8.3 Methods to improve Maglev performances Ë 283To exhibit the advantages of the pre-load method on lateral movements, Figs. 8.25a
and b shows the continuous multi-time levitation measurements when two HTS bulks
(S1 is 48 mm in diameter and 12 mm in thickness, and S2 is 68 mm long, 33 mm wide,
and 13 mm thick) went across the center position above the Halbach PMG during the
lateral movement, respectively. As shown in Fig. 8.25a, for the no pre-load case, the
levitation forces were decreased from 29.697 to 15.386 N when S1 initially and finally
crossed the center position. Thus, about half of the levitation forces were reduced due
to lateral movement in the experimental time. For the pre-load case, the levitation
force decay of S1 was also existent, but was obviously larger obviously than that in
the no pre-load case after the fourth time across the center position; moreover, the
decay rate was a little smaller than that in the no pre-load case. Therefore, the pre-load
method was applicable to reduce the levitation forces decay in this case. Figure 8.25b
Fig. 8.25:Levitation forces dependence on the lateral movement times in the continuous multi-time
no-pre-load and pre-load procedures above the Halbach PMG. (a) S1, (b) S2.