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Issue in driving sensored BLDC motor

Discussion in 'Microcontrollers, Programming and IoT' started by pica, Jul 27, 2017.

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  1. pica

    pica

    36
    0
    Jul 7, 2017
    Hello All,

    Good Morning!!!

    I have developed 12V and 24V BLDC motor driver with max current upto 20A

    The driver is working fine. The efficiency is good.

    Sometimes it is giving the issue. Sometimes once I turned on the power then suddenly blast happens and current reaches 70-80A.

    Please suggest me remedy over this issue. My design is still not getting approved just because of this issue.

    Please let me know if you will need more information on it.
     
  2. kellys_eye

    kellys_eye

    4,713
    1,309
    Jun 25, 2010
    Schematic is a basic necessity - we can offer zero advice without one.
     
  3. pica

    pica

    36
    0
    Jul 7, 2017
    Please find the attached schematic for your reference.
     

    Attached Files:

    • AP3.pdf
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  4. Alec_t

    Alec_t

    3,142
    856
    Jul 7, 2015
    What are the component values?
     
  5. pica

    pica

    36
    0
    Jul 7, 2017
    Hello Alec_t, Kellys_eye,

    Good Morning.

    The issue is coming randomly during power on. Not all the time while powering ON.
     
  6. kellys_eye

    kellys_eye

    4,713
    1,309
    Jun 25, 2010
    Sounds to me like a typical case of drive signal 'overlap' - when your drive signals don't have sufficient 'separation' to prevent the top/bottom devices from switching on together.

    Transients on the supply line?

    It may be related to the junction capacitance of the FETs you're using too. Adjust the switching signal period.
     
  7. pica

    pica

    36
    0
    Jul 7, 2017
    Hello Kellys,

    The issue is with randomly cases while power On. For other cases, the board is working fully fine and even not blasting even if it is run for 10 hours.

    Suddenly, at any power ON stage, it blasts.
     
  8. kellys_eye

    kellys_eye

    4,713
    1,309
    Jun 25, 2010
    Then it can only be associated with the output ports of your driver stage assuming some, random, non-known levels at switch-on.

    Your reset circuit (presumably based on the 555?) at U5 and the circuit C8/C9 and D7/D8 seem to be potential causes - the volt drop across D7 in particular.
     
    Last edited: Aug 1, 2017
  9. pica

    pica

    36
    0
    Jul 7, 2017
    Hello Kellys,

    As per the circuit diagram, I had posted earlier.
    What I think the circuit can not be changed. One thing is observable here.
    If I pull up the upper MOSFET lines with 5V in between micro controller and ULN2003 IC (U2). Does this will work for me?
     
  10. pica

    pica

    36
    0
    Jul 7, 2017
    Your reset circuit (presumably based on the 555?) at U5 and the circuit C8/C9 and D7/D8 seem to be potential causes - the volt drop across D7 in particular.

    Can you please explain me your lines as mentioned in a deep.

    I would like to work on it and then wanted to test it to see whether it is blasting or not.
     
  11. kellys_eye

    kellys_eye

    4,713
    1,309
    Jun 25, 2010
    Start by simply disabling the driver stages 'permanently' (i.e. hardwire the reset circuitry to a permanent 'reset' situation) - make repeated random switch-on attempts and see if the high-current fault still occurs.

    If it doesn't happen then the switch-on reset circuit is the cause. If it still happens, look elsewhere for the problem.
     
  12. pica

    pica

    36
    0
    Jul 7, 2017
    Hello Kellys,

    Sorry for the inconvenience.

    I still won't understand what you said. Don't get frustrated. Please,

    Can you please explain me in sequentially so that I can execute the same.

    Requesting you to go one by one and I will also do it on one by one to resolve the issue.
     
  13. kellys_eye

    kellys_eye

    4,713
    1,309
    Jun 25, 2010
    1. disable and ground the drive signal lines.
    2. power up repeatedly and check for over-current.
    3. if none, then enable the drivers but disable the clock
    4. power up and check for over-current.

    one or other situation will cause the fault. Isolate and identify.

    You DO have a proper switch-on reset for the controller don't you?
     
  14. Rikcasey

    Rikcasey

    3
    0
    Jan 13, 2018
    Use a time delay relay for start up and the relay coil should hellp load the circuit beforehand
     
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