Hello,
I am using STM32 Motor Control SDK / MC Workbench with sensorless FOC (STO + PLL) to drive a low-speed, high-inertia 24V 40W BLDC fan motor.
Power Board: X-NUCLEO-IHM07M1
Issues observed:
- Motor rotates stably but produces intermittent (not continuous) rubbing noise, mainly after settling at certain RPM.
- Large speed oscillations are visible in Motor Pilot (speed dial deviation).
- Motor does not reach max speed even when increasing current limit in MC Workbench.
- Reducing Iq PI gains(cut off frequency) does not significantly reduce the noise.
- Very low PLL gains are required for stable rotation; higher PLL gains cause oscillation or loss of speed feedback.
Questions:
For low-speed, high-inertia fan motors, what is the recommended observer / speed LPF cutoff frequency parameters?
- Can I reduce this intermittent noise and speed oscillation and run smooth motor control without noise?
Which parameters should be prioritized to:
Reduce speed oscillations
Eliminate intermittent torque/current stepping noise
Reach rated max speed?
- Are there any techniques recommended for this heavy load BLDC motor applications?
Thanks in advance for any guidance.
