Author Topic: Mini Dual Axial Project  (Read 12190 times)

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Offline Bryan1

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Mini Dual Axial Project
« on: January 12, 2012, 04:45:50 am »
G'day Guy's,
                    With the left over neo mag's off my 4kw motor conversion project (soon to come) I decided to have a go at making a mini dual axial genny. As I had enough magnets + one spare I decided on doing a 16/12 config.

This is the cad image of the coil/magnet setup

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Next is a pic of one of the mag rotors just cast

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A pic of the front mag rotor all machined up to true it and painted

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Here is the mount I made for it

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All setup ready for the one coil test

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My crude but effective test setup, I used some plastic tube and used somw magnet wire to connect it then powered it off my 50 volt DC motor using my 30 volt lab psu.

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here is the result from the test coil setup

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This weekend I'll get the stator all wired up and the stator mold sealed with my free motor winding varnish (which is a great MDF sealer) and grab a new bottle of catalst for that 4kg's of fiberglass resin I have here so I can get the stator done.

I do have my eye on a 170x50mm x3.3metre straight grain Oregon plank at work and tomorrow I'll ask the boss as it's not going to be used if I can have it for my blade set for this project.

More to come.....

Regards Bryan

 


Offline ChrisOlson

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Re: Mini Dual Axial Project
« Reply #1 on: January 13, 2012, 01:15:22 pm »
Hi Bryan,

Looks to me like you'll get 12 volts DC out of it at just a little less than 200 rpm (assuming you wire the stator in wye).

Are those little magnets about the diameter of a nickel?
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Offline oztules

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Re: Mini Dual Axial Project
« Reply #2 on: January 13, 2012, 03:42:23 pm »
I'm not sure your resistance figures are correct......     0.11R for the coil, and 0.16 for the leadin.... 45 turnsof wire for 0.11r and a few inches of wire for 0.16.... are you sure about this?

If 24v then around 370-390 rpm cutin. What blade size are you considering.... 2meters?



..................oztules
Flinders Island...... Australia

Offline Bryan1

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Re: Mini Dual Axial Project
« Reply #3 on: January 13, 2012, 04:49:34 pm »
G'day Oztules,
                       When I short the leads of my fluke 865 scope meter the reading isn't zero it is 0.16 ohms so to correct the ohm reading I have to subtract that figure from the result. Today's jobbie is connecting the coils on the stator and hopefully get it cast. next weekend is a trip to the salvage yard to find some hardwood for the blades and Yes I am going for a 2 metre blade set for this project. Also our house array is 24 volts so yes the cutin will be around 380 rpm.

Cheers Bryan

Inspired to get going again after a night of sparkling ale......

Offline ChrisOlson

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Re: Mini Dual Axial Project
« Reply #4 on: January 13, 2012, 05:10:18 pm »
Bryan, what is the size of those magnets and what air gap you using?  It would be interesting for me to try to figure backwards to see if I can figure the flux density in the air gap with those.
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Offline Bryan1

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Re: Mini Dual Axial Project
« Reply #5 on: January 13, 2012, 08:54:46 pm »
Hi Chris,
             The magnets are 16x13mm diameter and N50 grade. Off memory with the single coil test the air gap was 16mm. Anyway I got 2 phases wired up on the stator this morning but I had to go take the sons car back to the mechanic and by the time I got home the yard arm was waiting for me. Anyway with my elcheapo DMM each phase measured 0.8 ohms. Once I get all the wiring done I use my fluke 865 to accurately measure each phase. In the morning I'll get the stator finished and have it all ready for casting so I'll take a few pic's.

         I will see how the high cutin goes and I might endup making a new stator using thinner wire so I can get the cutin for 24 volts down.

Regards Bryan

Offline Norm

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Re: Mini Dual Axial Project
« Reply #6 on: January 14, 2012, 08:24:40 am »
Nice Byran,
     Showed the wife....see other people have clutter around their workbench too!
and she says.....'but that's not in the kitchen ! '
to me I'm impressed with the results.
Like your shop....I'll trade you any day !
BTW I'm not that into FaceBook but wife tells me yours just
has to look for Barb Fritzsche and ask to get on her facebook
and she will yes it okay?
Norm (& Barb) :)

Offline Bryan1

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Re: Mini Dual Axial Project
« Reply #7 on: January 14, 2012, 07:17:12 pm »
G'day Guy's,
                    Anyway got the stator all hooked up and took a few pic's so here goes...

This one is for Oztules showing the shorted leads





The Ohm reading from the U phase



The Ohm reading from the V Phase




The Ohm reading from the W Phase



I silver soldered the joints together then used self amalgamating tape to seal them



A pic of the Stator




Now as the shorted leas read 0.15 ohms this has to be taken off the Ohm reading so the average is say 0.70 Ohms less the 0.15 ohms which will make it 0.55 Ohms on average.

It does seem everyone goes with a star config so I reckon thats the way I'll go too.

Anyway got a brew of Ginger Beer to bottle then I can get on and get the connections finished and get the mold finished.

