Mary Dillon

Researched Problem-Solution Proposal

Topic:

Nonfunctioning magnetic levitation (Maglev) train at Old Dominion University (ODU)

Thesis:

Superconducting magnets, created by cooling electromagnets to low temperatures, can reduce

power consumption and cost. A combination of superconducting magnets, and a fusion of

electromagnetic suspension (EMS) and electrodynamic suspension (EDS) technology can both

reduce cost and provide stability between magnetic forces.

Background:

The Mechanics of a Maglev Train

Magnetic levitation (Maglev) trains operate through the use of electromagnets, which are

magnets created by electric current. An electromagnet is defined as “a coil of insulated wire

wound around an iron or steel cylinder”, and functions “when current flows through the coil,

[producing] a magnetic field” (Gibilisco, 2001). These electromagnets are used to lift the train

above its track, as well as propel it forward. For propulsion, most Maglev trains use

electromagnets as an element in linear motors. A linear motor is essentially a regular motor,

whose components have been unraveled and shaped into a linear configuration so that it can then

be laid flat, such as for some modern magnetically-propelled rollercoasters, and Maglev trains. A

linear motor is officially defined as “a motor in which the stator and rotor are parallel and

straight” (Gibilisco, 2001). In a regular motor, “a central core of tightly wrapped magnetic

material (known as the rotor) spins at high speed between the fixed poles of a magnet (known as

the stator) when an electric current is applied” (Woodford, 1999). In a linear motor, the rotor

glides forward past the stator in a linear configuration instead of around in a rotational one.

Figure 1. A simple visual representation of a normal motor and a linear motor. (Photo from

Woodford, 1999).

Some Maglev trains use designs with a magnetized track, and others use designs with magnets

solely located on the train, but electromagnets and linear motors remain key elements for lift and

propulsion in either design.

Types of Maglev Trains

For example, Old Dominion’s train uses what resembles a rollercoaster track as part of its “smart

train - dumb track” design (Rau, 2006). This simply means that, unlike other Maglev trains

around the world that use a smart track - dumb train design, ODU’s track is made of non-

magnetized steel, while all of the magnets are instead located on the train. Having the more

intricate technology located on the train instead of the track greatly reduces cost, as it is

expensive to lay miles of track that are magnetized properly for Maglev train use. Many

commercial Maglev trains currently in operation use the smart track- dumb train design as it has

proven to create more stable magnetic forces than the alternative. However, this is only a

realistic and viable design for commercial Maglev trains, as the income from passengers and

governmental funding help pay for the expansive magnetized track.

There are two main types of Maglev trains, electromagnetic suspension trains (EMS) and

electrodynamic suspension trains (EDS). The most significant difference between the two is that

EMS trains only use one varying magnetic field to maintain stable levitation above the track,

whereas EDS trains use a magnetic field exerted by both the track and the train to create a strong

and unwavering balance of forces. Because EMS trains only have one magnetic field to keep

them properly levitated, and magnetic attraction varies significantly with distance, a small

change in distance between the train and the track can cause the train to crash. A crash would not

likely cause damage as Maglev trains do not levitate very far above their tracks, but proper

levitation would then need to be achieved again before the train could progress. EDS trains do

not experience this difficulty as, if the train becomes too close to the track, the magnetic field of

the track repels it back to its original position.

Figure 2. Comparison of EDS and EMS technology. (Image from Letts, 2012).

Although EMS trains are not as stable as EDS trains, they are less expensive, due to all of the

electromagnets being located on the train instead of the entirety of the track as mentioned, and

are able to reach higher speeds. Old Dominion’s train is an EMS train, much like the one

pictured in Figure 2. Metal arms connect the train to the track, and the magnets used for

propulsion and lift are located in the bottom of the arm, beneath the track.

Figure 3. Old Dominion University’s electromagnetic suspension train. Notice the metal arms

that house the magnets connecting the train and the track. (Image from Frank Batten College of

Engineering and Technology, 2006).

EDS trains are more stable, but when operating at slower speeds, occasionally do not have

enough magnetic force to support the weight of the train without the use of mechanical means.

Because the track’s magnetic field cannot always support the weight of the train, the train must

have wheels to support the train until it reaches a speed at which it can accomplish levitation.

