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MCT8316AEVM: The best way to read motor phase current

Kenji
Intellectual 530 points
Part Number: MCT8316AEVM

Hi Team

I want to read the motor phase current, using SOx (ISENx) DACOUT2 and analog LPF.

I did ADC with external MCU, but I don't know the scale to convert current value (Ampere).
Please tell me how it scales inside the motor driver.

  • 0
    TI__Mastermind 24415 points

    Hi Kenji,

    As I mentioned in the previous post , we can only read the negative half cycle of the phase current on SOx because SOx only senses the Low side FET current. Since this device has an integrated controller, I don't see the purpose of sensing the CSA output externally. You can calculate the scaling factor by comparing the SOx output against the actual phase current.

    Regards,

    Vishnu. 

  • 0 in reply to Vishnu Balaraj
    Intellectual 530 points

    Hi  -san

    Controlling the motor is a means, not an end.
    I want to control the drone.

    I want to know the environment that drone is flying from the rotation speed and current of the motor.
    Even if the MCT8316 can control the rotation speed, the current value is different depending on the environment.

    About scaling factor, even if don't measure it, you are design the DAC output of ISENSx as scaling it by some means with a voltage divider resistor or amplifier, right?

    I just want to know 1volts of the SOx (ISENx) DAC output is equivalent to amps.

    I don't know what kind of circuit use for current sensing.
    But you should have the information of red circuit like below figure, because it's a design value.


    One more, is the DAC scale the same as the sensitivity of the Cycle-by-Cycle current limit?


  • 0 in reply to Kenji
    Intellectual 530 points

    Hi  -san

    Controlling the motor is a means, not an end.
    I want to control the drone.

    I want to know the environment that drone is flying from the rotation speed and current of the motor.
    Even if the MCT8316 can control the rotation speed, the current value is different depending on the environment.

    About scaling factor, even if don't measure it, you are design the DAC output of ISENSx as scaling it by some means with a voltage divider resistor or amplifier, right?

    I just want to know 1volts of the SOx (ISENx) DAC output is equivalent to amps.

    I don't know what kind of circuit use for current sensing.
    But you should have the information of red circuit like below figure, because it's a design value.


    One more, is the DAC scale the same as the sensitivity of the Cycle-by-Cycle current limit?


  • +1 in reply to Kenji
    Intellectual 530 points

    Hi -san

    Monitoring the current by SOx is difficult. 
    I decided to monitoring it, by different way. So, I will close this post.


    Thanks.