Enhanced Harmonic Elimination Using Genetic Algorithm Optimization in Multilevel Inverters

In this paper, an Enhanced method has been proposed to calculate the switching angles based on genetic algorithm (GA). It is well known that the pulse width modulation selective harmonic elimination control (SHEPWM) applied to a seven-level inverter can allow the suppression of only two low order harmonics. To improve the total harmonic distortion (THD), and without any modification to the seven-level inverter structure, seven low order harmonics has been successfully eliminated. This is done by suitably adding holes in the conventional staircase voltage leg. Furthermore, a hole distribution in agreement with the sin function shape is proposed. GA is applied to determine the optimized switching angles. For this purpose, a cost function containing the nonlinear equations under standard constraints is proposed. These constraints are weight up by conception parameters for a better reshape of the output voltage. This developed procedure can eliminate a desired number of low harmonics, only restricted by the maximal switching frequency of the power switches. Results of the suggested method are compared to the conventional SHE involved in seventeen-level staircase wave. They reveal that the developed method is a very effective one for optimal harmonic elimination technique in multilevel inverters.