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BOOSTXL-DRV8323RS: For 280025C Launchpad, the speed set by me, namely 'speedref', is too different from the estimated speed value

Katherine Wang
Intellectual 2210 points
Part Number: BOOSTXL-DRV8323RS

Hi Team,

I used my PM motor driver. The parameters are known, and the boards are 280025C Launchpad and BOOSTXL-DRV8323RS. The voltage of the power supply is 24V.

I ran it under the condition of 'BuildLevel = 3, MOTOR1_FAST defined', and I set the speed to 50HZ. The estimated speed value in the observation window was very small, but by observing the phase current through the oscilloscope, I found that the actual speed value was the same as the speed set by me, which is 50HZ.

Could you please tell me what might have resulted in the wrong estimated speed value?

Kind regards,

Katherine

  • 0
    TI__Genius 14120 points

    Hi Katherine,

    Thank you for posting to the Motor Drivers forum!

    I am going to be reaching out to the team internally an will aim to provide you a response before the end of next week.

    Best,

    ~Alicia

  • 0
    Genius 5040 points

    Hi,

    Katherine Wang said:
    but by observing the phase current through the oscilloscope, I found that the actual speed value was the same as the speed set by me, which is 50HZ.

    It's hard to tell the sinusoidal current frequency on the scope capture, but if you said the frequency is 50Hz (or 49.02Hz on scope) then the motor speed is correct; it depends on the number of magnet pole-pair the motor have, say the motor have 8 pole pairs, then the actual motor shaft speed = 50hz/8 = 6 turns/sec.

    Brian

  • 0 in reply to Brian Dang
    TI__Intellectual 2210 points

    Hi Brian,

    Thank you for your reply. My judgement of the speed of the motor diver is correct. The speed value estimated by FAST is abnormal. The problem is just that the 'speed_HZ' and 'speedEST_HZ' circled in red lines in the first picture are too different from the actual speed set by me, namely 'speedRef_HZ'. 'BuildLevel = 1' and BuildLevel = 2' are running smoothly. Now it is 'BuildLevel = 3' stage. The current load set by me can also work, but the speed feedback is abnormal. The motor parameters are provided by the motor manufacturer. Could you please tell me what might lead to the abnormal speed feedback?

    Regards,

    Katherine

  • 0 in reply to Katherine Wang
    TI__Genius 14120 points

    Hi Katherine,

    I will aim to provide feedback by the end of Wednesday.

    Best,

    ~Alicia

  • 0 in reply to Alicia Rosenberger
    TI__Intellectual 2210 points

    Hi Alicia,

    I reinstalled the environment, completely reimported the routines, and then this problem didn't occur anymore.

    Regards,

    Katherine