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MCF8316A: How can I read the MV (Manipulated Variable) of the internal PI speed controller?

Alisson Pereira
Prodigy 25 points
Part Number: MCF8316A

I am trying to tune the Speed PI controller, but I would like to have real time reads of the Manipulated Variable of the controller. I guess it is the duty cycle of the PWM input signal. Does the LDO/Buck out have anything to do with the excitation signal I need?

  • +1
    TI__Mastermind 24415 points

    Hi Alisson,

    Thanks for posting your question in MD forum. MCF8316A provides FOC (Field oriented control) solution. Output of the speed PI controller is the Q-axis reference current (Iq_ref). See FOC block diagram below. I'm not sure what you mean by excitation signal. Are you referring to the Speed command to start driving the motor? Speed can be commanded via PWM signal, analog signal or I2C communication. This has got to do nothing with the LDO/Buck. Purpose of LDO and buck is to power-up internal blocks of the IC and also to drive external loads (if any).   

    Regards,

    Vishnu

  • 0 in reply to Vishnu Balaraj
    Prodigy 25 points

    HI Vishnu,

    Thank you for answering. What I mean by excitation signal is the signal generated by the PI Speed Controller, which is the current Iq_ref as stated by you.

    If I'm not wrong, I can access this signal on a register, described on table below.

     

    Regards,

    Alisson Marden

  • 0 in reply to Alisson Pereira
    TI__Mastermind 24415 points

    Hi Alisson,

    Yes, you can read the IQ_REF_CLOSED_LOOP variable via I2C communication. 

    Regards,

    Vishnu