RE: How does a brushless motor work?
It"s called slip. The difference between the speed of the rotating magnetic field and the rotor speed. More load more slip. The ability of the drive unit to keep up with the demand frequency, i.e. speed of the motor, is the torque avai;able or current response of the drive unit.
When the motor doesn"t keep up then CEMF starts to have an effect. You probably don"t want to go there, LOL.
The difference in speed between the rotating field and actual rotor speed ( slip) has an effect on CEMF and torque/curent in motor will increase bringing the rotor speed back to within the slip tolerence designed into the motor. Therefore, more load slower = more slip = more torque = back normal rotor frequency or speed.
Anyway I teach a motors and generators/drives class for the elevator industry and you would be surprised how simmilar the motor and drive unit concept is.
Hope this makes some sense it"s kinda late tonight.
mike