The behavior of the inductive-levitation-coils in a DC-linear-motor system

The DC linear motor system proposed by the Railway Technical Research Institute of the Japanese National Railways is one of the new levitation-type high-speed ground-transportation systems. The behaviors of the inductive levitation coils for the system are examined in both static and dynamic states. The calculation methods are checked with the experimental results announced by the above Institute. It was proved that (1) the first truck receives around 5% stronger levitation force than that for the following trucks at 500km/hr and the difference is negligible at 200km/hr; (2) the ratio of the effective horizontal length of the magnet-pole to that of the levitation coil suggests the preferable value of 1.2 for obtaining the high ratio of the levitation force to the drag one with copper-volume fixed; (3) the stiffness factor is also the maximum for the ratio of the horizontal lengths of around 1.2; (4) the damping factor is found to be always positive in contrast with that for the synchronous motor systems.