Stator material, glass steel

[Teh Stork]

So, I've been wondering what way to go to reach extreme performance in e-applications. For me the logical way is a gearbox and some very high rpm's.

I've found a material witch I think enables this performance. It has a permeabillity of 600k (normal electrical steel is around 4k), a core loss of 0.3W per kg (40% of electrical steel grade M3) at 60hz - this is a spec sheet.

It comes extremely thin (0,9mils), punching and annealing would be a massive undertaking - but you would be left with 'the best of the best'. Sheets come in a width of a maximum of 8,4 inch - making quite large stators possible. And, could you anneal the whole stator in one piece - or would you need the individual parts to be annealed different ways? Annealing stil puzzles me some...

I haven't done much math on core materials, so if anyone could chime in if this is a no go or not - that would be great As I understand it, the high permeabillity of the material allows for more copper inside the stator. The relatively low saturation limit of 1,5T is a obstacle hi-rpm surely would beat

As for laminations between steel sheets, is kapton useable? Or is there another material that is preffered?

Just throwing it out here, I'm sure some will be intrigued I do not have the skills to 'reinvent' the motor, but I'm sure some of you do!

 

[Kingfish]

I have a great book for you: Brushless Permanent Magnet Motor Design

I'll dig around for the other good introduction to motor theory... somewhere buried in the back cave <blowing off the dust>...

~KF

 

[Miles]

0.9 mils that's errrrrr 23 microns! The stacking factor starts to need serious consideration below 100 microns....
About 700 laminations for a 1 inch stack.....

http://www.emetor.com/blog/post/rule-thumb-calculating-stacking-factor/

 

[Teh Stork]

0.9 mils that's errrrrr 23 microns! The stacking factor starts to need serious consideration below 100 microns....
About 700 laminations for a 1 inch stack.....

http://www.emetor.com/blog/post/rule-thumb-calculating-stacking-factor/

Uhm not sure I quite follow. Doesn't the insulating layer thickness need to be factored in here? Kapton or some other high-grade thin stuff would be needed.

I have a great book for you: Brushless Permanent Magnet Motor Design

I'll dig around for the other good introduction to motor theory... somewhere buried in the back cave <blowing off the dust>...

~KF

I've read some of it, and it's great. Its just that it will be next to impossible to build a motor witch would fully reap the benefits of this material. Annealing the metglass is another concern. You cannot anneal it the right direction for the whole stator in one piece.

Picture this: One toroid for each phase. The glass steel (and whatever insulating material) is wound in toroid shape - and then one slot is cut for magnets to pass. Cutting this would obviously be challenging, not shorting the laminations will be hard - but doable? The material could also be annealed 'the right way' before being wound into a toroid.

Just throwing my thougths out there

This way you would have a kind of axial flux engine, just with a inrunner style to it. The stator would allow extremely high rpm's with low losses, if I've understood it correctly.

 

[Miles]

0.9 mils that's errrrrr 23 microns! The stacking factor starts to need serious consideration below 100 microns....
About 700 laminations for a 1 inch stack.....

http://www.emetor.com/blog/post/rule-thumb-calculating-stacking-factor/

Uhm not sure I quite follow. Doesn't the insulating layer thickness need to be factored in here? Kapton or some other high-grade thin stuff would be needed.

I think the thinnest Kapton film is 7 microns. That would probably push the stacking factor below 50%. I guess the emetor data is for oxide layer insulation or a thin coating?