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BOOSTXL-DRV8323RS: Current Sense Amplifier noise and the IPD algorithm

Mohamed Saeed
Intellectual 310 points
Part Number: BOOSTXL-DRV8323RS

Hello,

I am using an EVM BOOSTXL-DRV8323RS to drive a BLDC (Sensorless). I have some difficulties in trying to implement the IPD method as described here,

I am monitoring the Current Sense Amplifier  (CSA) output from the board (in bidirectional mode), the outputs is always oscillating ( around 60mV up and down).

Since the peak value of the current during IPD is close to 150 mV, the noise is very large compared to the signal and the IPD algorithm always fails to detect the maximum current value of the six drive states and hence a wrong initial position.

The question is how to eliminate the noise from the CSA? or is there any other technique to follow to increase the value of the motor current so that the noise is small compared to the signal ?

  • 0
    TI__Guru 65250 points

    Mohamed,

    Are you using the EVM with any modifications? What power supply are you using? Can you show us a picture of the setup?

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    TI__Guru 65250 points

    Mohamed,

    I think this is solvable using some code changes. 

    We recommend increasing the IPD_PULSE_TIME as it currently seems too low. Usually we want at least 300mV to sense.

    Do this increment slowly by 50-100 counts per attempt and make sure to monitor your supply current.

    If you know the max rated current of your motor, you can increase the IPD_PULSE_TIME until your supply reads 25% of the motor's rated current during the IPD step.

    The purpose of IPD is to sense the position without the motor moving so obviously reduce this IPD_PULSE_TIME if the motor moves during IPD.

    Regards,

    -Adam