How to detect the rotor position reliably in case of locked rotor or very low speed

[maxxu]

hi

 I hope that my motor driver can still work at a very low speed or locked rotor. The current scheme is NXP's official sensorless and square wave drive scheme. The back EMF generator cannot work at a low speed. Is there any other scheme for reference? Thank you.

[pachamatej · Accepted solution]

Hello,

low-speed and locked rotor operation is a very specific task. If the open-loop operation doesn't work for you, e.g. you need reliable information about what is happening with the rotor, then you would need to "create" a sensor from the motor. There are many publications on such approach, e.g. An Improved Position-Sensorless Control Method at Low Speed for PMSM Based on High-Frequency Signal ... 

However, these methods require higher-end CPU and may be an overload to S12ZVM.

There are some others which require to know the motor parameters more deeply, e.g. Sensorless control of BLDC motor from zero to low speed based on rotor saliency - IEEE Conference Pu... 

or by measuring BEMF in two or three phases:

Sensorless control of BLDC motors at low speed based on differential BEMF measurement - IEEE Confere... 

Please consider the articles examples only. I would recommend to follow their citations or references to get more info. Deeper search on IEEE Xplore is also recommended.

Regards,

Matej

[maxxu]

Thank you very much.