DC Link Voltage Controlling of Multilevel Inverter for Improving the Optimal SHE Performance

In this paper, DC link voltage of inverter is controlled in order to improve Selective Harmonic Elimination (SHE) sufficiency. There are several procedures to solve the SHE problem. In this paper the recently developed evolutionary optimization method named Imperialist competitive algorithm (ICA) is used to solve the nonlinear transcendental equations of SHE problem. In the literatures, to solve SHE problem using evolutionary method, many objective functions have been presented which have same purpose. In this paper, two kinds of objective functions are analyzed and compared to identify which is more effective. To confirm the presented method accuracy, simulation and experimental results are provided. Although the SHE is an efficient method for achieving to desired fundamental component and eliminating selection harmonics, but for some ranges of modulation indexes the SHE nonlinear equations don't have solution. In this paper to overcome the mentioned problem an efficient solution is presented. A DC−DC converter has been used, for controlling DC link voltage of inverter in order to the modulation index be in an area that the SHE equations have to be solved. Also provided simulation and experimental results validate the feasibility and good performance of the suggested solution.

Keywords:

Selective Harmonic Elimination , DC−DC converter , Imperialist competitive algorithm