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

[Bablu]

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

[GMA]

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.

[Bablu]

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]

Hello @Bablu,

Did you use the Motor Profiler tool for your motor?

[Bablu]

Hi @GMA ,

Yes I used motor profiler tool for our Motor, My motor has 8 poles and a peak current rating of 1.6A. I attempted to profile it with a max peak current. Setting the current limit to the motor's peak of 1.6A resulted in intermittent speed feedback, and the profiling process failed to complete successfully.

To resolve this, I reduced the current limit to 1.2A, 1.1A, 1A, and 0.9A, which allowed the profiling to be successfully completed. I've attached one of the successful profiling data logs.

"BEmfConstant": 28.74778938293457,

    "compatibility": [

        "FOC",

        "sixStep"

    ],

    "description": "Mc_profile_motorB_1",

    "friction": 2280.68,

    "hardwareFamily": "MOTOR",

    "id": "prox_model_B_1",

    "inertia": 68422.59,

    "label": "prox_model_B_1",

    "ls": 2.46,

    "magneticStructure": {

        "type": "SM-PMSM"

    },

    "maxRatedSpeed": 258,

    "nominalCurrent": 0.8999999761581421,

    "nominalDCVoltage": 23.63232421875,

    "polePairs": 8,

    "rs": 1.811617136001587

Could you please help me understand why I had to reduce the current below the motor's peak rating for the profiling to work correctly? Is this expected behavior, or could it indicate a potential issue with my setup or the motor itself? Might this peak current reduction be causing the above-mentioned stalling-at-start issue?

Any guidance or suggestions will be greatly appreciated.

Best Regards

Rahul Kumbar