An adaptive sliding mode observer over wide speed range for sensorless control of a brushless DC motor

This paper proposes a novel adaptive sliding mode observer (SMO) over wide speed range for the sensorless control of a brushless DC motor (BLDCM) system. Designed with a sinusoidal saturation switching function whose boundary layer can be adaptively adjusted according to varying speed through fuzzy algorithm, the SMO is able to improve the estimation accuracy of the back electromotive force (EMF) as well as the rotor position and speed with properly selected parameters under both low speed and high speed circumstances. The asymptotic stability of this new strategy is verified, and its effectiveness and superiority to the conventional SMO are illustrated via simulations on MATLAB and experiments on a BLDCM sensorless control platform.