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Old Jun 04, 2012, 01:36 PM
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Turnigy C8085 Dual Controller 6-Phase Rewind

Here's a video of a C8085 outrunnner rewound in a 6-phase, wye configuration.

10 turns (1 meter per tooth) of #14 AWG
36 mOhm phase resistance
162 kV

For testing I am using two ebay "el cheapo" 100A (yah right) ESC's, one for each set of phases. At WOT the no load current is 3.7A @ 23.9V and 3917 rpm (3826 rpm as measured w/ scope). Operation at start-up and low rpm is a bit rough yet it starts to sing above 1500 rpm or so. I should probably verify that I have the controllers set to identical configurations. It's such a PITA to program these with just the throttle...

I kind of messed-up when connecting the phases internal to the motor and as a result I could not get the skirt housing/bearing assembly back in without it interfering (rubbing) with the windings so I am currently running it without that bearing. Up next will be a load test with a 30" prop. I hope it does not fly apart without the skirt bearing. The other outcome might be the controllers flaming-out. In any event it should make for some dramatic video.

Turnigy C8085 BLDC 6-Phase Dual Controller Rewind (4 min 29 sec)
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Old Jun 04, 2012, 03:43 PM
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Quote:
Originally Posted by mauimart View Post
Here's a video of a C8085 outrunnner rewound in a 6-phase, wye configuration.

10 turns (1 meter per tooth) of #14 AWG
36 mOhm phase resistance
162 kV

For testing I am using two ebay "el cheapo" 100A (yah right) ESC's, one for each set of phases. At WOT the no load current is 3.7A @ 23.9V and 3917 rpm (3826 rpm as measured w/ scope). Operation at start-up and low rpm is a bit rough yet it starts to sing above 1500 rpm or so. I should probably verify that I have the controllers set to identical configurations. It's such a PITA to program these with just the throttle...

I kind of messed-up when connecting the phases internal to the motor and as a result I could not get the skirt housing/bearing assembly back in without it interfering (rubbing) with the windings so I am currently running it without that bearing. Up next will be a load test with a 30" prop. I hope it does not fly apart without the skirt bearing. The other outcome might be the controllers flaming-out. In any event it should make for some dramatic video.

http://www.youtube.com/watch?v=LgRK4_4ElhU
I remember that Christian Lucas stated that 6-phase motor will be most powerful system for the 12-N stator. Yet I am also having the concern that how can i find two exactly the same 3-phase ESC to power the 6-phase motor. As you experienced, there might be some synchronizing problems. I am also not sure how better will the 6-phase system be when comparing with a 3-phase motor.

Another interesting thing is that: If I assume the 6-phase motor (I guess it is 2 LRK winding? ) works the same as a 3-phase dLRK motor, two identical 3-phase ESC powering the 6-phase motor with a load (propeller), assuming both ESC is carrying 100A current. To reach the same output power (same speed, same load), a 3-phase motor will be using 200A under the same voltage input?

To note that dLRK windings can actually be viewed as two LRK connected in series. While connecting the two LRK in parallel is not possible, using two separate ESC to power each LRK can be viewed as the two LRK are connected in parallel.
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Old Jun 04, 2012, 03:49 PM
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By the way, I noticed that you are not using the rear bearing (the large ring bearing), because wires will rub against it?

I rewinded two EMP 5340 (stator size, aka 6374) which is a smaller version of your 8085, while having exactly the same motor design including the bearing system. I hope this thread helps you to solve your issue.
http://www.rcgroups.com/forums/showthread.php?t=1607848

For each motor, I use single wire single direction technique to wind it, and connect them as dLRK and half parallel dLRK, if i remember correctly. To connect them as 2 separate LRK system, your 6-phase system, should not be harder than connecting them as dLRK or half parallel dLRK.
http://www.rcgroups.com/forums/showthread.php?t=1614226
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Old Jun 04, 2012, 04:36 PM
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Old Jun 04, 2012, 09:45 PM
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What's the benefit to two esc's? Does it allow for higher current or does it reduce the commutation load on using just one esc?
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Old Jun 04, 2012, 11:33 PM
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Originally Posted by jkrych View Post
What's the benefit to two esc's? Does it allow for higher current or does it reduce the commutation load on using just one esc?
I am not very clear but it is definitely not that simple. I think it is something about the magnetic flux density? Hope this thread will attract Christian Lucas attention. I cannot find the subscribe he posted regarding this specific issue.
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Old Jun 05, 2012, 10:04 AM
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http://www.rcgroups.com/forums/showp...0&postcount=35

Greg
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Old Jun 05, 2012, 01:22 PM
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maybe its lost in the translation but i cant see any answers-

what relationship would 2 esc play with Kv?
what about amp load and maximum power?
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Old Jun 05, 2012, 08:53 PM
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Long ago, before we had 5+kW or 300+A ESC, it was a method to use off the shelf controllers and get more power than the largest single ESC available.

The link I posted was what Christian had to say about six phases. I wonder though if Mauimart's motor is six phase or a parallel arrangement.

6 phase offers some efficiency improvement and reduced torque ripple over 3 phase according to some stuff I found online. In a 6 phase motor there is 30 electrical separation between phases compared to 3 phase at 60.

Greg
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Old Jun 05, 2012, 09:22 PM
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Originally Posted by gkamysz View Post
Long ago, before we had 5+kW or 300+A ESC, it was a method to use off the shelf controllers and get more power than the largest single ESC available.

The link I posted was what Christian had to say about six phases. I wonder though if Mauimart's motor is six phase or a parallel arrangement.

6 phase offers some efficiency improvement and reduced torque ripple over 3 phase according to some stuff I found online. In a 6 phase motor there is 30 electrical separation between phases compared to 3 phase at 60.

Greg
That is what i mean by giving this example :
Another interesting thing is that: If I assume the 6-phase motor (I guess it is 2 LRK winding? ) works the same as a 3-phase dLRK motor, two identical 3-phase ESC powering the 6-phase motor with a load (propeller), assuming both ESC is carrying 100A current. To reach the same output power (same speed, same load), a 3-phase motor will be using 200A under the same voltage input? "

Two parallelly "connected" LRK vs Two LRK connected in series (dLRK)
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Old Jun 06, 2012, 01:15 PM
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Quote:
Originally Posted by jkrych View Post
maybe its lost in the translation but i cant see any answers-

what relationship would 2 esc play with Kv?
what about amp load and maximum power?
Hi
Two ESC means two groups in parallel instead of in serial
So Kv is roughly multiplied by 2
In that example
1) Original C8085 8 turns Delta Kv (announced) 170 rpm/V
x 8 /10 should give 136 rpm/V (10 turns Delta instead of 8 turns)
/ 1.74 should give 78 rpm/V (10 turns Wye, in serial, instead of Delta)

2) Rewound 10 turns Wye : Kv around 164 rpm/V
(compared to 2 x 78 = 156 rpm/V)

Louis
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Old Sep 12, 2012, 10:33 PM
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Soft start

Do you think using soft start (not the esc soft start) on one set of windings will help the startup issues with BLDC 6 phase motors? Probably a RC time constant will work.
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Last edited by p901P901; Sep 12, 2012 at 10:54 PM.
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