Speed feedback error in sensorless foc at low RPM

[vishu]

While driving STM32303E-EVAL with STEVAL-IPM20B in sensorless (Observer +PLL) foc mode , speed feedback occurs at below 400 RPM and motor stops. 

[rozimer]

Your motor stops below 400 RPM because sensorless FOC with Observer + PLL loses reliable position estimation at very low speeds. The solution is to adjust startup/low‑speed parameters or use an encoder/Hall sensor for stable feedback.