Author Topic: My first axial flux alternator assembly photos (Read 4793 times)

force9BOAT · « **on:** January 01, 2006, 05:27:22 AM »

Hello,

Here is my first effort... Someday I may make a new stator. Mine is not as good looking as others. What great fun I'm having... Comments welcome

LINK

I have one question. I purchased two 35amp rectifiers but I don't understand how to connect them. They each have four blades for attaching wires, 3 oriented one way and the 4th perpendicular. How can I tell which get the AC leads and which get the DC leads?

Thanks all and Happy New Year!!

Rob Miller

Kirkland, WA

dinges · « **Reply #1 on:** December 31, 2005, 10:36:36 PM »

'[...] the hammer I tried first was a bad idea.'

LOL

At least you could get your hammer back loose again. :-)

But you won't win a beauty prize for the stator. As long as it works it's ok I suppose, but what went wrong? Also, I like to cast all the wires in the mould, that way they're much more protected; repeated flexing can break them, leaving you with a worthless stator (or at least, it'll require some major surgery to get it back operational)

What did you mix in the epoxy that you cast between the magnets in the rotors? Microballoons, or talcum powder, or something else? Looks very nice.

Very nice project, and professional looking too, excluding the stator.

Peter,

The Netherlands.

force9BOAT · « **Reply #2 on:** December 31, 2005, 10:51:07 PM »

Thank you Peter,

I agree about the appearance of the stator. Like I said, I may redo that later on. I had laid plastic wrap inside the mold so the epoxy would not stick to the mold. I guess the plastic got kind of wrinkled under the epoxy.

I added "Microfiber Gap Filler" from West Marine to the expoxy on the rotors. It turns the epoxy white and looks nice. Thank you for you nice coments about rotors.

Rob

ghurd · « **Reply #3 on:** January 01, 2006, 12:11:22 AM »

Hi Rob,

Happy New Year!

Looks great to me.

The positive terminal is usually different.

Like a perpendicular terminal, a longer wire, a notched housing corner, or marked '+'.

The negative terminal is usually opposite the positive terminal.

The AC terminals are often marked '~'.

You may want to consider changing the term 'impeller'.

G-

wpowokal · « **Reply #4 on:** January 01, 2006, 02:04:50 AM »

Rob the 4th is the DC positive, the diametrical oposite the negative the other two the AC .

Waterfront · « **Reply #5 on:** January 01, 2006, 06:40:52 AM »

Wow! Nice post! I agree with dinges, professionnal looking, minus the stator, but, since it's gonna be up flying high, who's really gonna see it right? hehe

I like those white magnet rotors, original...

For the rectifiers, I had that same question, if you got them from wondermagnet.com, all you need to do is look closely at the corners, and there's gonna be two corners with wave signs (~) on them, one with a negative (-), and one with a positive (+). AC goes in the waves, DC comes out the + and -.

Good luck with the rest of your project!

hiker · « **Reply #6 on:** January 01, 2006, 03:58:47 PM »

hiker · « **Reply #7 on:** January 01, 2006, 04:01:50 PM »

guess that should be --ac out from alt................

maker of toys · « **Reply #8 on:** January 01, 2006, 04:14:42 PM »

you may find that you are unhappy with the crimp-on connectors once you get your machine out in the weather. If you are going to use them on magnet wire, you'll likely want to use uninsulated ones and run some solder into the joint to keep water and vibration from eating the joint over time. then you can drip a little epoxy on them to insulate the works. . . . the crimp connectors do quite well on stranded wire and under shelter, but they're not as reliable on solid wire or exposed.

on the stator- perhaps some body filler and a coat of paint? 'little paint, little putty, noone will know the difference.'

and I think picmcmillin has a good tip for working the air out of stator castings; his method is to use an orbital sander to vibrate the mold.

force9BOAT · « **Reply #9 on:** January 01, 2006, 04:31:25 PM »

Thank you to all the answered my post. I got a lot of good tips from you all. I hooked up the bridge rectifiers and its working now. This has been a lot of fun. Now I'm starting to work on the prop.

Rob

picmacmillan · « **Reply #10 on:** January 01, 2006, 06:27:49 PM »

below is a picture of some 25 amp bridge rectifiers. you will notice the negative sign, and then the number"252"(denotes 25 amp), then "ac" (which is the positive)..

the steel pin above the negative sign is the negative, and the pin above the word "ac" is the positive.. a rectifier will 2 of each on it usually(one each side)

plug the wires from each phase of the stator to the "ac"(positive) on the bridge rectifiers..and just run the negative wires in parallel to the negative pin(-)...

