Brushless motor winding class

[donhuff]

Don, what about wire pulling lubricant? Think that would be of any value or just a gigantic mess?

I used it in the beginning, and it did seem to help a little. But back then I was trying to get every last strand in there that I could make fit. Now a days, I back off the wire count one or two strands, and I have a lot more success without shorts.

I wouldn't bother with it, and if you'll just ask me about how many strands to use, I can tell you. !!IF YOU USE 27 AWG size!! any other size and you'll have to figure it out yourself.

And BTW. the # of strands that will fit in one slot all by it's self, is NOT how many you can use, because that big of a bundle will be very hard to get around the turns. Not such a big deal on the first leg, an aggravating problem on the second leg, then on the third leg , you'll be cussing and throwing things cause you can't get the needle through the slot with all the other end turns in the way.

[donhuff]

Don, so......the crazy 3 turn D wind with the CCW/CW pattern is basically the Dynamite 2k. How do we adjust the resulting kv with the turns? Like if I want 1700 or if I wanted 2500? I still have the one that came in at 2900kv. Haven't found a use for that nonsense yet but I'll think of something.

haha How do it know?

Yes that's what the DYNM 2000k comes with, and it KVs right on 2000 every time. Do that same wind on a 1500, and you get 1920- 1960 kv. On an AQ you get 23-2400.

To "adjust" the kv, you have to do MORE TURNS FOR LOWER KV, AND LESS TURNS FOR A HIGHER KV. it's as simple as that. But it's all RELATIVE to everything else in the motor. For instance, length of the stator, diameter of the rotor, length of the rotor, "width" of the airgap between the rotor and stator, strength of the magnets, strength of the "coils" in the stator.

That 2900 kv motor IIRC is a 2 D wind. When you get to the lower turn numbers, ie 3-2, You see that going from 3 turns to 2 turns decreases the "length" of the wires by 33% and you can expect a big increase in kv. If it were a 10 turn and you went to a 9 turn, then the kv change will not be as severe because the length of the wire was not very severe.


NOW to get in between those one turn changes in kv, you can go to DDD or YYY and that will change the kv by a lesser amount because you are changeing the length of the wire is smaller increments. A 3d has 3 turns in an 18 slot rotor and has 3 coils per leg and lets say that the piece of wire to go through all those coils would be 3 feet long. Now if we wire it at 3 DDD, we would wire each of the three coils SEPARATELY, and the wire to do that would be 1 foot long. Got it so far??? So now we cut the wire length by 2/3 and we would expect the kv to go up by at least 66%.

But if you look at the normal 3d as 3 coils with three turns each, then you have 9 turns total..........and that gets us 2000kv, but we want closer to 2200 kv. By wiring our coils individually/ per leg, at 8 turns apiece, we shortened the wire by a much lesser margin than if we were to wind the motor a 2d (which would be actually 6 turns total for all three coils per leg) .......... Go back and read that again cause i'm sure it didn't make sense.

So working with the 2000kv motor at 3d, and your motor at 2900, we see that we can split that difference in kv with a ddd wind of 8 or 7. And those kvs will be evenly spaced in between the 2000 and 2900 kvs. But not easy to get because the DDD YYY is a lot more complicated to do.

You see now that the kv numbers are determined by the number of turns, and there are no easy ways to get a certain kv, if it's not what a particular motor wants to turn.

I bet this isn't exactly what you were asking for. But I'm trying to get ya'll to see where and how KV comes about and why some motors are one number and others are different. It seems that most folks think that to hit a certain number you do this!!! well you should see from the above that hitting a certain number is not so easy.

[donhuff]

I know it's funny but it's a real thing.
https://www.lowes.com/pd/IDEAL-32-oz...B&gclsrc=aw.ds

That's the stuff I used. But don't bother. If you need that stuff, you're doing it wrong.

[ray schrauwen]

My head is having a technical great time. DDD YYY ? Is that both a D and Y wind on same stator? I must go back, must have missed something.

[T.S.Davis]

I just finished my first 3D CCW/CW wind. Need to finish it to see how it went. The third turn on the third phase is a bit of a bastard to weasel through. Glad I didn't try for more strands. Having your needle just right is an absolute must guys. You can also tweak the thing a bit as you go by bending it this way or that. Then you can get it to exist the other end of the slot in a spot that you can squeak through.

