70 Ë 3 Magnetic levitation
Fair in 2004. Specifications of the Maglev vehicle are as follows [64]: track length
of 11 m and width of 1.7 m, vehicle length of 2.63 m and width of 1.25 m, maximum
levitation force of 20 kN (can be manned by 6).
Magplane Technology proposed the new concept using a Halbach array [65] of
PMs instead of the original LTS magnets [66]. This reduces the vehicle operational
complexity and the number of potential failure modes, but results in some compro-
mises: (1) to limit the weight of the PM systems, the operating gap has been reduced
from 15 to 10 cm; (2) the weight of the PMs in the baseline case is 40% greater than the
weight of the previous superconducting system. A past cruise speed of 500 km/h has
been modified to 160 km/h.
The on-board levitation and propulsion PMs use NdFeB. The Halbach array
magnets result in the maximum magnetic field at the guideway for a given weight of
magnets and at the same time result in the minimum magnetic field in the passenger
cabin. The maximum lift for a given weight of magnet is achieved when the magnets
are concentrated over relatively limited areas, but with significant array height. A lift
pad magnet weight of 5.9 tonnes, and sufficient lift can be achieved with four pads
(Fig. 3.1). The lift-to-magnet weight ratio is 5.4. The surface field at the pad and at 10 cm
from the guideway surface is 0.85 and 0.45 T, respectively [66].
Compared to other countries, Maglev systems in the USA will be important not
only as carriers of passengers but also as carriers of truck-type freight. There are
four USA urban Maglev systems under development at American Maglev Technology
(AMT), General Atomics, LaunchPoint Technologies, and MagneMotion. Both AMT
and MagneMotion use the EMS levitation technology. General Atomics uses the In-
ductrack levitation technology, which is essentially an EDS system with PM Halbach
arrays instead of superconducting magnets. Unlike the other three, the General Ato-
mics Maglev system theoretically has no stability issue, and control is only needed
for a satisfactory ride quality. Therefore, in terms of reliability, the General Atomics
Maglev system is better than the other three systems. LaunchPoint Technologies also
uses PM Halbach arrays for levitation, but it is different from the PM Halbach arrays
in the Inductrack systems.
MagneMotion and Old Dominion University (ODU) in the USA undertook a co-
operative agreement to demonstrate the MagneMotion M3 urban Maglev technology
[67, 68] on an existing elevated guideway on the ODU campus. The suspension and
guidance forces are provided by the PMs rather than the electromagnets. The on-
board suspension power using PMs is smaller than that with electromagnets. The use
of PMs on the guideway above and below in the Maglev M3 system allows doubling
the Maglev gap. Coils winding around the PMs are excited so as to stabilize the
suspension and control the magnetic gap. The key parameters for the MagneMotion
M3 Maglev system are 8.8-m vehicle length, 2.55-m vehicle width, 5.5-Mg vehicle
weight, 9.0-Mg maximum load, 1.40-Mg/m guideway girder mass, and 0.28-Mg/m
levitation mass [54]. The long stator linear synchronous motor (LSM) for propulsion
allows all propulsion power and control systems to be on the guideway and the LSM