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Axial DC motor project

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Amish_Fighter_Pilot:
Hello everyone. I'm planning to eventually create our own power systems around this property instead of the gas generators we're currently forced to use. We're being denied utilities by the city and power company so we've had to be creative...

Anyway, the motor I really want to build is a axial flux type motor, but I do not want alternating current. I know that DC axial flux motors are absolutely a thing because many electric vehicles use them. What I don't see is people building DIY versions as generators. So getting the information I need is proving harder than I'd hoped.

So, my plan for a test version of this general idea will probably use hard drive magnets. They're by far the easiest magnets for me to get and I will be creative to make them work even though they're oriented the wrong damn way for most things. I will be putting them on an axle and then I'll spin them over my stationary windings. I plan to take the same pole for all the magnets and orient it so the disk they are on makes one big ring magnet basically. Its going to look really weird because the drive magnets are curved, but that will be fine for a test model. I'm using recycled motor wire for the windings, so this thing will be quite the recycling project.

Wiring the armature is more of a complicated topic though. What I think I want for best copper density is two rows of windings, one forming a smaller "inner track" and one "outer track". The exact shape and configuration of the inductors is definitely somewhere I need help. I'm assuming the wedge-style inductors common on DIY wind turbines here would be acceptable. I'm assuming air core is probably best for this job, but I'm open to suggestions. Wire gauge, number of turns, and exact dimensions of the coils is still undecided. I was considering wiring the coils in parallel, but maybe in groups of series parallel. It would be nice to keep the output in the 12V range, but even up to 48V is pretty workable. If the output potential gets a lot higher than that, I do have a magnetic DC transformer I invented that could be used(though I don't know how efficient it is yet).

The first version of this motor will be tested by compressed air through a "Tesla Turbine", so the rotational speed should be pretty consistent at a given pressure. So, basically the rotational speed can be set to whatever I want and kept there.

hiker:
Some of those H. D. mags have a n. S. Pole on the same side..they snap in half fairly easy..use a vise or a pair of vise grips...easyer to do if you score one side with a hack saw..been a few members here that have built wind gens with h.d. Mags..check out the search box ...top right ?

Amish_Fighter_Pilot:
I did find quite a post where the guy was cutting them in half. That's certainly a much easier-to-handle size even despite the slight curve. I may try that.

Any thoughts about sandwiching my coils between moving magnets on both sides of the disk? I've seen this configuration on commercial products, but all the DIY versions are AC that I can find. I'm pretty adamant about getting low-to-no-ripple DC out of this thing.

joestue:
you can't get dc out of a changing magnetic field.

the only way to get ripple free dc power is the homopolar motor. its a practical option for a few tasks, such as making 1 volt at thousands of amps for electrowinning copper, before the invention of the diode. that's about it. there are superconducting homopolar motors being used for ship propulsion.

anyhow, 3 phase is sufficiently ripple free once you add an inductor and capacitor to the rectifier. if you need better, there are some practical options, such as 5 phases.

computer hard drive mangets are about ideal for an axial flux machine, on the order of 6 magnets, so that would be 12 poles. yes you can break the magnets in half and then cluster them together to make a larger machine, or increase the pole count beyond what is practical.

as far as the size of the coil: hard drive manufactures are interested in the highest angular acceleration they can get that read head moving for the least mass of copper: which means the coil is actually very close to ideal in terms of diameter, inside and outside diameter ratio and thickness.

if you want to make a compact axial flux motor, copy the profile of that coil and make (i think, 18) similar coils. squash the coils together so you get the overlapping, 2 layer, 3 phase coil structure, and make an axial flux machine from the magnets pulled from 6 identical hard drives. plan on finding more than 6 identical hard drives because some of the magnets will break when you pull them off the mu-metal backing.

Amish_Fighter_Pilot:
I'm not planning to make a changing magnetic field. I'm confused by what you mean by that.

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