Harmonic characterization of the output voltage in multilevel converters

The evolution of power converters towards modular and robust topologies for high power applications has led to the development of multilevel converters. One of the main advantages of this technology is the improvement of the output voltage quality. This article presents the characterization of the output voltage waveform for three five-level multilevel converters (the Neutral Point Clamped-NPC, the Flying Capacitor-FC and the Cascaded H bridge - CHB) which are controlled by Pulse Width Modulation strategies. The characterization is made by the determination of the Total Harmonic Distortion (THD), the Lower-Order Harmonic (LOH), the voltage stress of the switching devices and the analysis of the FFT of the output voltage. The results show the outstanding performance of the CHB topology under the parameters mentioned above.