I'm not understanding the DDD YYY nomenclature either. The coil count thing stuck though. So a 3 delta has 9 runs through slots. Basically. So to adjust the kv a tic we take one run through a slot out of each phase? Or add one for less kv. Wait.....doesn't that put the finish leg on the wrong end of the motor? I'm clearly not getting it.

Sounds like a lot of experienced guesswork for us yahoos on the Kv. I'm sure TP and Neu can just whip out a wind for a kv. We aint them.

[donhuff]

I'll put a drawing up of the DDD OR (Ray), YYY soon. But Ray, no you can't have both in the same motor. I guess you "could" but you'd have to have a way to switch back and forth like two esc, and then you would have to have half of the wire dedicated to each wind. Let's forget about that idea and move on to something sensible OK.


From now on it will be just a DDD, but you remember that it COULD be a YYY if you want it to be, But not both at the same time.

A big reason for me even mentioning the DDD is to try and drill it in ya'll, that you have to have three coils per leg. I think that Terry is finally getting it.

And Terry you are right that you can't leave one pass off of one coil, on a delta, because the wire has to get back out to connect with one of the other leads.

But with a Y you can do that because the bundles are all tied together inside the motor. Look in an AQ 1800 and you'll see this. The Y connection is in the front (pto) end. BUT!! when you do that, your leaving slots with less wire in them than they will hold. And that's not what were trying to accomplish with rewinding. We want to fill em up!

Another way of getting a "half" wind, is to wind one coil on a phase with lets say 3 turns, and the other coil with only 2 turns. This changes the kv a lesser amount than leaving a turn off of all the coils. I'm using a 4 pole here as an example because I have not seen this in a 6 pole motor, but you see it a lot in 4 poles especially with Leopard motors. Look at the specs for one of their motors and you'l l see a lot of half winds and a lot of different kv options. BUT AGAIN half of the slots do not have as much wire in them as the other side of the stator does. Again, I'm not saying that it won't work on a 6 pole, just saying that I have not seen it on a 6 pole.


Some motors don't do it that way though. Like the Neus. They have half winds and full to the rim with wire ?????? I have no idea how they do their half winds, and then they also do a .75! Again, I have no clue how to do that. I have unthreaded a couple of them, but I got totally lot before I under stood any of it.

" So to adjust kv a tic" Terry, Leave one full TURN off of a phase, to raise the kv. Add one full TURN on a phase to lower the kv. And like I said before, this will make big changes in the KV when your in the low turn counts winds, because your making big changes in the length of the wire. When you get into the high turn counts, the change is less drastic , because the wire length is not changing so much.

Look at the specs for a motor with a wide turn count available, for instance a TP 3640. See how big a change in kv between 2D and 3D (1900), then not but (170) between 10D and 9D.

I mentioned the DDD to try and illustrate how by winding EACH COIL INDIVIDUALLY changes the turn count per phase. I know without a pic, this still doesn't make sense, and I'm getting to the pic later.

[T.S.Davis]

Don, do you want some blank drawings to chicken scratch some of these patterns?

[donhuff]

" So a 3 delta has 9 runs through slots. Basically."

Terry, I'm not sure of what you mean by "runs" I don't think that I have used that term before. Do you mean turns?

If so then yes, a 6 pole, 18 slot, 3D, motor will have 3 turns per coil per phase, for a 9 turn total per phase. And lets say that the wire to do that is 1 inch long per turn 3 inch long per coil and 9 inches long per phase.

A 7D in that same motor, will have 7 turns per coil, 3 coils per phase, 21 turns total per phase. So on this one the wire will be 1 inch long per turn, 7 inches long per coil, and 21 inches per phase. And using that TP 3640 as an example, that makes a 2620 rpm difference in Kv between the two. BTW that TP is a 4 pole so the numbers would be different for a 6 pole, just using it as an example.

[donhuff]

Terry I would like them but I'm not very good with computers and probably wouldn't be able to get them to the printer. But what the heck, send me one and i'll give it a try.

[donhuff]

DSC_0002.jpg


Here is the DDD wind. This is a 4 turn DDD . It's called a delta delta delta because EACH COIL IS WIRED SEPARATELY FROM THE OTHER COILS ON THE SAME PHASE.

Looking at the pic you can see how each wire coming off of either side of each coil, HAS to go to a specific spot,( ie all S1 wires go together) to get twisted together, to form one of the 6 usual leads, that pairs of, get twisted together to form the three phase leads.

