Sensorless BLDC Motor Issues Using Nucleo-F401RE and X-NUCLEO-IHM16M1

[Bablu]

Dear ST Team, 

I am currently working on a 24V @ 1.5A sensorless BLDC motor control application using the following setup: 

• MCU Board: Nucleo-F401RE 

• Driver Board: X-NUCLEO-IHM16M1 

• Motor: Sensorless BLDC Motor

• Software Tools: MC Workbench 6.4.0 and Motor Pilot 

• Control Technique: Field-Oriented Control (Sensorless) 

Issues Observed: 

1. During startup, the motor produces loud noise, initial jerks, and fault indications in the IHM16M1 board. 

1. At higher RPMs, a mild humming noise is audible. 

1. When decreasing the speed to medium or lower RPMs, the IHM16M1 board triggers faults again in the IHM16M1 board. 

We have profiled the motor multiple times using Motor Pilot, and each profiling run gave slightly different values for parameters such as Friction, Inertia, and Back-EMF constant. 

To address this, we tested the system using the average, minimum, and maximum values obtained from multiple profiles. However, the same issues persisted across all tests — specifically during startup, low-speed operation, and at maximum speed. 

We’ve attached a profiling table for your reference 

Max Current	R(ohm)	L(mH)	K(Vrms/kRPM)	F(uN.m.s)	Inertia(uN.m.s2)	Max RPM
1.2	1.58	1.24	26.33	753.61	22608.98	306
1.2	1.59	1.25	26.93	937.67	28131.12	312
1.3	1.59	1.26	27	1242.01	37261.63	330
1.3	1.6	1.27	28.61	1339.53	40187.38	336
1.35	1.6	1.28	28.76	1497.54	44927.62	348
1.4	1.6	1.22	32.05	965.57	28967.94	324
1.4	1.61	1.23	32.3	1422	42661.48	330
1.4	1.6	1.21	29.03	754.78	22644.21	336
1.4	1.61	1.28	31.05	1050.73	31523.09	336
1.4	1.62	1.22	26.66	1198.17	25946.32	354
1.4	1.62	1.21	28.96	879.03	26371.63	336

Table 1 

Request for Support: 

• How can we reduce startup jerks and noise? 

• Is there any detailed guidance on how to tune the rev-up control table and observer settings for sensorless operation? 

• How can we stabilize the motor at lower RPMs to avoid fault generation in the IHM16M1 board? 

• Is there a way to reduce humming noise at higher RPMs? 

Any documentation, configuration guidance, or tuning tips specific to IHM16M1 and F401RE with sensorless FOC control would be highly appreciated. 

Thank you in advance for your support. 

Best regards, 
Rahul 

[GMA]

Hello @Bablu,

For Error description and management, refer to documentation available through "Workbench tool">About>Documentations>Documentation>"User manual" tab, "(FOC) Firmware errors" link.
At such low PRM values, 6-Step algorithm could be a better choice.

[Bablu]

Hi @GMA ,

Thank you for your response.

We have already reviewed the 'FOC Firmware Errors' section in the User Manual, as suggested. However, our concern is not limited to interpreting error codes, we are trying to identify and resolve the root causes of the faults from the IHM16M1 and undesired motor behavior observed during startup, low-speed, and high-speed conditions, specifically with sensorless FOC control on the IHM16M1 board.

We would like to clarify:

1. The faults occurring during low-speed operation and startup are not due to misinterpretation of error codes but appear to stem from observer instability, incorrect rev-up settings, or motor profiling inconsistencies.
2. While we understand that sensorless control has limitations at low RPMs, our application requires precise and smooth control, which is best achieved with FOC. Therefore, switching to 6-step control is not preferred.

We would appreciate specific technical guidance on the following:

• Best practices to tune the Rev-Up Control table for a sensorless motor with the parameters we provided.
• speed and observer parameters tuning for improving low-speed and startup stability.
• Suggestions to mitigate high-speed humming and parameter sensitivity

Kindly advise us on how to proceed with stabilizing the FOC algorithm under these operating conditions.

Thank you for your continued support.

Best regards,

Rahul