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MOSFET is high temperature on F28027

li ran
Prodigy 80 points

Hello,

     I'm try to Make my motor rotate more smoothly by  F28027,but the mosfet's temperature is so high when the speed_krpm  is 1.0.Meanwhile,when my motor's speed is more than 2000rpm,I can feel the the slight vibration of the cycle with higher temperature.In order to solve this problem ,I'm trying to reduce the value kp_spd,but System response time is more slow.Please tell what I can do for this question.

li

  • 0
    TI__Guru** 119560 points
    are you using a TI EVM and TI software?
  • 0 in reply to ChrisClearman
    Prodigy 80 points
    only CCS6.0,but I'm using matlab to observe the shape of the curve.
  • 0 in reply to li ran
    TI__Mastermind 27240 points

    Mosfet temperature high:

    It depends on what load your motor is pulling, and what power factor the motor is running at. If the current through the mosfet is high enough for its ratings, obviously it will heat up.

    Oscillations:

    You mentioned 2000 rpm. If the motor pole pair is high, then the number of carrier cycles  per electrical cycle may be low enough to result in such oscillations.

    If the speed feedback is not pretty linear, I mean, if there is more ripple in  the speed fbk, the speed controller will try to fix the Iqref to minimize the speed error to zero which in turn can result in oscillations. You need to verify the quality of speed feedback by running the motor in open loop at various speeds. High speed open loop operation may not be possible. But you should try to run the motor at as high speed as practical in open loop and verify if the speed feedback has minimum ripples.

  • 0 in reply to Ramesh Ramamoorthy
    Prodigy 80 points
    Ramesh,
    Thanks for your Detailed answer!
    There is without any load ,so the current is not big.In this situation,what reason could result in the mos with high temperature？