Asymmetric 21-level inverter topology with reduced device count for medium and high power renewable applications

Abstract

Multilevel Inverters (MLI) have received a lot of attention for providing a reliable and efficient interface between renewable energy sources like solar PV and the utility grid. This paper presents a modified diamond connection-based MLI for solar PV systems. The proposed topology produces 21-level output in asymmetric mode and 9-level output in symmetric mode. It utilizes ten switches, out of which four are bidirectional, and six are unidirectional. It also utilizes four DC sources. Comparative analysis of the proposed topology based on the device count, voltage stress and efficiency with the other state of art MLI topologies shows the benefits of the proposed topology. Matlab/Simulink environment is used for developing the model of the topology and verifying its performance. Nearest Level Control (NLC) is used in order to control the converter switching. The proposed topology is checked for constant and dynamic stability through simulation.