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Magnetic Levitation without a Superconductor
01/11/2021 9:59 PM
Here's something interesting-- magnetic levitation without the cryogenic hassle of a superconductor.
It works by spinning a magnet with a stationary magnet above it. Normally two magnets will always rotate and attract if not constrained. This trick works because the spinning magnet spins fast enough that the suspended magnet doesn't have enough time to rotate into the attractive orientation.
In place of the rotating magnet, perhaps you could use a circular version of a Halbach array consisting of several NIB magnets with the field directed in the direction of the levitating magnet.
Flux distribution for a refrigerator magnet
Another idea is replacing the permanent magnets with coils driven by multiphase AC to create a rotating field as is done in an AC motor.
It would be interesting to build a rotating field device to see if it would enhance the stability of the levitating object...perhaps a better mousetrap so to speak...
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In watching the video with the commentary, it appears that the magnetic field in each of the 4 control coils is sensed with hall effect devices. If the floating magnet tries to flip over, the control coil current is adjusted to compensate. The heavy lifting is done by the permanent magnet around the outside, and the 4 control coils just tweak the magnetic field
I might have to put one of these on my wish list.
Some years ago, I bought a "Levitron". It is an entirely passive device (all permanent magnets). The levitating magnet is spun, and it levitates until air friction slows it down. The common explanation is that the spinning magnet acts as a gyroscope, preventing it from flipping over. The actual explanation is more complicated and is described here.
It is pretty finicky and it's necessary to adjust the weight of the spinning magnet, the levelness of the base, and the rate of spin for it to work.
Once we're done with COVID, that looks like a fun demo when we do our Bring Your Kids to Work Day as one of those whiz-bang get your attention sort of thing. We try to do things to help inspire young minds to get an interest in the STEM fields.
Magnetic Levitation without a Superconductor
Re: Magnetic levitation without a superconductor
