Abstract：Cascaded H-bridge multilevel inverter is widely used in high-voltage high-power motor drivers. The biggest shortage is the use of multi-winding transformer which is bulk, complex and expensive. In order to eliminate the multi-winding transformer of the traditional cascaded H-bridge inverter, a novel transformerless cascaded multilevel converter is proposed in this paper. It’s derived from the generalized multilevel inverter topology and consists of a number of cascaded basic cells. All the dc capacitors are floating and the separated dc sources are not needed, so the multi-winding transformer is no more needed. Due to its high modularity, it can be easily extended to higher levels. By comparing it with existing main multilevel topologies, the new topology needs fewer components while producing the same number of output voltage levels, so it is more suitable for converters with a high number of voltage levels. By taking a five-level new topology as example, the operating principle and voltage balancing method of the proposed topology are presented. The validity of the proposed topology and control method is verified by simulation and experimental results.
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2011, Vol. 26 
