Development Of Magnetic Locking Idea Shows Great Progress

No matter how its done, with whatever level of fakery, magnetic levitation just looks cool.  We don’t know about you, but merely walking past the tackiest gadget shop, the displays of levitating and rotating objects always catches our eye. Superconductors aside, these devices are pretty much all operating in the same way; an object with a permanent rare-earth magnet is held in a stable position between a pair of electromagnets one above and one below, with some control electronics to adjust the field strength and close the loop.

But, there may be another way, albeit a rather special case, where a magnet can not only be levitated, but locked in place using a rotating magnetic field. The video shows a demonstration of how the mass of a magnet can be used to phase lock it against a rotating field. In essence, the magnet will want to rotate to align with the rotating magnetic field, but its mass will mean there is a time delay for the force to act and rotation to occur, which will lag the rotating magnetic field, and if it is phased just so, the rotation will be cancelled and the magnet will be locked in a stable position. Essentially the inertia of the magnet can be leveraged to counteract magnet’s tendency to rapidly rotate to find a stable position in the field.

Whilst the idea is not new, Turkish experimenter [Hamdi Ucar] has been working on this subject for some time (checkout his YouTube channel for a LOT of content on it), even going as far as to publish a very detailed academic paper on the subject. With our explanation here we’re trying to simplify the subject for the sake of brevity, but since the paper has a lot of gory details for the physicists among you, if you can handle the maths, you can come to your own conclusions.

Thanks [keith] for the tip!

16 thoughts on “Development Of Magnetic Locking Idea Shows Great Progress

  1. > these devices are pretty much all operating in the same way; an object with a permanent rare-earth magnet is held in a stable position between a pair of electromagnets one above and one below, with some control electronics to adjust the field strength and close the loop.

    True for those specific devices but what about Levitron? No electronics at all, only permanent magnets and a spinning top.

  2. Now replace the spinning magnetic with a static electromagnet that has a rotating magnetic field and you’ve got solid state magnetic levitation without the need for a superconductor, not to mention, you can then drive the rotation much faster.

    1. Came here to say the same thing. A properly driven near field antenna (or phased array) should do the trick, and could even work on a conductive but not magnetic object through induction. The biggest problem I can see is the inductance of the electromagnet. You need several amperes of current oscillating in the several kHz range (audio frequency), I imagine it would create quite a buzz.

      1. If the geometry of the coil was carefully chosen it might be possible to use a much higher frequency. Instead of simply driving the entire coil and having multiphase windings, in theory it should be possible to energize sections of a coil and then move the nodes of the standing wave. But still,granted, no doubt you’d need to feed it with plenty of current. Although perhaps a bifilar design might improve the response by negating a good portion of the self capacitance.

      1. No, I think they use a control loop with position sensing to stabilize unstable configurations. This, on the other hand, is inherently stable in a range of frequencies/rotational speeds.

    2. I beleive i saw video showing experiment with simple wire coil layed on top of copper plate. By running mains AC voltage through it (limited by variac) it was caused to levitate. But it was not extremely stable due to obvious reasons.

    1. Thank you for mentioning my work. The “time delay” stated above causing the floating magnet to sync to the opposite phase therefore creating the repulsion force is not merely a time delay due to the inertia. This is a characteristics of the driven harmonic motion inherited from harmonic motion, say the simple pendulum. Because of this, the effect don’t require a specific frequency, for example a frequency matching this “time delay”. Instead it works in any frequency about a certain frequency which can be identified as the resonance frequency. This mechanism is called “phase lag” and it is the working principle of reflex subwoofers (http://youtube.com/watch?v=v6K759IHXk8) .

      In this video the air going in and out from the passive speaker or from the hole in the same phase of the driven speaker where one can expect the opposite if the frequency is above 40Hz which is the resonance or characteristics frequency of this subwoofer therefore it gives strong bass volume above this frequency.

  3. Thank you for mentioning my work. The “time delay” stated above causing the floating magnet to sync to the opposite phase therefore creating the repulsion force is not merely a time delay due to the inertia. This is a characteristics of the driven harmonic motion inherited from harmonic motion, say the simple pendulum. Because of this, the effect don’t require a specific frequency, for example a frequency matching this “time delay”. Instead it works in any frequency about a certain frequency which can be identified as the resonance frequency. This mechanism is called “phase lag” and it is the working principle of reflex subwoofers (http://youtube.com/watch?v=v6K759IHXk8) .

    In this video the air going in and out from the passive speaker or from the hole in the same phase of the driven speaker where one can expect the opposite if the frequency is above 40Hz which is the resonance or characteristics frequency of this subwoofer therefore it gives strong bass volume above this frequency.

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