Mixed Technology Modular Multilevel Converter Cell - A Cost/Efficiency Analysis

As the modular multilevel converter (MMC) becomes more used in medium voltage applications, its usage along with wide band gap devices, with low conduction losses and high switching frequency capability, seems promising. Currently it is not rare to see these converters fully equipped with SiC-MOSFETS in their structure, even tough the costs still can be prohibitive. To investigate this issue, this paper presents an analysis and discussion of the application of different devices technology for the cells of a Modular Multilevel Converter, e.g. SiC MOSFETS and IGBTs. The study addresses the different loading of the devices and how to better apply and select them considering different MMC applications. To further increase the efficiency of the topology, an analytical comparison is realized to evaluate the losses in different technology devices in parallel. At the end, a cost/benefit analysis is presented.