For a project I am working with a three-phase AC brushless motor, connected to a motor driver. The driver allows digital control over the motor in position, velocity or torque modes.
Below are a few points leading up the final question
My understanding of three-phase motors in one sentence: the three phases over a number of coils produce a rotating magnetic field, that rotates the motor shaft with the same speed (synchronous).
- So the speed of the motor is completely determined by the frequency of the three-phase input. Correct?
- So the motor driver varies the frequency of the three-phase power going into the motor. Correct?
- So when the motor is stalling but not off, the frequency in the three phases simply drops to zero, resulting in three different fixed voltages. Correct?
Then how does the motor driver make the motor exert a target torque, independent of the rotational speed?