Optimal Modulation Method for DC-Link Control in Cascaded H-Bridge Multilevel Converters

This paper presents a new DC-Link voltage control method for Y-connected Cascaded H-Bridge Converters. Such converters have several redundancies which the presented method exploits to independently control the DC-Link voltages without affecting the output currents. This is achieved by solving an equivalent linear optimization problem subject to constraints. Simulation results are shown to verify that the method keeps DC-Links controlled even when power sources operate under different conditions.