12 slot 14 pole full parallel wind possible? - RC Groups
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Nov 26, 2017, 03:40 PM
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12 slot 14 pole full parallel wind possible?


Hi, my first post at RCgroups..
I must thank everyone for the knowledge collected here, i finished my first motor rewind with info from RCgroups - couldn't have done it without you!
I managed to get a 42% decrease in copper losses with an 8% increase in torque/amps, was pretty happy with those results for a first wind.

Now to my question:
I have a 12 slot 14 pole motor, same type that i rewound before. I will use it with a retro direct gearbox so motor will be driven both directions and controlled with hall sensors.

A shift from wye to delta connection offsets the stator magnetic field by 30 degrees and i guess that field shift will occur also when going from clockwise rotation to counterclockwise rotation of the motor.
I also assume that a wye connected stator field is not affected by a direction change in the same way.

Is this the case?

If so, then that delta connection gives me problems with the hall sensor signals not being correct in relation to the field after changing direction and therefore i want to switch to wye connection.

Original motor is wound dLRK delta, 45kV with 12 turns of 5x0.8 mm wire. It is a crappy winding.. Too many crossovers and voids result due to the many parallel wires.

To keep the fill factor high i am going to use thicker wire but that still leaves me at 25-26 turns with 2.5x1.25 wire since the slots are big. In wye connection the kV will be far too low.

Can this stator be wound full parallel (all coils of each phase connected in parallel)
Has anyone done this type of winding (full parallel dLRK wye) with good results?
What would the winding scheme look like for full parallel wye?


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Nov 26, 2017, 04:03 PM
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Ha! Oh boy, have you got a good question here, and yes I have done this, it was fun and interesting.

Start with the dLRK and why you have to double the number of turns when winding a series-parallel aka half parallel dLRK wind...it's because the inductance of the coils is halved when the coils are put in parallel.

Inductance determines the kv, an additional benefit tho is that you double the motor current capacity... double the wire spec
See my pic hp doubles both current specs in delta or wye

So now while you can make a motor with all parallel coils, how many turns will it take per tooth to get the kv you want?

On Manuel Vs turn calculator sheet ver 7 shows and I wound 10t hp dLRK wye for 650kv, now 5t dLRK wye would also get the same 650kv but only the value of the wire spec for motor current limit. So that 10 turns was easy enough, nice big roomy Scorpion motor case, really good quality motors

See my pic that explains a lot about motor circuits, current, and how much turns to wind for what kv, in dLRK wye it's kv, in hp dLRK wye it's double kv or double the turns for same kv, TC7 sheet says the same thing

Now I'm trying to think on the fly here how many turns for a motor with all parallel coils, high current capacity is possible, but you cut the inductance down a whole lot
Examining wye case only: dLRK 5t or 1 x turns, hpdLRK 10t or 2 x turns, all parallel guess is 4 x turns 40 turns per tooth for 650kv

So how small a wire would you need to get 40 turns per tooth?

I did this experimenting with one of my motors and I cannot remember which or where, maybe in my pancakes thread, but due to how this decreases the inductance and raises the kv for same number of turns, you probably won't want to do an all parallel wind, as you are presently working with a 45kv motor, takes a lot of turns to get that low, and many more when it's all parallel


It would be helpful if you would see the standard references to wires and sizes and situations and refer to them the same way we refer to situations, show some pictures of what you are doing, much more complete description... I re-read and saw you want 45kv

What's your motor, need pics, what stator size diameter and thickness or height?
What voltage and what prop you want to drive at what rpm... guessing it's 45kv maybe it's a camera gimbal motor and are you sure then it's delta and doesn't have a wye bundle? Well you see we need much more pictures and information.

I've learned a lot and played a lot with different kinds of winds, terminations, figuring out just how to successfully wind motors, not get shorts etc and you could see lots of these issues in threads I have joined in or started, see the 2215 scorpion thread I started learning in, the dt750 new big-un, my own pancakes thread has many good links in middle of thread to like ronaldopn threads with good layout n help for rewinding motors, a funny one on the half parallel wind where I have some fun with harbor freight bake on paint I fixed a stator with, it worked on a suppo 2217 motor I just didn't want to throw away

Would you use a special kind of ESC to change motor directions?


