Can someone explain the physics behind maglev trains?

[wendylai]

I've done some research on maglev trains, but the equations are too complex for me to solve, etc.

I haven't taken calculus nor studied magnetism yet,
can anybody explain just the basics of physics concepts used in a maglev train?

thank you!

 

[cragar]

The track that the maglev rides on is basically a bar magnet , And on the undercarriage of the train they have superconductors with liquid nitrogen in them to cool the super conductor so it will allow the magnetic field from the track to induce a current in the superconductor, and this flow of electrons will create a magnetic field in the opposite direction to levitate the train.


This is a cool video on a little maglev train and superconductors.

 

[sophiecentaur]

Is that really so? I though the track of a maglev was a high conductance metal in which eddy currents are induced by an alternating field in the vehicle coils. The resulting force (Lenz's Law) is repulsive, which is what you want. Small changes in the phases of the support coils can also generate forward of backward forces. Google Laithwaite, maglev and linear motors etc.

The (impressive) superconducting model in the movie is not representative of normal maglev systems. There is just not enough capacity for superconductive cooling to run a 'real' train... Yet.

 

[cragar]

I could be wrong but i swore i read somewhere that some of them had superconductors in them . And they absolutely have maglevs of what you described .

this talks about the superconducting maglev train.
http://reference.findtarget.com/search/JR%E2%80%93Maglev/

 

[sophiecentaur]

Yes. Superconductors may be used, sometimes, in the coils of electromagnets to allow huge currents to be used for achieving the high magnetic fields - but it's not just in the 'passive' arrangement of induced currents in a superconducting block over a permanent magnet, as in the movie.

I have never come across the sort of large permanent magnet arrays which would be needed to scale up the little model. The induced currents in a practical system are more likely to be in the rail.