High Temperature Superconducting Magnetic Levitation

6.8 Guidance forces stiffness Ë 173

Fig. 6.26:Guidance forces of the MSMG

bulk and the array of three SMG bulk in the

perpendicular mode [27].

Fig. 6.27:Schematic diagram of the HTS Maglev measuring system of tilted PMGs [37].
(1) Propulsion. (2) NdFeB PMGs. (3) Sensor. (4) Rectangular-shaped liquid nitrogen vessels.
(5) Gradienter. (6) Load. (7) Beam. (8) Support. (9) Fulcrum. (10) Jack.

and 6.28). The tilted PMGs were fixed in the SCML-01. The entire measuring equipment
included a pair of onboard HTS Maglev equipments (see Section 6.24) and PMGs which
can be tilted. Experimental results showed that tilted guideways helped to improve the
guidance forces.

6.8 Guidance forces stiffness

Wang et al. [38] also investigated the cooling height dependence of the lateral
magnetic stiffness. Defined as the slope of the line connecting the two acute corners
of the hysteresis loop, the concept of effective stiffness was adopted to study the
lateral magnetic stiffness of the HTS bulks in the lateral motion. Results are shown
in Fig. 6.29. It is clear from the figure that larger lateral displacement leads to less
effective stiffness. We could also increase the effective stiffness by field cooling the
HTS bulks at lower heights.