Magnetic Levitation: Advantages And Disadvantages

Magnetic levitation: advantages and disadvantages

Introduction

It is based on levitation through electromagnetism, which results in the possibility of traveling at great speeds overcoming those of high speed. The magnetic levitation train had its first great appearance in Germany (Transrapid). Proposed by Hermann Kemper in the 30s, it was an advance that not only implied more speed but also a environment more respectful of the environment, and while still being highly profitable. You can classify the Maglev trains depending on the technology they use to achieve this levitation.

Developing

Two main types:

EMS (electro-magnetic suspension)

The electromagnets of the train control the attraction to the normally magnetic conductive tracks (steel). For this type, the electromagnetic suspension, which is located under the road, is provided with electricity to generate an electromagnetic field of attraction between the electromagnet and the rayl leaving the suspended vehicle. 

The suspension distance is 8 to 10 mm. The last EMS trains are represented by German TR08 and Japan HSST100L. The TR08 levitation is achieved by the attractive power between the electromagnetic suspension installed in the vehicle and a long stator located on the road. The position is fixed by the attraction between the guide magnet and the side rails. The movement occurs with a linear engine with a long synchronous stator loaded.

Unlike the TR08, the HSST100L, is suspended and guided by the same electromagnet set and the traction is produced by a linear induction engine that is riding on the train first and then in it Rail.

 The magnetic field interacts with the induced current producing a vertical force that raises train cars at a height of 10 to 15 centimeters.

Use superconductor electromagnets or strong driver magnets, which create a magnetic field inducing current in nearby metal conductors, driving the train. EDS trains are suspended only when they reach a certain speed. When they are reaching this speed, the magnetic field in motion, aboard the train, will excite an induced current in the coils, acting as a suspension (using superconductors always at low temperature or using permanent magnets) located in the "road".

Experimental technologies

MDS (Magneto Dynamic Suspension)

Which uses magnetic attraction of magnets on a steel lane to raise the train and keep it in position there are various research on permanent superconductors and magnets, which can trigger in a future advance. Comparing EDS with an EMS train, the EDS system cannot be sustained when standing or with speed less than 150 km/h, however, the separation that is generated in this system is greater, so there is more control.

The main advantage of the EDS is that it is stable, if a slight increase in the separation distance occurs, the repulsive force is reduced so the vehicle returns to its correct position. In addition, attraction forces vary from the opposite form, but adjusting the train to its position when deviations occur, without the need for external control.

At low speeds, as we have explained before, the magnetic current is not able to withstand the weight of the train. For this reason the train must have wheels or some other support element that supports the train until reaching the determined speed and can be sustained by levitation. Taking into account that it may be necessary for the train to stop at any location, there must be a rayl that supports low and high speeds.

Another disadvantage of this technology is that it naturally produces a field on the road at the beginning and the end of the magnets that acts as a drag force. However, EMS technology requires us to constantly verify the separation, these small deviations and corrections can produce serious vibrations.

One more difference is the use of MLX Japanese train a low temperature superconductor to produce the magnetic field. For operational speed, the transrapid has a maximum speed of 400-500 km/h, the MLX 500-550 km/h, the HSST low speeds of 100 km/h allocating its use to urban environments. Throughout the history of this technology, different models have been used, the most used or with commercial success will be briefly described below by older to more modern:

For its propulsion, it uses a long stator synchronous linear engine, which works as a rotating electric motor alternating a magnetic field. The speed is regulated with the frequency of alternation of the current. The electrical power occurs with batteries inside the train that are recharged by generators installed in the support magnets, at low speed, not enough is transmitted by induction.

The structure is usually built as we see in the image below: 

• Currently after the more than 10 years of use, the question is whether it becomes more profitable and with better performance than the conventional train, with the different advances in batteries and a greater standardization of the pieces it is proposed to solve the following problems:
• Increase the load to respond to peak hours
• Decrease inner noise
• Increase the space space to improve the needs of an airport connection

Advantage

• Scarce maintenance, since there is hardly any contact between the tracks and the train.
• It is not affected by weather conditions.
• Higher speeds
• Loads are better distributed and lighter so you should not take into account the load concentration in the wheels.
• Control systems are automated and with a multitude of sensors that increase security and reduce the possible human failure.
• The Magleb train can climb pending with greater degrees.

Disadvantages

• The need to build all infrastructure and not be able to use the previous railway networks elevates the price. We can find high -speed trains that can circulate along lower speed or even different width.
• Keeping, as we have said before, it requires less, but electromagnets or superconductors require control since they can only work at a certain temperature.
• The need for large spinning radios hinders its implementation in cities.
• Extremely expensive, not being standardized and in the process of research many of these technologies cost yen trillions to develop infrastructure and train.
• At low speeds, it consumes more energy than a conventional train.

conclusion

For low speeds, the HSST has reached commercial success in both Korea and Japan, in China, the application of these lines in many of its cities is being created in China. The future focuses on the investigation of the suspension control to reduce the probability of failure and the reduction of costs will also be key by avoiding vibrations self-produced by the monitoring of the suspension space. 

Therefore, it can be a very interesting application for urban paths given its zero gase emissions, noise and speed. Although it should be noted that more research is necessary since LIM engines can only reach a 70% traction efficiency at 110 km/h reducing when the speed increases.

For high speeds, we are faced with great advantages, but we still can’t determine how it will work in the future since there is only the active Shanghai line. Settience, significant advances have been made since the implementation of this train, which increases efficiency to 90% traction efficiency (long stator synchronous traction). So it is reflected that much more research is needed that results in technological innovations that increase efficiency, as well as the lowering prices in infrastructure construction.

Bibliography

• Liu, Zhigang., Long, Zhiqiang., and Li, Xiaolong. Maglev Trains Key Underlying Technologies. 1st ed. 2015. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. Web.
• Han, Hyung-Suk., and Kim, Dong-Sung. Magnetic Levitation Maglev Technology and Applications . 1st ed. 2016. Dordrecht: Springer Netherlands, 2016. Web.
• Gonzalez-Gonzalez, Esther, Nogues-Linares, Soledad. Railways of the Future: Evolution and Prospects of High-Speed, Maglev and Hyperloop (1st part). Dyna, July 2017, Vol. 92, no. 4, p.371-373.
• Gonzalez-Gonzalez, Esther, Nogues-Linares, Soledad. Railways of the Future: Evolution and Prospects of High-Speed, Maglev and Hyperloop (2nd Part). Dyna, July 2017, Vol. 92, no. 4, p.371-373.
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• Maglev Technology Explained ’. North American Magleb Transport Institute. 1 January 2011. Archnedd from the original on 27 July 2011.
• Alan Kandel ‘Conventional High-Speed Rail vs. Magnetically Levitated Trains: was Magleb Ever in contention?’. 22 November 2011.