184 Ë 6 First manned HTS Maglev vehicle in the world
Fig. 6.39:Several HTS Maglev versions of HTSCs over an applied magnetic field from PM
or electromagnet [45]. Three versions of HTS Maglev that HTSCs levitated above, respectively,
(a) three vertical magnetized PMs, (b) two antiparallel magnetized PMs assembled with iron, and
(c) electromagnet with iron, where the arrows in PMs show the magnetization directions.
levitation schemes using both normal PMs and HTS bulk superconductors provides
many possibilities:
- All levitation forces can be generated by the interaction between normal PMs. The
guidance forces are provided by HTS bulks in field cooling (FC). - The levitation forces can be generated by interaction between two normal PMs
and by the interaction between a normal PM and bulk superconductors in zero
field cooling (ZFC). The guidance forces can be provided by HTS bulks in field
cooling. - Both levitation and guidance forces can be achieved by HTS bulk over a PMG.
An understanding of the first scheme is relatively easy. The levitation using normal
PM is very attractive all the time, since its levitation forces are high. The levitation
forces and the guidance forces are independent. An advantage of this scheme is that
the levitation forces are higher than the other schemes when the quality of the HTS
bulk superconductors is not very good.
The second scheme is complex and perhaps is theoretically superior. However, it is
difficult to design the best combination of both normal PMs and bulk superconductors.
Ren et al. [49] presented a hybrid Maglev vehicle using PMs and HTS bulks that
was similar to the second scheme. Some PMs were installed in the vehicle together
with HTS bulks. The HTS bulks provided guidance forces and a partial levitation force.
On-board PMs provided additional levitation forces.
Figure 6.40 shows the schematic diagram of the hybrid Maglev vehicle using PMs
and HTS bulks. HTS bulks were over the center of two parallel PMs (see Section 6.14)
so that a larger levitation force and guidance force could be created. The on-board
PMs were positioned over the two sides of two parallel PMs. These provided additional
levitation forces. The total levitation forces were generated by the on-board HTS bulks
and PMs. The hybrid Maglev vehicle did not need an on-board power supply and
achieved stable levitation, but the total magnetic levitation forces could be greater
than that of one of the HTS bulks over the PMG.
The levitation forces between a single PM and a single YBCO bulk and one between
two arrays of PMs and HTS bulks over a PMG were studied. Research results showed