If you wanted to get fancy, cross the postive to the other side of the rectifier to the other positive(it has two ac's on each rectifier)....some say it makes the genny run better..

i do this, and i havent had any problems...

looks great...good luck..pickster

picmacmillan · « **Reply #11 on:** January 01, 2006, 06:31:11 PM »

forgot to mention in my post above..the white stuff under the bridge rectifiers is dielectric grease..it is used to take the heat from the rectifiers and dissapate it into the aluminum heat sink below..you need both the dielectric grease, and a good heat sink,(nice size chunk of aluminum) to decrease the chance of overheating the rectifiers.. pickster

DanB · « **Reply #12 on:** January 01, 2006, 09:59:25 PM »

Hi Pickster - just a thought....

but if yours is a 12V machine there I thinkyour heat sink may not be up to the task. Ive had much larger heat sinks (with lots of fins) overheat on 12V machines with blades between 10 - 12; diameter.

DanB · « **Reply #13 on:** January 02, 2006, 08:27:08 AM »

looks nice Rob!

I wonder - did you use stainless hardware around teh stator? It may not be as big a deal the way you've inset the magnets, but even very slight cogging may make it tricky to balance your blades.

I also wonder about the use of 90 windings in your coils, #16 gage wire. What voltage system are you planning? I think it may be a touch too slow and the resistance a bit high for a 24V machine - and way too slow/resistive for a 12V machine.

Flux · « **Reply #14 on:** January 02, 2006, 08:53:42 AM »

Yes Dan, I also was puzzled about 38v ac at 250 rpm or whatever it was.

Seems much like a 36v machine but I could find no mention of prop size.

Flux

Ding123 · « **Reply #15 on:** January 02, 2006, 04:35:57 PM »

When I first viewed this post there were alot of pictures.Good pictures.Now the comments have taken the space up, I guess.

I wanted to ask you...where did you buy your supplies and were they expensive?And what a beautiful job you are doing!! I am just learning about this subject and your posting was the best I have seen on this site.......the otherpower.com.

I live in Nova Scotia and supplies are hard to find here.

Any suggestions?ThanksDing123(Dave)

force9BOAT · « **Reply #16 on:** January 02, 2006, 06:46:46 PM »

Dan,

To be clear, 90 turns are too many? The machine will be turning too slowly?

I used a lot of turns because I was concerned that we don't get much wind here. I was hoping that a lot of turns would allow me to reach cut-in speed in light air. I was thinking with fewer turns the machine might not reach cut-in voltage with fewer turns in the coils.

Assuming I have too many turns would it help if I canged the stator from "star" to "delta" format to reduce the voltage?

Thank you,

Rob

force9BOAT · « **Reply #17 on:** January 02, 2006, 10:54:12 PM »

Thank you for your nice comments. You can still see the pictures at my web site: http://www.atm-international.com/RenewableEnergy/Wind/axial_flux_alternator_project1.htm

I purchased the parts from http://www.otherpower.com/kitparts.html for a total price of a little over $500. I've spent an additional $150 or so on miscellaneous stuff. If you have questions about my project I'd be glad to answer. You can e-mail me directly.

Rob

force9BOAT · « **Reply #18 on:** January 02, 2006, 11:03:32 PM »

Flux,

I don't have a prop yet. I was turning the machine by hand. The RPMs was just my best guess because it looked like I was making about 4 revs per second when my multi-meter was reading 38V.

Rob

Flux · « **Reply #19 on:** January 03, 2006, 02:10:09 AM »

You will make things worse in all winds if your cut in speed is too low. You haven't said what voltage you are aiming for yet.

Assuming you are aiming for 24v then it is likely that delta will be a better option, but if low wind output is your main concern then you should have chosen the turns for star. Delta suffers from harmonic circulation in the stator and is always less efficient than star when used with rectifiers. This is not a big issue and without accurate wind measurement you will probably not see the difference so don't be put off delta this time but if you make a new stator bear it in mind.

If you are in a very low wind area you can take advantage of the low cut in speed by using a larger prop but you will have to furl early and you will have more tower loading.

There is so little energy in low winds that it is foolish to try for a cut in of less than 7 mph. If you aim below that you will get nothing worthwhile and you will seriously compromise the performance above 10 mph.

I think that if your winds are average you would manage with 10ft prop and delta.

If a really poor wind area then 12ft and star may do better but you will have a lower top output and will need sensitive furling to protect the windings.

Fit your rectifiers and try it into a 24 v battery and see if you can get an accurate cut in speed before you make any decisions.

Flux

DanB · « **Reply #20 on:** January 03, 2006, 09:08:44 AM »

Hi Rob -

I'm just basicly agreeing with flux here with a couple comments.

If you don't have a tach...

voltage is directly proportional to RPM, so get a digital clock that flashes seconds and just turn it round once per second. You can get pretty close that way so you know volts/rpm.

