Hyperloop
As a result, the loop becomes an electromagnet with the generated magnetic field moving in front of the original one with a 90 o phase difference (out of phase) under sinusoidal excitation. However, every conductor inevitably experiences inductance. When AC current (sinusoidal excitation) is applied to an inductor, impedance induced in it increases with frequency:
where R is the resistance of loop, K is total impedance, L is inductance and w is frequency
This impedance delays the current peaks (fig. 10), thus decreasing the phase difference between the MF from permanent magnets and the induced MF. Eventually, when a high enough frequency (train speed) is reached, drag starts decreasing, whereas lift continues increasing (fig. 11).
Figure 10
Figure 11
Figure 12
Figure 13
As one can see from figure 12(a), the electromagnet is in the Null-Flux position, where there is no net current inside the loop, since current induced according to Faraday’s law and Lenz’s law in the upper part is cancelled out by the one induced in the lower part. However, when the electromagnet is displaced from the equilibrium position (figure 12(b)), net current is no longer zero, and two opposite poles are produced. They oppose the change in flux and, therefore, tend to push the electromagnet to the equilibrium position. Since the 8-shaped coils are connected in pairs, they also introduce a horizontal equilibrium, which is maintained using the same principle as the vertical: creating net current in the loop when displaced. Form the technical point of view, this system is beneficial for use in Hyperloop, since it doesn’t require a feedback loop and is inherently self -stabilizing. A way of improving the EDS could be the arrangement of superconducting (SC) magnets in Halbach arrays, which could reduce energy consumption and solve the problem of the exposure of passengers to strong magnetic fields.
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