| High speed maglev system is inseparable from the cooperation work between power cable and signal cable, that leads to the crosstalk on weak lines caused by strong current in parallel line system. In this paper, we analyzed the crosstalk and suppression mechanism of magnetic coupling aimed at the electromagnetic coupling condition in parallel cable, and then did related investigations and experiments on the design of the magnetic shielding of magnetic shielding cable at low frequency.First, we theoretically analyzed the electromagnetic coupling of cable by the lumped parameter model. We investigated the electric coupling and magnetic coupling, respectively. We analyzed the suppression effect of the nonmagnetic shielding layer on electric and magnetic coupling. The conclusion is that nonmagnetic shielding layer has good suppression effect on the electric coupling and high frequency magnetic coupling, but shows no performance on the low frequency magnetic coupling.Second, we used the magnetic material as a shielding layer for the interference suppression on active magnetic coupling of power cable. Due to the low magnetic reluctance of the magnetic material that the magnetic shunt effect can be achieved,by the different winding modes of shielding layer wrapped around the power cable, we obtained corresponding magnetic coupling suppression effect. It shows that the magnetic shielding layer has no suppression effect on magnetic field in single cable case, but shows excellent performances in circuit cables with the same current magnitude and opposite direction. Flow through the current size of the 70 A loop cable in the use of magnetic materials along the X axis and the Z axis in the direction of the shielding effectiveness were 34.9dB and 26.4dB. The conclusion is verified by the simulation through a simulation software of Ansoft Maxwell magnetic field.Then we studied the interference suppression of magnetic shielding layer on passive magnetic coupling within cable signal. Also by the magnetic shunt effect of the magnetic material, we designed related experimental circuit and gave the experimental verification of feasibility. Then we used experimental circuit to analyze the magnetic coupling interference suppression effect of magnetic materials on signal circuit under different states. The conclusion is that magnetic shielding layer with suitable permeability and saturation magnetic induction intensity has excellent magnetic coupling interference suppression effect on signal cable. Through the experiment, it can be concluded that the magnetic shielding performance can reach 20 dB by using the suitable magnetic material as the signal cable.Finally, according to the experimental results, we designed and manufactured the power cable with the function of magnetic shielding and the signal with resistance of magnetic inductive coupling. And innovative design, processing a kind of diamagnetic properties of hybrid cable, it can not only realize the power transmission, but also can realize transmission of weak signals. |
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