magnetic levitation in trains

of 22/22

Post on 23-Dec-2015




1 download

Embed Size (px)


ppt for mech


Slide 1





INTRODUCTIONMaglev is the system of transportation that uses magnetic levitation to suspend ,guide and propel the vehicles using magnets.

First described by Robert Goddard, American Rocket Scientist, 1909 Scientific American.

Later in 1937 & 1941 a series of German patents for maglev trains propelled by linear motors awarded to Hermann Kemper .

In the 1960s in Britain Eric Laithwaite developed a functional maglev train.

TECHNOLOGYUses monorail track with linear motor

Uses magnets to reach a really high velocity

Floats about 1-10cm above the guideway on a magnetic field.

Propelled by the guideway

Once the train is pulled into the next section the magnetism switches so that the train is pulled on again.

The Electro-magnets run the length of the guideway.

There are 2 notable types of maglev technology:-

Electromagnetic suspension(EMS)

Electrodynamic suspension(EDS)


ELECTROMAGNETIC SUSPENSIONElectromagnets attached to the train

Has ferromagnetic stators on the track and 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.

Max speed -438km/hr

Has on-board battery power supply.


Supercooled superconducting magnets under the train.Levitate about 10 cm.

The field in the train due to superconducting magnets(JR-Maglev) or an array of permanent magnets(Inductrack).

The force in the track is created by induced magnetic field in wires or conducting strips in the track.

Naturally stable.requires no feedback.

Requires retractable wheels at low speed , max speed 522km/hr

MERITS & DEMERITS OF DIFFERENT TECHNOLOGIESTECHNOLOGYMERITSDEMERITSEMSMagnetic fields inside & outside the vehicle are less than EDS.No wheels or secondary propulsion requiredCan attain very high speed.(500km/hr).Constant monitoring correction of separation between vehicle & guideway using computer systems essential.Due to inherent instability and corrections ,vibration issues may occur.EDSOnboard magnets and large separation enable highest recorded speeds(581km/hr) and heavy load capacity.Naturally stable and hence no feedback control required.Strong magnetic field makes the train inaccessible to passengers with pacemakers or storage media like hard drives and credit cards.Vehicle must be wheeled for low speed travel.



MAGNET EDS)Failsafe suspension-No power required to activate magnets.Can generate enough force at low speeds to levitate the train.The train can slow down on its own in case of power failures.The array of permanent magnets are cost effective than electromagnets.Requires wheels when the vehicle is stoppedNew technology , still under development , no commercial version or full scale system prototype

PROPULSION EMS(Linimo) systems provide levitation & propulsion using onboard linear motor.

EDS system and Transrapid systems levitate using onboard magnets & use propulsion coils for propulsion .

Cost of propulsion coils increase over long distances.

LEVITATIONIn EDS , levitation coils levitate the train 10cm above the track. Levitates when speed reaches 100km/hr

In EMS , stator & support magnet levitate the train 1cm above the track. Levitates even when train is not moving.

STABILITYEMS system rely on active electronic stabilisation..

All EDS systems are moving systems.

Since these vehicles fly,stabilisation of pitch , roll and sway is required

In addition to rotation , surge , sway and or heave can be problematic.

GUIDANCESome systems use Null Current system

In EDS when the vehicle is in straight line , no current flows ,

When it moves off the line this creates changing flux ,generating a field that pushes and pulls it back to the line.

Some systems use coils that try to remain in the null flux point between repulsive magnets and reduces eddy current losses.

POWER AND ENERGY USAGEEnergy for maglev trains used to accelerate the train.

Also used to make the train levitate and to stabilise the movement.

Main part of the energy used to overcome the air drag.

For very short distances the energy for accelerating is considerable.

But the power used to overcome the air drag increases with cube of velocity and hence dominates at high speed.

COMPARISON WITH CONVENTIONAL TRAINS FEATUREMAGLEV TRAINCONVENTIONAL TRAINSpeedAllow higher top speeds since they dont rely on wheels for propulsion.Speed is limited by the use of wheels for propulsion.

MaintenanceRequire insignificant guideway maintenance.Their electronic vehicle maintenance is minimal Hence more reliableRail is subjected to wear & tear due to friction ,increases exponentially with speed.This increases running cost.All weather operationUnaffected by snow , severe cold , rain or high winds.Can accelerate & decelate regardless of slickness of guidewayMay encounter problems due to degradation of guideway caused by weather conditions.EfficiencyNo rolling resistance due to lack of contact between track & vehicle.This improves power efficiency.Efficiency is affected by rolling resistance due to the contact with the track.

WeightWeight of magnets in many EMS and EDS is a serious issue.Does not use magnetsNoiseMajor source of noise is displaced air.But they are found to more annoying at lower loudnessThough they produce more loudness , they are less annoying than maglev noise , hence have a 5-10 dB bonusDesign ComparisonsMaglev design eliminates the need for braking and overhead wiresDesign includes braking and overhead wires causing wearControl systemsRequires no signalling systems since the speed is computer controlHas a human operator to slow down or stop the train in time.

COMPARISON WITH AIRCRAFTMany maglevs have lift-to-drag ratio that exceed that of aircraft.

But jet transport aircraft take advantage of low air density at high altitudes to reduce drag during cruise.

Airlines cannot come close to the reliability or performance of maglev trains in all weather conditions.

Maglev fares are less susceptible to the volatile price swings in oil markets.

Has significant safety margin as they are designed not to crash into other.

ECONOMICSThe initial investment is similar to other high speed rail roads. (Maglift is $20-$40 million per mile and I-279 in Pittsburg cost $37 million per mile 17 years ago.)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.


120 m test track of General Atomics at San Diego , USA.

Tranrapid , a German maglev company has test track at Emsland , Germany of length 31.5km.

JR-Maglev , Japan has a test track that can reach a speed of 581km/hr.

SUMMARYThey consume less energy.

Require no engine.

Move faster than normal trains because they are not affected by ground friction; their rights-of-way, meanwhile, cost about the same to build.

Incompatible with existing rail lines, unlike traditional high-speed rail.

Initial cost is very high.