Sensorless vector control of brushless DC motors using disturbance observer

A sensorless motor drive system using disturbance observers for brushless DC motors is proposed in this paper. There are three observers in the control system, they are a disturbance voltage observer, a speed observer, and a disturbance torque observer. These observers are used not only for position and speed estimation in the sensorless vector control, but also for a current controller. The rotor position and speed estimator are robust for parameter variations of the EMF constant. The validity of this sensorless vector control of brushless DC motor is confirmed with computer simulations