Hi ST Community,
I'm working with a sensorless BLDC motor and using the ST Motor Control Profiler to extract the required motor parameters, as I don't have access to the exact datasheet values. I'm facing some issues and would appreciate guidance.
What I did:
Entered motor information including Max Current, Max RPM, and Number of Poles.
When I entered the actual Max Current, the profiler often gave Speed Feedback Faults or failed profiling.
To overcome this, I reduced the current in steps from 93% down to 80% of Max Current, and profiling succeeded with reduced current values.
Observations:
The profiler gave significantly varying results, even though the motor and setup remained the same.
- Not reaching max RPM Specified.
Some examples of variation:
BEMF Constant: ~±3 Vrms/kRPM
Friction: 700 to 1450 µN·m·s
Inertia: 20,000 to 45,000 µN·m·s²
This creates confusion — which profile values should I consider as trustworthy for tuning my motor with Motor Control Workbench?
Questions:
Which current value range should be ideal for profiling if the max current causes faults?
How do I decide which BEMF/Friction/Inertia values to trust if they vary this much?
Is there a recommended way or best practices to improve consistency in the profiler results?
Should I average the values from multiple profiles, or take the one with the least profiling current, or the one closest to the actual motor current?
Any advice or insights would be really helpful. Thank you!
Best Regards
Manikanta
