A Three-Phase, 41-Level Matrix Inverter Based on Modular Multilevel Converter Half-Bridge Modules

As the world moves toward renewable energy as the main energy source, power electronics systems particularly inverter has become an essential part of the world utility and grid system. The unpredictable nature of renewable energy sources necessitates the use of energy storage systems, especially batteries. The batteries reproduce the stored energy in DC, and because generally the grid and connected loads are AC, the inverter played the main role of interconnecting the batteries and the grid. The modular multilevel converter has been around for almost 20 years, and has been used extensively around the world. In order to reduce the output harmonics and deliver an almost clean sinusoidal output, a high number of output level is needed, hence the need for more components particularly the dedicated DC source for each module. However, in the multi-phase or three-phase version, each of the adjacent module actually operate on the same voltage level. This open the opportunity to use a common DC bus for all adjacent modules, which in turn creates a circuit similar to a switch matrix, hence the name matrix inverter. By using some modifications, the number of DC sources and switches in the inverter circuit will be reduced greatly. The matrix inverter topology validated by Matlab Simulink simulation of its 41-level version. The result shows that the new matrix inverter topology capable of producing an output similar to a 41-level modular multilevel inverter, with a total harmonics distortion of 1.98%, well below the limits set by IEEE 519–2014 standards.