How do Maglev Trains Work?

In the world, there are currently six commercial maglev trains in operation - three in China, two in South Korea, and one in Japan. These trains are known to be faster than their traditional counterparts. Compare the speeds of the two types of trains: A maglev train can go up about 500 kilometres (or 300 miles) per hour, whereas a conventional commuter train typically travels at half of that speed. 

This then begs the question: how can these trains go so fast? How do maglev trains work such that they can travel at a much faster speed than normal trains on wheels?

What is a maglev?

Firstly, what even is a ‘maglev’? Maglev, which is short for magnetic levitation, refers to the technology that uses magnetic forces to suspend, guide, and propel objects. Hence, a maglev train refers to a train that is levitated using magnets and relies on magnets - which are found on the train or the train tracks - to propel the train forward. 

How do maglevs work?

There is a fundamental principle that maglevs rely on - that is, the interaction between the poles of magnets. When unlike poles (one magnet has a North pole, the other magnet has a South pole) face each other, the magnets will attract each other. Conversely, when like poles (both magnets have either North pole or South pole) face each other, the magnets will repel each other. 

There are two types of maglev systems in operation, namely the Electromagnetic suspension (EMS) and the Electrodynamic suspension (EDS). 

• Electromagnetic Suspension (EMS)

When a train uses the EMS system, the train has electromagnets attached to the underside of the train below the track and at the side of the train beside the track (see the image's red rectangles), and the tracks are made with a ferromagnetic material, which can form an electromagnet as the track is connected to a large power source that supplies the electromagnets. 

The magnets found at the bottom of the train below the track (also known as levitation electromagnets) and the ferromagnetic material of the tracks will get attracted to each other. This upward attractive force will overcome the downward gravitational force acting on the train, causing the train to levitate about 10mm (or 1cm) above the track. When the electromagnets in the train create an alternating current, there will be attractive and repelling forces occurring between the sides of the train and the tracks, propelling the train forward. The side magnets are hence also known as guidance electromagnets. 

• Electrodynamic Suspension (EDS)

When a train uses the EDS system, there are magnets found on the side of the train, and two sets of magnets in the tracks: the inner layer has figure 8-shaped coils (see above image (a) for reference), and there are a second set of magnets in the tracks that allow the train to be propelled forwards. 

The magnets found on the train are superconducting magnets. These magnets, when below a certain temperature, will have zero electrical resistance and provide a powerful magnetic force. Hence the train will have to be constantly cooled using methods such as liquid helium for these magnets to work to their optimal capabilities. As seen from the image, the lower part of the figure 8-shaped coils found on the track has the same polarity as the magnets on the train, whereas the top part has the opposite polarity. This causes a mix of attractive and repelling forces, allowing the train to levitate to about 4 inches (or about 10cm) above the track. 

The second set of magnets in the tracks will alternate between the two polarities to propel the train and move forward. This allows the speed of the train to be controlled by the frequency of the switch between the two magnetic poles. However, this means that the train can be slow to lift off as it does not levitate constantly unlike the train using EMS. As such, while the train is moving at a slow speed, the train will have wheels deployed for the train to move forward. Once the train has reached a certain speed, only then will the wheels be retracted, and the train will levitate and move at the fast speed it is known for. 

Summary

In conclusion, maglev trains work on the principle of magnets. By using the property of magnets where unlike poles attract and like poles repel, maglev trains are able to levitate above the tracks they are on to move forward and travel at great speeds. Maglev trains would hence be able to reduce the friction between the train and tracks while the train is operating, allowing them to have a lower maintenance cost due to a slower rate of wear and tear. Unfortunately, maglev trains have an extremely high construction cost (monetary or otherwise) to build, discouraging countries from building such trains. Hopefully, as technology advances, this cost may be lowered and more countries will be able to access the efficiency that maglev trains can bring, thus improving their transportation systems greatly. 

Works Cited 

Australian National University. (n.d.). MAGLEV TRAINS. Available at: https://physics.anu.edu.au/engage/outreach/_files/MAGLEV.pdf [Accessed 29 Dec. 2023]

Boslaugh, S.E. (2016). Maglev train | transportation. In: Encyclopædia Britannica. [online] Available at: https://www.britannica.com/technology/maglev-train. [Accessed 29 Dec. 2023]

Electricity - Magnetism. (2023). What is magnetic levitation and how does it work? [online] Available at: https://www.electricity-magnetism.org/what-is-magnetic-levitation-and-how-does-it-work/  [Accessed 29 Dec. 2023].

Electromagnets in Daily Life. (n.d.). Maglev Trains. [online] Available at: http://electromagnets.weebly.com/maglev-trains.html [Accessed 29 Dec. 2023].

Interesting Engineering (2023). Unbelievable Technology: See the Magic Behind Maglev Trains. [online] www.youtube.com. Available at: https://youtu.be/8os4A4li674?si=OvY_e74psp9NQ9JC [Accessed 29 Dec. 2023].