Like flux said - you'll kill yourself if the cutin speed is too low. Its kind of a common mistake I think. Keep in mind - there is almost 0 energy available in winds below 5 or 6mph... just enough perhaps to get it up and spinning nicely but not much usable. Also remember, that before cutin (before we start charging) there is no load on the blades (they are free spinning) so they'll be running at a fairly high TSR (overspeeding a bit). For a 10' blade, which I assume is about the size you're shooting for here, a nice cutin speed is around 140 rpm - and if you have that, it will do very well in low winds. To get that, with the magnets you have there - you want about 70 turns in your coils and you should be able to fit #14 wire. I assume you're shooting for a 24 Volt system here?

picmacmillan · « **Reply #21 on:** January 03, 2006, 09:11:25 AM »

ya

thanks dan ..that was my first attempt at a heat sink a couple years back, but about that time, i seen your post about your heat sinnk being too small, and i remember that yours was 5 times the size of mine, so i quickly deducted that i needed to improve

thanks dan pickster

Gary D · « **Reply #22 on:** January 03, 2006, 09:20:36 AM »

Would a possible partial solution to the high number of turns per coil be to connect only three coils per 3 phase? In other words there would be 3 separate 3 phase sets... The rectifiers would need to be mounted on the top at the machine, similar to Hugh's plans though. Just a thought since the coil wires aren't burried in resin... Maybe bring up cutin speed enough to adjust the rest out with airgap opening? That's assuming it's for a 12 volt system and 10 foot blades similar to Dan B.'s design. The output would still suffer some due to the thinner wire, but could be usable(less chance of a stator meltdown)? Could just talking out of my butt here, hopefully flux or someone could verify or shoot down this possibility. Good luck, nice presintation Gary D.

paradigmdesign · « **Reply #23 on:** January 03, 2006, 09:25:52 AM »

Looks nice, but I was just wondering why you placed the magnets so far in on the disks? It seems like it would be better for gaining output to have the mags as far out on the disk as possible in order to max out the diameter the stator can be.

Gary D · « **Reply #24 on:** January 03, 2006, 10:34:44 AM »

I didn't explain the 3 separate 3phases at all, sorry. If you choose any coil as #1, then count over to #4 then to #7 those could be one 3 phase. The next would be #2, #5, and #8, that would be the second 3 phase. #3, #6, and #9 would be the third 3 phase. All 3 phases needing rectified separately. This would drop your resistance by two thirds per phase, similar to having "three in hand" (more like zubbly's motor conversions). Also it would increase cutin speed. You would then run DC down the tower, if this makes any sense... Gary D.

force9BOAT · « **Reply #25 on:** January 03, 2006, 03:38:01 PM »

Dan and Flux,

I want to thank both of your for your guidance. I built my stator without really knowing how many turns I should use. It was just a guess and I was concerned that I could not reach cut-in speed with less. This machine was intended as a 12V charger but I see now its not optimal for that. Before I spend a lot of effort trying to rework the stator I think I will switch to 24V and see how that does.

The next question I will have is how to make use of 24V power. I've got a number of devices and gadgets that run on 12V but I've never used 24V. Do you know of some web references I could read to get educated on that?

Thanks again,

Rob

picmacmillan · « **Reply #26 on:** January 04, 2006, 06:25:42 AM »

hi rob....my first stator i built was wrong also..i thought that the more turns the better ,.so i did 200 turns of #18 wire 0-0 way too many turns..i also didnt know you had to put a lid on the mold and squish it flat..so, of course my stator is just a visual aid now, but i do use if for that...best way to build in my opinion is to follow someone like dan, or anyone else who has a working project for the first time, then branch out...that will minimize the cost of a working turbine..what i did was what i believe you are going to do, and that is to now make that stator work and to change everything else to use that stator...from my experience it makes the whole rest of the project a challenge to match all the components up....i know that your next one will be real nice, and look forward to seeing it....it is better in my opinion to make a 12 volt machine first as the bigger voltage comes with more cost for other things in the system as well....good luck...pickster

dinges · « **Reply #27 on:** January 05, 2006, 09:31:07 AM »

Same story here; too many turns per coil on my first (well, actually 2nd) stator.

For my mini genny, I first used 70 turns/coil. But voltage was low, so I made a new stator with about 130 turns/coil, so I would get decent voltage at lower RPMs. A little voice in the back of my head was saying 'it can't be as easy as that' and the voice was right: when cut-in RPM is too low, you genny will stall... Then again, I'm glad I learnt this lesson on my mini-genny, instead of the soon-to-be 10 footer.

If it sounds too easy to be true, it probably is. My friends say I'm pessimistic, and that when I say something -may- work, it WILL work

Peter,

The Netherlands.

quote: 'if you think you can, you won't; if you know you can, you might.'

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Author Topic: My first axial flux alternator assembly photos (Read 4793 times)