Developed by China, 620 kilometers per hour!

When will the dream of "flying close to the ground" come true?

  He Chuan, Vice President of Southwest Jiaotong University: "If the state supports the construction of a long-distance test line, it will take two to three years as short as possible and five or six years as long as possible. I have full confidence.

  Our reporter Wang Di and Wu Xiaoying

  If you remove the wheels of the train and let it sprint along a place more than ten millimeters above the track, it can still run at a speed of 620 kilometers per hour, and one day it will even exceed the speed of an airplane... This is what we usually mean by "train "?

  This is the maglev train, a new type of transportation that has been around for many years but still makes people feel mysterious and may lead to a revolution in transportation in the future.

  Recently, a high-speed magnetic levitation prototype unveiled in Chengdu, Sichuan, once again aroused people's attention to this kind of sci-fi transportation.

  On January 13, the world's first high-temperature superconducting high-speed maglev engineering prototype and test line independently developed, designed and manufactured by China was officially opened at Southwest Jiaotong University.

This prototype car with full carbon fiber and streamlined head has a design speed of 620 kilometers per hour and is expected to create a new record for land traffic speed in an atmospheric environment.

  Compared with other magnetic levitation technologies, the high-temperature superconducting magnetic levitation technology is particularly suitable for future vacuum tube (tunnel) transportation, and the theoretically predicted speed can be higher than 1000 km/h.

Considering that the flying speed of a civil airliner is about 900 km/h, this speed can be called "flying close to the ground."

  "Cars, airplanes, modern ships, and originality are not Chinese. This includes the high-speed rail that we are now leading the world. It is also from the introduction, digestion, absorption and re-creation, from following to leading. But once our technology succeeds, it will be completely It is a Chinese original. It will become a subversive mode of transportation, filling the speed gap of land transportation and air transportation." He Chuan, member of the Science and Technology Committee of the Ministry of Education and vice president of Southwest Jiaotong University, commented on this prototype and experiment. The meaning of the line.

  High-temperature superconducting magnetic levitation train has "unique skills"

  Magnetic levitation is a new technology that completely relies on magnetic fields to make objects levitate.

Suction (or repulsion) can not only offset gravity and make the object hang in the air, but it can also lock the object firmly in a specific position and keep it stable.

  In order to help the public understand the working principle of the maglev train more intuitively, Professor Deng Zigang, deputy director of the ultra-high-speed vacuum pipeline maglev transportation research center of Southwest Jiaotong University, conducted an experiment on the track of the high-speed maglev prototype.

He lifted a rectangular aluminum plate with both hands and threw it over the permanent magnet track.

As a result, the aluminum plate did not directly hit the track: it fell first, then "floated" very close to the track, sliding a short distance in the direction of the track before landing, light as a feather.

  Deng Zigang told reporters that because the aluminum plate has resistance, the current will decay, and the aluminum plate will eventually fall onto the track.

If the aluminum plate is replaced with a superconductor, that is, a conductor whose resistance becomes zero at a certain temperature, a long-term suspension can be achieved.

  Maglev trains can use three principles to achieve levitation, namely electromagnetic levitation (EMS), electric levitation (EDS) and high temperature superconducting levitation (HTS).

The principle of electromagnetic levitation appeared earlier than the principle of high-temperature superconducting levitation. The principle of high-temperature superconducting levitation was proposed after the discovery of high-temperature superconducting materials in the late 1980s.

Trains using the principle of electromagnetic levitation have been commercially used in the low-to-medium-speed and high-speed regions, while high-temperature superconducting levitation has not yet entered commercial use.

  Some people at home and abroad have used the previous two principles to create a maglev prototype with a speed of 600 kilometers per hour.

  In 2015, Japan's low-temperature superconducting magnetic levitation central Shinkansen set a new world record for manned speed of 603 kilometers per hour, which attracted widespread attention.

  In 2019, China's 600 kilometers per hour high-speed electromagnetic levitation test prototype rolled off the assembly line in Qingdao, marking a major breakthrough in China's high-speed maglev technology.

  Professor Zhang Weihua, chief scientist of the Ultra-high-speed Vacuum Pipeline Maglev Transportation Research Center of Southwest Jiaotong University, believes that high-temperature superconducting levitation technology has its own unique advantages.

  First, operating costs are low.

The so-called "high temperature" refers to minus 196 degrees Celsius, which is significantly higher than the temperature requirement for low-temperature superconductors (minus 269 degrees Celsius), which means that suspension can be achieved in a more economical way.

