Selective Harmonics Minimization for Multilevel Inverters

This paper introduces a new approach based on linear programming for minimizing the undesired harmonics produced by multilevel inverters. The proposed approach differs from the methods of harmonics elimination discussed in the literature by being easily applicable to optimally minimize any number of undesired harmonics, for any possible amplitude of the main harmonic. This approach is explained, and then applied for a five level multilevel inverter to minimize the third till the 29 th harmonic and higher, and for minimizing harmonics with different weights. A method is proposed for varying gradually the amplitude of the main harmonic while keeping low values for the undesired harmonics. Then it is shown that this approach can be applied for multilevel inverters of any number of levels. The paper gives for some cases, the resulting pattern of the output voltage, and shows for most cases very low values of the undesired harmonics and their total harmonic distortion.