INTRODUCTION TO MAGNETIC LEVITATION

&ITS APPLICATION

Driving without wheels, Flying without wings

byVISHWANATH NEHA(12K41A0270)

Under the guidance of

O.SRIKANTH(Asst. prof)

What is Magnetic Levitation?

Magnetic Leviation 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 Transrapid magnetic lift trains.

Basic Principle of Maglev TrainsMagLev trains have to perform the following functions to operate in high speeds

1.Levitation

2.Propulsion

3.Lateral Guidance

Types of Maglev TrainsBased on the technique used for Levitation there

are two types of MagLev trains

1. Electromagnetic Suspension -Attractive

2. Electrodynamic Suspension -Repulsive

Electro Magnetic Suspension(EMS)Electromagnetic Suspension uses

electromagnets to leviate the train

EMS Levitation Principle:

Principle of Magnetic LeviationIn 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.

The rail, which is in the shape of an inverted T, is a ferromagnetic rail.

When a current is passed through it, and the electromagnet switched on, there is attraction, and the levitation electromagnets, which are below the rail, raise up to meet the rail. The car levitates.

EMS Propulsion Principle

Principle of PropulsionA linear electric motor (LEM) is a mechanism which

converts electrical energy directly into linear motion without employing any intervening rotary components

Linear Induction Motor (LIM) is basically a rotating squirrel cage induction motor opened out flat

Instead of producing rotary torque from a cylindrical machine it produces linear force from a flat one.

LIM thrusts vary from just a few to thousands of Newtons , depending mainly on the size and rating.

Gap SensorThe attractive force is controlled by a gap sensor that

measures the distance between the rails and electromagnets.

Principle of Lateral GuidanceThe levitation magnets and rail are both U shaped(with rail being an inverted U).

The mouths of U face one another.

This configuration ensures that when ever a levitational force is exerted, a lateral guidance force occurs as well.

If the electromagnet starts to shift laterally from the center of the rail, the lateral guidance force is exerted in proportion to the extent of the shift, bringing the electromagnet back into alignment.

Electrodynamic Suspension Electrodynamics Suspension uses Superconductors for

levitation, propulsion and lateral guidance

Superconductivity Superconductivity occurs in certain materials at very low

temperatures. When superconductive, a material has an electrical resistance

of exactly zero. It is also characterized by a phenomenon called the Miessner

effect. This is the ejection of any sufficiently weak magnetic field from the interior of the superconductor as it transitions into the superconducting state.

The SCM (Super Conducting Magnet)Each SCM contains 4 SC coils. The SCM features

high reliability and high durability.The cylindrical unit at the top is a tank holding

liquefied helium and nitrogen. The bottom unit is an SC coil alternately

generating N poles and S poles.

• The passing of the superconducting magnets by figure eight levitation coils on the side of the track induces a current in the coils and creates a magnetic field. This pushes the train upward so that it can levitate 10 cm above the track.

• The train does not levitate until it reaches 50 mph, so it is equipped with retractable wheels.

PRINCIPLE OF MAGNET LEVITATION

• 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.

PRINCIPLE OF PROPULSION

• 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 LATERAL GUIDANCE

An EDS system can provide both levitation and propulsion using an onboard linear motor.

EMS systems can only levitate the train using the magnets onboard, not propel it forward.

Advantages of Magnetic Levitated Transportation System Maglev uses 30% less energy than a high-speed train traveling at the same speed (1/3 more power for the same amount of energy).

The operating costs of a maglev system are approximately half that of conventional long-distance railroads.

Research has shown that the maglev is about 20 times safer than airplanes, 250 times safer than conventional railroads, and 700 times safer than automobile travel.

OTHER APPLICATIONS NASA plans to use magnetic levitation for launching of space vehicles into low earth orbit.

Boeing is pursuing research in MagLev to provide a Hypersonic Ground Test Facility for the Air Force.

The mining industry will also benefit from MagLev.

There are probably many more undiscovered applications!