Voltage and Current THD Minimization of a Single-Phase Multilevel Inverter With an Arbitrary RL-Load Using a Time-Domain Approach

This article presents a time-domain optimization technique for minimizing harmonic content in the output voltage and current waveforms of a single-phase multilevel inverter (MLI) topology with an arbitrary
$RL$
-load. The effect of the modulation index and the load parameters variation on the harmonic content of load voltage and current have also been analyzed. A single-phase 21-level MLI is developed to verify the proposed switching technique. The total harmonic distortion (THD) of the current and voltage in the time-domain is considered as the optimization constraint to compute the inverter’s optimal switching angles. In addition, the load time constant has also been considered during optimization problem formulation, which enables superior inverter performance in terms of lower THD in the output response. The detailed theoretical, simulation, and experimental analysis are carried out on the presented topology to verify the proposed switching technique’s performance.