Brushless motor winding class

[jaike5]

Now imagine an 8 pole 24 slot motor!!![/QUOTE]
Plettenburg ?
cheers, Jay.

[donhuff]

AHHHHHH!!!

So you could have 18 start/terminations to join? And 15 of them should be inside the can. What a pain in the a$$.

Sorry to make you go through it again Don. It's tough to follow. Probably tough to type it too.

I don't think it will work like that.

Six go to one leg, six to the other, and six to the third leg. Inside or out, but not some one way and some the other.

[donhuff]

Now imagine an 8 pole 24 slot motor!!!

Plettenburg ?
cheers, Jay.[/QUOTE]

Yeah in a way BUT, that's not a DDDD. It's just a plain delta.

[donhuff]

Let me try it again Terry, because I think your completely missing the point of DDD vs D type of wind.

Let's try a different analogy, and use battery packs as the example.

I believe, that you're thinking that in my explanation above, that after getting all the coils wound, we connect the three coils per leg together in series inside the case, and end up with just the start and finish wires sticking out of the case. That's not right.

Using the 3D, 6 pole, 18 slot DYNA 2000 as an example. That has 3 turns per coil, 3 coils per leg, and 3 legs. Using our 2 foot long single strand of wire to keep it simple, we wind 1 coil with 3 turns, then hop over 2 slots do another coil with 3 turns, hop over again and wind the third coil with 3 turns, all with one continuous piece of wire. So we can describe it as a 9 turn wind, per leg, using a 2 foot long piece of wire. Now do the same thing with the other 2 legs. We end up with 6 wires sticking out of the stator. 3 starts and 3 finish ends. Then those get joined in pairs according to the wind type, and you end up with the usual 3 leads sticking out. Solder connectors on those three leads and we are finished.

For this example, we want to wind the stator to get the same KV, but were going to do this one as a DDD. Since we want the same KV, the length of the wire HAS to stay the same length of 2 feet. To do that we gots to do 9 turns on just one coil. Note that you used up the 2 foot piece of wire on just one coil instead of 3, so we have to make another one and wind the second coil, then do the same for the third one. Looking at what we have now we see a stator with 6 wire ends sticking out ( instead of the usual 2 like what we would have in the normal 2 d wind).

And this is where I think you got off Terry. I think,that you thought, to connect all the coils IN SERIES like you do with batteries to get higher voltage. So for example let's think of the coils as batteries and just for the sake of example, lets say that ONE TURN makes ONE VOLT. Series is not what we want to do here, because we want to end up with 9 volts per leg. Series would give us a 27 turn (total per leg and 27 volts) motor with a very low KV. Instead, we connect the three coils in PARALLE , which will give us 3 coils with 9 turns apiece, but still the electricity is only going to follow a 2 foot long path to get to the other end! And we end up with the same 2000 KV as the standard DYNA 3D 2000kv.

Now you can do all those connections on the inside of the case, if you have enough room, but it gets very bulky because of all the extra lead wire going around the rear of the stator to all connect to make just the three leads. OR you can make the connection on the outside, like I did with my Squid motors.

[T.S.Davis]

Yer the best Don. I totally got it this time. In your example wouldn't the 9 turn coil be a mere 4 strand bundle in the 2k dyno stator? Flimsy needle that one.

There is a problem with the squid motor in my opinion. The whole point of the 36mm x 60mm rule that NAMBA passed was that you could only pack so much power into that sized package. In theory at least. The wires being joined outside the can is kinda cheating the system. I'd have to think on that some.

[donhuff]

Yes only 4 strands. And you'd be lucky if you can get all 9 turns in there with just the 4 strands. You would think that 36 strands would be the same no matter what, the turn count is. But you'd be wrong. Because the strands tend to overlap each other and leave a bunch of air space with the higher turn counts, making the slot fill up quicker.

"kinda cheating the system" ????????????? You do understand it's racing , right? I never give a damn about what the rules SAY, it's what they DON"T SAY that, I pay attention to!

[Doug Smock]

"I never give a damn about what the rules SAY, it's what they DON"T SAY that, I pay attention to"!

[raptor347]

I just got back to reading this thread. Don, thank you for sharing!!! This is what makes this hobby so much fun.

So, back when I was winding motors for Aveox (1997-2000) we built what I would consider the ultimate p-ltd motor platform, 1406-1.5yHC FAI. The motor was built for the US F5B team to take to the 1998 worlds. It was a 24 slot HyperCobalt stack and 8 pole pie wedge magnet rotor. The bill for just the stack and rotor was over $400 (in '98 dollars). We did win the WC that year!

I can see an advantage to the DDD wind motors. Properly set up, it will have significantly less resistance compared to a standard D wind. Might have to get a little creative to get the phase leads out of the case.

On stripping the coating off good wire, we used to use a wire wheel. Quick and no fumes or caustic materials.

[donhuff]

Pie wedge shaped magnets sounds good and I think you could add some power with bigger magnets, but as you noted, that can get expensive. And also the Neo magnets are so dang strong in the first place! I was shocked at the size of the magnets the first time I looked at the rotor of a NEU motor. Those cobalt magnets were 2.5 to 3 times the mass of the magnets I was use to seeing in AQs and TPs.