"Japan's low-temperature superconducting magnetic levitation technology requires minus 269 degrees Celsius and requires liquid helium for cooling. This is a scarce resource in the world. However, high-temperature superconducting magnetic levitation uses liquid nitrogen. 78% of the air is nitrogen and liquid nitrogen. The cost is lower than the cost of mineral water." Zhang Weihua said.

  Second, the system is simpler.

Also take Japan's low-temperature superconducting magnetic levitation vehicle as a reference. It needs to be accelerated to a certain speed in order to levitate, and the use of high-temperature superconducting technology can realize the static suspension of the train, thus eliminating the need for a complicated starting system.

  According to the project team of Southwest Jiaotong University, the HTS suspension technology has another important advantage, that is, it has completely independent intellectual property rights.

  "Once our technology succeeds, it will be completely original by the Chinese. From basic research to basic application, from practical technology to industrialization, all Chinese are doing it." He Chuan said.

  It is worth mentioning that no matter which technical route is adopted, compared with other modes of transportation, maglev trains have many common advantages, including low maintenance costs, high safety, and less environmental pollution.

  Because there is no wheel-rail contact, the train does not need wheel-rail, gearbox, bearings and other parts, so the maglev train is much better than the high-speed rail, and it will not be delayed due to rain and snow;

  Because the force of the magnetic field can keep the train stable in the horizontal and vertical directions, and the maglev train adopts the "rail-holding car" or "car-holding track" structure, the possibility of derailment of the maglev train is greatly reduced; Noisy, the train can run more quietly.

  However, under the existing technical conditions, the commercialization of maglev trains still faces considerable challenges, mainly due to the high construction cost and low rate of return.

Globally, there are only three commercial maglev trains in operation in China, Japan and South Korea.

  Due to lack of funds, progress was once slow

  In Deng Zigang's view, the biggest achievement of his team in the past 20 years has been to greatly improve the high-temperature superconducting technology's suspended load performance.

The suspension load performance refers to how much suspension force can be produced per unit area.

  At the end of 2000, the research team of Wang Jiasu and Wang Suyu of Southwest Jiaotong University developed the world's first manned high-temperature superconducting magnetic levitation experimental vehicle "Century".

At present, through optimization research, the suspension performance of this car has been improved by 6-7 times.

  "Improving the levitation performance first needs to study the mechanism of the on-board high-temperature superconductor and permanent magnet track. This is a systematic research work. With the research conclusion as a guide, the specific implementation process is like a jigsaw puzzle." Deng Zigang said.

  The general size of superconducting blocks is small, because the larger the size, the higher the requirements for the process.

Researchers need to choose the shape of the superconducting block, such as round, square or regular hexagon, and then study the arrangement in which it is arranged, and strive to combine into a larger volume block under the premise of the smallest gap. The performance of each piece of superconductor.

  The design of magnetic tracks faces similar problems.

Deng Zigang revealed that “currently, the 1-meter-long track is made up of 90 segments of small magnets.” They have to figure out how to arrange the magnets to achieve the maximum magnetic field performance at the lowest cost.

  The early orbital magnetic field was symmetrically distributed up and down, which meant that the half of the orbital magnetic field that was not on the working surface was wasted.

After continuous simulation optimization and experiments, Deng Zigang's team can now make more than 90% of the permanent magnet magnetic field concentrate on the track, playing a key role.

  There are also challenges outside of technology, such as raising research and development funds.

Deng Zigang confessed that because he has not secured an investment of tens of millions of yuan to construct a test line, "the research progress has been very slow in the previous 10 years."

Seeing Brazil and other countries have created small-capacity, short-distance test lines for high-temperature superconducting magnetic levitation according to similar technologies, he felt very anxious.

  In 2012, in order to support the development of my country’s original high-temperature superconducting magnetic levitation technology, Professor Zhang Weihua, director of the State Key Laboratory of Traction Power of Southwest Jiaotong University, allocated a special fund of 1 million yuan to the high-temperature superconducting magnetic levitation research team, and finally established a 45 Meter-long circular experimental line.

  "It can be said that it has opened a new world, brought this technology back to life, and made the outside world see the high-temperature superconducting magnetic levitation technology again." Deng Zigang said.

  Realize "floating" and "moving"

  The official opening of the world's first high-temperature superconducting high-speed maglev engineering prototype and test line on January 13 is another milestone.

The project was jointly developed by Southwest Jiaotong University, CRRC, China Railway and other units. It is an important step for China to promote high-temperature superconducting maglev technology from the laboratory, and can verify the high-speed and long-term reliability of high-temperature superconducting maglev trains .

