To ensure the reliability of a magnetically levitated transport system, it is important to verify the durability of ground coils as they are vibrated by electromagnetic forces when a train passes. The RTRI therefore developed an electromagnetic vibration test apparatus to perform bench tests for this purpose.
   To perform an electromagnetic vibration test for a scenario where a train runs over a ground coil, the objective coil is set to face the superconducting magnet of the apparatus with an magnetomotive force of 800kA (Fig. 1), and a current is supplied under test conditions from an inverter power source. Long-term unmanned durability tests can be implemented as the testing apparatus is equipped with a ground coil-cooling unit and an automatic control and measurement system. The apparatus can be placed in a movable soundproof chamber.
   Electromagnetic vibration tests on a range of ground coils using this apparatus have shown that the characteristics of the electromagnetic force used to simulate the passage of a train correspond with analytical results. As a result, the RTRI was able to confirm the possibility of tests equivalent to actual train running in terms of load distribution and vibration frequency. The RTRI also acquired data on durability, including changes in the vibration acceleration in different parts of the ground coil, through durability testing (Fig. 2). This study was promoted with a subsidy from the Ministry of Land, Infrastructure and Transport.