| These tests were done so i can come up with a suitable design for a stator for my new 24v, 14" diameter alternator. This stator will be very similar to my last 3 phase stator (9 coils) and will be aproximately 18" in diameter when the final casting is done. First, i have to come up with a coil design i think is adequate. To do this i made a new winder pictured below.
Here you can see how i waxed the inside of the winder so the crazy glue does not stick to the wood winder. This winder produces a coil 1/2" thick and the hole in the center is large enough to allow a magnet to pass through.
This coil is made with 2 strands of 14AWG wire. There are 47 turns. The hole in the center of the coil is large enough for a magnet to pass through with out covering other windings. In the end i might have to shrink the center a little. I know it will lead to slight losses, but as i stand now, I dont think i can squeeze the right amout of wire in to the coil with out it being too wide (i need 4 or 5 more turns). my other option, is to make the coil thicker or use smaller wire. i really dont want to do either. i havent decided what to do about this yet.
Here is my test coil. These coils are rather large and i had to figure out a way to hold it in the lathe securely. I ended up making a mould and casting it. there is a quarter next to it for scale. the big bolt allows me to clamp it securely in the lathe swing arm.
here you can see how i welded "wings" on the bolt to better secure things. it worked out well.
here is me. :-) im using the big turret lathe.
here i am turning it at 66RPM. The volt meter reads 3 volts. My air gap is kinda wide still. I might try this again with it decreased. I might get better results.
here is a better shot of how i clamp the test coil in to the swing arm. This makes it very easy to position once it is clamped.
This is a good equation for figuring out RPM and frequency. I obviously can read frequency with my meter so i didnt really need this. It is however, handy when you are dealing with multiple coils (with a single coil, you can read frequency directly). my test data is in the box. I will wire this stator in star, so I can say the following:
- RPM = 3vac x 3 coils x 1.73 = 15.57
- RPM = 4vac x 3 coils x 1.73 = 20.76
This falls a little short of my expectations. I wanted this machine to cut in at around 75 RPM. As it is, it looks like it will cut in at aprox 95-100 RPM. I need to find a way of winding my coils a little tighter and i think i can fit the right amount of wire in. I also want to shrink the airgap a little. I think this will make a big difference.
having fun as allways!! :-)
RoyR |
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