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Old 11-16-2008, 06:00 PM   #1
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Default A sensored vs sensorless question

I've been doing a bit of research as I want to buy a couple of new motors to stick in the parts box as options for different tracks and I've started noticing that a lot sensor-less motors seem to be rated in whole winds (IE 6T, 10T etc) and sensored motors tend to be rated in 0.5s (IE 6.5, 10.5 etc)

My question is.... WHY?... and what makes the difference?

I've also noticed that if I compare Kv and wattage ratings I find that (as an example) that a 10T sensor-less tends to compare with a 10.5T sensored... or at least very close... but as most clubs/organisations tend to say a class is limited to 10.5T or whatever, its seems that it limits the motors that can be bought

Is this something the rule makers need to look into?
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Old 11-16-2008, 06:27 PM   #2
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I'm not sure why sensored motors seem to come in half winds only and sensorless in whole number winds, but I've been wondering about that too... In most spec racing, it'll be a moot question, because all the spec classes I've seen call for sensored motors only, and i've never seen a sensored motor available in a whole number wind..

I know from the brushed motors a hemi wound motor was considered to be a half turn less than a crossover wound of the same number of turns, maybe it's something like that with the brushless, but I don't know for sure...

Or am I missing the point?
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Old 11-16-2008, 06:48 PM   #3
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10.5 is Wye (star) wind while 10r is delta Wind.

It refers to the way the 3 phase windings are connected together. I think the more appropriate question would be, which is the better wind for our application, Delta or Wye?
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Old 11-16-2008, 06:58 PM   #4
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Based on the brushless motors I made for flying, I'd think delta would make a ton more power and eliminate some of the insane gearing we're having to run, but run times would go down significantly... winds would have to go up to keep parity with brushed motors in the spec classes... a 17 turn delta would flat out demolish a 27 turn brush motor...
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Old 11-16-2008, 08:03 PM   #5
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Ok. So. What's the difference between a "delta" wind and a "Y" wind? I hope this isn't too off topic for the thread.
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Old 11-16-2008, 08:16 PM   #6
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Basically, it refers to how the three windings in the motor connect to each other. Each winding has a start and an end. In a Y connection, all three starts would be connected together, then the three ends would go out to the solder tabs. In a delta connection, the start of each wind is connected to the end of the previous wind, then the three connected pairs go out to the solder tabs.

In the airplane motors I was making (I was scavenging CDROM motors and rewinding the cores and then making rotors with small neodymium magnets) the same motor connected as a delta put out significantly more power than it did when connected as a Y, but at the cost of more current draw and more heat.
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Old 11-16-2008, 08:53 PM   #7
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Quote:
Originally Posted by Trips View Post
Basically, it refers to how the three windings in the motor connect to each other. Each winding has a start and an end. In a Y connection, all three starts would be connected together, then the three ends would go out to the solder tabs. In a delta connection, the start of each wind is connected to the end of the previous wind, then the three connected pairs go out to the solder tabs.

In the airplane motors I was making (I was scavenging CDROM motors and rewinding the cores and then making rotors with small neodymium magnets) the same motor connected as a delta put out significantly more power than it did when connected as a Y, but at the cost of more current draw and more heat.
Lemme see if I got this right. A "Y" wind would be considered a parallel connection, where a "delta" seems like more of a series connection. Correct?
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Old 11-16-2008, 09:49 PM   #8
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Quote:
Originally Posted by SpraydbySprague
Lemme see if I got this right. A "Y" wind would be considered a parallel connection, where a "delta" seems like more of a series connection. Correct?
Correct.

And a Delta wind will produce 1.73 times the power of the same wind as a WYE.
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Old 11-17-2008, 06:39 PM   #9
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Correct.

And a Delta wind will produce 1.73 times the power of the same wind as a WYE.
Is this due to the fact the current has a shorter path to go from one phase to the next in a "delta" wind vs a "Y" wind?
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