Motwani, Jayesh KumarLiu, JianBoroyevich, DushanBurgos, RolandoZhou, ZhiDong, Dong2024-03-062024-03-062024-02-120885-8993https://hdl.handle.net/10919/118284With ever-increasing power-density requirements, technologies such as energy storage systems and electric-vehicles can benefit greatly from interfacing medium-voltage (MV)-AC grid like 13.8kV or 30kV using high-AC/low-DC voltage converter. Using modular high-AC/low-DC voltage converter can help increase power-density and efficiency, while reducing total conversion steps and providing flexibility. Full-bridge modular multilevel converters (FB-MMC) and solid-state transformers are existing solutions for such operations, but suffer from limitations of high semiconductor requirements, large submodule capacitors and/or many high-frequency transformers. Three new hybrid-MMC (HMMC) topologies are proposed in this paper as alternative solutions for such high-AC/low-DC voltage operations. Each of the three developed HMMCs utilizes a unique combination of low-frequency high-voltage switches and fast-switching lowvoltage switch based submodules to generate multilevel-AC voltage. HMMCs are compared extensively to state-of-the-art FB-MMC and are shown to have semiconductor savings of over 27%, 38% lower submodule capacitor size, and 53% lower losses for 13.8-kV-AC/6-kV-DC operation. Due to these benefits like higher efficiency, significantly smaller submodule capacitance requirements, and fewer semiconductors, HMMCs can be an excellent option for high-AC/low-DC applications. Practical considerations like snubber and DC split-capacitor requirement are also elaborated for developing and commercializing HMMCs. Comparison results are verified using a 17.5 kW three-phase MV laboratory prototype.Pages 1-15application/pdfenCreative Commons Attribution-NonCommercial-NoDerivatives 4.0 InternationalHybrid modular multilevel convertersmodular multilevel convertersmedium voltage converterelectric vehicle chargersenergy storage systemssolid state transformerArticle - Refereedhttps://doi.org/10.1109/tpel.2024.3361908PP99Burgos, Rolando [0000-0003-0570-2768]Boroyevich, Dushan [0000-0001-9538-4980]Dong, Dong [0000-0002-7236-3439]1941-0107