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Author Topic: Twin brushless on ONE esc  (Read 2676 times)

rayna

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Twin brushless on ONE esc
« on: May 15, 2016, 06:39:25 AM »

Are there any problems using one ESC and using twin motors.
Presume if ok the ESC needs to be rated to handle max sum of the two currents.
thanks in advance
Rayna
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Leaky Bottom

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Re: Twin brushless on ONE esc
« Reply #1 on: May 15, 2016, 07:10:54 AM »

Yes there is a problem, they won't work.


The way I understand it is that the ESC sends pulses of current in turn to each pole of the motor at the correct timing, now if the motors are not in exact unison with each other one motor will be getting a supply of current at the wrong pole at the wrong moment, the outcome will be the motors just keep juddering back and forth.



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malcolmfrary

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Re: Twin brushless on ONE esc
« Reply #2 on: May 15, 2016, 09:04:22 AM »

Yes there is a problem, they won't work.


The way I understand it is that the ESC sends pulses of current in turn to each pole of the motor at the correct timing, now if the motors are not in exact unison with each other one motor will be getting a supply of current at the wrong pole at the wrong moment, the outcome will be the motors just keep juddering back and forth.


Even with brushless, provided that both (sensorless) motors are identical as regards type, wiring and loading, there are documented cases where it does work very well.  In all of the circuit diagrams that I have so far seen of brushless ESCs, the one thing that is absent is a feed back path from the output transistors to allow the ESC to regulate its timing.  A FAQ on brushless regards setting the ESC timing, so the inference there is that the ESC just dumbly sends its pulses and the motor, or motors, lock to the frequency just like any other AC motors on a common 3 phase supply.
It has been done - http://www.rcgroups.com/forums/showthread.php?t=2293170&page=4&highlight=2+brushless - with a video to show it being done.
However it is quite possible that two ESCs each capable of handling its own motor might be simpler and cheaper than one really big one as well as being more versatile.
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Martin [Admin]

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Re: Twin brushless on ONE esc
« Reply #3 on: May 15, 2016, 08:50:04 PM »


It has been cover here on Mayhem and from memory,  in great depth!

( Someone will find it and post the link...)

  Meanwhile, see:
  https://www.youtube.com/watch?v=zeYAWqt2rIE
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Martin [Admin]

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Re: Twin brushless on ONE esc
« Reply #4 on: May 15, 2016, 08:51:47 PM »

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rayna

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Re: Twin brushless on ONE esc
« Reply #5 on: May 16, 2016, 01:05:00 AM »

Well certainly have got a great deal of feedback so thanks for that.
I think that as certain parties have commented with the cost of budget ESCs so reasonable the best solution is to use two of them with a "Y" lead from receiver.
I think I will follow that route .
Thanks again for all input.
Rayna
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steamboat66

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Re: Twin brushless on ONE esc
« Reply #6 on: August 07, 2016, 09:06:08 PM »

from reading elsewhere, brushless speed controllers use the unpowered phase to sense position, and therefore work out timing. obviously the unpowered phase changes numerous times per revolution. that makes it quite obvious that only one motor can be used on an ESC. brushless ESCs are as little as 5!! so why the OP question? just buy 2 and a Y lead.
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rayna

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Re: Twin brushless on ONE esc
« Reply #7 on: August 08, 2016, 10:47:35 AM »

You got it. Thanks
Rayna
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davidm1945

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Re: Twin brushless on ONE esc
« Reply #8 on: August 08, 2016, 03:25:45 PM »

brushless ESCs are as little as 5!!


Please, please tell me where I can get a 60 amp brushless boat esc with reverse for a fiver and you will have a friend for life!  O0


PS only joking....
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steamboat66

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Re: Twin brushless on ONE esc
« Reply #9 on: August 08, 2016, 05:20:40 PM »

ok, you got me! but a quick look on banggood and i've found one for 7.11 !!!!!!!!!!!!!!!!  :o
AND it claims 320 amps forward, 160 amps backward. take the usual pinch of salt and it should do your 60 amps fine.
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malcolmfrary

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Re: Twin brushless on ONE esc
« Reply #10 on: August 08, 2016, 08:35:29 PM »

At a rough guess, just looking at the very familiar numbers, it sounds like one of the universal BRUSHED ESCs that come from China, where specifications are just marks on paper for the purpose of decoration rather than information.  The OP is looking for a BRUSHLESS one.  If there an actual link to this beast?
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steamboat66

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Re: Twin brushless on ONE esc
« Reply #11 on: August 21, 2016, 06:39:48 PM »

found a hobbyking brushless ESC with BEC for 10.88p from uk warehouse.
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Brian60

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Re: Twin brushless on ONE esc
« Reply #12 on: August 23, 2016, 06:36:30 PM »

found a hobbyking brushless ESC with BEC for 10.88p from uk warehouse.

I'm off to check out the link, I need 5  :o :o
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