Comparative analysis of 9 levels cascade multilevel converters with selective harmonic elimination

This paper presents a comparative analysis of the H-bridge multilevel cascaded converters with common source and with independent source, and both with selective harmonic elimination (SHE). Two prototypes of nine levels of output voltage are implemented, which use a standard step modulation and optimized PWM modulation (using genetic algorithms). The non load and the load test determine the total harmonic distortion (THD) differences and the behavior of the RMS values. Finally, the converter output waveforms and performance are discussed, also the behavior of the DC buses and the cost of both prototypes.