¶ … Magnetic Levitation Propulsion Systems in North America and Around the World How Magnetic Levitation Propulsion System Works?

Development of the Maglev Technology

Design Differences in the German and Japanese Maglev Technology

Advantages of Maglev

Disadvantages

Cost Factor

Other Applications and spin-offs

Potential Projects in the U.S.A.

Magnetic Levitation Propulsion Systems

With air travel and the highways becoming increasingly congested, the need for an efficient, fast and comfortable mode of alternative travel has been felt in many countries of the world. One of the possible solutions is the Magnetic Levitation Propulsion System or high-speed trains called the Maglev train (short for magnetic levitation). The recent question mark over the safety of air travel and the fear of flying created among the general public by the events of 9/11 has renewed interest in the Maglev technology. In this paper we will discuss how the Magnetic Levitation Propulsion System works and briefly overview its history of development. The different types of designs developed so far, the cost of developing such systems, and the potential for its expansion and use in transportation systems in the United States and all over the world will also be discussed.

How Magnetic Levitation Propulsion System Works?

We all know that the opposite poles of a magnet attract while the like poles repel each other. This is the basic principle on which the Magnetic Levitation Propulsion System works. In magnetic propulsion systems, powerful electromagnets are used. The three basic components of a maglev train system are: A large electrical power source, metal coils that line the track or guide-way, and large magnets attached to the underside of the train. There is no conventional engine in maglev trains. Instead, the force for propulsion is achieved by a combination of the magnetic fields created by the electrified coils in the tracks (called the guideways) and the guideway walls.

When the magnetic coils lining the track or guideway repel the magnets attached to the underside of the train's carriageway, it makes the train levitate 1 to 10 cm above the track (the guideway). While the train is levitated, power is supplied to the coils in the guide-way walls that creates a system of magnetic field, providing a combination of 'pull' and 'push' forces to propel the train forward. Alternating current is supplied to the coils in the guideway walls that constantly changes the polarity of the magnetized walls. This causes the magnetic field in front of the train to exert a 'pulling' force on the train while the magnetic field at the back of the train 'pushes' the train forward adding more momentum to the forward thrust.

Development of the Maglev Technology

The concept of magnetically levitated trains is not new; it was first identified at the turn of the century by two Americans, Robert Goddard and Emile Bachelet. In the 1930s a German engineer (Hermann Kemper) further developed the concept. A patent was granted to Americans James R. Powell and Gordon T. Danby in 1968 for their design of such a train. After some years of serious research initially, interest and research in high speed Maglev technology was virtually halted in the U.S. In 1975 after the withdrawal of federal funding. However, in the past few decades, most effective research and development in Maglev technology has been carried out overseas -- notably in Germany and Japan. R & D. In Maglev technology started in earnest in Germany and Japan in the 1970s. In Japan the Railway Technical Research Institute (RTRI) has built and tested prototype Maglev trains on test tracks and attained speeds of over 400 km / hr. It is also engaged in the development of several key components of the Maglev train, e.g., the enhancement and reliability of the superconducting electromagnets (SCM) and special aerodynamic breaks.

The development and research in Germany has been equally promising and the development of the Transrapid system has recently attracted the attention of the Chinese who have chosen to install the system in its Shanghai City. This 20-mile link will connect the new Shanghai airport with its downtown business district that is due for completion in 2004. The Chinese have much more ambitious plans for the Maglev train as they propose to connect Shanghai with Beijing with an 800-mile connection if the Shanghai airport project is a success.

Design Differences in the German and Japanese Maglev Technology

As noted earlier, most of the effective and state-of-the-art research in the Maglev technology has been conducted by the Japanese and the Germans....

Let us look at some of the basic differences in the design developed by them so far. The German design that has been adopted by the Transrapid system (chosen by the Chinese for the Shanghai airport -- downtown connection) uses magnetic attraction to levitate and propel the train. The train's wheel-free undercarriage wraps around a T-shaped guide edged with thin metal "guidance rails." The train is kept to within three-eighths of an inch of its guide rail and approximately six inches above the guideway through a combination of computers, sensor controls and guidance magnets on the undercarriage. In the German design, the underside of the guideway is also fitted with windings that generate their own magnetic fields when electrified and attract the support magnets. In this design, the energizing of the whole route is not necessary as the track windings are switched on and off section-wise as the train passes.
The Japanese, on the other hand, are working on a system that uses repulsion instead of attraction of magnets. The other difference in the German and Japanese design is the use of superconductors as magnets by the Japanese. Superconductors are materials that, when cooled sufficiently, offer no resistance to electric current. The practical implication of this characteristic of a superconductor is that once such a magnet is energized, it retains its magnetization even when its electrical source is removed -- provided the required low temperature is maintained. Research in developing and discovery of better superconducting materials is going on. The goal is to develop materials that become superconductors at higher temperatures than is possible at present -- this will improve the economics of the Japanese design.

Another difference is that in the Japanese design, the train does not levitate until it reaches a speed of 40-km / hr (25 miles / hr). This necessitates the use of retractable wheels that are used at the beginning and end of the train run. The Japanese designers have also provided a wider gap between the train and guideway to cater for some deformation of the track during an earthquake activity.

Both the systems are similar as far as the generation of electricity for the internal functions of the train are concerned (heating, lighting etc.). This electricity is generated by the interaction between the conductors installed on the train and the magnetic fields generated as the train moves along the guideway.

While the Japanese design is more sophisticated and in test-runs they have achieved higher speeds, the German design is more developed and is ready for deployment (as is being done by the Transrapid for the Chinese). The Japanese design is expected to be fully ready in a few more years.

Advantages of Maglev

Faster Trips

For medium distances of up to 500 kms, the Maglev train technology would result in faster door-to-door trips. While most highways have speed limits and traffic congestion especially before entering and after exiting the highway, airports entail lengthy access and boarding times, and conventional trains are just too slow -- Maglevs are capable of high speeds (300 mph +) and have rapid acceleration and braking abilities.

Reliability

Maglev trains would be less susceptible to weather conditions -- the bane of air travel and even road and highway travel. Less than one-minute delays in schedules are possible, keeping in view the record of existing high speed trains in several countries.

Less Polluting

Being electrically powered Maglev trains would be less polluting than vehicles running on fossil-fuels since it is easier to mitigate pollution at the source of electricity generation, i.e., large electric power stations. It would also lessen dependence on imported fuel in countries which are deficient in fossil fuels but can generate electricity from indigenous sources.

Higher Capacity

Maglev trains would have the capability of higher capacities as compared to airlines and it has been estimated that they would be capable of transporting 12,000 passengers every hour in either direction. The potential capacity of Maglev trains is likely to cater for the required passenger traffic of the 21st century -- this cannot be catered for by the air and road infrastructure without dramatic expansion.

Comfort and Safety

Maglevs would provide greater comfort than air-travel due to roominess, and a smoother ride due to absence of air turbulence and frictionless motion due. The lack of physical contact between the train carriageway and the track results in substantial reduction in the noise level as well. Trains generally have high safety record and this is likely to apply to Maglev trains too.

Disadvantages

Despite its many advantages, the Maglev technology has its share of disadvantages too.

Incompatibility

Probably the biggest disadvantage of the Maglev technology is its complete incompatibility with the existing system -- train tracks for conventional trains…