270 Ë 8 New progress of HTS Maglev vehicle
Fig. 8.9:Autospectra in the vertical direction at different FCHs.
As shown in Fig. 8.9, the autospectrum curves in the frequency domain indicate
that the natural frequency is about 3 Hz. The autospectrum curves become flatter at
lower FCHs and have more peaks. Moreover, it is the other experimental evidence
that the effective FCH should be 30 mm to obtain a more dynamically stable HTS
Maglev vehicle. Under the condition of 30 mm FCH, the WH of the HTS Maglev vehicle
is around 25 mm which is also a perfect levitation height for HTS Maglev vehicle
applications.
8.2.2Dynamic Maglev characteristics under moving applied magnetic field
As is well known, the series of quasi-static “force-displacement” or “force-time”
measurements have been accepted as an effective laboratory procedure to validate the
application feasibility of the first HTS Maglev test vehicle (see Chapter 6) and help the
successful development of HTS Maglev vehicle demonstrations or short-distance test
line models. Based on those quasi-static results, the dynamic behavior characteristics
of the HTS Maglev appear to be a significant science problem, especially the running
situation under normal rail speeds. To understand the dynamic running performance,
the HTS Maglev dynamic measurement system, SCML-03 [23] (see Section 5.6) at
ASCLab of SWJTU in China, was developed in-house to simulate the HTS Maglev
vehicle’s translational motion above a circular PMG of 1.5 m diameter under different
running speeds. The rotation of the circular PMG could be controlled to realize the
translational movement of HTS bulks with respect to the PMG. The rotational speed
could be set to simulate the different running speed operations of a HTS Maglev
vehicle. The highest experimental linear equivalent speed was 238 km/h.
Previous designs and studies on quasi-static levitation performance were under
the assumption that the magnetic field generated by the PMG is uniform along the
longitudinal direction. However, the magnetic field generated by a real long-distance
PMG is inevitably inhomogeneous due to the magnetism differences between