Sensorless vector control of brushless dc motors based on instantaneous power

This paper presents a new control strategy for brushless de motor drive without position and speed sensors. The rotor position is calculated from the model position and the position error between rotor and model position. The position error cannot be detected directly, however, it can be estimated by the information of the instantaneous power which is calculated by the terminal voltages and currents transformed to the motor axis. The rotor speed can also be calculated in a similar way. The useful features and validity of this proposed sensorless control scheme is confirmed by computer simulations.