Electric Motor Secrets

[Jetijs]

Ok, thank you Peter
I guess this is why my grammar spelling program always underlines the word startor I will use the correct word (stator) for now on

[Peter Lindemann]

Looks Good to Me

Ok, how about this?


The startor pole arc is 70 degree of an arc, so is the rotor. Also there is a little bit wider area at the shaft hole.
Thanks,
Jetijs

Jetijs,

This looks like a viable physical geometry to me. The system should be capable of high torque and high speed. In fact, your motor re-wind shop may have a stator very similar to this IN STOCK. If so, we should look very closely at what they have available, as it may save you the step of building the stator from scratch.

Does anybody else have something to add?

Peter

PS.. Jetijs, you may have noticed over the course of the many posts here, that I use the word "stator" and you use the word "startor". The correct English word is "stator". The word is derived from the word STATIONARY, meaning the part of the motor that does not move. The word "startor" is slowly creeping into usage in place of the proper spelling of the word "starter". A Google Search on these two terms shows that the word "startor" shows up 13,000 times, whereas the word "starter" produces 147,000,000 hits. Either way, the word refers to something that initiates a movement, usually the operation of a large engine.

[Jetijs]

Thanks for your opinion, elias

[elias]

Ok, how about this?


The startor pole arc is 70 degree of an arc, so is the rotor. Also there is a little bit wider area at the shaft hole.
Thanks,
Jetijs

Jetijs,

I think that this rotor will fly to about more than 6000-7000 RPM. This one I suppose will have about 50% more mechanical output compared to the geometry of you previous motor in my opinion, not considering your small airgap, which will increase the torque way up. Wider stators may increase the effect of attraction. I think that this is a very powerful design. I am getting really excited about your new design.

Let's see what Peter has to say.


Elias

[Jetijs]

Ok, how about this?


The startor pole arc is 70 degree of an arc, so is the rotor. Also there is a little bit wider area at the shaft hole.
Thanks,
Jetijs

[Peter Lindemann]

SR Motor Design

Jetijs & Peter and All,

I've been following this thread closely, and would like to "Build Along" with this next project. I know too many Chiefs spoil the Pot; so I'd like to offer my suggestion (4 rotor, 6 stator) as a compromise for consideration. Which ever motor design is selected for the next build project, works for me.

- Schpankme

Schpankme,

Thanks for joining in the discussion. The 4 pole rotor mating with the 6 pole stator is one of the standard designs used in Switched Reluctance Motors. For high torque with no recovery, this design works extremely well. The main problem with it for our purposes is that it does not provide space for a "pause" between one set of coils going off before the next set of poles are in alignment and read to turn on. When you FORCE the switching, there are huge CEMFs to overcome. The switching has to allow for the natural decay of the magnetic field before the next field is produced.

In a Switched Reluctance Motor, the magnetic field in the stator never really decays. Its intensity stays pretty high all the time. The rotor turns because the POSITION OF THE POLE FACES are moving. One set of coils goes off at the same moment another set of coils turns on. That's why it is called "Switched Reluctance".

What we are wanting to build is really a "Pulsed Reluctance" motor where the magnetic field in the stator turns ON and OFF completely before switching to the next position. This requires a slightly different physical structure in the stator.

I hope this helps you understand things a little better.

Peter

[Peter Lindemann]

Good Start

This is what I have came up with so far:


The whole diameter of the startor is about 100mm. This design will have plenty of space for bifilar windings. The rotor piece is about 40mm in length. I don't know if I should make the middle part of the rotor thiner and the ends wider or not. Has anyone any thoughts? Don't mind that gap, this is only a sample drawing

Thanks,
Jetijs

Jetijs,

This is a great start. It looks like the open space between the stator poles could be a little bit smaller. See what it looks like with the stator pole faces at 70 degrees of arc, and the open spaces at 20 degrees of arc.

I agree with Steven about the width of the rotor. Its dimensions should be straight across the stator pole faces or even slightly wider around the shaft so the magnetic field doesn't get pinched there.

This geometry allows the rotor to be in the attraction mode about 75% of the time, so mechanical energy production should be quite good.

Peter

[Peter Lindemann]

Other Possibilities

Peter

which bi-filar winding do you use ???

Four types of bi-filar wound coils
parallel-wound, series connected
parallel-wound, parallel connected
counter-wound caduceus coil (series)
counter-wound caduceus coil (parallel)

Thanks Kevin

Kevin,

Thanks for joining the forum and asking this question. Actually, when I use the term "bi-filar coil" it simply means two strands of wire wound on a spool at the same time. That's all it means. These two strands of wire can be right next to each other, or wrapped as a twisted pair. The term "bi-filar" does not connote whether or not these two strands of wire are connected to each other. In all of John Bedini's motors, the bi-filar or tri-filar windings are separate, and connect to different parts of the circuit. Likewise, in these motors here, the purpose of the "bi-filar" winding is to increase the induction between the strand of wire used as the power input and the other strand that is used as an isolated output winding.

I hope this helps answer your question.

