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BL motors : Why wye?

BL motors : Why wye?

Old 03-30-2007, 03:46 PM
  #16  
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Originally Posted by Steve Weiss
.....master plans to take over the world.....
Ooooooo DO TELL!!!! I WANNA KNOW!!!!!!

heheheheheh
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Old 03-30-2007, 03:47 PM
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Conflicts with what Bob and Charlie have stated in the past, which is.....Wye made the motors similar in power to a brushed and a delta wound motor would make brushed look slow.......

Now its, cause wye is better than delta....

Later EddieO
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Old 03-30-2007, 03:59 PM
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I can't find where Charlie said it, he may of told me it in person......but, I found this


Posted by the LRP race team manager

There's a good reason IFMAR, EFRA and ROAR went for "Wye/Y wind only" for brushless motors...
-> it is more in line with brushed motors power and powerband wise.
-> it's better to have "brushed motor characteristic" with a wye wind due to different feedback to the controller.
-> Delta would offer WAY too much power in brushless with the 05 size motors we use.

@Charlie: Wye isn't able to make as much power as Delta, it's something like 50-60% less power output with a similar wind (they'll always differ by a minimum of 0.5turns...), if I remember correctly. Luckily I wasn't the designer of our brushless system...
Also in case someone doesn't know: wye winds are always 0.5 winds (because of the opposite common connection) while delta's are even winds.




Later EddieO
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Old 03-30-2007, 04:10 PM
  #19  
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I cannot account for anything Charlie or Bob have said in the past... all I can do is share with you the data I just gathered and the information my engineer has told me to share!
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Old 03-30-2007, 04:21 PM
  #20  
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EFRA has allowed Delta winds this year and GM Racing has some Delta motors available: 7T Delta Wind motor

Guess we will find out what's hot and what's not, soon enough
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Old 03-30-2007, 04:28 PM
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Am I to assume delta wind and wye winds are the same difference as a triple double or single as if it were brushed motors?
And if so as long as its in mod why would it matter other than certain speedos would be more appropriate.
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Old 03-30-2007, 04:43 PM
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No, its totally different....

I will do my best to explain it....


Basically.....on a delta wound motor, you start at oen tab.....go down, wind that segment.....come up to the next tab then go back down to and wind the next segment.....this goes till you get back to the first segment......basically, you use ONE big long piece of wire....

On a wye wound motor.....you start at the tab up top.....go down and wind the segment and you terminate it at the bottom.....then you do the same for each segment......each segment uses its own piece of wire....

This is a generalization of how it works......other designs and winds (double, triple, etc) can differ how it works....

Brushed are pretty much all delta in RC that I have ever seen.......brushless there is both....

Later EddieO
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Old 03-30-2007, 05:46 PM
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So delta is 1 wire and wye is 3 wires, right?
But the carictoristics in the way they rev up are the same difference as a single double or trple, right?
One has more RPM And one has more torq. One has more punch at the bottom end, and the other woud have a smoother bottom end. I hate to be a bugg, just trying to get it straight.
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Old 03-30-2007, 05:55 PM
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Originally Posted by EddieO
Conflicts with what Bob and Charlie have stated in the past, which is.....Wye made the motors similar in power to a brushed and a delta wound motor would make brushed look slow.......

Now its, cause wye is better than delta....

Later EddieO
Dear Eddie,
I will tell you exactly why I wrote the rules with a Wye wind only. First off I personally never said that a Delta wound brushless motor was faster than a Wye wound brushless motor. I knew from our computer simulations that a Delta wound brushless motor just simply was very inefficient and would not produce the horsepower that an equivalent Wye wound motor would produce. To further investigate this fact we actually built several different motors using this winding technique and tested them on our dyno and as Steve posted you can see from the numbers the Delta wind motor just doesn’t have it. You also have to remember at the time that we wrote these rules the 10 turn brushed motor was the only allowable modified motor allowed it touring car racing. With the brushless rules we wanted to mimic the brushed rules as close as possible believing that they would be more readily accepted. Also with the tech problem for an equivalent 10 turn brushless motor it would simply be easier if we only allowed one type of wind. Seeing that the Delta wind motors were horribly inefficient, and we were trying to sell the low maintenance and higher efficiencies of brushless motors to the existing car customer, we chose Wye. Now if you consider looking out for the average racer by giving them a better product with these rules as a conspiracy theory, than I plead guilty.
Bob Novak
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Old 03-30-2007, 05:57 PM
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Originally Posted by EddieO
I have read a ton on the gobrushless forums today...
Glad I'm not alone, I was up all night reading that thing. I found some of the stories people were telling about building their own motors intriguing. Pulling apart old hard drives and cooling fans to find that perfect stator, etc. It's reminiscent of going to the junkyard looking for pieces to make your car's engine perfect.
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Old 04-09-2007, 11:02 AM
  #26  
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That is the great thing about engineering. There is usually more than one path to a desired result.

If we were talking about the same motor designs there would be a big difference in the delta vs wye. However we mess with so many other parameters that effect the end result.

Perfect example is the Novak wye wound motors. The same motor with a delta wind should have 1.73 times the KV. Yet the Novak motors have higher kv than any of the delta motors offered by other companies with the same turns.

http://www.rcgroups.com/forums/showt...t=delta+vs+wye

So delta vs wye when comparing apples to apples makes a difference, but when designing for a specific application it is just one piece of the puzzle. They are all crazy fast.

To my knowledge no one has ever submitted a delta or slotless motor to roar for approval or offered any kind of design specs. That is about to change.

In our opinion there is no need for 10kv motors. The heat produced by the high rate of commutation makes up for the heat saved with the lower currents. With a delta motor you can gear it to the moon and work with a more reasonable rpm. We started out driving our 3turn geared as low as possible and have really ended up with a 5 or 6turn 4kv to 4.5kv geared tall being our favorite. The 3 turn almost thermals the controller, while the higher turns barley warm it up.. and we turn similiar laps. Also Kv's in the 4 to 7 range fit the car gearing a lot better. There is a sweet spot between too much rpm and too much current for torque. Regardless of the technology used, that is the best answer for reliability and happy consumers.

Those who think a wye wind is superior should not be concerned since our designs will obviously be inferior and non-competitive.

Jim Campbell
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Old 04-09-2007, 11:23 AM
  #27  
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The EFRA handbook (they made it available for download for the first time ever): http://www.efra.se/pdf/handb07weblocked.pdf

it indeed says delta and wye is approved
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Old 04-09-2007, 11:25 AM
  #28  
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I would like to see what ever happens with brushless down the road that we are not forced to pretty much one brand. Would be nice to have many brands to choose from.
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Old 04-09-2007, 02:14 PM
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wyd, nice fantasy.
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Old 04-09-2007, 03:21 PM
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Go by the roar rule

Last edited by mattnin; 05-08-2007 at 12:51 PM.
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