A Generalized Derivation Method of Tree-Type Active Neutral-Point-Clamped Multilevel Topologies

Improving the power density of multilevel converters is a crucial task, particularly in high-power applications where the volume of passive components is significant. To achieve a high number of voltage levels with minimal device count, this article presents a novel and generalized derivation method for a new family of tree-type active neutral-point-clamped (TANPC) multilevel topologies. By utilizing the two-level bridge and three-level neutral-point pilot bridge as fundamental cells, the proposed method enables the extension of output voltage levels in a simple and straightforward way. Each derived TANPC topology is equivalent to a single-pole multi-throw switch without the need for flying capacitors, where n+1 voltage levels can be generated with only 2n active switches. The related pulsewidth modulation and neutral-point voltage balancing strategies for the derived TANPC multilevel converter family are also introduced. Experimental results are presented, demonstrating the effectiveness of the proposed topology derivation method through the implementation of a novel fivelevel TANPC converter.