Leonard
Last edited by leonard3k; Nov 26, 2017 at 04:51 PM.
Nov 27, 2017, 07:24 AM
Registered User
Hello,
Thanks for the quick response, this is my application:

My motor is kV45 and equipped with hall sensors:
http://www.revolt.org.il/rv-120-model/rv-120-pro/

I use it for an ebike so it is driven with a Kelly KLS7230 controller:
http://kellycontroller.com/kls7230s2...er-p-1343.html

Winding choice:
I plan to go to wye connection from delta:
kV in delta = 45 --> kV in wye = 25
Full winding of slots:
kV, 12turns winding = 25 --> kV, 25 turns winding = 12
Possible change to get a higher kV:
kV series connection = 12 --> kV full parallel connection = 48

Hence my question

I want to keep the kV at least above 45, preferrably at 60-80.

The reason i get so many turns is that the wire i use is rectangular 2.5x1.25mm. I cannot pass thicker wire through the slot openings as they are 3mm wide and the slot can max fit 25turns of this (single) wire. Also thicker wire will cause a lot of AC losses due to skin effect.

Wire is so stiff that i don't believe in doing parallel strands - maybe two layers would be possible but then the connections will be difficult to fit.

All suggestions how to proceed are welcome!
Nov 29, 2017, 04:07 AM
Registered User
Hello,
After some extensive searches here i found an answer:
https://www.rcgroups.com/forums/show...DDD-connection

The full parallel is not an option for me as it will cause major losses from circulating currents.

I wonder how the large motors are wound, seems to me there will always be bad fill factor due to that many parallel strands have to be used.
Nov 29, 2017, 06:42 AM
Registered User
Hi Lars
Wow, it's not an airplane motor, $300, heavy stuff. I could see how you wouldn't want to rewind this too many times n take a chance messing up the stator

I've been working with small motors 2 to 5 # thrust and interesting ideas about theory and winds and experimental; THIS demands much more power and larger motors

Recently clarified that the inductance determines kv ( all other things being constant, unless you want to change the magnets or something )

Sounds like you have very tight limits so any wind that made more turns might be difficult, Z-matrix thread about splitting strands on a delta wind to lower kv, before I really understood what he was talking about, got me to thinking about increasing inductance by winding more than just 4 teeth per phase conforming to the wind pattern like even all 12 teeth on 12n motors

I'm going to play with this with test wind wire on a 5208Q multirotor motor, see how it works, should take 1/3 # of turns for same kv as one winding 4 teeth per strand

Maybe some good idea might come to you

Leonard
Nov 29, 2017, 11:20 AM
Jack
jackerbes's Avatar
I am not sure I completely understand the question and discussion here but when you mentioned wanting to have a higher Kv it brought the parallel winds to mind for me because of the fact that a YY wind would double the Kv from a Y wind and a YYY wind would triple it. So I played with the Winding Scheme Calculator a little and came up with the attached images.

To do that I went to the calculator, entered 12 and 14 for slots and poles and chose the Y termination, too the default 2 Layer setting (1 Layer is the LRK wind) and calculated the first image.

Then I clicked on the Advanced mode so I could edited the winding scheme there.

The first image generated the scheme AabBCcaABbcC and that had a Winding Factor of = 0.93301. And this, of course, is the standard 12N14 dLRK-Y winding

In the second image I edited the winding scheme to make it a YYY by changing the AabBCcaABbcC with slants to make it read AabB/CcaA/BbcC and hit the Calculate button again. That produced the second image and the winding factor stayed the same at 0.93301.

I wondered if there might be an advantage to rearranging the winding sequence a little and then I took the AabB/CcaA/BbcC scheme and changed that to AaAa/BbBb/CcCc to put the four arms in each phase in sequence and that changed the winding factor to 0.080801.

But neither changed the winding to an unbalanced winding and the only real differences in them is the winding sequences and the winding factor. A 0.93301 motor would be more efficient than a 0.80801 motor but I would not hesitate to try the latter if there was some attraction arising from the different winding sequence.

I have never done either of the YYY winds and don't know for sure that they are good ones or how they will work but thought they may be worth considering.

Jack
Last edited by jackerbes; Dec 02, 2017 at 09:44 PM.
Dec 05, 2017, 04:31 PM
Registered User
Thanks for the input Jackerbes, looks promising!

What does yyy mean actually?
What kV would it be with this wind, 36?

If it's more on the experimental side then i'm doubtful, last rewind took me something like 24hrs..

What about using double controllers to separate/double LRK windings?