Peter

[Schpankme]

4 rotor, 6 stator

Jetijs,

Does anyone else have ideas for Jetijs' new motor?

Peter

Jetijs & Peter and All,

I've been following this thread closely, and would like to "Build Along" with this next project. I know too many Chiefs spoil the Pot; so I'd like to offer my suggestion (4 rotor, 6 stator) as a compromise for consideration. Which ever motor design is selected for the next build project, works for me.

- Schpankme

[Jetijs]

Steven,
thank you very much for pointing these things out. I did not know about the hindered flux flow thing and also I was concerned about this torque ripple. Also thank you for your video, I watched it with great interest. It makes you think

Thanks,
Jetijs

[redcar1957]

bi-filar windings

Peter

which bi-filar winding do you use ???

Four types of bi-filar wound coils
parallel-wound, series connected
parallel-wound, parallel connected
counter-wound caduceus coil (series)
counter-wound caduceus coil (parallel)

Thanks Kevin

[nali2001]

Design

Nice, but keep in mind that that hole you put through the rotor cuts the total metal cross section in half, you in a sense lower the permeability of that core section. In still other words you have less metal there so it will hinder flux flow, unless saturation levels are very low to start with. So add metal there. See attached 'artwork'. Also if you want some torque you need more than just a small air gap. You also need 'interaction surface' remember a mini toy motor http://www.rc-truckncar-tuning.com/i...rArmature1.jpg has like the same flux interaction contact area that your current motor. One might get deceived quicky when one looks at the bulkiness of a motor, but it the contact area that does the work. So you might want to sack a fair number of laminations. I think total 10cm high would be nice. One other thing to keep in mind that in this design there will be a very big torque ripple. I do not know how advanced you might want to go but some other rotor/stator finger amounts will give a smoother overall performance (under mechanical load) Like these: http://www.infolytica.com/en/coolstu...08_6%20SRM.PNG
http://www.sapiensman.com/ESDictiona...ges/motor1.jpg
In a sense you can just browse google images for variable reluctance layouts and just work from there since most of these layouts are likely bases on real world produced motor which are likely well calculated/simulated. Just add the small air gap and back spike recovery and off you go. (grain of salt here.)

Regards,
Steven

[Jetijs]

This is what I have came up with so far:


The whole diameter of the startor is about 100mm. This design will have plenty of space for bifilar windings. The rotor piece is about 40mm in length. I don't know if I should make the middle part of the rotor thiner and the ends wider or not. Has anyone any thoughts? Don't mind that gap, this is only a sample drawing

Thanks,
Jetijs

[Peter Lindemann]

Keep it Simple

Good news everyone
Today I called that motor rewinding company and they told me that they have and can sell me these transformer lamination sheets. I don't know the price yet, but it shouldn't be very expensive. I will arranged a meeting with them on monday, then they will show and tell me everything I want to know This means that I have an opportunity to make my own custom design startor core. I could reduce the pole count to maybe eight and also increase the spacing between the poles to give the motor extra breathe time. Also such a design would be easier to wind. If I make the startor core round, that gives me the ability to use a lathe to grind the inner surface of the rotor perfectly round and even. That way I should be able to get the air gap between startor and rotor 0.1mm thin or even thinner. So, do you have any suggestions about the custom design core bfore I start make the cad drawings?
Thanks,
Jetijs

Jetijs,

If you are going to make your own stator, I recommend using just four poles. The pole face to the rotor should be about 60 degrees of arc, with a space of about 30 degrees of arc to the next pole. The rotor is a simple "bar rotor" defining 60 degrees of arc with two flat sides defining 120 degrees of arc.

This gives the motor "time to breathe" (30 degrees off time) but not so much that you have huge OFF times during the rotation. Keep the rotor as small as possible within a balanced design. This maximizes the tangential forces and assures high speed and high torque performance. If you can practice .1mm gap, the motor should have excellent mechanical energy production.

For this "first model" based on this design, don't make the stator too thick. I suggest limited the stator thickness to no more than 60mm for this first model. This is plenty to test out all of the design features, including the bearing systems, air-gap tolerances, commutator, recovery circuits, etc. Also, if you have the room, which I believe you will with a four pole stator, I recommend winding the coils "bi-filar" so you can recover energy back to the front of the circuit.

This is a simple, practical design that will demonstrate all of the motors features, but is not overly complicated.

Does anyone else have ideas for Jetijs' new motor?

Peter

[Jetijs]

Good news everyone
Today I called that motor rewinding company and they told me that they have and can sell me these transformer lamination sheets. I don't know the price yet, but it shouldn't be very expensive. I will arranged a meeting with them on monday, then they will show and tell me everything I want to know This means that I have an opportunity to make my own custom design startor core. I could reduce the pole count to maybe eight and also increase the spacing between the poles to give the motor extra breathe time. Also such a design would be easier to wind. If I make the startor core round, that gives me the ability to use a lathe to grind the inner surface of the rotor perfectly round and even. That way I should be able to get the air gap between startor and rotor 0.1mm thin or even thinner. So, do you have any suggestions about the custom design core bfore I start make the cad drawings?
Thanks,
Jetijs