Efficient Solar Water Pumping System Using Maximum Power Point Tracking (MPPT)

Abstract

A simple and efficient solar water pumping system utilizing an induction motor drive (IMD) is presented in this paper. This solar water pumping system comprises two stages of power conversion. The first stage extracts the maximum power from a solar PV array by controlling the duty ratio of a dc-dc boost  converter. The dc bus voltage is maintained by the controlling the motor speed. This regulation helps in the reduction of motor losses by reducing motor currents at higher voltage for the same power injection. To control the duty ratio, an incremental conductance based maximum power point tracking(MPPT) control technique is utilized. The proposed system is modelled, and its performance is simulated in detail. The scalar control eliminates the requirement of a speed sensor/encoder. Consequently, the need of motor current sensor is also eliminated. Moreover, the dynamics are improved by an additional speed feed forward term in the control scheme. The proposed control scheme makes the system inherently immune to  the variation in the pump constant. The prototype of PV- powered IMD emulating the pump characteristics is developed