High Temperature Superconducting Magnetic Levitation

6.19 Long-term stability of the HTS Maglev vehicle in 2001–2003 Ë 209

Fig. 6.74:Variation of the total levitation

forces of entire HTS Maglev vehicle over

the PMG [12].

In December 2000, the total levitation forces of the eight on-board HTS Maglev
equipments over the PMG were 9222 and 7563 N at levitation gaps of 15 and 20 mm,
respectively. In July 2001, the total levitation forces were 8940 and 7271 N at levitation
gaps of 15 and 20 mm, respectively. The total levitation forces were 8633 and 7049 N at
levitation gaps (subtract the 3-mm bottom thickness of the liquid nitrogen vessel) of
15 and 20 mm, respectively, in March 2003.
Figure 6.74 shows the variation for the total levitation forces of the eight on-
board HTS Maglev equipments (entire HTS Maglev vehicle) over the PMG from 2001
to 2003 [12].
The total levitation forces of the entire HTS Maglev vehicle were 8486 and 6908 N
at levitation gaps of 15 and 20 mm, respectively, in May 2002. At a gap of 30 mm, there
was a 46% decrease in levitation force compared to the gap of 15 mm.
The data set of total levitation forces for March 2003 was slightly higher than
that of May 2002. This was because the center lines of the on-board HTS Maglev
equipments and the PMG were laid to overlap more accurately in March 2003. The
overlap accuracy of both center lines directly impacts the magnitude of the levitation
forces.
The comparison of total levitation forces of the entire HTS Maglev vehicle during
the 10-month period from July 2001 to May 2002 showed that the levitation force
decreased by 5.1%, 5.0%, 4.6%, and 4.8% at levitation gaps of 15, 20, 25, and 30 mm,
respectively. All data were nearly the same, i.e. each levitation force decrease was
about 5.0% at the different levitation gaps.
The levitation forces became lower after 2 years. Up to September 2009, over
40,000 passengers had ridden on the Maglev vehicle, and the total recorded shuttle
distance was about 400 km. Experimental results indicate that the long-term stability
of the HTS Maglev vehicle is better in the static mode than when the vehicle is
operating at low speeds. HTS Maglev can be used in high-speed traffic, but the pinning
behavior must be at a higher level, which is better adapted to high-speed needs.
Therefore, the investigation of the dynamic properties of the HTS Maglev vehicle at
the high-speed operation is extremely important.