This paper deals with the optimization of common source cascaded multilevel inverter with 17 steps per line, using a multiobjective genetic algorithm that allows generate an optimized PWM modulation waveform. The aim is to minimize the total harmonic distortion (THD) to a value close to zero, but keeping the root mean squared (RMS) voltage at the desired value, while the magnitude and the frequency of the output voltage waveform change progressively. To evaluate the performance of the algorithm, a simulation was carried using an asymmetry converter with two H-bridge stages and a 1:3 transformation ratio. The results allow verifying the THD optimization in the first 50 harmonics and to obtain the RMS voltage value the same as the rated value.