Design and Implementation of a Multilevel Inverter Fed by Photovoltaic Generators with MPPT

Abstract

In this paper is presented an implementation of a fundamental frequency on a three-phase multilevel inverter supplied by a photovoltaic generator in a stand-alone system. The high cost of photovoltaic solar power makes it necessary to track the maximum power point (MPP) of the photovoltaic generator regardless the adopted scheme for the power converters. Several maximum power point tracking techniques for photovoltaic systems have been developed to maximize the produced energy and most of these techniques are well published. The topology adopted for this implementation consists of two main blocs. In the first one, a buck-boost-type converter is used to interface the photovoltaic generator (PVG) to the voltage bus of the inverter. The second bloc contains a five-level diode-clamped multilevel inverter (DCMLI), generating fundamental modulation staircase three-phase output voltages. A microcontroller is used to control both converters. Experimental tests were done using a set of two tanks, one for extracting water and the other for the storage. The pumping system is built around an induction motor coupled to a single centrifugal pump. The main idea of such a system is to improve the global efficiency by increasing the stored water in a day.