Enhanced Modulation Index Range for Mitigation of 5^th and 7^th Harmonics in a Five-Level Three-Phase Inverter

This paper introduces a novel methodology for determining critical switching angles in a five-level, three-phase inverter, significantly improving the harmonic mitigation range to effectively mitigate the fifth and seventh harmonics. This method adheres to stringent grid codes over a wide range of modulation indices, as confirmed through detailed simulations. Analyzing five unique cases, the research expands the modulation index spectrum for mitigating fifth and seventh harmonics to 91.5%, a 30% increase over previous limits, without altering inverter switching frequency, number of angles, or fundamental voltage. This novel approach not only broadens operational ranges but also sets a new standard in harmonic suppression, as demonstrated by extensive graphical and MATLAB/Simulink-based simulation evidence.