How does a sensorless brushless motor work?
“A typical sensorless brushless motor has permanent magnets fixed on the rotor with the electro-magnets mounted around the edge of the motor. As the motor picks up speed it starts to generate electro-motive force in the stator coils. As an example, with the unit switched off and the rotor being spun (for example by a bicycle dynamo) this can be used to generate electricity. “