A practical comparison between the series-stacked and neutral point clamped converters

Various multi-level converter topologies have been developed over recent years to address the industry demand for higher power and voltage levels. This paper compares two of these converter topologies, namely a 2-level series-stacked converter, using regular 2-level space vector modulation, and a 3-level neutral point clamped converter, which makes use of 3-level space vector modulation. The space vector switching schemes are analysed and applied to simulation models of the series-stacked and neutral point clamped converters. Focus areas are the control complexity, stray inductances causing over-voltages and the capacitor ratings and performance within each topology. These results are verified practically on a reconfigurable converter operated as a series-stacked or a neutral point clamped converter respectively. The results obtained will assist in the selection of the appropriate topology for a given application.