Hi Anders,
Sorry for delayed response.
Comment about BEMF constant calculation :
DRV10983 has built in BEMF observer and it estimates BEMF internally. It calculates BEMF constant by integrating estimated BEMF.
My experience has been that Motor Datasheet always are not always straight forward and accurate enough, can you measure it on bench while spinning motor manually.
BEMF constant is used in closed loop for abnormal Kt lock and calculating voltage limit based on current limit using formula Ulimit = (Acceleration_Current_limit) * motor resistance + speed * motor kt
Comment about open loop drive:
Generally for BEMF based sensorless solution, motor is driven blindly in open loop i.e. commutation is based on open loop parameters without any feedback from BEMF observer. Whereas in close loop it is driven based on calculated BEMF. There will be difference in current because the commutation in open loop is inefficient because phase current and BEMF are out of phase (drive angle is not optimized).
Regards,
Krushal
Sorry for delayed response.
Comment about BEMF constant calculation :
DRV10983 has built in BEMF observer and it estimates BEMF internally. It calculates BEMF constant by integrating estimated BEMF.
My experience has been that Motor Datasheet always are not always straight forward and accurate enough, can you measure it on bench while spinning motor manually.
BEMF constant is used in closed loop for abnormal Kt lock and calculating voltage limit based on current limit using formula Ulimit = (Acceleration_Current_limit) * motor resistance + speed * motor kt
Comment about open loop drive:
Generally for BEMF based sensorless solution, motor is driven blindly in open loop i.e. commutation is based on open loop parameters without any feedback from BEMF observer. Whereas in close loop it is driven based on calculated BEMF. There will be difference in current because the commutation in open loop is inefficient because phase current and BEMF are out of phase (drive angle is not optimized).
Regards,
Krushal