Keywords: induction motors, inverter, maximum power point, MPP, photovoltaic array, space vector modulation, SVM, photovoltaic water pumping system, water pumps, centrifugal pumps
Space vector modulation based single stage inverter with maximum power point tracker for photovoltaic water pumping system
Photovoltaic (PV) water pumping systems commonly use permanent magnet dc motors because of their simple circuit configuration and control strategy. However these systems require frequent maintenance. On the other hand, PV pumps driven by ac motors employing a dc-dc converter followed by an inverter use more number of power semiconductor switches which will add to the cost of the system and suffer from reduced overall efficiency. In this paper, a PV water pumping system using an induction motor (IM) driving a centrifugal pump is considered. IM is powered by a space vector modulated three phase inverter and it performs two functions, viz. 1) converts dc power into ac power, 2) forces the system to operate at maximum power point. Space vector modulation (SVM) is adopted in order to use dc link voltage efficiently and to ensure that the IM line currents are approximately sinusoidal. The viability of the control strategy is demonstrated through steady state and dynamic simulation results.