motional feedback (MFB) with inductive sensor

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Something more akin to a traditional loudspeaker motor (albeit not rotationally symmetric) works a lot better. Here's a horseshoe like design. the top center section is a Neo35 magnet magnetized longintudinally = horizontally. it is 26 mm long and 12 mm high. I am sure the length is not crucial.

The gap got changed to a more realistic 2 mm width. The side bars are 1008 steel, as are the pole shoes, which are 30 mm long. I used to have nasty shoulders of the field as well as a strange dip in the center of the gap.

I changed both the meshing options and the geometry. The slight trapezoid undercut of the shoes cured the shoulders (but is still in need of optimization). The center area of the gap now has a very flat field. The center dip also went away once I introduced the undercut, but this might be more related to the meshing options.
 

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And here is the field along the center line of the gap. The ears at the end points need some optimization of the pole shoe goemetry.

I suspect the slight tilt of the center region will go away once I use a second magnet on the bottom side. However, this is a solution that needs a very long voice coil neck to live in...
 

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