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  • Roopal Mundepi

Magnetic Levitation (Maglev) - State of the Art

Maglev technology lifts, centers, and propels trains along a guideway using strong magnets. Strong magnets can produce magnetic fields up to ten times stronger than regular electromagnets, enough to suspend and push a train. Usually, the train's carriages are equipped with a superconducting magnet. The magnets are embedded into the railway and are constructed of a titanium alloy that has been cooled to minus 452 degrees Fahrenheit. They interact with some other magnets in the walls of the U-shaped concrete guideway. When matching poles face each other, these magnets resist each other in the same way as regular magnets do.

What is Magnetic Levitation?

Magnetic levitation or Maglev or magnetic suspension is a way of suspending an item using just magnetic fields as support. The magnetic force is utilized to counteract the gravitational and other forces' effects. The phrase magnetic levitation has come to be used in a range of applications ranging from suspending a small laboratory-scale stationary object so that it is isolated from vibrations in its surroundings to large-scale mobility applications such as maglev vehicles capable of hauling people and commodities at speeds of several hundred miles per hour or the planned assistance in spacecraft launch.


Maglev trains, contactless melting, magnetic bearings, and product display all employ magnetic levitation.


History of Maglev

As a doctoral student in physics in 1909, Robert H. Goddard, the legendary American rocket scientist who NASA would later recognize for inventing the liquid-fuelled rocket, was the first to propose the concept of a magnetically levitated train. In the late 1940s, Eric Laithwaite, a British electrical engineer at Imperial College London, created the first full-size working model of linear motor induction. In the 1960s, this notion and its possibilities were improved. The first patent explaining the physics of a maglev train was granted in 1967 to two American physicists working at Brookhaven National Laboratory, Dr. Gordon T. Danby and Dr. James R. Powell. Dr. Powell had the concept for a maglev train when stuck in a traffic jam on the Throgs Neck Bridge on his way to Boston in 1960. Dr. Powell mentioned the notion to his Brookhaven colleague Dr. Danby. Dr. Danby and Dr. Powell were already strong supporters of magnetic force, having previously employed magnets to create the world's most powerful particle accelerator, the Alternating Gradient Synchrotron. Dr. Danby and Dr. Powell were already big fans of magnetic force. Their plan called for superconducting electromagnets to provide "a suspension force, for floating the train above the ground," with thrust provided by a "propeller, jet, [or] rocket." For their efforts, they were awarded the Benjamin Franklin Medal in Engineering in 2000.


The first commercially operating high-speed superconducting Maglev train began service in Shanghai in 2004, with others in Japan and South Korea following suit. A variety of routes are being investigated in the United States to connect cities such as Baltimore and Washington, D.C.


Working Principle of Maglev Technology

What if it was possible to go from New York to Los Angeles in less than seven hours without boarding a plane? On a Maglev train, that could be achievable.


Maglev technology lifts, centers, and propels trains along a guideway using strong magnets. Strong magnets can produce magnetic fields up to ten times stronger than regular electromagnets, enough to suspend and push a train. Usually, the train's carriages are equipped with a superconducting magnet. The magnets are embedded into the railway and are constructed of a titanium alloy that has been cooled to minus 452 degrees Fahrenheit. They interact with some other magnets in the walls of the U-shaped concrete guideway. When matching poles face each other, these magnets resist each other in the same way as regular magnets do.


These magnetic fields interact with basic metallic loops embedded in the Maglev guideway's concrete walls. The loops are built of conductive materials such as aluminium, and when a magnetic field passes through them, an electric current is generated, which further produces another magnetic field. Inside the guide way, there are a number of horizontal and vertical loops/coils fixed on the walls. Normal conductors make up these coils.


Three types of loops/coils are placed at particular intervals in the guideway to accomplish three critical tasks: First, horizontal coils, which provide a vertical magnetic field. The vertical magnetic flux is ejected by the superconducting magnet S due to the Meissner effect. The horizontal coils are referred to as levitating coils because they levitate the train and keep it aloft on the guiding path, approximately 5 inches above the guideway; the second maintains the train steady horizontally. Magnetic repulsion is used in both loops to keep the train car in the correct position; the farther it travels from the center of the guide way or the closer it comes toward the bottom, the more magnetic resistance pulls it back on track.


