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CCS/TMS320F28069M: TMS320F28069M, min acceleration possible

Prodigy 20 points

Replies: 5

Views: 98

Part Number: TMS320F28069M

Tool/software: Code Composer Studio


We want a slow acceleration of about 25 rpm per hour with a pump we are running. In lab 5c, we are setting acceleration on 0.000006 krpms. running the pump for about 15 hours from 1000 rpm, we never reached any higher speed with that acceleration.:


I wonder if there is a limit in the acceleration? Is there any way of having such a low acceleration working?

There is too much variation in speed as may noticed as well. 

Thank you in advance

  • The concerned engineer is on vacation and he may reply on his return. Thanks for the patience.
  • In reply to Ramesh Ramamoorthy:

    The minimum value limits to the resolution of IQ format since the instaSPIN-FOC uses IQ24. It seems like you set a too small value, the real minimum value depends on the MAX_ACCEL_KRPMPS_SF that is calculated by _IQ(USER_MOTOR_NUM_POLE_PAIRS*1000.0/USER_TRAJ_FREQ_Hz/USER_IQ_FULL_SCALE_FREQ_Hz/60.0). So the minimum acceleration must be greater than 1/MAX_ACCEL_KRPMPS_SF.

    Simply, you may check if the ctrl.traj_spd.maxDelta equals to ZERO, if yes, that means the setting value is too small.
  • In reply to Yanming Luo:

    Hi Yanming,

    Thank you for your reply, I could not wail to hear back!

    I have got the following:



    Yet, I am unable to find :

    ctrl.traj_spd.maxDelta & SER_TRAJ_FREQ_Hz.

    I have attached some screenshots here and will appreciate your advice:



  • In reply to zachary barnes:

    Hi Zachary, the contacted engineer will be in on/off mode for his e2e response due to vacation, before he's back to work the coming Monday. Thank you for your patience before that!
  • In reply to Hui Tan:

    You might try to add "ctrlHandle->traj_spd.maxDelta" to express window, and ensure it is greater than 1 (long integer format)by increasing the acceleration.

    You should find the USER_TRAJ_FREQ_Hz in user.h as you have attached, it is based on USER_CTRL_FREQ_Hz, and USER_CTRL_FREQ_Hz is from USER_CTRL_FREQ_Hz. You may post your "user.h", we could help you to calculate the minimum acceleration if you can't do this again.

    The minimum acceleration = 1/MAX_ACCEL_KRPMPS_SF, where the MAX_ACCEL_KRPMPS_SF uses the number by long integer format.