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TMS320F28379D: Instaspin Lab4 Troubleshooting

Mark Feller
Expert 1220 points
Part Number: TMS320F28379D


I am going through the lab exercises using custom HW that is also based on the 28379D.  Lab3 works well, and I'm reasonably sure the voltage and current scaling is set correctly.

I am also using the Anaheim_BLY172S_24V motor for testing, so the motor parameters in user.h should be correct.

When trying Lab 4, the power supply immediately becomes current limited.  The motor does start to spin.

If I connect a USB logic analyzer, I see this:

Where DAC1 is the PWMDAC output of angleFoc_rad.  The DAC1 waveform is on a 20Hz cycle, which is what is set for the SW.  At 4 pole-pairs, this should be 5Hz mechanically, and the motor seems to be running at about half that.

1) Does the PWM waveform look okay?  

2) Do you have suggestions on troubleshooting steps to understand what the issue may be?

Note that for Lab3, the motor seems to be higher current at lower speed_ref, such as 750mA at 20Hz.  So at 2.5Hz, maybe it is no surprise that the motor is drawing such high current.  

Thanks!

  • 0
    Expert 1220 points

    Just to add comment, I went back to Lab 3 and dropped the SpeedRef down to 1Hz, and the current stayed in that ~750mA range. (Here, I refer to the current use shown by the power supply)

  • 0 in reply to Mark Feller
    TI__Guru** 116090 points

    Lab3 can only fully verify the current sensing signal waveform, and can't verify if there is any delay on current and voltage sensing signal to estimate an exact rotor angle for lab 4.

    Please refer to the DAC in example lab to use the DAC. You should add a offset to output the angle to DAC since the angle value is -PI to +PI. And check if the estimate angle is similar as the generated angle in lab3.

    If you are using sensorless-FOC, the low speed (<5Hz) is not better for test.