Dual rotor axial flux motor design

[plasmadust]

Any rpm
We can optimise specific rpm and torques by varying the gap between winding and maganet rotors, winding density and the such. Now moving on to a newer and more efficient winding board. Run some fea and you see what happens with flat printed windings and what to do to fix.

[flathill]

Any rpm
We can optimise specific rpm and torques by varying the gap between winding and maganet rotors, winding density and the such. Now moving on to a newer and more efficient winding board. Run some fea and you see what happens with flat printed windings and what to do to fix.

You wouldn't happen to work for these guys?
http://www.boulderwindpower.com/the-bwp ... cb-stator/
I think the motors are so efficient they can use low temp grade neo out of California (no dysprosium need)

[fechter]

I think we may have passed you by on an axial flux motor.
The photo is a cut out of the 1hp prototype. one of the two maganets and a slice of the pc board ''windings'', which are not windings at all can be seen.
The pc board stays put and the two maganet plates rotate on the shaft. Maganet plate is neo pie shaped encapsulated in plastic and bonded to the only matalic part in the motor that serves as return of the flux lines and is what is attached to the shaft.
This thing <2lbs., has no latteral loading, Flux lines weave back and forth, the windings are a printed circuit board, there is nearly NO back emf ( so we use very inexpensive audio grade componets in the controller). No cogging, no noise, no heat and is less expensive to manufacture than any motor ever built.
That's a uniball pen next to the motor, which is 3.250 dia. and little less than 2.00 H.
For stark contrast, second photo is 3MW of the same thing and in production to replace gearboxes and crap that breaks all the time on large wind turbines. Notice the guy walking past the assembly on the left.

That's pretty cool. What is the thin disk below the windings?

And... how is Luke going to fit that 3MW one on his bike?

[Miles]

What is the thin disk below the windings?

The non-sectioned encapsulated magnets, I think. The upper disk is sectioned.

[Miles]

Just came across this:

Design of an Integrated Starter-Alternator for a Series Hybrid Electric Vehicle:
A Case Study in Axial Flux Permanent Magnet Machine Design.
Jessica L. Colton University of Nebraska

[Miles]

Magnet shape modified to give a more equal flux density across the laminations.

This actually won't matter. I can't demonstrate this without full 3D modeling, but the flux won't be limited to just the narrow lower section of the core - it will spread across the entire volume of the core, so any worry about the narrow section of the core saturating first are mostly unnecessary.

I guess I just assumed that it would stay separated because of the reluctance of the inter-laminar insulation. Or, do you mean that it spreads across only as each lamination approaches saturation?

Ref: viewtopic.php?p=557247#p557247

As I'm milling pockets for the magnets anyway, I could increase the airgap distance towards the inner radius by milling the pocket at a slight slope. Good idea? Magnets tapered in thickness would probably be too expensive....

I'm still not sure how much the minimal lateral flux flow will increase as saturation of the narrower lams is approached?

[plasmadust]

The thin disc is one of two maganets.
One above and one below the winding pcb. the pie slice taken out of the entire upper maganet and Fe rotor for ease of viewing the assembly. The same pie slice is taken out of the winding pcb and lower Fe rotor, but maganet disc is intact.
The resolution of rotation is about 0.3 arc deg. and the orintation of the upper and lower maganet plates are so as to have + on one and - on the other giving the wrap of the flux lines a path off one thru the FE rotor and retuning in phase to the other. Hence the lack of heat generated.
It is a 3 phase brushless motor by any definition, but effeciencies are as good or better that AC induction.
We have made this and it is in production at Core Outdoor Power.
www.coreoutdoorpower.com for a better view than a cut up proto type.

[Miles]

Core Motion Inc patent:

[flathill]

Any rpm
We can optimise specific rpm and torques by varying the gap between winding and maganet rotors, winding density and the such. Now moving on to a newer and more efficient winding board. Run some fea and you see what happens with flat printed windings and what to do to fix.

You wouldn't happen to work for these guys?
http://www.boulderwindpower.com/the-bwp ... cb-stator/
I think the motors are so efficient they can use low temp grade neo out of California (no dysprosium need)

http://www.boulderwindpower.com/about-u ... matt-jore/
"Prior to founding Core Motion, Matt was founder, CEO and Chairman of Jore Corporation, an innovative power tool product company based in Ronan, Montana. Under his leadership Jore Corporation grew from a start up to a publicly traded company with more than $50 million in annual revenues and partnerships with major OEM power tool multinationals including Makita, Black & Decker/DeWalt and Bosch. "

I see you lost control of your last business to the banksters. What a comeback story! Best of luck with you new venture!

[fechter]

We have made this and it is in production at Core Outdoor Power.
http://www.coreoutdoorpower.com for a better view than a cut up proto type.

Here's the picture:

400-Exploded-View_horizontal-300x241.png (101.56 KiB) Viewed 802 times

[Miles]

Accepting some imbalance, I'm leaning towards increasing the number of turns from 4 to 6 and missing out the first half turn from the first module of each phase. Might as well gain the advantage of losing an endturn, too

Reasonable compromise?

I kept the endturn for the sake of uniformity

It makes for a neat connection.

[Miles]

Data for the 6t wind:

Kv 100 rpm/V (estimated)
Kt 0.0955 Nm/A (estimated)
Rm 8.8 milliohms (calculated)
Nominal speed 4000 rpm
Flux frequency at nominal speed 533 Hz
Core volume 8.5222E4 cubic mm (calculated)
Core mass 0.672 kg (calculated)
Voltage @ nominal speed 40V
Total parasitic losses @ nominal speed (Arnolds thin gauge GO 0.15mm @ 1.5T) 40 Watts (estimated)
No load amps @ 40V 1amp (estimated)

[Miles]

Above data in Drive Calc:

[Miles]

Finished designing the stator (for now...)

[Miles]

Comparison with Astro 3220 7t which weighs the same as my 'motor' and has the same torque constant. Not fair to compare theoretical against empirical but interesting nevertheless...

[fechter]

8X less loss at the current limit would be nice. If you can come anywhere close to predicted it will be great.

[Miles]

Just because I like rendering...

[TylerDurden]

Bling!

[Miles]

Bling!

[fechter]

Solid gold windings should have less resistance than copper.

[Miles]

Solid gold windings should have less resistance than copper.

You'd think so but apparently not, which is why they are gold plated silver

Ref: http://www.thecarpcstore.com/cms/index. ... &Itemid=68

[TylerDurden]

And the stator lams?

[Miles]

And the stator lams?

Platinum plated Cobalt alloy

[Arlo1]

Solid gold windings should have less resistance than copper.

You'd think so but apparently not, which is why they are gold plated silver

Ref: http://www.thecarpcstore.com/cms/index. ... &Itemid=68

Sounds like a cheep build so lets get to production.

[Kingfish]

Plating: I believe that to assuage intermetalics between layers that it needs to be Copper-Nickel-Gold.

Quick, place it under glass so it won't get dirty...
A jewel to behold in any Keep! KF