROS CONS

EMS(Electromagnetic suspension)

Magnetic fields inside and outside the vehicle are less than EDS; 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; due to the system's inherent instability and the required constant corrections by outside systems, vibration issues may occur.

TECHNOLOGY PROS CONS

EDS(Electrodynamic suspension)

Onboard magnets and large margin between rail and train enable highest recorded train speeds (581 km/h) and heavy load capacity; has recently demonstrated (December 2005) successful operations using high temperature superconductors in its onboard magnets, cooled with inexpensive liquid nitrogen

Strong magnetic fields onboard the train would make the train inaccessible to passengers with pacemakers or magnetic data storage media such as hard drives and credit cards, necessitating the use of magnetic shielding; limitations on guideway inductivity limit the maximum speed of the vehicle; vehicle must be wheeled for travel at low speeds.

PROPULSION•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.•Braking is accomplished by sending an alternating current in the reverse direction so that it is slowed by attractive and repulsive forces.

Propulsion force This is a horizontal force which causes the movement of train. It requires 3 parameters.

i. Large electric power supply ii. Metal coil lining, a guide way or track. iii. Large magnet attached under the vehicle.

Techniques of propulsion

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

a. Linear synchronous motor (LSM) in which coils in the guide way are excited by a three phase winding to produce a traveling wave at the speed desired; Trans Rapid in Germany employs such a system.

b. Linear Induction Motor (LIM) in which an electromagnet underneath the vehicle induces current in an aluminium sheet on the guide way.

c. Reluctance motor is employed in which active coils on the vehicle are pulsed at the proper time to realize thrust.

How does it work

o A maglev train floats about 10mm above the guideway on a magnetic field.o It is propelled by the guideway itself rather than an onboard engine by changing magnetic fields.o Once the train is pulled into the next section the magnetism switches so that the train is pulled on again. o The Electro-magnets run the length of the guideway.

Principle of Lateral Guidance

When one side of the train nears the side of the guideway, the super conducting magnet on the train induces a repulsive force from the levitation coils on the side closer to the train and an attractive force from the coils on the farther side.

This keeps the train in the center.

Principle of Vertical Guidance•The electromagnets on the underside of the train pull it up to the ferromagnetic stators on the track and levitate the train. •The magnets on the side keep the train from moving from side to side.

Advantages•The train is earthquake proof because the greater space (10 cm) between the track and the train leaves more room for track deformation.

•Only the part of the track that is used will be electrified so no energy is wasted.

• It’s top speed with people aboard is 350 mph.

• Since there is no friction these trains can reach high speeds.

• It is a safe and efficient way to travel.

•As no engine is required so there is no problem of attaching and detaching the engine to run the train on either side.

Economic Aspect• The initial investment is similar to other high speed rail roads.

• Operating expenses are half of that of other railroads.

• A train is composed of sections that each contain 100 seats, and a train can have between 2 and 10 sections.

• The linear generators produce electricity for the cabin of the train , Thus it also consumes less energy.

Current Projects • Currently operational systems include Transrapid (Germany ) and High Speed Surface Transport (Japan ). There are several other projects under scrutiny such as the SwissMetro, Seraphim and Inductrack. All have to do with personal rapid transit.

• Germany and Japan have been the pioneering countries in MagLev research.

THANK YOU

REFERNCES• http://en.wikipedia.org/wiki/MAGLEV_TRAIN

• J. Powell, G. Maise, and J. Paniagua, “MAGLEV: A new concept for very low cost transportation using technique of magnetic levitation,” paper IAF-01-S.6.04, 52nd International Astronautical Congress, Toulouse, France, Oct. 1-5, 2001.