378 Ë 10 HTS Maglev launch technology
Tab. 10.2:Dimension parameters of three coils [23].
Coil shape Circular-shaped
single pancake
Circular-shaped
double pancakeRacetrack-shaped
single pancakeInner diameter (mm)^38 −−^38 Long axis: 75Short axis: 12
Outer diameter (mm) 41.5−−41.5 Long axis: 103.5Short axis: 41.5
Height of the coil (mm) 4.1 9.2 4.1
Turns 12 24 100
Length of the HTS type (mm) 183 337 339
Critical current (A) 66.5 67.05 64.2
train. One way to reduce the size or weight of the motor is the usage of super-
conducting materials. A LSM prototype with a high-temperature superconducting
excitation system has been developed to conceptually study operation features and
to investigate the feasibility for its application in Maglev trains. This LSM prototype
only makes use of superconducting components in the excitation system (i.e., the
field windings), which is also the moving part of the system. In most LSM systems,
the excitation system contains either magnets or electromagnets. When the stator
generates a moving magnetic field, the magnetic field of the excitation system is forced
to move, with a velocity equal to the frequency of the moving magnetic field multiplied
by the pole pitch. The three-phase stator is made of conventional copper coils with a
coil pitch ofw=42 mm and iron teeth to enhance the magnetic flux density along the
z-axis,Bz.
10.6.1The 2G HTS coil-type excitation system
Superconducting wire with conducts higher current replaces the copper wiring of the
electromagnets of the moving part. The introduction of superconducting wire gives
a stronger thrust force while reducing weight and increasing the power density. The
superconducting coil is made of a Ru-doped YBCO-coated conductor since it has been
found that ruthenium enhances the in-field performance of the critical current of 2G
superconducting wires.
Single pancake and double pancake are two basic structures for the coil ma-
de of the superconducting tape. Three separate coils with different shapes we-
re studied: circular-shaped single pancake, circular-shaped double pancake and
racetrack-shaped single pancake [23]. The dimension parameters are shown in the
Tab. 10.2. A power supply was employed to conduct DC current to the supercon-
ducting coil. The profiles of the magnetic field component along thez-direction and
thex-direction generated by the racetrack-shaped superconducting coil, across its
x-axis atIDC=40 A and a distance of 10 mm, are displayed in Fig. 10.4.