Optimized phase disposition sinusoidal pulse width modulation classical multi-level inverters using curve fitting techniques and genetic algorithm

Abstract

This paper presents an open-loop optimization methodology for three classical multi-level inverter types: cascaded H-bridge, neutral point clamped, and flying capacitors inverters controlled by Phase Disposition Sinusoidal Pulse Width Modulation (PD-SPWM) to minimize Total Harmonic Distortion (THD) in a single-phase output voltage while maximizing efficiency. The optimization process encompasses data collection through simulating the three inverter types from three to seventeen levels in MATLAB/Simulink, optimizing the sinusoidal reference waveform amplitude and carrier waveform frequency for each level of the three multi-level inverter types corresponding to the lowest THD and within a predefined desired output voltage range. Curve-fitting techniques are then employed to predict the optimal operating points for levels beyond seventeen by analyzing the data collected from the simulations of the three multi-level inverters for levels below seventeen, identifying underlying patterns and relations, and then forecasting the futuristic data. A genetic algorithm is subsequently used to select an appropriate filter, ensuring that the THD remains below 5 %, in compliance with IEEE Standard 519. The optimal points obtained in this study are compared with existing works, demonstrating consistently lower THD across all configurations.