Shop OBEX P1 Docs P2 Docs Learn Events
controlling dc brushless motors? — Parallax Forums

controlling dc brushless motors?

ScarecrowScarecrow Posts: 38
edited 2005-04-16 09:03 in General Discussion
HOW DO YOU GUYS DO IT???? :S hehe im in serious need of info about that, also are there any readly available modules with brake·and other features?

Comments

  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-03-12 01:18
    I dunno if this applies to brushless motors but heres an article about controlling dc motors with a brake: http://www.edn.com/article/CA189474.html?pubdate=01/10/2002&text=brake
  • MatthewMatthew Posts: 200
    edited 2005-03-12 03:58
    Check out: www.teamnovak.com/

    Their prices can sometimes be high (be sure to bye their products from www.towerhobbies.com), but they're considered the best in the R/C hobby world when it comes to ESCs (electronic speed controllers).
  • ScarecrowScarecrow Posts: 38
    edited 2005-03-13 09:26
    well those novak controllers seem like a good option but theyre kinda big sad.gif, ive seen some chips for controlling brushless motors but it seems a bit complicated, have anyone done that?, some of the controllers ive seen is the allegro 8904 and the l6234, i know that if you manage to make a brushless speed controller outta one of those it would be a killer one........
  • MatthewMatthew Posts: 200
    edited 2005-03-13 20:37
    What power source will you be using, and how many amps do you need?
  • ScarecrowScarecrow Posts: 38
    edited 2005-03-13 20:54
    lithium-ion batteries and the motors are rated 1-7 A each with a max surge of 12 a

    maybe if someone can give me some tips on any of those chips above it would be cool, 1st because it would have been builted by myself and 2nd because it would be somehow cheaper and could be all integrated in my own pcb design =P, we could post the diagrams of the progress here so ppl may also build it
  • MacGeek117MacGeek117 Posts: 747
    edited 2005-03-13 21:51
    You could always use a MOSFET.
    bugg

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    But I canna change the laws of physics, Captain!
  • ScarecrowScarecrow Posts: 38
    edited 2005-03-14 00:37
    a brushless motor is not a traditional motor
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-03-31 23:29
    I was wading through Freescale's products, and I came across thier motor control section. Comparing some online references discussing brushless motors and thier different motors, I think that a brushless DC motor is the same as what Freescale calls a Permanent Magnet Synchronous Motor, and they have a page dedicated to this type of motor and various control chips they use to drive them here: http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=02nQXGrrlPZL8l&tid=tMfp·this maybe a customer specific link, if so, it can be found under the following link traversals: Freescale > Motor Control > Products > Permanent Magnet Synchronous Motor
  • ScarecrowScarecrow Posts: 38
    edited 2005-04-02 07:39
    excellent link, very usefull in info at last! hehe thanks
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2005-04-02 10:54
    The link does not really clarify the problem of using these motors for r/c airplanes. Their motors are 120AC and 12/24DC. It is useful conceptual material though.

    The DC is somewhat of an illusion. These are really Three-phase motors that have power originating from a DC battery, but is converted to three phase AC.

    Currrently they are the hottest R/C motors on the market because they can provide more thrust than the actual weight of the airplane. That allows for vertical take off and just about any kind of aerobatics you want to dream up. It also allows you to almost fly an aero-dynamically unstable design by overpowering its short comings.

    The DC to three-phase AC converters need to provide anywhere form 4amps and up [noparse][[/noparse]as high as 30amps!] at peak performance with relatively low voltage.

    It seems that the whole concept started with rewinding CD Rom brushless motors for heavier current and with better magnents. But what has evolved is that the 'controller/convertor' has become as or more expensive than the actual motor. It is not uncommon to pay $50 USD for the motor and $75 USD for a programible speed controller/converter.

    No one seems to want to provide a 'generic' solution as it will cut heavily into their profits.

    So, you have to become an expert at DC to three-phase conversion, speed control for three-phase, and programing microcontrollers in assembler [noparse][[/noparse]either a PIC or an SX-Ubicom].

    After all that is done, you have to get it into such a small package that you don't crowd your R/C airplane.

    Sad to say, but this is one of those things that you just might be more satisfied to buy your way out of that to DIY. There is a lot of beautiful and reliable product out there. I suppose that eventually, they will oversupply the market and the price will collapse.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    G. Herzog in Taiwan

    Post Edited (Kramer) : 4/2/2005 10:58:11 AM GMT
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2005-04-16 09:03
    There are several documents at Microchip PIC's site which discuss Brushless DC motors in detail.· Some are introductory and others are long [noparse][[/noparse]Take a look at PIC document AN843 and consumer electronics-motors].

    The Ubicom Sx can do the same thing as a PIC and maybe even better.· It seems that the PIC had to work around having two hardware PWM outputs·and one software PWM output.· Why not just have all of them be software and in synch with each other?

    They are actually controlling 208volt 3-phase motors, but it can be downsized to r/c model airplanes.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    G. Herzog in Taiwan
Sign In or Register to comment.