The third loop’s set is an alternating current propulsion system because of the vertical coil that produces a horizontal magnetic field that propels the train forward. As a result, the vertical coils are referred to as propelling coils. Magnetic attraction and repulsion are employed to propel the railway car down the guideway in this case. Consider a box containing four magnets, one on each corner. Magnets with north poles facing out are used in the front corners, whereas magnets with south poles facing out are used in the back corners. Electrifying the propulsion loops creates magnetic fields that both pull and push the train ahead from the front.

The train has retractable wheels, similar to those seen on aeroplanes. The train's wheels are pulled into the body, and it floats forward on the air cushion once it has been levitated in the air. The power to the levitating and pushing coils is turned off when the train is to be stopped. The train slowly lowers onto the guide way and travels a little distance before coming to a complete stop.


The benefit of levitation is that it reduces energy waste during friction, allowing the train to reach a top speed of 581 km/h. Also, despite this speed, this floating magnet design ensures a smooth journey, and passengers experience less turbulence than on regular steel wheel trains because the only source of friction is air.


Another significant advantage is safety. The powered guideway "drives" Maglev trains. Because they are all propelled to go at the same pace, and any two trains on the same path cannot catch up and collide with one another. Similarly, typical train derailments caused by too-rapid cornering are not possible with Maglev. The greater the magnetic force forcing a Maglev train back into place grows as it moves away from its regular location between the guideway walls.


Applications of Maglev

Jonathan Swift depicted the maglev island of Laputa in Gulliver's Travels (1726), which was capable of attaining levitation heights of many kilometres. Magnetic levitation reached new heights in the comic books of Dick Tracy and Spiderman.


Magnetic levitation was used to support aeroplane models in wind tunnels, which was one of the first important uses. Researchers discovered that mechanical support structures can occasionally interfere with airflow sufficiently to cause greater drag than the model's drag force. Magnetic levitation (also known as a "magnetic suspension and balancing system") was invented in the 1950s by Gene Covert and his MIT colleagues.


Magnetic levitation, the utilization of upward magnetic forces to counteract gravity's widespread downward effect, has already found several other essential applications in science and technology.

Maglev now aids with the circulation of blood in human lungs, makes integrated circuits with multimillion-dollar photolithography devices, monitors precise dimensions with subatomic resolution, and so on. Magnetic levitation has been used for a variety of applications, including maglev trains, contactless melting, magnetic bearings, and product display. Furthermore, magnetic levitation has lately been tackled in the field of microrobotics.
  • Maglev for Transportation

Maglev, also known as magnetic levitation, is a transportation system that suspends, steers, and propels vehicles, primarily trains, by employing magnetic levitation from a large number of magnets for lift and propulsion. This mode of transportation has the potential to be quicker, quieter, and smoother than wheeled public transit systems. If used in an evacuated tunnel, the innovation has the capacity to reach speeds of over 6,400 km/h (4,000 mi/h). When not operated in an evacuated tube, the power required for levitation is typically not a big fraction of the total power required, with the majority of the power utilized to combat air drag, like any other high-speed train. The fastest maglev train speed ever recorded is 603 kilometres per hour (374.69 mph), accomplished in Japan on April 21, 2015; this is 28.2 kilometres per hour faster than the traditional TGV speed record.


In Qingdao, Shandong Province, China has recently launched a high-speed maglev train capable of reaching speeds of up to 600km/h. The train is believed to be the quickest maglev transit system to roll off the assembly line in the world. The maglev train will travel from South China's Shenzhen to Shanghai in around 2.5 hours, as opposed to the present ten-hour high-speed rail journey.

  • Maglev in Magnetic Bearings

A magnetic bearing uses magnetic levitation to sustain a load. Magnetic bearings allow moving elements to be supported without direct touch. They can, for example, levitate a spinning shaft and allow relative motion with extremely little friction and no mechanical wear. Magnetic bearings have the greatest speeds of any bearing type and no maximum relative speed. Magnetic bearings are utilized in a variety of industrial applications, including power production, petroleum refining, machine tool operation, and natural gas management.

