Novel Symmetric Modular Hybrid Multilevel Inverter With Reduced Number of Semiconductors and Low-Voltage Stress Across Switches

In this paper, by using a modular hybrid structure, a new topology for symmetric multilevel inverters (MLIs) with a small number of semiconductors and low voltage stress across switches is proposed. Despite many other topologies, this topology can inherently produce negative and zero levels without using the H-bridge. The voltage stress across a particular switch of the proposed MLI is inversely proportional to the switching frequency of that switch in a voltage period. The proposed structure is based on two types of modules, that is, the f-module and the e-module. The e-module uses a capacitive voltage divider to double the number of nonzero levels. The voltages of the capacitors are approximately balanced without complex control methods. The basic structure of the proposed topology is formed by connecting the f-module and the e-module in series with each other, and the cascaded topology is developed by cascading multiple f-modules with an e-module. To investigate the proposed topology and prove its practicability, simulation results obtained using MATLAB/Simulink, analysis of the capacitor voltages, and experimental results are presented. A comparative study is also performed to show the merit of the new MLI over other topologies.