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Theorectical benefit of ferro magnet holder for generator

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brandnewb:
I am building a alternator/generator. I am wondering if there is any benefit of having the magnet holder made out of a ferro magnetic conductive material or not.

I have ran some test earlier that seem to suggest it does not but I must admit I probably conducted the experiment in an incorrect manner.

On the other hand when I look at a store bought 3 phase 12 sector magnet pole generator the magnets are housed in a laminated iron sheet holder. So this is what lead me to wonder if that holds any merit.

Any theoretical conclusions are very welcome at this stage.

Adriaan Kragten:
A PM-generator has an armature and a stator. The magnets are mounted in the armature and the coils are mounted in the stator. The armature is normally made of low carbon iron or mild steel as this iron has a very low magnetic resistance and this gives the highest magnetic flux. As both the magnets and the iron of the armature are rotating, there is no fluctuation of the magnetic flux in the armature and so there are no magnetic losses in the iron of the armature. Mild steel has a very low resistance to a magnetic flux so one shouldn't use ferro magnetic material in the armature as ferro magnetic material has a much higher magnetic resitance than mild steel. Ferro magnetic material is normally used for ferroxdure magnets which have a much lower remanence Br than neodymium magnets.

The coils are mounted in the stator. The are two options, a stator with no iron in the coils like done for most axial flux generators and a stator with iron in the coils like done for generators made from asynchronous motors. Assume that we have a stator with iron in the coils. As the stator is stationary, there will be fluctuation of the direction of the magnetic flux in the iron of the stator when the armature is rotating. This gives eddy currents in the iron of the stator. This reduces the efficiency and the stator can become very hot. Eddy currents can be reduced if laminated iron with electrical isolation in between the sheets is used. The lamination must be in the direction of the magnetic flux and so perpendicular to the direction of the eddy currents. Ferro magnetic material has almost the same magnetic resistance as air and so there is also no advantage of using ferro magnetic material in the stator.

brandnewb:
First of all, thank you a lot for your contribution.

I am 3d printing my axial arranged magnet holder. I am using PLA filament at the moment but can change to PLA with up to 30% iron powder in the filament. I can also print it hollow so I can fill the whole magnet disk with 99.6+% iron powder CUT 150um if that makes sense.

What would you recommend?

brandnewb:
the CUT 150 um iron powder I am talking about is not electrically conductive. Only magnetically conductive ;)

MattM:
Everything I've seen about magnetic fields suggests they do not conduct, only form new fields when they interact with matter or light.  Every new field risks the scattering of the strength within the fluxlines, kind of like a diffuser scatters energy from a light bulb.  In motors they use induction to jump gaps to form magnetic fields.  But magntic fields don't work like electricity.

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