A Review of the New Structures of Cascaded Multilevel Inverters with Separate Voltage Sources with the Approach of Reduced Semiconductor Switches Count

Cascaded multilevel inverters are very attractive for advanced systems such as energy conversion, flexible transmission systems, drives, etc. One of the most important features of multilevel inverters is the production of high-quality waves, modularity, operation without a transformer, the ability to change voltage and current, and operation at high voltages. However, multilevel inverters have disadvantages, usually due to the presence of a large number of components, especially power semiconductor switches. In recent years, the proposal of new multilevel inverters with fewer components has been one of the most important topics discussed in power system academic forums. The main purpose of this paper is to summarize and compare the recent cascaded multilevel structures with fewer components based on their advantages, disadvantages, and structure. In one category, cascaded multilevel inverters are divided into symmetric and asymmetric categories that both groups will be investigated in this study. To confirm the optimal performance of multilevel inverters, the simulation results have been evaluated in MATLAB/SIMULINK software.