FAULT_CODE_ABS_OVER_CURRENT during FOC detection on custom VESC hardware (FW 6.05 / Tool 6.0.2)

Esk8 Electronics
1

Hi,

I am debugging a custom VESC-based motor controller and I get FAULT_CODE_ABS_OVER_CURRENT every time I run FOC detection in VESC Tool.

My setup is:

  • Firmware version: 6.05

  • VESC Tool version: 6.0.2

  • Current sense amplifier: INA181A1 (gain 20)

Sequence:

  • Enter motor parameters

  • Start Run Detection

  • Motor makes inverter sound

  • After about 10 seconds, detection stops with FAULT_CODE_ABS_OVER_CURRENT

I understand that this fault means the measured current exceeded the configured limit.
What I am trying to determine is whether this is caused by a real overcurrent event or a false current measurement on my hardware.

I already found that some apparent power noise on my oscilloscope was caused by the probe ground lead. Using a spring ground reduced that significantly, but the motor still does not rotate correctly and the same fault remains.

At this point I want to isolate whether the root cause is:

  • actual overcurrent,

  • wrong current sense scaling / polarity / offset,

  • phase or current-sense mapping,

  • amplifier or filtering behavior,

  • or PCB layout / switching noise.

Could anyone suggest the most effective step-by-step troubleshooting procedure?

In particular:

  • How do you distinguish real overcurrent from false measurement in this situation?

  • Which waveforms should I check first during detection?

  • What are the most common causes of FAULT_CODE_ABS_OVER_CURRENT during FOC detection on custom hardware?

  • Is there a recommended way to verify the current measurement chain before running detection again?

I am looking for a fact-based troubleshooting path so I can isolate the problem step by step.

Any advice is appreciated.

Thank you.

1 Like
2

you have access to an oscilloscope

If you could recreate the problem then I would log it with that and see what it says the current values are and for how long they are that high.

You can go to your advanced motor settings and set your current fault stop time to something very short

1 Like
3

Thanks, that helps.

I think the key point is to determine whether this is a real overcurrent event or noise / false current sensing. If I can see the current sense amplifier output on the oscilloscope when the fault happens, that should tell me whether I need to focus on the power stage/control side or on the current sensing/layout side.

I will try that.

4

RigolDS0
RigolDS01024×600 72.5 KB
I

I captured oscilloscope screenshots of the phase signals (MOSFET gates) as Ch2 cyan color in the picture and the current sense amplifier output as Ch1 yellow color in the picture around the time FAULT_CODE_ABS_OVER_CURRENT occurs.

I would like to post them here and ask for advice on how to interpret them.

The scope was used in single trigger mode, with the trigger level adjusted so it would capture only near the fault event. If the trigger level is set any higher, it does not trigger. If it is set any lower, it triggers before the fault. Based on that, I believe these screenshots were captured very close to the error event.

Any thoughts on how to interpret these waveforms would be appreciate.