Now using our example motor from the above post, where it took 1 inch of wire to make 1 turn. With this motor I did only 4 turns to keep it from looking to congested, and to so the ho much change it can make in the kv. So 1 inch per turn, and 4 turns per coil, equals 4 inches of wire per coil. Now you see the drastic difference in the length of wire per phase between a normal 3d @ 9 inches long. And this 4DDD @ 4 inches long.

We know from before that we can't go below 2 turns, or the motor won't run. 2 turns on our example motor would be 2 turns per 3 coils equals 6 turns total per phase. 1 inch per turn times 6 total turns equals 6 inch long wire. But with the 4DDD we have 4 turns times 1 inch per turn, so 4 inch long wire. A reduction of 33% and you would expect at least 30 to 40% increase in kv, but probably more.


You see from this that lets say we have a 4 turn normal wind on our test motor. 4 turns per leg and 3 coils per phase (wired in series) . 1 inch per turn, so 12 inches of wire. Our next closes option for increasing the kv is with a 3 turn which we know from above will make a 9 inch long wire. But by using the DDD format, we can now get in-between those two winds because were no longer stuck with multiples of three coils and can wind each coil separately (wired in parallel), and get more winds in-between the previous 3 or 4 D, which for sake of explaining let call them by their full turn count of 9 and 12 turns (total for all three coils in a phase). So by going DDD we can now get an 8 -9 -10 and 11 turn count per coil per phase.

Think about the length of the wire. That's what ultimately determines the kv.

[donhuff]

Terry,

Glad you mentioned the needle has to be right. Absolutely!!! On the first phase not so much, but the second yes, and the third it has to be right. 2 or 3 coats of ca for the third one, and sand it smooth will help too.

I didn't say before about bending the tip of the needle, because I think that's one of the things that you'll have to learn as you go and can't really be explained with text. In person I could show you how in a few seconds.

Since you know about bending it. Sometimes it will help to bend a small curve 1/4 -3/8" the from the end. Then start it in the corner of a slot, and wiggle and twist it back and forth a little to make the point push the other strands out of the corner, so the needle can get all the way through.

[TRUCKPULL]

Don in your picture in post #100

The F2 in the upper right, should that not be F1??

Larry

[ray schrauwen]

Got it Don, thanks!

[donhuff]

Yes Larry your right. Should be fixed now.

You're getting good at catching my f-ups. Keep it up cause I don't want to confuze anyone more than I already have!! Even when it 's correct, it's confusing as hell.

[donhuff]

Larry, it seems fixed on my end.

You did notice that all I did was mark over the F2 and write F1 beside it. But if that didn't get it,i'll post it again.

DSC_0002.jpg

[ray schrauwen]

Just saw this. Basics but informative.

[donhuff]

Yes basic but still he's hitting on the one main thing that WE are interested in, HORSEPOWER and how to increase it. Only he calls it by the electrical proper term ( I think) Torque Efficiency.

He names some ways to increase HP toward the end. Bigger displacement (mainly the size of rotor), bigger/stronger magnets, tighter air gap, and more copper.

[donhuff]

4-Pole-brushless-DC-motor-animation.jpg


Lets have a little test, to see if ya'll have been understand what I've been preaching about.

In the picture above, I want you to describe the motor to me. It's laid out differently that the way I have been drawing them, but it's still showing you the same thing, only in a more congested but all together and round layout. More like a real motor would look if you were to slice it in half across the shaft.


I want to know. Click on the pic to make it big enough to see well.

1 number of turns
2 number of poles
3 number of slots/teeth
4 and the hard one, wye or delta. This might be a little hard for you because of the way it's drawn, but remember it all about where the ends of the wire END.

[donhuff]

And after all my searching and explaining NOW I find this somehow. The picture is a real good drawing of what we've been talking about.

I'll give a link to the forum where I go it to so you can see how this guy rewound his motor. Very ambitious to do it with a single strand of big wire too. I think he needs to learn about the powder coating of the stator.

18n6p diagram.jpg


http://www.rc-network.de/forum/showt...P-Innenlaeufer you'll have to convert it to english.

[T.S.Davis]

1 number of turns 5
2 number of poles 4
3 number of slots/teeth 6
4 and the hard one, wye or delta. wye

Would be easier to see in our usual elevation view we've been doing.

