Magnetic Levitation Vehicle

Other Unique Engineering Ideas
Magnetic levitation, or “maglev,” is a technology used for high-speed trains in which the vehicle is lifted from the roadway or “guideway” by a magnetic field. Propulsion is by means of a moving magnetic field. The highest recorded speed of a maglev train is 581 km/h (361 mph), achieved in Japan in 2003, 6 km/h faster than the conventional TGV speed record.

1. Description

2. Why

3. How

4. Future Trends

5. Related Links

Description

Magnetic levitation (maglev) is a relatively new transportation technology in which noncontacting vehicles travel safely at speeds of 250 to 300 miles-per-hour or higher while suspended, guided, and propelled above a guideway by magnetic fields. The vehicle does not have an engine in the traditional sense. The metal coils are electrically induced to generate dynamical magnetic fields. Two different set of magnets work on the bottom and the side to keep stability and induce movement.This method has the potential to be faster and quieter than wheeled mass transit systems, potentially reaching velocities comparable to turboprop and jet aircraft (900 km/h, 600 mph).

Why 

Maglev systems could offer an attractive transportation alternative for many time sensitive trips of 100 to 600 miles in length, thereby reducing air and highway congestion, air pollution, and energy use, and releasing slots for more efficient long-haul service at crowded airports.Attributes of Maglev

  • Safe
    The vehicle is designed so that it ‘interlocks’ with the guideway, so there is no risk of derailment. The electromagnetic field level inside the vehicle is no more than that in conventional electric trains.

  • Reduced noise and vibration
    When the vehicle is running there is no physical contact between the carriages and the guideway which minimizes rolling noise and vibration.

  • Accelerates and decelerates quickly
    Acceleration and deceleration can be rapid and fairly steep grades can be climbed easily.

  • Low maintenance
    There are fewer moving and rolling parts so wear and tear is less, ensuring easy maintenance of vehicles and guideways.

  • Economical
    The HSST can operate on fairly steep gradients and tight curves, and there is no axle load on small spans of track, so guideway construction costs are quite low.

Other advantages of the maglev system are low power requirements, magnets that do not require supercooling, relatively simple guideway construction, and derailment-proof design.

How

A Magnetic Levitation System has three basic elements:

  • An electrical power source

  • Metal coils lining a track

  • Guidance magnets attached to the underside of the train

There are two forms of magnetic fields:

  • One is static (permanent magnets)

  • And the other dynamic.

In the case of MagLevs, the magnetic field is dynamic and as such generated by fast moving electric charges. Some systems use moving permanent magnets to generate the electric field, but the levitating field is dynamic in nature.Japan and Germany are developing different types of normal-conductive magnetically levitated linear motor trains. Japan is developing the High Speed Surface Transport (HSST) system, while Germany is developing the Transrapid system. The two systems are similar in the sense that they both use linear motors for propulsion, and electromagnets for levitation. However, the type of linear motor used is different.

  • It uses ordinary electromagnets that exert an attractive force and levitate the vehicle.

  • The electromagnets are attached to the car, but are positioned facing the underside of the guideway’s steel rails.

  • They provide an attractive force from below, levitating the car.

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

  • A control circuit continually regulates the current to the electromagnets, ensuring that the gap remains at a fixed distance of about 8 mm.

  • If the gap widens beyond 8 mm, the current to the electromagnets is increased to create more attraction.

  • Conversely, if the gap becomes less than 8 mm, the current is decreased.

  • This action is computer controlled at 4000 times per second to ensure stable levitation.

In 1979, the German Ministry of Research and Technology produced the Transrapid International TR05, the first magnetic levitation vehicle licensed to carry passengers. In 1988, the model TR06 (see Figure 1) set a speed record of 257 mph.

  • The Transrapid vehicle frame wraps around the guideway and the car is levitated by magnetic attraction to the underside of the guideway.

  • A closed-loop control system maintains a clearance of 3/8” from the guideway. The power for levitation is supplied by on-board batteries charged by linear generators.

  • Propulsion is by syncronous linear induction using active long-stator coils mounted on the guideway, and passive rotors on board.


The HSST is propelled by linear induction motors. The HSST primary coils are attached to the carriage body and the track configuration is simple, using steel rails and aluminium reaction plates. On the other hand, Transrapid trains are propelled by a linear synchronous motor. The motor primary coils are mounted on the guideway, and the levitation magnets are attached to the car and act as field magnets.

Future Trends

The first patent for a magnetically levitated vehicle was granted in 1968 to U.S. scientists Gordon Danby and James Powell . Funding for their project lasted only a few years, allowing Japan and Germany to take the lead in maglev development. U.S. interest was revived in the 1980s but funding was lost around 1992. Interest in maglev transportation is again on the rise in the U.S. as evidenced by a recent $1 billion appropriation bill.Commercially operating lines exist in Japan, such as the Linimo line. Maglev projects worldwide are being studied for feasibility. In Japan at the Yamanashi test track, current maglev train technology is mature, but costs and problems remain a barrier to development, alternative technologies are being developed to address those issues.

Keywords

Transrapid vehicle, Maglev, HSST, Magnetic Levitation, guideway

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