Maximum Efficiency Operation of a Single Stage Inverter Fed Induction Motor PV Water Pumping System

Photovoltaic (PV) water pumping systems have been increasingly popular in remote areas where grid is not accessible or is too costly to install. These systems are mostly used for agriculture and household purposes. Generally, such systems use permanent magnet dc motors because of their simple circuit configuration and control strategy. However these systems require frequent maintenance. On the other hand, the conventional PV water pumping systems driven by ac motors  employ a dc-dc converter followed by an inverter. The conventional systems use more number of power semiconductor switches (increases the system cost) and suffer from reduced overall efficiency as two power converters are connected in series. In this paper, a PV water pumping system using a single stage inverter fed induction motor driving a centrifugal pump is considered. The inverter simultaneously performs two functions, viz., (i) converts dc power into ac power and (ii) forces the induction motor to operate at maximum efficiency. The system considered has a simple control strategy and the viability of the control strategy is demonstrated through steady state and dynamic simulation results.