A new Anti-Lenz motor concept

[bistander]

This can be controlled by air gaps ...

For equal cross sectional area, a 0.001" air gap will have similar mmf to 4" length of electric grade steel core, not to mention the relative permeability of the magnet material being essentially that of air.

I'm not trying to discourage you, but rather understand how the flux through the coil will vary.

Carry on,
bi

[broli]

Got the first 3d simulation result. Currently not showing much just the field. Currently the field is equally divided as the magnet is perfectly in the center.

[Smudge]

Sadly FEMM cannot simulate this setup as it's not possible to model it in 2d if someone has a 3d FEM simulator I would be very interested to see the results.

It can be modeled in FEMM, see image.  The force on the moving part is not in the direction you stated, it is pulled inwards.  I have put the moving part outside the ends of the top and bottom rails where it becomes obvious that is the direction.  There is a 10mm grid in the image and the depth is 10mm for those interested.  The pull-in force by the FEMM stress tensor method is 1.8 Newtons and the flux in the coil is 2.56E-4 Webers.  Inward movement does not change the coil flux much as Bistander predicted.  It increases the coil flux slightly.  And if that slight increase drives current in the shorted coil, its effect is not to enhance the movement, but just the opposite as in normal motors.  Sorry about that.

Smudge

[broli]

It can be modeled in FEMM, see image.  The force on the moving part is not in the direction you stated, it is pulled inwards.  I have put the moving part outside the ends of the top and bottom rails where it becomes obvious that is the direction.  There is a 10mm grid in the image and the depth is 10mm for those interested.  The pull-in force by the FEMM stress tensor method is 1.8 Newtons and the flux in the coil is 2.56E-4 Webers.  Inward movement does not change the coil flux much as Bistander predicted.  It increases the coil flux slightly.  And if that slight increase drives current in the shorted coil, its effect is not to enhance the movement, but just the opposite as in normal motors.  Sorry about that.

Smudge

Hey Smudge, that's actually a clever model you have there, I didn't think of that. I might use it to speed up simulation times.


Meanwhile I have the first 3d simulation results in and they also seem to indicate the same result as Smudge got, that there is indeed an attracting force not repelling. I used multiple refining passes to ensure the force would converge as much as possible but it's clearly attracting.


Before giving up on this idea I would like to try a few variations. The result also seems to contradict a very crude experiment I did in real life where a repulsive force seemed to be present i.e. a coil+core repels a magnet if their fields are parallel and in the same direction, but this may have been a poorly setup experiment.


Edit: @Smudge, I spoke a bit too soon about your 2d model, one key point is to have the part which has the field in the same direction as the magnet closest to the magnet, in your 2d design case it's fartest from the magnet.

[broli]

I'm running some simulations and the results are rather interesting but I know that could also mean nothing as I may be interpreting them wrong. But first of all let me start off with the field density plot calculated for a line that goes through the entire setup. The value that is used is the B field value normal to this line (in the current sim case this is the y axis of the B field). This is shown in the first diagram, where the large valley is the magnet and the two smaller ones are where the coils are located. The graph also shows that the left side has a higher density than the right due to the magnet being closer to it. It's at about 65% more which is not very negligible.


I am currently running simulations where I "artificially" run a current through the coils to simulate an induced current due to the flux change and solving the force on the magnet. This is faster than using the transient solver but even that takes a while to solve. Initial results do show something interesting though.


EDIT: Also added a field density plot where the magnet is in the middle for reference.