Predictive control of a grid-connected cascaded H-bridge multilevel converter

A predictive control scheme for a three-phase cascaded h-bridge rectifier is presented. The main objectives of this control scheme is to minimize the error between the input active and reactive power and their references, and to balance the dc-link capacitor voltages. These objectives are expressed as a cost function to be minimized. A model of the converter is used for calculation of the predicted value of the controlled variables for a set of switching states. The switching state that minimizes the cost function is selected and applied. In order to reduce the number of calculations needed to select the optimal state, a method for reduction of the evaluated switching states is also proposed. Results show that the proposed control scheme achieves fast control of the active and reactive power and keeps the capacitor voltages balanced.