A quasi-sliding mode speed and position observer with a chattering elimination filter

This paper proposes a quasi-sliding mode rotor speed and position observer for surface permanent magnet synchronous motors. The proposed algorithm features a chattering elimination filter used for suppress the chattering over the waveforms of the estimated electromotive forces, from which speed and position are estimated. Such filter is formulated by using equations that ensure a simple design procedure for the observer gains. This chattering elimination strategy is based on the pondered average between the chattering amplitudes of two different estimated electromotive force signals. This technique is viable only because the rotor speed and position observer are designed in a way that guarantees that the estimated electromotive force crosses the sliding surface at each discretization period. Theoretic issues and design procedures for the developed algorithm are discussed on this paper. Simulation results show evidences for the good dynamic performance of this system in a surface permanent magnet synchronous sensorless vector drive. It is achieved despite any parameter uncertainties and load torque disturbances.