"Wedgerep"

Analysis of the original 12-magnet + shield "Repmag" idea showed that the attraction forces on magnets entering or exiting the shield were far larger than the repulsion forces between adjacent magnets, and could potentially cause problems, as discussed previously.

A repulsion-only device

I decided to investigate a development of this idea that would have no attraction forces at all — only forces of repulsion. See below:—

"Wedgerep" magnet motor

This model has two thin full-circle drum rotors, one inside the other, both turning clockwise. The rotors are made of NdFeB35, magnetised radially, repelling each other. As the magnets come close together, their flux densities in that region will drop significantly, so they will not be repelled much as they enter the gap between the two semi-circular NdFeB35 stator magnets.

However, the rotor magnets are far apart as they exit from the repelling stator magnets, so they will be strongly repelled there. The question is: will the extra energy gained by this be enough to exceed the loss that must occur as the magnets close up again? In a word, the answer turns out to be "No".

"Wedgerep" showing magnetic flux densities

This flux density plot shows the magnets do behave generally as described above, but the force and torque results from magnetostatic analysis show there is no net energy gain.

A salient-pole version — but still no energy gain

"Wedgerep" salient pole version

I also analysed a "salient-pole" version of the above idea, with individual rotor magnets as shown. Once again, the drop in flux density as the magnets close up can be seen, as well as the higher flux density as they exit the stator magnets. But, as before (with a lot more analysis required), the force and torque results show there is no net energy gain.

Conclusion

It is not worthwhile to spend any more time on this "Wedgerep" idea.