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.
In this process an object is suspended above another with no other support but magnetic fields.
The electromagnetic force is used to counteract the effects of gravitation. But it has also been proved that it is not possible to levitate using static, macroscopic, `classical' electromagnetic fields.
The forces acting on an object in any combination of gravitational, electrostatic, and magnetostatic fields will make the object's position unstable.
The reason a permanent magnet suspended above another magnet is unstable is because the levitated magnet will easily overturn and the force will become attractive. If the levitated magnet is rotated, the gyroscopic forces can prevent the magnet from overturning.
Several possibilities exist to make levitation viable.
It is possible to levitate superconductors and other diamagnetic materials, which magnetise in the opposite sense to a magnetic field in which they are placed.
A superconductor is perfectly diamagnetic which means it expels a magnetic field (Meissner-Ochsenfeld effect). Other diamagnetic materials are commonplace and can also be levitated in a magnetic field if it is strong enough.Diamagnetism is a very weak form of magnetism that is only exhibited in the presence of an external magnetic field.
The induced magnetic moment is very small and in a direction opposite to that of the applied field. When placed between the poles of a strong electromagnet, diamagnetic materials are attracted towards regions where the magnetic field is weak.
Diamagnetism can be used to levitate light pieces of pyrolytic graphite or bismuth above a moderately strong permanent magnet. As water is predominantly diamagnetic, this property has been used to levitate water droplets and even live animals, such as a grasshopper and a frog.
Superconductors are perfect diamagnets and when placed in an external magnetic field expel the field lines from their interiors (better than a diamagnet). The magnet is held at a fixed distance from the superconductor or vice versa. This is the principle in place behind EDS (electrodynamic suspension) maglev trains. The EDS system relies on superconducting magnets.
A maglev is a train, which is suspended in air above the track, and propelled forward using magnetism. Because of the lack of physical contact between the track and vehicle, the only friction is that between the carriages and air. So maglev trains can travel at very high speeds (650 km/h) with reasonable energy consumption and noise levels
3. INTRODUCTION:
Also known as maglev or magnetic suspension.
It is a method by which an object is suspended
with no support other than magnetic fields.
In the past, magnetic levitation was attempted
by using permanent magnets
Magnetic levitation is based on the principle of
magnetic pressure.
Magnetic levitation is used for maglev train,
maglev bearings and for product display
purposes.
4. FUNDAMENTALS :
Different pole of two magnet attract
with other.
Same pole of two magnet repel with
with other.
One arrangement is here where one
bar magnet is levitate.
Earnshaw’s theorem proved
conclusively that it is not possible to
levitate stably using only static,
macroscopic, paramagnetic fields.
6. WAYS TO MAGNETICALLY LEVITATE:
There are mainly two types of Maglev technologies used for
the levitation purpose:
Electromagnetic Suspension (EMS)
Electrodynamic Suspension (EDS)
7. MAGLEV TRAINS:
Electromagnetic Suspension
Electromagnets are attached to the train.
Has ferromagnetic stators on the track to
levitate the train.
Has guidance magnets on the sides.
A computer changes the amount of
current to keep the train 1 cm from the
track.
Has on-board battery power supply.
9. MAGLEV TRAINS(CONTINUED)
Electrodynamics Suspension
Super cooled superconductors under
the train levitate about 10 cm.
The force in the track is created by
induced magnetic field in wires or
conducting strips in the track.
Naturally stable.It Requires no
feedback.
Requires retractable wheels at low
speed.
11. MAGLEC TRAINS(CONTINUED)
Braking is accomplished by sending an
alternating current in the reverse direction
so that it is slowed by attractive and
repulsive forces.
Gap Sensor
The attractive force is controlled by a gap
sensor that measures the distance between
the rails and electromagnets.
12. MAGLEV TRAINS(CONTINUED)
Comparison with Ordinary Trains
Less polluting.
uses 30% less energy.
Require no engine.
Move faster.
Safer.
No fuel required.
Incompatible with existing rail lines.
Initial cost is very high ($20-$40 million per mile).
13. MAGLEV WIND TURBINES:
Operate on the repulsion characteristics of
permanent magnets.
The vertical axis wind turbine platform
floats on a magnetic cushion with the aid
of a permanent magnet suspension.
This technology eliminates nearly all
friction and delivers maximum wind
energy to the downstream linear
generator.
The efficiency of turbine is increased by
replacing the bearings by magnets as the
magnetic levitation helps the turbine to
spin at a much faster rate.
14. MAGLEV WIND TURBINE(COND.)
Advantages of Maglev Wind Turbines:
A massive tower structure is not required, as they are mounted
closer to the ground.
They are located closer to the ground and hence easier to
maintain.
Require no lubrication.
Capable of generating power from wind speeds as low as 1.5
m/s.
Produce 20% more energy than a conventional turbine in the
same time.
Decrease operational costs by 50%.
15. MAGLEV SPACE PROPULSION:
A Maglev launch system use magnetic fields to levitate and
accelerate a vehicle along a track at speeds up to 600 mph.
16. MAGLEV BEARING:
A magnetic bearing is a bearing
which supports a load using
magnetic levitation.
Magnetic bearings support
moving machinery without
physical contact, for example,
they can levitate a rotating shaft
and permit relative motion with
very low friction and no
mechanical wear.
17. CONCLUSION:
Magnetic levitation is an exciting technology with the potential
to change the world. Its applications are far ranging from
transportation to household fixtures and decorations. While the
technology is currently expensive to implement, its potential
merits continued research. In the future cost-effective and
practical applications of magnetic levitation will change the
dynamics of business and life.