  Deng Zigang commented on this, "The 1:1 scale prototype and test line are necessary for the research of all key technologies. Without the engineered prototype and test line, there will be no way to move towards real engineering applications."

  This 165-meter test line is just the beginning.

  "Our current test line has achieved the two goals of "floating" and "moving". To achieve the goal of "running", it is necessary to carry out a 600-kilometer-class real car test on the long-distance test line. The final step of verification of the high-temperature superconducting high-speed maglev train before it is put into civil use.” said Jin Chaohui, the project leader, deputy dean of Chengdu Southwest Jiaotong University Design and Research Institute Co., Ltd. and dean of Kunming branch.

  How long will it take to run?

  The speed of China's development in high-speed rail technology has attracted worldwide attention.

In just a few decades, China has never had a one-inch high-speed railway, and has developed into the world's longest-running high-speed railway. China's high-speed, plateau, alpine, and heavy-haul railway technology has reached the world's leading level.

  Today, China is trying to achieve similar success in magnetic levitation technology.

Gou Jinsong, general manager of the Maglev Engineering Division of Beijing Rail Transit Technology and Equipment Group Co., Ltd., once wrote that China, Japan, Germany, the United States, and South Korea are the five countries with the most patents for maglev train technology in the world.

According to the statistics he completed on November 26, 2017, the number of patents for maglev trains in China already accounts for 27.11% of the world.

  China is also one of the most active countries to promote the implementation of magnetic levitation technology.

The Shanghai maglev train opened in 2002 became the world's first commercial high-speed maglev train line.

The Shanghai maglev train uses electromagnetic levitation, and Qingdao's high-speed electromagnetic levitation test prototype with a speed of 600 kilometers per hour is the result of further optimization on the basis of Shanghai maglev train technology.

In 2019, the Central Committee of the Communist Party of China and the State Council issued the "Outline for Building a Powerful Transportation Country", clearly proposing to rationally coordinate the research and development of technical reserves such as high-speed maglev systems with a speed of 600 kilometers per hour and low-vacuum tube (tunnel) high-speed trains.

In 2020, Yunnan and Zhejiang respectively announced plans to invest more than 100 billion yuan to build high-speed maglev trains.

  Jin Zhaohui believes that China already has the foundation for building a high-speed maglev test line and industrial landing.

First of all, the civil engineering technology of the high-temperature superconducting maglev train is very close to the existing high-speed rail technology. The forms of bridges, tunnels, and roadbeds are all similar. The main change is that the steel rails are turned into magnetic rails with linear motors in between.

The advantage of this is that it can make the civil engineering technology have a higher degree of maturity, and can also use the existing mature industrial chain.

Therefore, it is fully equipped with construction conditions in civil engineering technology.

  Second, China has extremely rich reserves of rare earth resources. If it is applied to high-temperature superconducting maglev lines, it will be sufficient to support track construction. Therefore, the magnetic track also has the conditions for construction, production and industrial landing.

  Third, many domestic units can prepare high-temperature superconducting bulk materials, but due to the small demand, mass production has not yet been achieved.

If the engineering application is realized, mass production can be realized in a short time under the market drive.

  Fourth, China already has mature technology and complete industrial chain support for other such as linear motors, train control technology, and safety management technology.

Therefore, China's high-speed superconducting maglev train is fully equipped with the foundation for the construction of high-speed test lines and subsequent industrial landing.

  Jin Zhaohui believes that the high-temperature superconducting high-speed maglev train technology is basically mature, suitable for various environments and terrains including mountainous areas, and is particularly suitable for tourist tracks or intercity high-speed railways.

The current imperative is to build a long-distance test line in combination with application scenarios, complete the verification of the total system integration, and get through the final stage of commercialization.

  In addition, when construction begins, it is necessary to further reduce construction costs.

In civil engineering, due to lighter trains, smaller sizes, and uniform loads, the cost of civil engineering will be lower than the existing high-speed rail model.

However, new products such as linear motors and magnetic tracks have no large-scale application scenarios before, and the cost is still high.

The R&D team also needs to work hard to reduce construction costs and make the high-temperature superconducting high-speed maglev technology more competitive.

  Regarding the timetable for the commercial use of high-temperature superconducting high-speed maglev trains, He Chuan predicts, "If the state supports the construction of long-distance test lines, it will take two or three years as short as possible, and as long as five or six years, I have full confidence."