An Improved SMO for Position Sensorless Operation of PMSM Driven Solar Water Pumping System

An improved sliding mode observer (ISMO) for sensorless operation of permanent magnet synchronous motor (PMSM) driven solar water pumping system (SWPS) is proposed in this paper. The ISMO technique eliminates the chattering issue associated with conventional sliding mode observer (SMO). This is achieved through incorporating the synchronous frequency tracker based second order generalized integrator (SFT-SOGI), which filters the estimated back electro motive force (BEMF) and removes the chattering and accurately estimates the rotor position and speed. As the solar photovoltaic array offers a non-linear voltage current characteristic, a maximum power point tracking technique is required for extracting the peak power. Owing to its simple structure and ease of implementation, an incremental conductance algorithm is used for peak power extraction. The SWPS performance is validated experimentally in the laboratory with both the techniques, i.e. proposed ISMO control technique and conventional SMO technique. It has been observed that the proposed ISMO technique provides an effective estimation of rotor position and speed thereby improves the behavior of the SWPS.