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Old 03-29-2007, 11:05 PM   #1
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Default BL motors : Why wye?

Does anybody have an idea why Novak and others chose the Wye connection over the delta connection when the built the first brushless motors? Please share the knowledge

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Old 03-30-2007, 12:24 AM   #2
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Well, I am sure I will piss some people off with this....but...

Supposedly they decided to Wye wind them, because it supposedly made them more comparable to brushed motors in terms of power.......and they were hoping for quicker acceptance of the motors if nothing really differed except the supposed cost savings.....

However....

The companies at the time that had brushless motors in production (hacker, platenberg, etc....) made all their motors delta....and from my understanding said they wouldn't make a brushless wye wound cause it simply wasn't the smart way to do it.....so.....an easy way to cut out the competition.....

I probably would of done the same thing though........smart business.....

So, I am sure some will get butt hurt about me saying it......but thats the truth.....regardless of what anyone says.

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Old 03-30-2007, 01:02 AM   #3
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I believe it was done simply because Wye wind motors are much more difficult to drive with a sensorless controller. The back EMF the controller needs to start and control the motor are much weaker off a Wye wind motor compared to a Delta wind motor.
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Old 03-30-2007, 01:32 AM   #4
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There's a lot of talk about this in the airplane brushless world. They ultimately seem to prefer wye because of the torque it produces at a given power. The gobrushless.com forum has a lot, LOT of talk about it.

Graupner's got a new line of motors available in wye/star or delta. I get the feeling delta motors produce more RPM per volt, possibly making them more suitable for certain applications.
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Old 03-30-2007, 01:44 AM   #5
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https://shop.graupner.de/webuerp/servlet/AA?wgr=853

You can see they're offering many of their new motors as wye/star or delta.
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Old 03-30-2007, 02:29 AM   #6
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My 3.5r is too much power for my skills. I'm thinking of rewinding it up to 13.5. Do you think the sensors will still work if I tried delta winds?
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Old 03-30-2007, 03:11 AM   #7
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I tried it. Delta will work in Novak can + sensors, but dont go under 6 turn very hard time for GTB.
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Old 03-30-2007, 02:39 PM   #8
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We have experimented with delta winds in our motors and with our design delta winding yeilds a motor with less starting torque and less running efficiency.

Essentially in our slotted design with a delta wind you have two coils fighting each other which results in this inefficiency.

For giggles I just grabbed a standard 3.5R and the 5 turn delta motor and ran them on our dyno.

We can measure the time to certain RPMs... 5,000, 10,000, 15,000 etc... at each test point the delta wind motor trails the wye wound motor by approximately 0.1 seconds.

It also takes more current for the delta wound motor to reach these RPM points than the wye wound motor...and at full RPM... the 3.5 took 22.6A ...where the delta wound equivalent took 54.7A

3.5R

RPM Time Current
5,000 0.16 106.1
10,000 0.34 67.2
15,000 0.6 41.6
20,000 1 59.9
25,000 1.8 46.7
30,000
35,000

Delta
RPM Time Current

5,000 0.22 118.3
10,000 0.44 99.5
15,000 0.74 51.7
20,000 1.14 29
25,000 1.78 65.3
30,000 2.96 65.6
35,000

3.5 Max RPM 29,761 @ 22.6 A

Delta Max RPM 33,244 @ 54.7 A (incidentally at 29,809 RPM the current draw is 65.7 A)

So you can see that in our design the delta wind really doesn't really seem to buy you much of anything except some very inefficient extra RPM.
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Last edited by Steve Weiss; 03-30-2007 at 02:43 PM. Reason: ug... data did not format correctly.
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Old 03-30-2007, 02:46 PM   #9
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Quote:
Originally Posted by Steve Weiss
We have experimented with delta winds in our motors and with our design delta winding yeilds a motor with less starting torque and less running efficiency.

Essentially in our slotted design with a delta wind you have two coils fighting each other which results in this inefficiency.

For giggles I just grabbed a standard 3.5R and the 5 turn delta motor and ran them on our dyno.

We can measure the time to certain RPMs... 5,000, 10,000, 15,000 etc... at each test point the delta wind motor trails the wye wound motor by approximately 0.1 seconds.

