Research and Development of the Superconducting Magnetic Levitation (Maglev) System

Katsuji AKITA
Executive Director

    The superconducting magnetic levitation (maglev) system is a next-generation super-high speed transportation system, the development of which is being pioneered by Japan. Its technological goal is to enable the 500 kilometers between Tokyo and Osaka to be traveled in one hour and will transport 10,000 passengers per hour each way.

    In 1970, the Railway Technical Research Institute (RTRI) took the opportunity to build a basic test device to verify the technological feasibility of the superconducting maglev concept. Subsequently, maglev technology was further developed as an R&D project by the then Japanese National Railways (JNR), a prototype vehicle recording a speed of 517km/h on the seven-kilometer Miyazaki test track in 1979. Superceding this, the current RTRI, the Central Japan Railway Company and the Japan Railway Construction, Transport and Technology Agency initiated a joint R&D project in 1990 to develop the technology needed for commercial operations, constructing the 18km-long Yamanashi test track with the support of the national government. On this track, high-speed tests were carried out to develop system components technology and to validate the function and performance of the system as a whole.

    Superconducting coils are mounted on the vehicle and the guideway equipped with ground coils that are fed with energy from a power converter in a substation, thus moving the cars by electromagnetic force. Speed is controlled by varying the feed current frequency. Levitational stability and guidance is ensured by means of repulsing electromagnetic forces produced between current flowing in the superconductive coils and current induced in the ground coils. At low speeds, since the levitational force is insufficient, the train rides on rubber tires. In normal operation, the regenerative brakes functions to bring the train from a high speed to a standstill. As a safety backup, the train is equipped with disk brakes on the wheels and aerodynamic brakes that utilize air resistance in ultra-high speed operations. The advantages of these systems are (i) their safe operation even in the event of an earthquake, by gliding 10 centimeters above the guideway, (ii) the advantages of ultra-high speed operation even on steep grades, and (iii) the integrated control at the substation of both train speed and intervals between trains.

    On the Yamanashi test track, not only has a world record speed of 552km/h been attained, but operations are regularly tested at maximum speeds of 500km/h, demonstrating the excellent control stability and reliability of the system. As a result, in 2000, the technological assessment commission of the Ministry of Transport (now the Ministry of Land, Infrastructure and Transport) evaluated this system to be technologically feasible for commercial operations. To date, the train has been operated over a cumulative distance of more than 300,000 kilometers, and carried more than 60,000 passengers on test runs. We are now working to reduce the cost of vehicles and ground equipment, and improve system quality. Areas in need of further attention and verification by long-term testing include lowering aerodynamic noise levels at ultra-high speeds, enhancing ride comfort, and improving equipment durability. In this context, a new type of aerodynamically improved car introduced at the Yamanashi test track has performed satisfactorily. In addition, we broke our world record by achieving a speed of 581km/h in 2003 year-end. To reduce costs, we have been developing the PLG coil that will replace both the propulsion and levitation/guidance coils. Furthermore, we are committed to basic research regarding the use of deep underground tunnels in urban areas, and researching applications for future high-temperature superconductor technology.

    In the case of a comparison using the Tokyo-Osaka model, the energy consumption per seat-kilometer by the superconductive maglev system is only about half that of an airplane, proving that this means of transportation is excellent for preserving the global environment. Although it is necessary to make further quality improvements and reduce construction and maintenance costs, we can conclude that the superconductive maglev system is now at the technological level that allows its commercial operation.

    We hope that construction of a superconductive maglev system will reach fruition as soon as possible within the framework of a massive national project.