A Study of Asymmetrical Multilevel Inverter Topologies with Less Number of Devices and Low THD: A Review

Multilevel inverters (MLI) are attracting researchers and industrialists due to their power conversion significance and versatile applications in the power sector and industrial automation. All industrial and domestic power applications require a smooth sinusoidal waveform, which cannot be produced directly by means of power sources like fuel cells, batteries, photovoltaic arrays, etc. A more similar looking modified sinusoidal waveform can be obtained by increases the output voltage levels of the inverter by using power electronic semiconductor switches, where more number of levels results in low Total Harmonic Distortion (THD). To do so, a large number of devices are used, which eventually decreases the overall power conversion efficiency of the MLI. This paper presents a technical comparison between the latest state of the art asymmetrical multilevel inverter topologies having low THD that is implemented using less number of switching devices to produce a high-level output. The study indicates improved overall power conversion efficiency of the MLI with respect to the reduced number of devices, irrespective of the inverter's THD.