[T.S.Davis]

Don, on the 4 turn DDD example do we end up with three dead teeth again?

Also... that particular arrangement will produce a Kv of X. What ever it is I don't really know. Lets say I use the tach and it comes out at 1500kv or so but I really wanted 1600 for example. Could I just take one turn out of the center coil so that it's 4,3,4? Just trying to make sure I'm getting it.

[donhuff]

1 number of turns 5
2 number of poles 4
3 number of slots/teeth 6
4 and the hard one, wye or delta. wye

Would be easier to see in our usual elevation view we've been doing.

Your right on everything except the number of turns. I see only 2 turns. This is a concentrated wind, so it looks a bit different from the distributed version that we have been doing. But the wire makes only 2 full trips around each tooth.

[TRUCKPULL]

1 number of turns -2
2 number of poles - 4
3 number of slots/teeth - 6
4 and the hard one, wye or delta. - wye

Don - you posted while I was typing.

Larry

[donhuff]

Don, on the 4 turn DDD example do we end up with three dead teeth again?

Also... that particular arrangement will produce a Kv of X. What ever it is I don't really know. Lets say I use the tach and it comes out at 1500kv or so but I really wanted 1600 for example. Could I just take one turn out of the center coil so that it's 4,3,4? Just trying to make sure I'm getting it.

The bottom of the DDD wind, should look exactly like the bottom of a D wind. The difference will all be on the other end where the connections are made.

I don't KNOW the answer to that next question Terry. I know some 4 pole motors have fewer turns on one coil than are on the other coil, on the same phase, and it has a different kv that if both coils had the same amount of turns.
I have never see that on a 6 pole motor, but I don't see why it wouldn't work on them.


BUT, I don't see WHY you would want to leave copper out just to hit a certain kv, when you know more copper means more POWER!!!

Is hitting a certain kv number more important to you than going faster?

It seem like a lot of people relate kv to power some sort of way, that aint true. Kv has nothing to do with power.

[donhuff]

Sure Larry


Just kidding, I believe you. Hard to believe someone types slower than me though.

[TRUCKPULL]

Sure Larry


Just kidding, I believe you. Hard to believe someone types slower than me though.

I had copy and pasted your question,
Then spent the time looking at your picture for the answers.
1 number of turns
2 number of poles
3 number of slots/teeth
4 and the hard one, wye or delta.

Larry

[ray schrauwen]

1 number of turns 5
2 number of poles 4
3 number of slots/teeth 6
4 and the hard one, wye or delta. wye

Would be easier to see in our usual elevation view we've been doing.

Only because I’ve been sleeping in the class I get the same for 2, 3 and 4. I get 1.5 turns for 1.

[ray schrauwen]

I was close! I can understand winding the motor easier with the round cross sectional drawing.

[ray schrauwen]

The bottom of the DDD wind, should look exactly like the bottom of a D wind. The difference will all be on the other end where the connections are made.

I don't KNOW the answer to that next question Terry. I know some 4 pole motors have fewer turns on one coil than are on the other coil, on the same phase, and it has a different kv that if both coils had the same amount of turns.
I have never see that on a 6 pole motor, but I don't see why it wouldn't work on them.


BUT, I don't see WHY you would want to leave copper out just to hit a certain kv, when you know more copper means more POWER!!!

Is hitting a certain kv number more important to you than going faster?

It seem like a lot of people relate kv to power some sort of way, that aint true. Kv has nothing to do with power.

That’s interesting. I forgot you mentioned a bit about this. I look for a certain KV at times that would turn a certain prop on a certain size hull to avoid going too big on prop on smaller hulls that may cause walking.

[donhuff]

Really Ray, 1.5 turns?

Remember in the pics of my practice stators, when I showed the "bottoms" of the windings. It was easy to see the turn count because all 3 or 4 or whatever number was in the turn count, there would be that many strands of wire showing, of the bottom end turns.

DSC_0006.jpg

See here that there are 3 turns. But if you look on the other end it will only show two because of the start coming in , around 3 times, and then the finish going out.

IN the pic in my test, we are looking at it either end I suppose, as the start of a individual coil is on one end, and the finish is on the other. So you should be able to look at either end of this one, and it will show 2 turns. And all the "connections" are on the outside diameter.

I have another pic here that I cant seem to get rid of, that shows the start end. it's not the one were talking about.