Abstract

Active NPC voltage source converters feature a higher degree of controllability than standard NPC converters due to the additional power switches which allows several different connections of the neutral point. In this paper, these switching redundancies are used to minimize and evenly distribute the energy losses. The predictive control scheme proposed is separated in two stages: The first one controls the output reference currents and keeps the dc voltages balanced. The second stage uses the switching redundancies given by the ANPC VSC to distribute the energy losses evenly. The energy balance is performed with a model-based estimation of the switching and conduction energy losses. In order to test the proposed algorithm, a comparison of the energy distribution between the proposed strategy and a NPC converter is presented. © 2010 IEEE.