9" Radial Axial - Mags on Armature - Renderings

[arc]

Hey All,

Just thinkin' out loud here, feel free to chime in and cut it to ribbons if you like. I haven't put more than a few hours of thought in on this yet so it won't hurt my feelings one bit. Not trying to reinvent the wheel, pretty similar to an induction motor in many ways and there are probably others who have gone this route in making an alternator, I haven't really looked. My thoughts stem from using what I have around or can easily obtain and my belief that using the greater speed at the perimeter can be used to some advantage.

Another low budget build here.

Magnets:  28 Neos 1/2" Diameter x 1/2" length

Coils:    21 wound one direction - number of wraps and wire size TBD

Rotor:    ~9" Diameter

Wiring:   3 Phase Star

Cut-In:   ~200 RPMs - TBD but this is my estimate at this time

Blades:   3 with 5 blade option

Diameter: 36" to 60" - Depends on coil wraps and wire size TBD

Voltage:  Anybody's guess but hoping for 14.2V min. @ 300 RPM under light load

Aperage:  Very Low

My reasoning here is that I would like to use a 9" Diameter brake disk for the rotor. I don't know how hard the steel is, hopefully it can be cut with a hacksaw or jig saw then the bottom of slot filed to shape.

An axle assembly with hub and disk would be ideal. Perhaps I can find one for a small car, ATV or riding lawnmower that would work. Ideas?

If there is no backing plate then I will manufacture brackets to mount the stator.

(I even thought about making a laminated rotor but I'm not sure if I would gain anything and manufacture would be a bit more work I think - haven't ruled it out entirely yet)

Currently I don't have a clue of what would make the best laminated stator rings but if I can use sheet metal then I know I can make them. I am assuming they need some insulating layer between plates to cut down eddy currents but I'm hoping this design will provide a good path for the flux lines to follow.

I would probably rivit the plates together to keep them tightly compressed and uniform. Drilling is relatively easy and if I chamfer the holes for the windings and break sharp edges I should be able to avoid shorts. I would likely impregnate the coils with super glue or resin if I can figure out a way to keep it contained and to get it to penetrate well. I suppose I could just cast the stator one side at a time if you think it's needed.

arc

Slim Compact and fairly lightweight overall.

Lamination should be nice and rigid, just lots of holes and slots to cut.

Holes in Laminations will be drilled then sawed after to cut the slot.

Here I've removed the Laminations to get a better view of magnet to coil relationship.

Spacing is shown with 28 Magnets and 21 Coils.

Nice narrow air gap is the plan

Inside diameter of coils is 1/2" wide x slightly longer legs.

At least 4 Stand-offs using threaded rod to allow for adjustment.

[Flux]

You are just reinventing the wheel but doing it in a way that is less effective than has been done for the last 100 years.

Alternators have been built that way from about 1880 onwards but most used wound fields until recently, Permanent magnets made little inroad until neo became available.

Never in that 100 or so years has anyone chose to leave out most of the coils and stick to this 4/3 ratio single layer winding. It just happens to suit axial air gap machines, it makes no sense in a radial iron cored machine.

The fundamental problem with iron cored machines is that they need very specialised magnetic steels to work acceptably with reasonably low loss. For the average person the only option is to adapt a commercial core ( motor conversion).

Wind is particularly demanding in that the efficiency needs to be highest in the lowest wind. All conventional alternators are designed for maximum efficiency at full load and under those conditions the iron losses are not serious and in fact you trade iron loss for copper loss with maximum efficiency when the iron and copper losses are equal.

A wind alternator with high iron loss doesn't work in low wind, something we fought hard with for many years and it was something of a revelation when we suddenly had magnets strong enough to get rid of the iron completely.

Yes it is perfectly possible to build what you propose but you need the patience and experience of Ed Lenz to put up with the physical challenges and even then you will have core material costing several times the magnets. If this is a labour of love but no cost project then avoid iron cores at all cost.

