Time domain optimization of voltage and current THD for a three-phase cascaded inverter with three H-bridges per phase

This paper presents the results of voltage and current Total Harmonic Distortion (THD) minimization for a three-phase cascaded H-bridge inverter with a fundamental staircase modulation. Theoretically optimal switching angles are found using THD minimization time domain constraint optimization problem formulations. Numerically obtained optimal switching angles and minimal voltage and current THD values are presented for a cascaded three-phase converter with three H-bridge modules per phase. While optimal voltage THD solutions were already reported in literature, optimal current THD ones are presented for the first time. While voltage optimal solutions are essentially discontinuous, current optimal angles have only one discontinuity.