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DRV8962: Use with INA240A4D for BLDC FOC application

Tony
Prodigy 20 points
Part Number: DRV8962
Other Parts Discussed in Thread: DRV8412

Tool/software:

I am looking at a design with the DRV8962 to control a range of BLDC motors using FOC.

This requires more accurate coil current sense than is provided using the IPROPI pins so we are considering using the INA240A4D to measure the high side current. for the three coils. The output from the the INA240A4Ds will be fed into the ADC inputs of the microcontroller controlling the DRV8962.

The logic level supply voltage for the MCU,  INA240A4D and DRV8962 is 3.3V, the ADC input range is nominally 0V-3.3V

Is this a recommended way to do the current sensing in this application?

Regards

Tony

  • 0
    TI__Mastermind 45125 points

    Hi Tony,

    Thank you for your post.

    Tony said:

    This requires more accurate coil current sense than is provided using the IPROPI pins so we are considering using the INA240A4D to measure the high side current. for the three coils. The output from the the INA240A4Ds will be fed into the ADC inputs of the microcontroller controlling the DRV8962.

    The logic level supply voltage for the MCU,  INA240A4D and DRV8962 is 3.3V, the ADC input range is nominally 0V-3.3V

    Is this a recommended way to do the current sensing in this application?

    You are free to choose whichever method of current sensing is suitable for your needs, no issues. However, keep in mind the on-chip IPROPIx is used for internal current regulation. If you don't need this internal chopper regulation to be active, which seems to be the case you must connect all the IPROPIx pins to GND and input VREF > 0.05 V, for example you can connect this to 3.3V. This will ensure the internal current chopping Itrip function is disabled.

    For BLDC application please make sure the fixed dead-time of 300 ns of the DRV8962 will be suitable for your application. Thank you.

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Prodigy 20 points

    Hi Murugavel

    Thanks for your reply, I was hoping that this method using TI current sense ICs had been tried and someone had some specific advice on them.

    Can you expand on this:

    Murugavel4637 said:
    For BLDC application please make sure the fixed dead-time of 300 ns of the DRV8962 will be suitable for your application. Thank you.

    I thought the DRV8962 was designed for BLDC applications?

    Regards, Tony

  • 0 in reply to Tony
    TI__Mastermind 45125 points

    Hi Tony,

    Tony said:
    Thanks for your reply, I was hoping that this method using TI current sense ICs had been tried and someone had some specific advice on them.

    We do not have specific advice on these current sense ICs. You may want to reach out to INA240A4D experts by mentioning the device in the subject line instead of the DRV8962.

    Tony said:
    I thought the DRV8962 was designed for BLDC applications?

    DRV8962 is a general purpose quad half-bridge driver. It is primarily used with brushed motors and solenoids. Because BLDC motors require 3x half-bridges this device could be used with BLDC motors. Some BLDC applications may require very short dead time 50 ns. Hence my word of caution. 

    DRV8962 is not a primary choice for driving BLDC motors. TI has a portfolio of device that are primarily meant for driving BLDC motors. See, https://www.ti.com/product-category/motor-drivers/brushless-dc/overview.html and https://www.ti.com/product-category/motor-drivers/brushless-dc/integrated-control-bldc/overview.html. Thank you.    

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Prodigy 20 points

    Thanks for the additional information Murugavel

    One of the reasons we would like to use the DRV8962 is the ability to drive both BLDC motors and stepper motors. Is there another option that would achieve that, with a voltage range of 48V and current up to at least 5A?

  • 0 in reply to Tony
    TI__Mastermind 45125 points

    Hi Tony,

    Tony said:
    One of the reasons we would like to use the DRV8962 is the ability to drive both BLDC motors and stepper motors. Is there another option that would achieve that, with a voltage range of 48V and current up to at least 5A?

    Understood. For 48 V and at least 5 A continuous current stepper driver you may have to consider the DRV8962 in DDV (external heatsink) package. For DDW bottom thermal pad package 48 V / > 5 A would be outside its thermal capabilities.

    Another device in our portfolio would be the DRV8412 which is in DDW package but only support 3 A max. Note, its DRV8432 variant is obsolete. This device has very low dead time should this be required for driving a BLDC. These are our currently available options. Thank you.

    Regards, Murugavel