  • Maglev for Rocket Launch

At NASA's Marshall Space Flight Center in Huntsville, Alabama, a magnetic levitation track is now operational. The experimental track is housed within the Marshall Center's high-bay facility. Marshall's Advanced Space Transportation Program is working on magnetic levitation, or Maglev, technologies that might provide a "running start" for a space launch vehicle to break away from Earth's gravity. A Maglev launch system would employ magnetic fields to lift and propel a vehicle at speeds of up to 600 mph down a track. The spacecraft would then switch to rocket engines for the ascent into orbit. Because maglev systems are fueled by electricity, and affordable energy source that stays on the ground—unlike rocket fuel, which adds weight and expense to a launch vehicle—they might drastically lower the cost of travelling to space.

  • Maglev in Microrobotics

Magnetic levitation techniques have been researched in the realm of microrobotics. It has been proved, in particular, that such a method can regulate several microscale-sized agents inside a given workspace. [20] Several research investigations reveal the successful use of various bespoke configurations to achieve the necessary control of microrobots. A bespoke clinical scale system comprising both permanent and electromagnets were employed in Philips facilities in Hamburg to conduct magnetic levitation and 3D motion of a single magnetic item. Another study group used a greater number of electromagnets, resulting in more magnetic degrees of freedom, to accomplish 3D independent control of several objects by magnetic levitation.

  • Maglev in Helathcare

Maglev has further uses, including the possibility for use in healthcare. A team of medical experts from the University of Texas and Rice University employed magnetic levitation to create three-dimensional tumour models in 2010. Researchers injected cancer cells with magnetic iron oxide and gold nanoparticles, placed the cells in a Petri dish, and then placed a coin-sized magnet on top of the dish. The cells were raised by the magnet, and when they expanded in suspension in the liquid, they looked like tumour cells. Researchers constructed cell models in the hope that they could one day lead to improved cancer therapies.


Advantages of Maglev:

Better than self-driving trucks and cars, which will merely add to the already-congested streets and roads. This Maglev system, with all of its cars on centrally-controlled guideways and running at faster speeds, will allow for a larger vehicle density without risk. Other, more traditional cars would continue to function on traditional streets and highways, which should be significantly less congested than previously.


Very-Huge Objects: There was a very large scientific device (perhaps a particle detector for CERN) that was incredibly difficult to convey overland. Such a massive item could be transported if two parallel Maglev elevated guideways were built. The speed would be sluggish, significantly less than the 300 mph that Maglev is capable of, but it would still be much faster than anything else. Once this extraordinary cargo has been received, the twin Maglev monorails can either become part of a Maglev network or be salvaged and deployed in another similar network somewhere.

The two fundamental challenges associated with magnetic levitation are:

  1. Lifting forces: delivering an upward force sufficient to overcome gravity, and

  2. Stability: ensuring that the system does not spontaneously slide or flip into a position where the lift is neutralized

Patent Analysis of Maglev Technology

Top 10 Players

Out of the total 2721 patents, 20 percent are owned by the top 10 players in the maglev technology shown in the graph. With 116 patents, Toshiba leads the graph, while Hitachi with just one patent less is at second with 115 patents and Mitsubishi Electric at third with 76 patent filings.

Top 10 Markets

From the graph given below, we can see that China leads the graph with 337 maglev-related patents, followed by the United States and Korea, with 302 and 170 patents, respectively. Although maglev technology development in China began pretty late (in the late 1990s), the number of filings climbed from eight in 1998 to 663 in 2016, an increase of 82.88 times in less than 20 years. As a result, China has emerged as a key source of maglev-related patents. Clearly, China's technical innovation and autonomous R&D capabilities have advanced rapidly in recent years. Furthermore, among Chinese patentees, knowledge of IP and rights protection has risen.


Patent Filing Trend

The number of maglev technology patent submissions looks to be going up and down for the past ten years. As seen from the graph, in the recent years, there has been a steady growth from 2018 to 2020, with a peak in filings in 2020 after 2017. After 2020, the numbers started decreasing drastically as the pandemic situation started and kept the maglev technology on hold.

Conclusion

Like the history of maglev, development demonstrates, skepticism and the expense of investment can be hurdles to acceptance. True, maglev technology is quite expensive, but the Return on Investment (ROI) is unquestionably there for the correct material handling applications. Cost/benefit analysis is going to open up many additional options for magnetic levitation managing technology in the logistics business as the technology evolves further.


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