Since ground coils used in the Maglev system are exposed outdoors for long stretches of time, periodical maintenance work to inspect their condition is important. However, given the large number of ground coils along Maglev tracks, a system was developed using RFID technology aimed at reducing the effort required for such inspections, while at the same time improving reliability of the Maglev system.
When positioning RFID tags on ground coils, it is important to consider the influence of variable magnetic fields produced when onboard superconducting magnets pass by. Consequently, using a rotation test bench with 1 tesla magnets placed on either side to reproduce the magnetic field environment, and the RFID tag was confirmed to have no loss of data (Fig. 1). It was also confirmed that the RFID tag data was not influenced by ground coil vibration, voltage and temperature.
Next, a ground-coil individual-data management device was developed in order to be able to read/update maintenance data specific to the ground coil itself (product number, product history, maintenance records, etc.) using a handy type RFID reader. Use of this device facilitates maintenance management of the ground coil. Pursuant to the idea of using built-in type readers with large antennas to collect individual ground-coil data from onboard a maintenance vehicle, driving tests were carried out to read data from 58 RFID tags positioned along the tracks. These tests made it possible to confirm that individual 16-byte data could be read at a speed of approximately 60 km/h (Fig. 2).
This function therefore makes it possible to identify product numbers and read maintenance records from onboard a vehicle, and opens the possibility of applying this system in practice to ground coil maintenance management.