Fuzzy sliding mode observer based sensorless Indirect FOC for IM drives

In recent decades, several Induction Motor drives techniques without speed sensor have been proposed. In this paper, an improved Sliding Mode observer for rotor fluxes and speed estimation from measured stator terminal voltages and currents is presented. It introduces a Fuzzy logic algorithm instead on the sign function in order to reduce the chattering caused by the classical Sliding Mode observer. The stability of this observer is proved by the Lyapunov´s theorem and the feasibility of the proposed method is verified by simulation under Matlab /Simulink.