The speed relative to the track is not a factor in levitation with EMS trains such as ODU’s train,

as EMS trains reach higher speeds much faster, and at any speed can effectively sustain

levitation if the right balance is found. EDS trains’ inability to levitate at slow speeds, and EMS

train’s instability both create issues of safety. Because a train may need to stop at any location on

the track due to technical failures or other urgent situations, the entire track must be able to

withstand a train travelling slowly or attempting to come to a stop by mechanical means.

Advantages of Maglev Trains:

For Old Dominion’s Maglev train in particular, the train could provide safe and fast transport

across the highly trafficked road, Hampton Boulevard, as well as through the rest of campus. The

train car is designed to hold approximately 100 passengers at a time, and, because there would be

multiple stops along the track, only reaches a top speed of about 45 miles per hour. This is still

an improvement over otherwise travelling on foot through campus (Frank Batten College of

Engineering and Technology, 2006).

Maglev trains have other advantages in general as well. Because no contact is made between the

train and the track, Maglev trains allow for near-frictionless travel. This near-frictionless travel

has numerous benefits including higher speeds, less noise, resistance to poor weather conditions,

and decreased maintenance. Maglev trains initially cost more than conventional means of

transportation during construction, but with conventional transport, friction between the wheels

and the track often causes damage over time, which requires both funds and labor to repair.

Maglev trains do not experience this physical stress, and thus, require only slight further funding

once they are built. Maglev trains are not entirely frictionless, however. They simply experience

no surface friction, which does help decrease maintenance and power consumption. Maglev

trains do, however, still experience air resistance and slight electromagnetic drag, but these

conditions are present in negligible amounts. The air resistance experienced does create sound,

but seeing as this is the singular source of sound, this makes Maglev trains quieter than

conventional transport as well. Minimal human interfacing is required beyond the construction of

the trains and programming of systems, as most systems used to control the train are computer

operated or otherwise automated. Furthermore, as most Maglev trains are elevated above the

ground, there is little danger of the train colliding with anything, such as other vehicles or

pedestrians, and the powerful electromagnets keep the train firmly on the track at all times.

Problem:

Old Dominion University’s Maglev train is currently not functional due to a variety of technical

shortcomings experienced during its construction and testing. Firstly, the amount of power

required to levitate the train off of the track is difficult to achieve and costly. During initial stages

of testing, the train was only able to maintain proper levitation above the track for a short

distance. It is often the case that problems arise with Maglev trains with the “cost [and] difficulty

of developing suitable electromagnets. Enormously powerful electromagnets are required to

levitate and move a train, [and] consume substantial amounts of power” (Woodford, 1999).

Secondly, power is also consumed when the train is attempting to “overcome air resistance, as

with any other high-speed form of transport” (Prasad, 2014). Lastly, it is also difficult to

maintain the proper distance from the track because Old Dominion’s train is an EMS train,

making it more unstable and harder to balance than EDS trains.

Solution:

Superconducting Magnets

To reduce the amount of power consumed and associated cost, the electromagnets used for lift

and propulsion of the train can be replaced with electromagnets cooled to low temperatures,

making them superconducting magnets. “[…] If electromagnets are cooled to low temperatures,

electrical resistance disappears almost entirely, which reduces power consumption considerably”

(Woodford, 1999).

A superconducting magnet is an electromagnet that is cooled to as close to absolute zero, or 0

Kelvin, as possible using “liquid helium or nitrogen” (Woodford, 1999). The electromagnet is

contained in an apparatus known as a cryostat, which is simply “a chamber for maintaining a

very low temperature for cryogenic operations” (Gibilisco, 2001). For structural integrity, safety,

and conservation of materials the cryostat is usually constructed with an outer shell that holds

liquid nitrogen, and the electromagnet itself is in an exterior structure composed of copper.

Copper is excellent for conductivity and therefore can also be used to provide a path of low

resistance. Optimally, the power supply for a superconducting magnet should be high current and

low voltage, as magnets are very inductive, and changes in current can cause spikes in voltages.

Spikes in voltage provoke safety concerns, both for the system and for potential passengers. Old

Dominion’s train has precautionary measures in place to alter current gradually including “a

computer with new programming [. ] and additional sensors” to control these processes (Frank

Batten College of Engineering and Technology, 2006).

