The development of Superconducting Magnetically Levitated Transportation System has reached the stage at which the whole distance of 1000 km (roughly equivalent to the distance from Tokyo to Osaka and back) can be covered reliably in one day on the Yamanashi Test Line. Current challenges include verification of reliability and durability as required by the Practical Technology Evaluation Committee of Superconducting Magnetically Levitated Transportation Systems, technology development to reduce costs, and improvement of the aerodynamic performance of vehicles. In fiscal 2001, these challenges were tackled and verification was carried out in running tests on the Yamanashi Test Line.
      The following developments were financially supported by the Ministry of Land, Infrastructure and Transport.

1. Technology Development on Yamanashi Test Line
[Profile of running tests in 2001]
      High-speed running tests were performed on 169 days in one year to verify reliability and durability. The yearly running distance reached 72,600 km, and the accumulated running distance from the start of running tests reached 208,600 km. The number of test runs with a top speed equal to or over 500 km/h exceeded 700 a year, and 1,100 km was recorded as the longest running distance in one day. Fig. 1 shows the history of running tests on the Yamanashi Test Line.


[Main test results]
(1) Development of a New Feeding System
In order to reduce the costs of power supply systems, a new feeding system is under development with a duplex feeding system instead of the conventional triplex feeding system.
Instant change over duplex feeding system (Fig. 2) is simple in its system configuration and contributes greatly to reduced costs. Running tests simulating this system on the Yamanashi Test Line were performed, and riding comfort was evaluated at various operating currents (Fig. 3). The tests verified that the system could be applied under special conditions such as in sections of constant speed/decreasing speed where the required propulsion force is small, though riding comfort decreases in proportion to operating current (thrust).
Variable section length feeding system (Fig. 4) does not generate thrust change during section switching, though the number of switches increases. Load switching tests of vacuum bulbs will be performed in the next fiscal year onward to verify switch life.







(2) On-Track Test of a Distributed-type linear generator System
A system offering an on-board power supply without contact poses a challenge for Superconducting Magnetically Levitated Transportation System. The development of a combined superconducting magnet-type inductive power collection system has been promoted, in which power is collected by a collection coil on the superconducting magnet (SCM) surface of each bogie. On-track tests were also performed using a combined superconducting magnet-type inductive power collection bogie with SCM for inductive power collection on one side (Fig. 5). The tests verified that the PWM converter controlled a power-factor of one properly, and the targeted power of 25 kW per one side of bogie could be collected steadily at 400 km/h or more (Fig. 6).
A basic test was also performed aimed at improved riding comfort by causing vertical force between ground and bogie through devised control of the inductive power collection system.






(3) Development of a Asymmetric Coil
The conventional levitation and guidance coil on the Yamanashi Test Line is wound in a figure-of-eight, and similarly-shaped upper and lower coils are placed symmetrically. Our resent study showed that the magnetic suspension property which acts on vehicle and levitation and guidance coil could be improved and lateral-running stability enhanced if upper and lower coils are made asymmetric with a smaller upper coil height. Calculations demonstrated that levitated running could start at a lower speed than with the conventional coil figure arrangement.
This fiscal year, measuring coils were mounted temporarily on the Yamanashi Test Line for measuring characteristics to fully understand the nature of electromagnetic forces in vertically asymmetric levitation and guidance coils (Fig.7). It was verified that the measured values roughly corresponded to the calculated values.
The introduction of vertically asymmetric levitation and guidance coils opened up the prospect of reducing levitation start speed by about 50 km/h (Fig. 8).





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