A generalized optimization in cascade and Modular multi-level inverters by harmony search method

In This paper a generalized formulation for selective harmonic elimination for cascade and Modular multilevel converters is considered. Modular multilevel converter is a new type converter that is similar to cascade multilevel converters. This converter consists of several sub-modules. In this formulation the amount of DC sources are considered as variables with certain constraints. Therefore the degree of freedom is increased in comparison with conventional method and low order harmonic elimination and THD minimization is achieved by optimum selection of switching angles and amount of DC sources. For the solution of this problem a method based on harmony search approach is used because this method has high rate of convergence, precision and simplicity compared to other optimization methods. Simulation results show the effectiveness of this method.