What is difference between sensor brushless dc motor and sensorless brushless motor?

Sensor brushless dc motors use the Hall element in the motor to sense the status and position of the rotor, while non-inductive motors use the ESC back-EMF signal to determine the commutation of the rotor position. The sensory motor can know the position of the rotor when it is at a standstill, but the sensorless motor can only be judged when it is rotated. Therefore, the sensorless motor will shake when it first starts, and it is more difficult to control at low speed. The sensory motor uses Hall Component induction, not easy to be interfered, judgment is more accurate

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Can a brushless motor run without Hall sensor?

A sensorless brushless DC motor (sensorless BLDC motor) is quite simply a brushless DC motor without hall effect sensors. ... This can be useful for maintaining set speeds and is particularly useful at start up as the rotor position dictates the start up sequence for the motor.