Multilevel Voltage-Source Converter Topologies With Internal Parallel Modularity

This article presents a new multilevel converter topology synthesis concept-the internal parallel converter (IPC). In the IPC concept, each phase of an IPC topology consists of one low switching frequency part and several parallel-connected high switching frequency (HSF) modules. Compared to existing topology synthesis principles, the IPC topologies feature the merits such as reduced device current stress, modularity, hybrid utilization of different types of devices, etc. Also, by interleaving the HSF modules, the number of output voltage levels can be increased without complicating the control of the converter. Detailed discussions on the advantages of the IPC concept are presented in this article. Two example topologies are introduced and adopted in simulation and experiment. The results of the interleaving operation show that the number of output voltage levels can be effectively increased, demonstrating the functionalities of the proposed IPC topologies.