This paper deals with the minimization of the harmonic distortion to improve the power quality by using 9 steps multilevel power converter, using genetic algorithms to optimized a multi-PWM modulation, and minimizing Total Harmonic Distortion (THD) to almost zero. A novel numerical technique is develop as the optimization approach to obtain a math expression that quantifies the THD in the 9 steps multilevel PWM waveform, in terms of the firing angles and the position of the levels in the first quarter-wave modulation. A prototype was development for experimental verification.