DC Brushless motor Controller

Discussion in 'General Electronics Chat' started by gusmas, Feb 10, 2012.

  1. gusmas

    Thread Starter Active Member

    Sep 27, 2008
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    Hey

    I understand how a normal DC motor work, but now the DC brush less motor I'm interested in has 3 phases, configured in star topology. Now the document I have comes from Microchip (Document name posted at the bottom). I understand by powering certain segments the rotor will be moved accordingly. Can I assume that the current stator position (North Pole) is represented by the hall sensor combination in table 2 (Using Figure 1 as the reference)?

    AN857.pdf
     
  2. Mark_T

    Member

    Feb 7, 2012
    47
    8
    I can't see the table, but have seen many before and the basic answer is yes....but you may find depending on your motor windings and magnetic poles that you have to repeat the pattern twice for one complete rotation. So you could be 180 degress out.
     
  3. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    239
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    It is on page 4, Table 2
     
  4. Mark_T

    Member

    Feb 7, 2012
    47
    8
    Also, it tells you which segment you're in, which isn't very accurate. The halls are usually digital in nature.
     
  5. Mark_T

    Member

    Feb 7, 2012
    47
    8
    Yep, thats the table,let me know if you need any more info on drining BLDC motors.
     
  6. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    239
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    I need help check youre private messages :)
     
  7. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    239
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    The thing is I dont understand really how that table comes up with its values, because according to the table 2 to move in a clockwise rotation those phases has to be put after one another, so why is it forcing the rotor to go from 001 (Phase 6) to 010 (Phase 4)?? and not from 001 (Phase 6) to 101 (Phase 1) which is actually clockwise???
     
  8. Mark_T

    Member

    Feb 7, 2012
    47
    8
    Are you just energising one coil manually? If so this thing moves fast and has overshot the phase you are looking at and is stuck 180 degrees out? maybe.
     
  9. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    239
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    I have no circuitry yet just researching it but want to understand first before i blow something up
     
  10. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Most people buy an brushless motor controller module (sold for radio control model use).

    It will do all the work of driving the motor and current limiting etc, and all you need to do is feed it a control pulse width 1.0->2.0mS like an RC servo.
     
  11. zaw

    New Member

    Feb 13, 2012
    3
    0
    I don't know much about BL motors ESC in details but I played with enough Helicopters to know that if you reverse Any 2 of 3 wires the motor will spin reverse.
     
  12. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,013
    1,531
    This is because a BLDC motor is really 'three phase', this is the also the way a three phase AC motor is reversed.
     
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