Motor Windings

maxemum610

1 µW
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May 28, 2022
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Greetings, be kind I'm new here, I have nagging question that I need more learnered opinions on.

If a Sinewave/ FOC Controller is the better way to go, then a motor with Distributed Windings would make the perfect marriage.

Found this,
concentrated%2Bvs%2Bdistributed%2Bwindings.jpg

to help me compare what the PRC 'factories' will show.

I bought (what I thought were TopPower) 2 x 48v 1000w Sine Wave Motors. On receipt they were in a bit of bubble wrap (not the TopPower Factory - possibly a clone or product created for a seller/ trader) and so I did an inspection which included pulling the end plates off and found the windings looked 'concentrated', (I took photo's) and their online image looks similar
HTB1Pn9fJpXXXXciXFXXq6xXFXXXB.jpg

Its possibly the marketing department are saying if we use their Sine Wave Controller, then the motor is Sine Wave?

I continued my search and found Wuxi Helanda Mechanical & Electrical who use this image in the top description
H3628bc07c5c54738877b2c539383d1dd5.jpg

and I think here we go, this looks distributed, but correspondence with 'Frank' says their motors are square wave and another image further down the page shows
H17664ec184a743ecb670e8f6a44c4609N.jpg

Wish I knew what motor the previous image came from, as that looks distributed windings.

The search continues.
What I'm asking have I got it right in what I think is distributed, was that image above from Helanda distributed, or are the windings on the TopPower Sinusoidal

Thankyou
 
I'm going to hypothesis that I am seeing different ends of a distributed winding.

One end I count 15 up and over, is that a long metre or so bunch of straight winding wire for each phase wound around, miss 4 slots then back down and up on the next slots etc ?

That is, if most Permanent Magnet BLDC motors have distributed windings (as seems implied)

Here's TopPowers page and you can buy direct
https://cnluxe.en.alibaba.com/minisiteentrance.html?spm=a2700.wholesale.cordpanyb.2.491096aedFSORo&from=detail&productId=1600276122177
 
Ok, seems there are some misunderstandings in these posts, i’ll try to clarify.

What’s called ”sinewave motors” have a sinewave shaped BEMF, something like this (i just took this pic from the web):
0E7FBFEA-3546-44B4-9D4B-8B6E83C14E03.jpeg

”square wave” or ”trap”/”trapezoid” motors have a BEMF something like this:
8B2A69FF-6AC2-45E3-8C7E-6DC71FED4BC9.jpeg

In theory each type of motor is best driven with the corresponding wave form controller output for best efficiency and torque. Thing is, most of the motors used here at ES have more or less sinewave BEMF and only the lower grade hobby ESCs and controllers are square/trap drive type these days. There are still millions of cheap controllers and ebike kits with square/trap drive produced in China and sold each year and these work but won’t give the best efficiency, it’s worth it to pay slightly more for a sinewave or even FOC controller.

Then about distributed vs concentrated windings:
Distributed windings have the advantage of being able to cancel out some of the harmonics in phase current and reducing torque ripple, hysteresis losses and eddy currents. There can be a reduction in these types of losses but the distributed winding does not win in overall losses: it has much longer windings due to the longer wire transits between each slot. Therefore (for the same stator) they always get a higher phase resistance than with concentrated windings. Copper resistance losses dominate at higher loads and because of this a motor with distributed windings normally has a lower efficiency than a motor with concentrated windings.

So: most BLDC/PMSM motors used for traction drive have concentrated windings and there’s no reason to buy a motor that has distributed winding as the advantages of a distributed winding (low torque ripple) aren’t as important in ebikes/emotos as efficiency and torque/power density.
 
For very low speed applications that require very smoothly turning loads, distributed windings may be better, but this isn't typically the case for vehicles, bikes. etc. Without knowing the details of your project, I can't say for sure, but I think you would be better off with the concentrated winding type of motor.


To test any motor for trap vs sine design, just spin it up from an external source (drill, etc) with no power on the motor windings, and use an oscilloscope to see the waveform between phase windings. If it looks like a trap form (lower picture in Larsb's post), you can sue a trap style controller to best match it. If sine (top pic), then use a sine controller (this is the most likely case).
 
Worth noting that none of the motors you've pictures of above are distributed winding motors. The fact that the end turns overlap in some I do not think makes them distributed.

How you drive them (optimally) depends on the backemf waveform.

I have yet to find a motor that runs better with square wave than FOC. They probably do exist, I'm told they exist...

FOC takes parameters and tuning which depending on the controller software can be easy or hard, BLDC/trap can sidestep this.
 
mxlemming said:
Worth noting that none of the motors you've pictures of above are distributed winding motors. The fact that the end turns overlap in some I do not think makes them distributed.

Actually, this is distributed (coil spans over more than one tooth):
01DC77C5-E06A-44DF-9D37-8D55974CCCEE.jpeg
This looks concentrated (but hard to see clearly)
6ADD53F0-184D-4162-A71D-6C1062079F8C.jpeg
 
Isn't it just wound like this?

Screenshot_20220529-231427.png

I didn't think that's distributed... Just... An interesting combo. It obeys the same rules as a concentrated wind...

Maybe I'm getting my terminology wrong :confused:

Edit after thinking through this and having a bit more time:
stator-e1488797545950.jpg
This is my idea ofa distributed winding. You can see there are clearly several slots next to each other with the same phase and same direction.

My assumption up until now was that the end turns are irrelevant. Only what's in the slots is important; that being phase and direction.

2+ adjacent slots with same phase and direction = distributed.
Different phase or same phase different direction =concentrated.

I may well be wrong.
 
You guys are so cool and knowledgeable.
 
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