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INA226: How to sense motor current with INA226 in a H-bridge (VNH2SP30)?

Alexander Gabrecht
Prodigy 10 points
Part Number: INA226
Other Parts Discussed in Thread: INA240

Hi,

I am actually using a Hall Effect based current sensor (ACS714) inline between to the Motor in the H-bridge.

My V+ is 5.5V, the H-bridge is a VNH2SP30 based evaluation Board (Sparkfun MonsterMoto-Shield).

Since the internal current sensor from the VNH2SP30 is not accurate enough and the Hall Effect based one gets massive electromagnetic distortions from the turning motor, I wanted to evaluate the INA226 as a replacement.

What is the best way of current measuring? Can I simply replace the ACS714 with an INA226 and a proper shunt or do I have to switch to low-side current sense?

Thank you,
Alex

  • 0
    TI__Expert 4915 points
    Hi Alex,
    Thank you for posting on the E2E Forums.

    You can use the INA226, but accuracy will be affected by common mode swings if you are using PWM to drive the motor.
    I suggest a look into the INA240 as a better replacement option due to the better common mode rejection. You can set an analogue reference at 1/2VCC (2.5V?) and have a drop in replacement for your hall sensor.

    As to the electromagnetic distortions... are you differentiating the freewheeling currents by synchronizing the ADC readings with the PWM on time? If not you will get opposite readings during the PWM off time.