6.3 Levitation forces of HTS bulk above PMG Ë 159Tab. 6.3:Levitation force (N) of different seven-block YBCO [24].
Sample Gap (mm)
5 10 15 20 25 30
4-32 103.3 73.8 52.9 35.2 24.9 18.2
4-35 101.4 71.0 48.6 33.3 23.9 17.2
4-39 101.6 69.6 47.7 33.8 23.9 17.2
4-53 103.3 72.9 48.6 34.3 23.9 17.2
4-54 103.3 72.9 51.0 34.3 24.9 18.2
4-67 101.6 69.8 47.7 32.6 23.0 19.2
4-80 101.6 70.6 49.9 35.3 24.9 18.2
Array* – 264.1 206.7 167.5 133.0 106.2*Array is total magnetic levitation of a seven-block YBCO.
6.3.4Comparison of levitation forces per unit length [26]
The levitation forces of different arrays of multi-block HTS YBCO were investigated
over the specially designed NdFeB PMG. Different arrays of multi-block YBCO HTS are
shown in Figs. 6.2 and 6.4. The levitation forces per unit length of different arrays are
listed in Tab. 6.4. The data in Tab. 6.4 was measured at 20-mm gap between HTS YBCO
and the NdFeB PMG.
Table 6.4 shows that the levitation forces of per unit length of array 8 was the
largest. It merits our attention that the data were measured under given conditions,
for example, the thin-wall liquid nitrogen vessel, the NdFeB PMG whose concentrating
field in the center of the surface was up to 1.2 T and still 0.4 T at a position of 20 mm
above it, and so forth.
The test results of different arrays of YBCO bulks show the different levitation
forces between each array and the NdFeB PMG and can be used as a reference for the
design of a Maglev vehicle. The measured results were different if the PMG was not the
same. Because the external magnetic field for various bulks array was not completely
identical, it may not be precise for the system design, but it provides a reference.
6.3.5Levitation forces of multiple-seeded melt-growth YBCO bulk [27]
Song et al. [27] reported the experimental results of magnetic levitation forces on top-
seeded melt-growth (TSMG), multi-seeded melt-growth (MSMG) YBCO bulks above the
PM guideway in parallel and perpendicular mode between the length directions of a
Tab. 6.4:Levitation forces of per unit length (N/mm) of different arrays of YBCO bulk [26].
Array No. 1 2 3 4 5 6 7 8
Levitation force (N) 105 123 136 118 145 193 177 163
N/mm 1. 75 1. 50 2. 27 1. 97 1. 20 1. 44 1. 68 2. 32
Figure of merit 4 6 2 3 8 7 5 1