308 Ë 8 New progress of HTS Maglev vehicle
- The multi-pole PMG configuration can play an important additive role for
guidance performance of a levitation system due to the potential-well field
configuration. - The homogeneity of magnetic field along the PMG is very important for the
practical application. Since the Halbach PMG does not produce a homogenous
magnetic field, much attention should be paid to the precision and assembling
precision of each small PM. - For practical application, the pole number should be chosen according to the
shape, distribution, and working gap of the on-board bulks. If the HTS Maglev
vehicle is designed to run at a large levitation height (over 15 mm) and the
precisions of each small PM can be guaranteed, the highly efficient Halbach PMG
is recommended.
8.4.2A T-shaped HTS Maglev monorail system
A T-shaped monorail HTS Maglev system was also proposed to achieve the design
targets of low-cost and high-performance. This T-shaped monorail produced not only
a strong periodic magnetic profile in the upper space of the array, but also a strong
symmetric magnetic field in the lateral spaces of the array.
The 2D view of the T-shaped HTS Maglev monorail system is shown in Fig. 8.50.
The system’s PMG with T-shaped cross section was notlike the present typical PMGs
with a rectangular cross section. Conversely, the HTSCs could be cooled in the
upper (#1), left (#2), and right (#3) liquid nitrogen cryostats which were fixed in
the bed plate of the vehicle, corresponding to the up, left, and right sides of the
T-shaped PMG. It also can be observed that the structure of the T-shaped PMG took
advantage of the Halbach PMG in the horizontal direction and the “Century” PMG in
the vertical direction. Figure 8.50 also shows the magnetization directions of PMs and
the magnetic field distribution of the T-shaped PMG.
Figure 8.51a and b shows the simulation results of the magnetic field distributions
above two kinds of PMG under the same calculation conditions. It is obvious that the
T-shaped PMG had a wider high-field region than the present popular PMG with equal
PM cross-sectional area. At the height of 15 mm, the magnetic field of the T-shaped
PMG was still up to 0.45 T which was a better applied magnetic field for a Maglev
system. In addition, Fig. 8.51b showed that at the 15-, 10-, and 5-mm lateral gaps of
PMG, the magnetic fields of the T-shaped PMG were about 3, 2, and 1.5 times stronger
than the present popular “Century” PMG [25], respectively.
Figure 8.52a further shows the calculated results of levitation forces at 45 and
40 mm FCHs of the T-shaped monorail HTS Maglev system. At 45-mm FCH, the
levitation force density at the #1 liquid nitrogen cryostat, i.e. the levitation forces due
to the per unit volume PM, could be about 55.9×103 kg/m^3 when the levitation gap was
5 mm. At 20-mm levitation gap, the levitation force density still was 13.9×103 kg/m^3. It