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Associate II
September 1, 2025
Question

BLDC Motor Not Rotating in Sensorless Mode (Shows Running State in Motor Pilot)

  • September 1, 2025
  • 1 reply
  • 698 views

Hello,

I am working with a BLDC motor in sensorless mode using ST Motor Control Workbench and Motor Pilot.
When I press the Start button in Motor Pilot, the motor status changes to Running based on the target speed I set, but the motor shaft/wings do not actually rotate.

Additional observations:

  • The motor is not in a locked condition (not drawing stall current).

  • If I try to manually rotate the motor during startup, it still does not continue spinning.

  • On Motor Pilot, the motor state shows Running, but physically it is stationary.

My Questions:

  1. Why does the motor state show Running while the rotor is not moving?

  2. How can I debug this issue further to ensure proper startup in sensorless mode?

Any guidance or suggestions will be greatly appreciated.

 

Thank you

Best Regards

Rahul

1 reply

GMA
Technical Moderator
September 3, 2025

Hello @Bablu,

Did you use the motor profiler for your motor?

  1. Sensorless mode uses an estimator. In noisy current use cases, for example, the estimator might make an incorrect decision. You can tune the Variance Threshold and B-emf consistency tolerance in the Workbench Speed Sensing Config. tab, Observer + PLL (Sensorless) section, to enhance error detection in this case.

  2. You can tune the Rev-Up sequence (currents and duration) to start the motor correctly.

GMA_0-1756904593429.png

 

 

If you agree with the answer, please accept it by clicking on 'Accept as solution'.Best regards.GMA
BabluAuthor
Associate II
September 9, 2025

Hi @GMA ,

Thanks for the feedback and suggestions. We've implemented the recommended changes, including tuning the parameters in the Observer + PLL (Sensorless) section and adjusting the Rev-Up sequence. Unfortunately, we're still experiencing a persistent overvoltage fault,  Any further insights on potential causes or troubleshooting steps would be greatly appreciated.

Any guidance or suggestions will be greatly appreciated.

 

Best Regards 

Rahul Kumbar

GMA
Technical Moderator
September 16, 2025

Hello @Bablu,

Did you use the Motor Profiler tool for your motor?

If you agree with the answer, please accept it by clicking on 'Accept as solution'.Best regards.GMA