Can someone confirm this in FEMM?

[robbie47]

Hi Lumen,

Just a quick check before I will simulate.

The process is reversed by again inserting the lower small magnet with reversed polarity, at .015" from the center line of the upper small magnet. Now the large magnet will move back to the starting position.

I understand the following steps are needed to do your COP calculations:

Starting from the FEMM file you attached:
1) Move the long magnet 0.55 inch to the right
2) Remove the bottom small magnet (shift it to the bottom of the workspace)
3) Reverse the polarity of the bottom magnet (180 degrees)
4) Shift the bottom small magnet in from bottom to near the long magnet (the start position)
5) Move the long magnet 0.55 to the left (the start position)

Is 4) and 5) done simultaniously or sequential?

How did you determine your COP?

[0c]

Never use for calculate 3D problem program designed 2D only. Try program Maxwell 3D from Ansoft (for example) - and you find no overunity in this system.

You've done a Maxwell 3D model? Great, how about sharing it?

(PS: If you're handy with Maxwell, I've got a model I'd like to see done.)

[jonifer]

maxwell have very simply draw and program JmagStudio too (demo version obviosly)

[robbie47]

@ Lumen,

I made some preparations for the simulation:
1) I changed the mesh size of the workspace to 0.1 (to increase accuracy)
2) The mesh size of the magnets was also set to 0.1 (to increase accuracy)
3) I composed a group for each magnet: top small magnet is set to be group 1, long magnet is set to group 2, bottom small magnet is set to group 3
I grouped the magnets so its easier to move the magnets using a script.

The modified file is attached

[lumen]

@Robbie, The small bottom magnet is supposed to move in and out of the screen and I know this cannot be done in 2d software so down will have to do. When inserting the small magnet back into position it needs to have been shifted over .140" so it again starts out .015" from center line of the top small magnet, but on the other side of center line because now it will be going the other way.

Other wise you are correct.