7-level cascade multilevel inverter using a single DC source and minimum THD of Output Voltage

In this paper, a cascade multilevel inverter using a single Dc source is considered. Switching angles are obtained using a smart technique to remove the selected harmonics. Changing voltage of DC-link has been employed to change the output voltage rather than the change of the switching modulation. Problems due to the change of the modulation switching (e.g. changes of THD value and undesirability of the inverter output waveform) are improved by using this technique. Furthermore, it leads to the simple design of the inverter output filters. The equations have been presented in several sections and simulations performed by PSCAD/EMTDC software.