Will that double the kV as well?
Last edited by larsbig; Dec 05, 2017 at 04:42 PM.
Dec 05, 2017, 06:04 PM
Jack
jackerbes's Avatar
The YYY means that it is a three part motor and each part is terminated Wye. It would be essentially the same a three four arm stators running in parallel. When we talk about Half Parallel that is also called a two part motor so it could be a DD or YY motor depending on the termination (all parts have to be terminated the same way of course).

If you got a 25 Kv for 12 turns in a dLRK wind terminated Wye going to a three part motor with a YYY termination would give you a 75 Kv (three times the 25 Kv).

Quote:
What about using double controllers to separate/double LRK windings?
Double speed controllers or ESCs? Is that the question? I don't know but maybe someone will have an answer for you. I'm a little confused by the question because with only one motor I'd think you would only need or want one controller. But I might not be right.

Jack
Dec 05, 2017, 08:58 PM
Registered User
What i mean is to wind two sets of LRK windings and drive them separately like two motors on the same stator. I think it's been up here some times but i don't know the effect on kV.

As they will be separated i would assume that kV doubles as then only 25 out of 50 (possible turns to fill each slot) are wound on each "motor"

But is this the case?
Dec 05, 2017, 10:26 PM
Jack
jackerbes's Avatar
So only one set of windings or the other would be driven at a time and the other set is just along for the ride.

And the two windings would have different turn counts to give different Kv's right?

I really don't know if that would work or not but it is an interesting question. The two sets of winding would have to share the slot, one set would not have any voltage on it and the other would.

Do I have it right?

We might have to wait for one of the real experts to come by, like Christian Lucas or Louis Fourdan...

Jack
Dec 06, 2017, 03:29 AM
Registered User
Both windings would be used at the same time with separate controllers (sensored, no risk for cross-talk between windings affecting a sensorless controller)

I believe it's sometimes done but what will be the effect on kV?
Dec 06, 2017, 09:15 AM
Jack
jackerbes's Avatar
That is what baffles me. If there are two sets of winding with different turn counts and both being used one will be trying to turn at a different rate than the other...

Jack
Dec 06, 2017, 09:58 AM
Registered User
I must be explaining badly, sorry for that.
the winds will be the same no of turns and have the same kV, my goal is to get a lower kV with good fill and i want to use a wye connection.
Dec 06, 2017, 11:58 AM
Jack
jackerbes's Avatar
Quote:
Originally Posted by larsbig
I must be explaining badly, sorry for that.
the winds will be the same no of turns and have the same kV, my goal is to get a lower kV with good fill and i want to use a wye connection.
OK, now I understand. If you make a two part motor it doubles the Kv and you want to avoid that.

We used the Turn Calculator family of spreadsheets to look at the turn count and termination options on LRK, 2PdLRK (Half Parallel dLRK), and dLRK winds. That spreadsheet has some later version with more option, all of them can be downloaded here and you can run them with the free OpenOffice Calc spreadsheet application:

https://www.rcgroups.com/forums/show...&postcount=260

or here:

https://www.rcgroups.com/forums/showthread.php?240993

I ran Turn Calculator 5 (for it's less complicated presentation) used the 12 turns and 45 Kv in your first post to "salt" TC5 and get the turn count and termination and Kv info for the LRK, 2PdLRK (Half Parallel dLRK), and dLRK winds. I took a screen shot of the result and it is attached. I added labels over the columns so you can tell which columns are for which wind and there are columns for the Delta and Wye (Star) terminations for all three winds.

I marked the 45 Kv from your 12 turn wind in a red box and that is result for 12 turns dLRK terminated Wye. That and all the other data is generated by the turn count an Kv I entered into the yellow boxes at the top.

Depending on what Kv you want to have on the finished motor you can look at the info there and decide which wind you want to try. If you have some wire on hand you can do some tests winds to see how many turns you can get on arm for LRK (empty arms on both side allow for larger wire) or the other two winds (adjacent arms are wound so the wire must be smaller than for LRK).

Look at this image a little bit and see if you see a possible answer or solution in it.

Jack
Dec 11, 2017, 01:24 PM
Registered User
My problem is that motor is delta wound already and i want higher kV so my question is still open..

A full slot witht the wire i have will be 25 turns 2.5x1,25 square wire as i have already tried it on another wind on the same stator

My reasons for the choice is:
AC losses grow too much above 1.5mm wire thickness
Square wire is easy to pack
slot openings are 3mm so the 2.5mm width fit well
It is really hard to get good fill so i don't believe in several parallel strands - would this still be rcommended?

What could i wind to get higher kV?


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