Flux

[arc]

well, I'd rather hear if from you than to go to all the work of building it then discover it will only light one LED.

As always, appreciate your comments.

arc

[ghurd]

Under the "cut it to ribbons" section,

Never sink magnets in an iron hole.  It sort of shorts out the flux.

Seems like a lot of work (and more money) for basically a large diameter, very thin, motor conversion.

G-

[arc]

Hi Ghurd,

I just learned something then, didn't realize that burying the magnets would mess up the flux ... now that you pointed it out, it makes good sense.

I guess the plan is to let the magnets do their thing and just draw from that potential with copper windings moving through the path of the natural flux lines.

At the far end of that flux loop, iron (if placed along the natural flux path) helps bridge (or complete) the circuit to bring it back home to the (attracting) opposite pole. I can see now how "burying" just bridges ("shorts out") the circuit right at the magnet so it doesn't ever reach out to where it can be utilized by the windings.

It's bad enough having rather small magnets ... let alone squandering the potential that they do have. I can sure see how attracting poles placed at that far end of that loop (on the opposite side of the windings) helps tremendously.

Yup, dual rotor axial (with attracting, adjacent poles) is the way to go. I can still place the neos near the perimeter of the 9" disk (on just one rotor for now) and still come out way ahead (of anything like what I've shown above).

Flux ... Ghurd ... ya both saved me headaches, broken knuckles and some major disappointment in the results. So thank you for that ...

If I ever go the radial route it should definitely be with another conversion.

They have shaft, bearings armature base and fields in a handy package and have some potential if the right one is chosen and it's done Zubbly style. I'd make sure I had access to a lathe and learn to pour resin if I were to ever try one again.

I'm convinced that a small axial designed in such a way as to allow more magnets to be added later would be a fun project that might be able to take advantage of the poor wind conditions here and still produce some usable energy.

Thanks for the input!

(Literally, "back to the drawing board")

arc

[Airstream]

Please don't take offense, you've done some precision renderings that I'm sure you took some time with...

I have to point out the waste in using 600kb of images where 60 or 80kb would have sufficed. Non-photograph graphic images can use a very small file size and still have all the information present that was intended.

The following two images were stolen, starved, and snuck back into this post are 1/10th the size of those posted above. The first has displayed colors limited to 128 and the second 64, both were blurred slightly even before saving at the lowest JPEG setting.

Don't get me wrong, I think the pictures up above are Art, but the reason I post this tip is I just spent four minutes on dial-up looking at bars and blocks loading one line at a time across all your eight images, I could not view one while the others loaded. And maybe 8kb or 11kb is extreme but few images warrant more than 50kb or 60kb when 640x480 format, and with the auto-scaling web browsers even a 500 pixel image can work well.

[arc]

Hi Airstream,

No offense taken ("so it won't hurt my feelings one bit"), I'm glad you said something so I won't keep making the mistake. I may be up on dial-up soon myself, so your comments do resonate and I can relate to having to wait for painfully slow, huge files to download.

I was trying to be sure to comply with the pixel restrictions and never even looked at the file size, my apologies to all who were effected by these.

With that in mind, I can always show an abbreviated version here and link to my Flickr account for higher resolution drawings showing greater detail if I feel that's needed.

Thanks for pointing this out, point well taken and I'll be more thoughtful in future posts.

arc

[arc]

They should be quite a bit better now, I got them all pics down to the neighborhood of 12-15kb file size now ...

... surprisingly enough it doesn't make that much difference to the eye.

arc

[ghurd]

They still look great.

Curious.  Can you save them as a gif file, and if so, how drastic is the quality change?

G-

[arc]

Quality doesn't suffer any as far as I can tell ...

... but the file size is more than half again as large.

Jpg file that was 97k went to 166k when I converted it.

A good use for gif's though is for small animations which are larger than still pics for the same pixel size but can be a reasonable file size, if kept to around 10% of allowed picture size (or 64 pixels) width.