A Complete Solution of Harmonics Elimination Problem in a Multi-Level Inverter with Unequal DC Sources

In this paper, the problem of eliminating harmonics in a multi-level inverter with unequal DC sources is considered. The main objective is to improve the method of solving the equations for proper switching angles which reduce the total harmonic distortion (THD) in the output voltage. The basic concept of this reduction is to eliminate specific harmonics, which are generally the lowest orders, with an appropriate choice of switching angles. This paper employs Homotopy algorithm to solve the transcendental equations for finding the switching angles. This method solves the nonlinear transcendental equations with a much simpler formulation and without complex analytical calculations for any number of voltage levels. Also, several informative simulation results verify the validity and effectiveness of the proposed algorithm.