Jetijs,

Everything Lighty and Steven are saying is correct.

All motors that I know of are wound by hand. To prevent the damage at the edges, where the wire comes around the stator section, they insert a thin layer of material in a U shape to fill the slot. You can see these insulators in Steven's photograph. This is what Lighty was referring to as sheets of mylar. Even a thick paper is sufficient for this. Here in the USA, we use a thick paper material for file folders. It's about .010" thick (ten thousandths of an inch). If you have a similar material, just make your own slot insulators. Make them slightly longer than the slots, so the wire bends the paper around the edge as you wind the coil.

Another trick is to glue little pieces of wooden doweling cut in half to the ends of the stator pieces, to produce a semi-round end to the stator cores. This, along with the paper insulators makes winding the coils easy (ha ha ha) and prevents all possibility of breaking the insulation on the wires.

The "trick" to being able to wind a good coil is the ability to provide tension on the wire. If you mount your stator in a vise that is firmly mounted to your work bench, and then tie the beginning of the wire strand you are winding to some immovable object, then you will have BOTH HANDS free to manipulate the wire and keep tension on the turns as you make them, as well as on the turns you have already wound. It is a tiring and tedious operation. Your hands get very tired, but HEY, that's how it is done!

Wind one coil, leaving about a foot of extra wire at each end. Fill each slot to about half way. Then, unwind this coil and measure the length of the wire. This is the standard length all the coils will be. Cut 23 more lengths of wire at this length and wind each coil separately. Tie off the ends of each coil when it is done.

You only have 24 coils to wind, so by the time you wind the last ones, you'll be really good at it.

Remember, magnetic field strength is AMPERE-TURNS. You need to be able to get enough turns on the pole faces to create sufficient magnetism to attract the rotor. Since this is very similar to Steven's design, you may wish to take directions from him on what wire size to use and how to switch the currents.

This motor is a much more ambitious project than your first design, but if you stay focussed, you can do it.

I say, "GO FOR IT!

Peter

Hello Jetijs & All,

One of my favorite books on this subject is - Armature Winding and Motor Repair 1st edition (1920)
Practical Information and Data Covering Winding and Reconnecting Procedure for Direct and Alternating Current Machines, ... Armature Winders in Electrical Repair Shops

- Schpankme

Here I have a video that might be of some interest. I must say that not all might be clear since this a part of a bigger video but is shows that although they are all silicon steel there are very big differences in core behavior especially when it comes to residual magnetism and how fast a core releases its static magnetic fields. Also you will see some coil 'tricks'. It boils down to that steel grain orientation plays a big role.

http://home.planet.nl/~sintt000//02_.../CoreTests.wmv

Regards,
Steven

Thanks!

Here is a link so anyone can get the book for free in dejavu, pdf or txt format:
Internet Archive: Details: Armature winding and motor repair; practical information and data covering winding and reconnectig procedure for direct and alternating current machines, compiled for electrical men responsible for the operation and repair

Awesome video, I also have been testing cores to see draw for the ssg, I think from your video I have a means of testing good core material from poor.

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

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

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

Attached Images

LikeSo001.jpg (29.0 KB, 33 views)

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

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

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

Attached Images

Electric_Motor_4Rotor.jpg (13.4 KB, 15 views)

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

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

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

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