Because electrical resistance is decreased with the use of superconducting magnets, the

installation of such an electromagnet could reduce Old Dominion’s Maglev expenditures.

Figure 4. A Superconducting Magnet. Notice areas designated for liquid helium and nitrogen, as

well as the outer casing –the cryostat. (Image from BRUKER Biospin, 2006).

Combining EMS and EDS technology (Bogie)

As mentioned, Old Dominion’s Maglev train is an EMS train, meaning that it is capable of

higher speeds, but is inherently less stable than an EDS train. If elements of EMS and EDS

technology are combined, this could create greater stability between the magnetic forces

levitating the train. Old Dominion has already released plans including a cart called a “bogie”,

which runs along the undercarriage of the train providing a counterbalance to the downward

magnetic force much like EDS technology, but works in tandem with the existing EMS

technology. In essence, instead of magnetizing the entire track, the bogie would achieve the same

amount of stability between magnetic fields, but using only enough resources to span the

undercarriage of the train. However, Old Dominion’s current design includes an array of

permanent magnets rather than superconducting magnets. “The permanent magnets on the

vehicle are organized into pods [and] the pods are combined into a bogie that will be used”

(Thornton, 2008). For the most part, the proposed bogie design would be effective in suspending

the train, propelling it forward, and “control[ling] the magnetic gap” that has presented itself as

an issue, but the addition of superconducting magnets would merge well with the design and

keep the cost of operating the train down (Thornton, 2008).

Figure 4. Head-on view of EMS/EDS Bogie designed to fit under the train and stabilize magnetic

forces. Grey post at bottom represents one of the posts supporting ODU’s elevated track, and

the green line represents the track. (Photo from Thornton, 2008).

Conclusion:

The problem of Old Dominion University’s Maglev train’s power consumption, due to levitation

and overcoming air resistance, can be solved with the use of superconducting magnets. These

cryogenically cooled magnets “[…] support a very high current density with a vanishingly small

resistance. This characteristic permits magnets to be constructed that generate intense magnetic

fields with little or no electrical power input”, thus reducing operational cost as well (American

Magnetics, 2012). Furthermore, the superconducting magnets could be placed on the bogie

underneath the train, effectively combining electromagnetic suspension and electrodynamic

suspension technology to overcome stability issues between the magnetic forces encountered

when testing and operating the train.

References:

Bonsor, Kevin. How Maglev Trains Work. (2000). Retrieved from

http://science.howstuffworks.com/transport/engines-equipment/maglev-train.htm

Characteristics of Superconducting Magnets. American Magnetics. (2012). Retrieved

from http://www.americanmagnetics.com/charactr.php

Gibilisco, Stan. The Illustrated Dictionary of Electronics. (2001).

Letts, A. Sustainability Through Technology Part 1 - Magnetic Levitation. (2012).

Retrieved from

http://www.personal.psu.edu/cjm5/blogs/west_of_everything_with_english_003_fall_201

2/2012/12/it-is-not-certain-that.html

MAGLEV Approach Shows Promise. Frank Batten College of Engineering and

Technology. Old Dominion University. (2006). Retrieved from

http://eng.odu.edu/interaction/archive/20061030/

Prasad, Shesha V. The Magnetic Train. Science Association. (2014). Retrieved from

http://www.samalnad.com/index.php/forum/scientific-inventions/5-the-magnetic-train

Rau, Michael E. ODU's Rail Project Is Truly Magnetic. (2006). Retrieved from

http://articles.dailypress.com/2006-11-13/business/0611130169_1_maglev-project-

american-maglev-technology-maglev-train

The Magnet and Magnet Dewar. BRUKER Biospin. (2006). Retrieved from

http://triton.iqfr.csic.es/guide/man/beginners/chap4-6.htm

Thornton, R., Clark, T., Perreault, B., Wieler, J., Levine, S. (2008). Retrieved from

http://www.magnemotion.com/userfiles/files/Maglev/pdf/M3Maglev08.pdf

Woodford, Chris. (1999). Linear Motors. Retrieved from

http://www.explainthatstuff.com/linearmotor.html