Electric Motor Secrets

[Necchi]

(I think this is the term you were looking for in your last post btw - Armature (electrical engineering - Wikipedia, the free encyclopedia)).

On second thought I guess this is wrong since the whole drum is the armature. I've tried again to think of a term and I came up with "armature conduit". So the lindemann cross has 2 armature conduits, and my diagram also has 2 armature conduits. Or you could say magnetic conduit or magneto-conduit.

[Beshires1]

Yes, thats it "armature" , I was experiencing confusion (the results of a brain fart). I said that your design would have little or no torque thinking about it having a iron armature. Now throwing that aside, if you plan on a PM hub motor that would work. Of Course it would not be as efficient, as the Iron armature attraction motor(It would consume a lot more battery), But it would give you a lot more torque, and higher speeds on the flats. But you might gain some battery coasting down hills. But only if it is brushless.

[Necchi]

No I don't want a PM motor, I want a lindemann hub motor, or at least to rule out the possibility. I'm currently looking into non permanent ceramics as the material for the rotor in my drawing.

[Jetijs]

Necchi, I see another problem with your design. Lets suppose the rotor is turned so that the stator pole is between two rotor poles. If you apply the power to the coils now, it will try to go both ways as the attraction will be equal to both rotor poles.

[Necchi]

Is that not also an issue with lindemann's cross design? Or do you mean at the low rpm of a bike wheel?

"At 10 MPH a 27 inch bicycle wheel would be turning about 125 RPM, a 24 inch one about 140 RPM"
--http://www.fieldlines.com/story/2006/10/16/113432/61

[Beshires1]

Necchi, I see another problem with your design. Lets suppose the rotor is turned so that the stator pole is between two rotor poles. If you apply the power to the coils now, it will try to go both ways as the attraction will be equal to both rotor poles.

Yes this is true but... Its also true that if yours stops with the rotor aligned up with two stator poles it will experience lock-up. This is why most electric motors have a odd number of poles between the stator and armature. So that its impossible to have these "dead "spots. In case you missed it back up in this thread and look at the design I posted This addresses this issue. Especially if you want to build a self-starter.

[Necchi]

...most electric motors have a odd number of poles between the stator and armature. So that its impossible to have these "dead "spots. In case you missed it back up in this thread and look at the design I posted This addresses this issue. Especially if you want to build a self-starter.

Is it possible to contrive an arrangement which causes the rotor to always accelerate in one direction without an intelligent circuit?

[Beshires1]

Is it possible to contrive an arrangement which causes the rotor to always accelerate in one direction without an intelligent circuit?

Honestly I don't think you can with an all metal, Iron armature. Basically its because your creating a magnet to metal attraction. when ever a coil is pulsed the iron will go to the closest magnet field be it forward or backward. When you run a magnet over a piece of iron that is relatively the same shape of the magnet, the iron will jump to the magnet and stick, usually on the edge of the magnet. because the attraction will grab the iron before it centers the magnet. That is why I think the iron armature should be round this will rotate the shaft to the closest point of contact, at which time the magnet turns off. The timing controller could be reed switches or hall effect.

[Jetijs]

Hi all
Here's my first attempt of prewinding coils. At first I built a block from acrylic that is exactly the shape of my stator poles. There is a hole drilled through the block so that I can bolt two end plates to that block that will hold the wire from the sides. Now I wrapped a piece of baking paper around the core, because nothing sticks to this stuff. I put the end of the bolt in a lathe and set it to rotate at the slowest possible speed. I pulled the wire hard in the winding process so that the windings get as dense as possible. When the first layer was wound, I covered it with some epoxy resin (the kind that is used in gluing glass fiber). Then I wound the next layer backwards and again covered it with epoxy. I wound five layers this way. When the 5 layers were done, I put another layer of epoxy on them and let it cure. After that I just unscrewed the bolt, removed the end plates with some gentle hitting and pushed the core piece out. I used 1.3mm thick wire for this test coil. I calculated, that 5 layers should make the coil "wall thickness" exactly what I need to be able to slide the coil on the core. Unfortunately a wire this thick does not bend too good and the wall thickness became bigger. But this was just a test run to see how this works and if I will be able to wind it properly when the time comes. Works good. But I will need to use a smaller gauge wire. I think 0.9mm wire should be fine.
Here are some pictures:




Edit: I made another test coil using 0.7mm thick wire, this is almost 2x smaller wire diameter than with previous coil. This time it was a lot easier to wind the coil and everything came out much better. My calculations show that with 0.7mm wire I can wind about 100 windings till all of the allowed coil area is filled. That makes about 50 turns of bifilary wound coil. In this case each of the coils will have about 1Ohm of resistance.


Anyway, this is a great way to make prewound coils, it is a LOT easier than winding the coil on the stator directly and you can do this alone without any help from others.
Thanks,
Jetijs

[Jetijs]

Got my Christmas present early this year. I found a guy who was willing to do all the lathe work before holiday season. All the parts that I could not do by myself are now done. Tried the prewound coils on the stator - works very well. This is great because I will have something to do during the long holiday season



Thank you and Merry Christmas to you all!

Jetijs

[broli]

Looks very nice indeed. I also didn't know you were making two. Are they part of the same system or are you going to make two separate motors?

[Jetijs]

Look at previous posts in this thread. I am making two separate motors with shafts coupled together and offset timing for each motor so that when one motor rests and moves only with the inertial force, other motor switches ON and takes over the load. So that there is no inertial movement and the system operates at 100% ON time. Should give some very good results

[ren]

super nice JET

Love your work. Those coils came up a treat. Im rebuilding the window motor and pre fab'd coils like that is what I am going to do. Make for easy removal and testing etc. The resin is a great idea too.

I like your train of thought with the two rotors coupled together on the same shaft being out of phase with each other.

Keep up the good work

[Jetijs]

Thanks Ren

[aladinlamp]

Hi Jetijs
how will be your rotors attached to the shaft?
thanx