Robust current control for speed sensorless DC motor drive using reduced-order extended observer

A practical disturbance estimation algorithm for DC motor current control is presented to enhance robustness against parameter uncertainty and remove the need for a speed (or position) sensor. Analysis using the singular perturbation theory has been performed to verify that the additional feedforward compensation with the proposed algorithm can improve the robust transient performance under both parameter uncertainty and slowly varying disturbance. One of the advantages of the proposed approach is that the mechanical part of the motor equation is not necessary for the controller design. Performance of the proposed algorithm has been tested through computer simulations and experiments.