The work proposed in this paper concerns the study of harmonic pollution generated by static converters, particularly inverters, which largely contributes to the degradation of the supplied electrical energy quality. So, we studied in first the EMC of the conventional two-level inverter to highlight the harmful pollution of this kind of converter. We then looked at multi-level inverters to characterize their degree of pollution according to their number of levels in order to propose practical solutions for industrial applications. Thus, we considered three structures of multi-level inverters namely: a diode clamped inverter, a flying capacitor clamped inverter and a cascaded h-bridge inverter. At the end of this study, we retain that these three structures make it possible to obtain a waveform of the output voltage close to the sinusoidal form. The results of simulation obtained and compared to the STD international standard templates, also allowed us to conclude that among the three structures studied the cascaded h-bridge inverter is the most interesting from the electrical energy quality point of view. In addition, this converter has the advantage of owning a reduced number of switches which results in a weight and a cost, better than those of the other two studied inverters.