About the DDD winds. I don't understand enough about resistance to know which would be better D or DDD. The length of the wire ends up being almost exactly the same (for the same kv) and I thought that the wire length was the main factor determining the resistance. But like I said, I don't "really" know.

The easy way to get the leads out is to put a lot of holes in the rear end bell. Did you see the picture of my "SQUID" motor?

DSC_0055.jpg

[donhuff]

I can see how the wire wheel for stripping would work, but I've gotten so use to the lye that it's no big deal to me anymore.

[jaike5]

ohhh! I'm back in class now that there is a way round the lye thang. gonna have to repeat this semester though gonna re read this and get on with it.
J.

[donhuff]

Waiting for the questions Jay!

[jaike5]

Don, better get a few more boxes of pop corn, and keep that phone handy!

[Darin Jordan]

OK, so I haven't finished ready all this just yet, but I gotta ask... Is anyone really setting the world on fire with these motors?

Seems like a TON of work to go through, and I can't help think that this level of "prep" is best saved for those who have already perfected EVERY Other part of their racing... Nailing starts... driving to perfection... running a setup that can be run WOT for the entire course.

Does anyone have any numbers to prove this is worth the effort? I've been known to go to extremes with my boat builds and prep work in the past, so I'm not averse to going through this, but...

Honestly just curious.

[raptor347]

Don,
Yes it has the same mass of wire. The DDD advantage is this: Start by breaking the wind down into it's 3 component coils and remember that resistance is a linear function of wire length for the same copper cross section. In the standard D wind those coils are in series so you have a wire length of each coil x3. The DDD wind has those same coils tied in parallel so your wire length is the coil x1. Right off the top the DDD has 1/3 the resistance of the standard D. Then heat produced by powering the coil has been cut by 2/3. Don't be surprised if the current capacity more than doubles. The limit of the motor is likely now the magnetic saturation point of the stack structure and rotor magnets.

There is always a point where a motor reaches saturation and won't make any more power, just excess heat.

[raptor347]

The pie wedge magnets had to be ground to shape before the were magnetized.

[donhuff]

But Brian, for the two winds to have the same kv. the DDD length of wire for ONE coil in the parallel set of three (let's call it 3 feet), will have to be the same length as it is for the Ds THREE coils wired in series (still 3 feet long).

The cross section has gotten small because now there are more turns hence fewer strands. Lets say that in our sample motor and with both winds having the same kv, a 2D will have 2 turns times three coils in series = 6 turns total. DDD will have 6 turns per coil, three coils in parallel, but still just 6 turns total. And the cross section should add together I would think, and end up about the same.

But like I said before, I'm not sure on any of this so tell me if I'm wrong and make me understand it, please. I guess I should wire a couple of stators with the two different winds, and measure them to see the difference. That wouldn't be to hard to do. But I don't even know how to measure resistance!!

[donhuff]

The pie wedge magnets had to be ground to shape before the were magnetized.

That makes sense.

I have made some 8 and 10 pole rotors for limited, and I had to grind the magnets a lot to get them to fit on the rotor hub.

[donhuff]

Darin,

In November 2019 the p-ltd mono saw record was 55 mph IIRC. 8 year old Will Schafer broke that @58 mph. Not really a big deal only 3 mph right. Then in December when it got NAMBA day the wind was blowing and waves were high. I'm not very good at going straight, (I hit the bank on my one and only try!) so I asked Martin Truex if he would drive it for me. I was able to do this because the water was so rough that even the big gas monos wouldn't run and I had the water to my self, and Martin was free to help me.

When I asked him to drive my little 29" boat he looked at me like I was some kind of an idiot. "That little boat in this water?" he chuckled and said "sure I'll drive anything". I told him that he shouldn't have to go past half throttle, and to just try to keep it right side up. I knew it would make it because it had gone 77+ mph at home and we still weren't full throttle!

Martin did a couple of short burst to get the feel for it, (he doesn't drive electric, nor does he drive monos) he called for the timer, READY? Ready they replied, and vroom vroom, and we had a new record. 60.2! Martin said he didn't think that he ever even got to half throttle. With Martin still driving and the water getting even rougher as the morning wore on, he was able to get the ltd mono 1/3 mile oval and the ltd offshore oval record. One of those was with my full sized 34" hull and a much milder motor.

Then this past November, again 9 year old Will Schafer broke Martin's ltd mono oval record. Again with a 34" racing hull and one of my motors.

So yes, they are really a lot stronger than stock. Setting the world on fire??? not sure, but if I ever get to hold the throttle on full Wabbit for a complete pass, I'm thinking 77-80 mph for a limited mono is FIRE breathing performance. This was with a 3656mm motor, my new 3760s are a good size step up in power.

[raptor347]

Don,
We're going to have to do some experimenting. My understanding, and I may be wrong, is that kV is related to the number of turns in each coil not the overall length of wire. We're building 9 electro magnets in each motor. I don't believe it maters if you power each coil independently (parallel DDD) in series (D wind), power up/down time is insignificant as you've said. Changing turn count for a coil changes the magnetic property of that coil. Like I said, I may be wrong, time to experiment.

