Hyperloop
2.3 Inductrack
Inductrack is in fact a subtype of EDS, which is nowadays regarded as a separate type. It also relies on electromagnetic induction, but in this case currents are induced in the loops of wire mounted in the track under the vehicle. The system could also operate using a simple conductive non-magnetic flat track. The train in turn is equippedwithHalbach arrays of permanentmagnets, which generate a strong downward-oriented magnetic field (fig. 14):
Figure 15
Figure 14
The working principle of Inductrack is very similar to that of EDS, the only difference is that coils are mounted under the vehicle and permanent magnets are used instead of SC magnets. One of the features of Inductrack is that it provides levitation starting from very low speeds (3-5 km/h) by using multiple arrays of magnets in the vehicle, although since we are talking about speeds beyond 1000 km/h, this can’t be regarded as a benefit. However, at high speeds the lift tends to a certain constant value (fig. 11), whichmakes it stable in the vertical dimension. In order to function, Inductrack also requires transverse stabilization, which is relatively simple to achieve using either passive (inductive coils) or active (electromagnets) systems. Its main advantage over other systems is simplicity of construction and reliability.
Environment and finance
Now that we have compared the independent levitation and propulsion methods from the technical side, we must not forget about the environmental and financial aspects. First let us look at motors. LIM is cheaper to produce, since it doesn’t require a feedback algorithm for determining the position of secondary and doesn’t make use of permanent magnets. However, it is significantly less energy - efficient than LSM, since there are fewer losses through heat from conductors as currents are induced in them. Therefore, LSM is a better option in the long run. Both of these systems are able to regenerate energy from braking. In regard to levitation, EMS is the least competitive due to its complicated feedback loop and low energy-efficiency, which makes it more expensive than others. Inductrack in turn defeats EDS: although they both use magnets, EDS requires more powerful SC magnets, while Inductrack relies on common room-temperature magnets. Ordinary SC superconductors are normally cooled by liquid helium, whose production is very energy-consuming and gives off tons of CO 2 . The SC metals are very rare-earth, which makes their production extremely expensive and harmful to nature. The situation might change soon, since HTS (high-temperature superconductivity) magnets have already been developed and aremuch cheaper in use than ordinary ones. However, thoseHTSmaterials are even more precious, so their exploitation is still questionable. In contrast, Inductrack requires regular permanent magnets, which are not as rare as superconductors.
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