Rotor position estimation at zero speed in a sliding mode controlled PMSM

Abstract

In this paper a rotor angle estimation for permanent magnet synchronous motors under sliding motion is proposed. In the sliding mode control design stage, if the motor saliency (dependency of the stator inductances with the rotor position) is not considered, the decoupling process provide three independent switching functions that are fully decoupled among them. The technique proposed at this work uses the small deviations that appear in the switching functions when motor saliency is considered. In presence of saliency, the position of the rotor can be estimated measuring the slopes of the switching functions. The novelty of the method is that it can work at zero speed, where most of the estimation techniques based on observers fail, and without the necessity of injecting high frequency signals.