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.