It also takes more current for the delta wound motor to reach these RPM points than the wye wound motor...and at full RPM... the 3.5 took 22.6A ...where the delta wound equivalent took 54.7A

RPM 3.5 Time 3.5 Current Delta Time Delta Current
5,000 0.16 106.1 0.22 118.3
10,000 0.34 67.2 0.44 99.5
15,000 0.6 41.6 0.74 51.7
20,000 1 59.9 1.14 29
25,000 1.8 46.7 1.78 65.3
30,000 2.96 65.6
35,000

3.5 Max RPM 29,761 @ 22.6 A

Delta Max RPM 33,244 @ 54.7 A (incidentally at 29,809 RPM the current draw is 65.7 A)

So you can see that in our design the delta wind really doesn't really seem to buy you much of anything except some very inefficient extra RPM.
This is way less interesting than Eddie's conspiracy theory!
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Old 03-30-2007, 02:48 PM   #10
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Here's what Aveox has to say:

At Aveox, we have essentially deemed the Deltas as secondary to Wye winds in any application, except where a very high degree of uniformity in both directions is very important. Things like robots that move in both directions equally put up with the efficiency losses. Since the motors are very insensitive to timing changes (unlike the Wye winds), you don't have great performance in one direction, and poor in another(without adjusting the timing). You have good performance in both. (but it is not worth the losses in a model)

They have been discontinued at Aveox for a couple of years. We do what we can to get them out of circulation by changing them over at a loss. (However, they are really easy to make if you insist).

Aveox was the first company in the world to commercialize brushless DC motors for the R/C industry. Our motors have won numerous championships and achieved records on land, water, and in the air. We cater to large OEM accounts (where we can private label our motors and controllers)
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Old 03-30-2007, 03:07 PM   #11
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Interesting numbers.....

Kinda fleets what Bob said way back when why he recommended Wye.....as I remember it saying something to the likes of.....a delta wound motor would blow everything a way....

I think I will stick with my theory.....

I have read a ton on the gobrushless forums today......which just makes my point more solid.....all those guys seem to think delta vs wye is really no difference when the motor is designed for the winding pattern...

So the reason to go wye when pretty much everyone else was delta?

Competition elimination....


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Old 03-30-2007, 03:15 PM   #12
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Quote:
Originally Posted by syndr0me
This is way less interesting than Eddie's conspiracy theory!

Hahah yeah, fact is oftentimes much less entertaining than fiction

I also forgot to mention... winding a motor delta-style is MUCH easier than winding it wye style... so from a production standpoint it would be better... so you can be sure that if it worked better than wye winding we would be doing it!
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Old 03-30-2007, 03:25 PM   #13
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Anothing you need to realize is that everyone else was going the slotless/sensorless route...

I don't think I need to belabor the reasons why we went sensored...those have been gone over time and time again...

One of the reasons the three slot design was used was in an effort to make it "closer" and more acceptable to what the brushed rules currently allowed for.

There was a frame of context for having a 3 slot design whereas there was none for a multi slot or slotless type design which may or may not benefit from a delta wind more-so than our 3 slot design would.

The 3 slot design also allows for easier technical inspection and production.
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Old 03-30-2007, 03:28 PM   #14
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Well, Steve.....the fact is.....Bob made the comment, not I.....and I believe even Charlie restated once on here before.....

And to further.....Bob helped write the rules.....and funny, delta was not allowed....

The fact a novak motor works better wye wound than delta wound isn't surprising.....they are designed to be wye wound.

Better or not, there was no reasons to allow them out of the rules other than to eliminate the competition that was already making motors that were delta wound. Nothing that has ever been stated about the logic behind the brushless rules has ever made sense.....



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Old 03-30-2007, 03:42 PM   #15
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This guy asked why we decided to wind in Wye instead of Delta.

I answered his question to the best of my ability/knowledge about why we decided to wind in wye instead of delta.

I guess you'll have to discuss the deeper motives/marketing/master plans to take over the world with Bob

Quote:
Originally Posted by rough512
Does anybody have an idea why Novak and others chose the Wye connection over the delta connection when the built the first brushless motors? Please share the knowledge

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