New adaptive sliding observers for position- and velocity-sensorless controls of brushless DC motors

A new adaptive sliding observer is proposed for position- and velocity-sensorless controls of a cylindrical brushless DC motor. Stability of the proposed observer is guaranteed easily, because it is based on a linear model of the motor. Sliding mode is applied for the current estimation. Under the sliding mode, the order of the observer's error equation is reduced. This makes the stability analysis easier, so that robust position and velocity estimations might be achieved by the pole assignment. Experimental results show that the proposed method is very effective.