Having problems in starting Bldc motor with mc33035

Discussion in 'The Projects Forum' started by aaditpj, Jul 3, 2014.

  1. aaditpj

    Thread Starter New Member

    Jul 3, 2014
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    I have made a driver circuit for a sensored bldc motor using mc33035. This circuit is similar to the application circuit(given in fig.19 and fig 36) in the ic's data sheet. I have used TIP127 and TIP122 as upper and lower gate mosfets respectively. The frequency is determined by a 10kΩ resistor and 10nf capacitor. The current limiting is set for 4.25 A by using a 0.5Ω resistor and voltage reference of 2V given the the op-amp integrated in the given ic.


    however I am having problem in starting the motor. The motor does not start on its own for some positions of the the rotor and also once I stop the motor by using brake or by making its speed 0, it does not start on its own. it also starts vibrating at some rotor positions.The motor runs well once i start the motor by hand. The motor has sensors at 120° and is a out-runner motor.
     
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    It's a common problem with sensored BLDC drivers.

    Google "motor starting system on sensored BLDC driver" or similar. :)
     
  3. aaditpj

    Thread Starter New Member

    Jul 3, 2014
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    I did try that before but did not find and substatial information to solve this problem.
     
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Keep trying!

    It's a common problem, I think one common fix is to first manually activate a couple phases in sequence to give the rotor a "kick" which gets the hall sensors working and gets the motor phased right.
     
  5. Experimentonomen

    Member

    Feb 16, 2011
    331
    46
    With a sensored system, there should never be any dead spots, if there are, the motor is either phased wrong or you have a 60/120deg sensor spacing issue, some controllers do have a select pin for this.
     
    MaxHeadRoom likes this.
  6. Alberto

    Active Member

    Nov 7, 2008
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    Check if pin 22 of your controller is pulled up or down. This pin Select the sensor angle.

    Cheers

    Alberto
     
  7. aaditpj

    Thread Starter New Member

    Jul 3, 2014
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    yes pin22 is pulled low for 120 degree sensor angle. And I have confirmed with the motor manufacturer for the sensor angle and he too told me that the sensors were placed at 120 degrees. And for the motor works perfectly fine if I connect it with with an another circuit bloc driver circuit that is a bit different.
     
  8. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
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    tip 127 and tip122's are "fet's"? last time I looked they were called darlington transistors.
     
  9. aaditpj

    Thread Starter New Member

    Jul 3, 2014
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    Ok it was a problem with the IC I suppose. I ordered other ones and the circuit works perfectly well. Thanks for the help.
     
  10. aaditpj

    Thread Starter New Member

    Jul 3, 2014
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    They are darlington transistors, but I figured out that they work better than FETs and are cheaper
     
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