Multilevel converters are considered recently as one of the industrial solutions for high-power and power quality demanding applications. Casacade H-Bridge (CHB) converter is one of the well known topologies among multilevel converters. CHB converter is characterized by its high modularity allowing its power to be easily increased. Modularity also allows any faulty cell to be isolated, so the load can be fed by the remaining operative cells, which leads to an unbalanced output voltage of the CHB converter. To avoid the unbalanced operation, recently a solution based on modifying the phase and the magnitude of the voltage refereces has been proposed. This thesis presents a method to control...