8.4 Some developed designs of the HTS Maglev vehicle system Ë 309Fig. 8.50:(a) Schematic drawing of the overall HTS Maglev system. (b) Calculated magnetic field
profile of the T-shaped PMG. (1) Vehicle body. (2) Bed plate. (3) T-shaped PMG (arrow shows the
magnetization direction). (4) Iron. (5) #1 liquid nitrogen cryostat. (6) HTSCs. (7) #2 liquid nitrogen
cryostat. (8) HTSCs. (9) #3 liquid nitrogen cryostat. (10) HTSCs.
was exciting that there was still a large levitation force density at higher positions. On
the other hand, the calculated values for the guidance force density at different lateral
gaps are shown in Fig. 8.52b. It can be seen that at the same FCH, the guidance force
density of the system increased greatly with decreasing lateral gap. For example, the
guidance force density of the #2 liquid nitrogen cryostat at 5-mm lateral gap was much
larger than that at 15-mm lateral gap. This was because, for this system, the guidance
forces depended not only on the pinning forces of the HTSCs in the #1 cryostat but
also on the lateral restoring forces. The lateral restoring forces came from two parts.
One part resulted from the interaction of the left magnetic field of the T-shaped PMG
and the induced currents of the HTSCs in the #2 liquid nitrogen cryostat. The other
part resulted from the interaction of the right magnetic field of the T-shaped PMG and
the induced currents of the HTSCs in the #3 liquid nitrogen cryostat. The sum of the
two parts was much larger at smaller lateral gap since the gradient of magnetic field
increased greatly with decrease of the lateral gap. Therefore, the system possesses a
larger lateral restoring force and better stable levitation for small lateral gaps.
For supplement, Tab. 8.8 compares the calculated levitation force density for
two kinds of PMG with different levitation gaps at 45-mm FCH while Tab. 8.9 shows
the guidance force density for these two kinds of PMG at different lateral gaps. It is
seen at 15-mm levitation gap, the levitation force density of the T-shaped PMG was
23,216 kg/m^3 , and the present popular PMG was 12,584 kg/m^3 , which was reduced
by 46%. Thus, with almost the same amount of PM, the T-shaped PMG had a larger