Evaluation of Optimal Switching of Modular Multilevel Inverter with Independent Voltage Sources

Abstract

This paper deals with the problem of the defining optimal switching times in modular multilevel converters (MMC) with independent voltage sources, if no pulse width modulation (PWM) technique is used. By using MATLAB Simulink modulation several schematics were analyzed (starting from 3 level MMC till 15 level MMC) with different module switching patterns. Different switching patterns of modules of MMC are compared by one parameter - total harmonic distortion (THD) of the output voltage waveform. Mathematical background of calculation of optimal switching times is also presented.