have now examined most of the basic electro-physics involved in magnetic levitation. In the next section, we will begin applying these physics to the magnetically levitated train. Levitation by RepulsionA maglev train has a system designed to provide the force for levitation. Since the levitation system is separate from the propulsion system, a designer can choose from various propulsion systems. One propulsion system uses Linear Synchronous Motors (abbreviated as LSM's). Another propulsion system uses Linear Induction Motors (abbreviated as LIM's). This page focuses on the levitation system that can be used with either type of propulsion system..This is a cross section of the Magneplane vehicle and its guideway. This setup achieves levitation through repulsion. The propulstion system is not explicity diagrammed in this picture; however, other sources reveal that the Magneplane system uses a LIM. (Image source: page 338, Linear Motion Electromagnetic Systems.)Now we will move on to develop equations to model a simple repulsive levitation system.We will model the levitation system using two separate coils. One coil is part of the vehicle, and carries a direct current in the counter-clockwise direction (as viewed from above the coil). The second coil is part of the track, and carries a direct current in the opposite (clockwise) direction. In practice, the currents need to be quite large to produce a force strong enough to counteract the weight of the train. The resistance of the coils is a very important factor when the cost of providing the power is considered. Smaller resistances allow for more current to be generated using less power, making the magnetic field induced stronger. For this reason, it is most efficient for the coils to be superconducting. However, the cost of superconducting coils and magnets is also considerable. The magnetic field strength at segment AB due the magnetic field created by segment A'B' isThe force on the up...
