An analytical method for evaluating the power density of multilevel converters

Multilevel converter topologies have shown greal potential in high power converters with advantages including high efficiency and low distortion, and could provide the high power density necessary in new space and weight-constrained applications. A comparison of the passive component requirements, in terms of stored energy, of both flying capacitor multilevel converters (FCMCs) and modular multilevel converters (MMCs) is presented. The two topologies have different advantages, and their respective power densities. For low switching/modulation frequency ratios the MMC is favorable whereas the FCMC can yield higher power density in applications where the ratio can be large, e.g. in dc-dc, line-frequency converters and variable speed drives.