Cheers Bryan

Offline oztules

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Re: Mini Dual Axial Project
« Reply #8 on: January 14, 2012, 09:22:25 pm »
 Thanks Bryan.
It's a shame the DVM's dont have a zero function to calibrate the R scale..... not even the expensive ones apparently.

Good low R in the stator. Should control your blades pretty well.


.............oztules
Flinders Island...... Australia

Offline rossw

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Re: Mini Dual Axial Project
« Reply #9 on: January 14, 2012, 10:03:24 pm »
It's a shame the DVM's dont have a zero function to calibrate the R scale..... not even the expensive ones apparently.

I have a "reasonable" one - Uni-T UT71E (cost me about $150).

5 digits, reads ohms to 2 decimal places - but *DOES* have a "relative" mode, which works perfectly as a lead "Zero".

If anyone has a meter with a relative mode, it works nicely as a pseudo-zero.

Offline Bryan1

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Re: Mini Dual Axial Project
« Reply #10 on: January 21, 2012, 06:48:53 pm »
G'day Guy's,
                    Nice sunny day here so got the stator wiring all finished and the mold done. Just need to wait for the ISONEL 642 varnish to dry then I'll be ready to grease everything up and get the stator finally cast.

The Mold



The Finished Stator



The ISONEL 642 I used to seal the MDF mold to make it waterpoof



Anyway hopefully in the hot sun that varnish will go off rock hard and I can get the stator cast this afternoon.

Cheers Bryan

Offline Bryan1

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Re: Mini Dual Axial Project
« Reply #11 on: January 25, 2012, 07:35:54 pm »
G'day Guy's,
                    Well sanded back the mold this morning and greased it all up then decided to go for it and cast the mold. I mixed up approx 900ml of fiberglass then added some Q-cell in and got the amount just right with the only wastage coming from when I put the lid on and sealed it up. Not too hot today so got the mold out in the sun so it can cure and hopefully this weekend it can come out of the mold.

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                   Now for the question as it is full summer here and the average temp will be around 30C in the shed would saturday be the right time(thats 2 days) to pull the mold apart ot should I wait longer.??????

Cheers Bryan ( Hiding the last of the homebrew ginger beer from the missus as she near polished off the lot)

Offline oztules

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Re: Mini Dual Axial Project
« Reply #12 on: January 25, 2012, 11:59:13 pm »
"or should I wait longer"
Due to an energetic mutt that bumped me while I was pouring in the hardener/catalyst.... mine took about 8 minutes... complete with smoke coming out the sides and all the attendant excitement. It was stuffed to the gills with glass matting, and that saved it. It has been flying for about 4 years now.... so depends how you mixed in the ratios and temperature.

Here is the instant stator :
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And the critter that caused the high speed curing..
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In other words.... err.... how long is a piece of string????



...............oztules
Flinders Island...... Australia

Offline Bryan1

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Re: Mini Dual Axial Project
« Reply #13 on: January 27, 2012, 04:47:07 pm »
G'day Guy's,
                    Well first quiet friday night in ages so got on early this morning to get the mold out of the stator. After taking all the clamps off and the top not coming off I knew I was in for some fun. I had to basically cut the lid of in small bits and found out the top had completly stuck to the top of the stator. When I got the top completely off a few taps got the mold moving but the centre came out with it. Anyway not be to be put off I went and got my head knife and proceeded to skive off all the mdf. So although the mold did pass the water test and it was fully sealed all I can say if one does want to a mold out of MDF you have been warned....

The mold and result



The Head Knife used to skive the MDF off



The Top of the stator



The Bottom of the Stator



I did see a few wires were exposed on the top of the stator so first job is paint some of that varnish on to totally seal the stator then I'll do a top coat.

Now as the stator is only fiberglass with some cloth on both sides I do feel if I need to short the winding in wild weather it could break the stator so I'll make up some perspex and glue them on both sides to give the stator outer a bit more strength.

Got a few house jobbies to do then I'll get back to it and hopefully tomorrow I can get the lathe test done setup and done.

Cheers Bryan

Offline oztules

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Re: Mini Dual Axial Project
« Reply #14 on: January 27, 2012, 08:33:50 pm »
I was trying to find a mold amongst the bit of wood..... but I couldn't.

I was worried mine would do that, so placed a garbage bag in the mold.... so I knew it would come out. (mine was chipboard)
It works but gives a textured look to the stator... makes no difference, just looks poor.... but at least it won't stick.

That aside, the stator looks pretty sturdy, the perspex won't lend it any real support, you may be better to just add another layer of glass over the top each side. This will seal your wounded wires, and add real strength to the stator.

Mine is supported in 9 places with 1/2 inch bolts. I regularly short break it (all the time actually) from power as high as 5kw.... with no ill effects.

(My Electric Vehicle charges from the mill. Plug it in, the mill starts, when the car is full, it just turns the mill off..... it does not wait for a lull in the wind)

It's coming together nicely by the looks.


...............oztules
Flinders Island...... Australia