[donhuff]

Well yes, your right by saying that the number of turns is what determines kv. BUT (and this is a big but) turn count also determines wire length!

I think what your not seeing is that the DDD wind, will HAVE to have a higher turn count, to have the same kv as a D wind.

Our sample motor for instance is a 2 D 6 pole 18 slot, we'll say that this gives us 2000 kv. To get the same kv using a DDD wind, you will have to go to 6 turns per coil. If you were to wind it a 2 DDD the kv would skyrocket!!! It would be something like three times the 2D kv.


Nobody ever talks about the length of the wire because it seems irreverent, but it's my (self taught) understanding that the length of the wire is what determines the turn count! You can't have one without the other.

Time "Insignificant" did I say that?? I'v said so much I have no idea anymore!


I think that the length of wire determines how much TIME it takes the Positive and the negative to collide and start working on the coils core, and then it takes a little more TIME to get the magnetic RISE and COLLAPSE of the coil. I find very little information on the subject, and the info I do find is way over my head. So, I'm basically talking out of my azz here.

[ray schrauwen]

Darin,

In November 2019 the p-ltd mono saw record was 55 mph IIRC. 8 year old Will Schafer broke that @58 mph. Not really a big deal only 3 mph right. Then in December when it got NAMBA day the wind was blowing and waves were high. I'm not very good at going straight, (I hit the bank on my one and only try!) so I asked Martin Truex if he would drive it for me. I was able to do this because the water was so rough that even the big gas monos wouldn't run and I had the water to my self, and Martin was free to help me.

When I asked him to drive my little 29" boat he looked at me like I was some kind of an idiot. "That little boat in this water?" he chuckled and said "sure I'll drive anything". I told him that he shouldn't have to go past half throttle, and to just try to keep it right side up. I knew it would make it because it had gone 77+ mph at home and we still weren't full throttle!

Martin did a couple of short burst to get the feel for it, (he doesn't drive electric, nor does he drive monos) he called for the timer, READY? Ready they replied, and vroom vroom, and we had a new record. 60.2! Martin said he didn't think that he ever even got to half throttle. With Martin still driving and the water getting even rougher as the morning wore on, he was able to get the ltd mono 1/3 mile oval and the ltd offshore oval record. One of those was with my full sized 34" hull and a much milder motor.

Then this past November, again 9 year old Will Schafer broke Martin's ltd mono oval record. Again with a 34" racing hull and one of my motors.

So yes, they are really a lot stronger than stock. Setting the world on fire??? not sure, but if I ever get to hold the throttle on full Wabbit for a complete pass, I'm thinking 77-80 mph for a limited mono is FIRE breathing performance. This was with a 3656mm motor, my new 3760s are a good size step up in power.

Wow! I'm curious as to what kind of prop you were using on that boat Don?

What are the 3760's??

[ray schrauwen]

The pie wedge magnets had to be ground to shape before the were magnetized.

Whoa... I was always curious what happens when you change a rotor to higher or lower number of poles and you guys are modifying rotors??!! Wholly cow man!

[donhuff]

Ray,

I was using an ABC 1717-17-45 on the SAW boat. The kv on that motor is 2550 I believe. For the oval I swapped to a 1714 to get the speed down some. Then the offshore boat had an 1814-17-45 prop, but it was a 2100 kv motor like we use for racing.

Both those motors were 6 poles. The jury is still out on whether increasing the pole count is really worth it or not. It's a lot of trouble to do it, and the ones that I have done aren't leaps and bounds stronger than the 6 pole they replace. They really seem to be about the same strength. I think that "crowding" the magnets against each other, is making one overlap it's neighbor a bit (magnetism wise) and killing off any benefit of having the extra magnet volume. Like a 6 cylinder and a V8 car engine, when the displacement of the two is the same, total achievable power is usually about the same.

And ya can't just add magnets, sometimes the stator has to change too. And this is all about the motors that I have worked with, so like going from a 6 pole to an 8. A 6 pole rotor can use a 9 or 18 slot stator, where an 8 or 10 pole can use a 3- 6 -9-12-15-18 slot stator.
And then you can't wind them all the same either. Some will need to be distributed and some concentrated, some will have to be wound AAA BBB CCC, some ABC ABC ABC, and then there's the Aab BCc Aab BCc, etc etc.

[ray schrauwen]

I’m quite impressed or in awe or both.

Thanks for the response. Hopefully I will get out more this summer to run and give one of your motors a try. The one I have is still virgin.

Take care an$ keep doing what you’re doing, it’s great.

[donhuff]

OOPS Ray,

I forgot to tell you what a 37x60 motor is. That's the maximum size allowed by the NAMBA rules.

[ray schrauwen]

Yeah, I figured that. Where did you get a motor with those dimensions? An outrunner?

[donhuff]

I didn't buy it with those dimensions, I had to make it have those dimensions.

[ray schrauwen]

ok, thanks