Robust Fault Detection for a Permanent Magnet Synchronous Motor using a nonlinear observer

The present paper proposes the adoption of a robust nonlinear observer of the rotor angular position and velocity, which can be used for fault detection purposes. Convergence of such observer is ensured by the enforcement of a sliding motion on given surfaces, based on motor currents, which are of course affected by all faults influencing stator currents and can easily detect them. Simulations with additive faults have been reported, proving the reliability of the proposed solution. Note that observer and control design are not performed in the $(d,\,q)$ reference frame abut in the ($\alpha$,$\beta$) frame, since any fault affecting the angular position measurement could invalidate the whole model and the consequent design.