Superconducting Magnetically Levitated Transportation System technology has been researched and developed based on the five-year plan started in fiscal 2000. Aimed at the establishment of practical technology, challenges have been undertaken in such areas as verification of reliability/durability, technology development for cost reduction and improvement of vehicles' aerodynamic characteristics. Fiscal 2002 saw the promotion of verification of performance and characteristics of vehicles/ground facilities. A range of facilities such as new vehicles and new-type sidewall was also manufactured and introduced, and their characteristics were verified.
      In the Kunitachi Laboratories, the development of basic technology such as the ground coil and superconducting magnet was promoted.
      The following developments were financially supported by the Ministry of Land, Infrastructure and Transport.

1. Technology Development on the Yamanashi Test Line
(1) Profile of running tests in 2002
      From July 2002, new facilities such as vehicles, a high-efficiency power converter, and new-type sidewall were introduced on the Yamanashi Test Line and their characteristics were verified.
      Speedup tests and passing tests were performed on new vehicles to verify their running performance. Aerodynamic characteristics such as running resistance and micro-pressure waves, and internal environment characteristics such as riding comfort and internal noise were also verified. Also examined were the basic and power loss characteristics of the power converter, whose research and development has been promoted for the purpose of cost-reduction.
      Similarly, the new-type sidewall was also examined to verify the characteristics of dynamic response during running and running resistance (eddy current loss).
      The plans are progressing well, with 150 days of running in fiscal 2002. The yearly running distance has reached 62,600 km, with the total running distance since the start of running tests at 271,000 km. 42,400 people have already experienced a trial ride. Fig. 1 shows the history of running tests on the Yamanashi Test Line.

(2) Development of a New Vehicle
      New vehicles (one leading and one intermediate) have been developed for aerodynamic improvement and provided to the Experimental Line running tests since mid-July (Fig. 2). Speedup tests to the top design speed of 550 km/h as well as passing tests were performed, and the following characteristics were verified:
(i) Aerodynamic improvement
      The new vehicle adopts a rectangular form as the basic section shape of the car body bottom (similar to that of the bogie) to control airflow turbulence near the bogie. This contributed to the reduction of aerodynamic drag by about 10%. By elongating the nose portion of the leading vehicle to the maximum length, tunnel micro-pressure waves could also be reduced.
(ii) Improvement of riding comfort
      In a conventional intermediate car body, the primary bending natural frequency is close to the pulsating frequency of the levitation force received from the ground, leaving room for improvement in terms of riding comfort. In newly manufactured intermediate vehicles, vertical/lateral flexural rigidity is increased to 1.7 times that of the conventional vehicle. An improvement in lateral riding comfort of about 3 dB through this increased rigidity was verified.
(iii) Reduction of internal noise
      Analysis of measurements in conventional vehicles showed that most noise penetrates through side windows. The thickness of the air layer inside the double-glazing glass was therefore raised from 6 mm to 75 mm, increasing transmission loss at 300 Hz or more for incoming noise through side windows.
      Vibration-reducing characteristics were also improved at side windows and at the mounting points of interior materials, and measures to reduce noise (such as decreasing sound emission to passenger cabins) were taken. Internal noise was consequently reduced by about 3 dB.

(3) Development of New-Type Sidewall
      New-type sidewall developed for the purpose of reducing costs were installed on parts of some Yamanashi Test Line sections, and running tests were performed to verify a range of characteristics.
      Based on an evaluation of three existing systems, a new guideway sidewall was developed by focusing on improving workability and reducing weight. In terms of workability, to increase the efficiency of work such as guideway installation and track straightening/replacement, an inverted T-shape was selected as the section form. This enables the pre-cast reinforced concrete sidewall to be free-standing and structurally stable. The sidewall is also structured so that it can easily be fastened to the track bed. The wall was made lighter by reducing thickness and selecting a minimum shape for the foundation (Fig. 3).

      Cement asphalt (CA) mortar was adopted as the filler for the track bed to avoid resonance and secure mounting precision. A new mixed material that can achieve the required strength in one hour was developed for this CA mortar for use in straightening work on commercial line tracks. Additionally, a special spacer made of high-strength mortar was developed for the foundation fastener so that the sidewall can be moved by }20 mm if necessary.
      A reduction in manufacturing and installation costs for new ground coils was achieved by reducing coil size. This was done by adopting a single-layer propulsion coil arrangement instead of the conventional double layer arrangement, and by simplifying the mounting structure through sharing coil mounting bolts with the levitation coil. To further reduce running costs, attempts were made to reduce eddy current loss in propulsion and levitation coil conductors. To increase reliability, improvements were made to the structure of the propulsion coil connector and the vertical force support structure of the levitation and guidance coils.

(4) Performance Enhancement of Power Converters
      To reduce the costs of DC-AC power converters for linear motors, a high-efficiency converter was developed using new semiconductor elements and a converter control system that can provide the required output at capacities lower than conventional systems.
      The energy loss of the new power converter is about 1/3 that of conventional converters, leading to a reduction in operating costs (Fig. 4). Running tests were performed in fiscal 2002 by replacing some power converters on the Yamanashi Test Line with the newly developed ones to verify the calculated cost reductions. The equipment dimensions were reduced to about 40% volume, allowing a reduction in installation space.
      A sequential saturation control system was developed as a new method of increasing power converter output voltage using control software without changing hardware. Verification tests of this method were conducted on the Yamanashi Test Line. By adopting this control system, facility capacities for the required output can be reduced with increased apparent capacities of inverters. With the inverter configuration on the Yamanashi Test Line, for example, the facility capacities can be reduced by about 15% with the new control system, resulting in possible construction cost reductions. Furthermore, by combination with the neutral point bias control developed in fiscal 1999, a reduction of up to 27% in facility capacities can be expected (Fig. 5).

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