Model Boat Mayhem

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: Twin brushless on ONE esc  (Read 3949 times)

rayna

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 96
  • Location: Hamilton New Zealand
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
Logged

Leaky Bottom

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 170
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.



Logged
"Leave me alone I know what I'm doing"

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 6,027
  • Location: Blackpool, Lancs, UK
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.
Logged
"With the right tool, you can break anything" - Garfield

Martin (Admin)

  • Administrator
  • Full Mayhemer
  • *****
  • Online Online
  • Posts: 23,359
  • Location: Peterborough, UK
    • Model Boat Mayhem
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
Logged
"This is my firm opinion, but what do I know?!" -  Visit the Mayhem FaceBook Groups!  &  Giant Models

Martin (Admin)

  • Administrator
  • Full Mayhemer
  • *****
  • Online Online
  • Posts: 23,359
  • Location: Peterborough, UK
    • Model Boat Mayhem
Re: Twin brushless on ONE esc
« Reply #4 on: May 15, 2016, 08:51:47 pm »

Logged
"This is my firm opinion, but what do I know?!" -  Visit the Mayhem FaceBook Groups!  &  Giant Models

rayna

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 96
  • Location: Hamilton New Zealand
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
Logged

steamboat66

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 145
  • maybe it will float!
  • Location: retford
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.
Logged

rayna

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 96
  • Location: Hamilton New Zealand
Re: Twin brushless on ONE esc
« Reply #7 on: August 08, 2016, 10:47:35 am »

You got it. Thanks
Rayna
Logged

davidm1945

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 363
  • Location: Worcestershire UK
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....
Logged
Never worry about theory as long as the machinery does what it's supposed to do. Robert A Heinlein.

steamboat66

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 145
  • maybe it will float!
  • Location: retford
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.
Logged

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 6,027
  • Location: Blackpool, Lancs, UK
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?
Logged
"With the right tool, you can break anything" - Garfield

steamboat66

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 145
  • maybe it will float!
  • Location: retford
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.
Logged

Brian60

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,315
  • Location: Hull,UK-but currently residing in Los Martinez, Spain.
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
Pages: [1]   Go Up
 

Page created in 0.112 seconds with 21 queries.