Analysis of Minimum Modulation for the 9-Level Multilevel Inverter in Asymmetric Structure

The main function of multilevel inverters is to synthesize a desired AC voltage output starting from several input levels of direct current voltage. There are several circuit topologies and modulation strategies to generate the desired output voltage of an inverter, among which stands out the traditional Sine Pulse Width Modulation (SPWM) technique with several variants. Phase Disposition (PD), Phase Opposition Disposition (POD) and, Alternate Phase Opposition Disposition (APOD); are presented considering switching frequencies, the spectrum of the output waveform of the inverter, and total harmonic distortion. In this paper, the SPWM techniques are studied due to its easy implementation and for being the most widely used family of multilevel converters, applied to the 9-level Asymmetrical Cascaded Multilevel Inverter (ACMLI) with the trinary structure, which is not a traditional case by means of a simulation environment.