Modular Multilevel Converter Based Topology for High-Speed, Low-Voltage Electric Drives

The increasing demand for higher power density and more efficient electric drives, in particular, from the automotive industry, has pushed engineers investigating new solutions. Recently, wide bandgap devices have been proposed to improve performances of classical ac/dc converters, mainly in terms of power conversion efficiency. In this article, an alternative approach is proposed, aiming to obtain the desired improvements in the overall drive performances using a more complex power conversion system, based on standard silicon devices. In particular, a modification of the modular multilevel converter (MMC) is proposed in order to eliminate the submodule voltage ripple that would otherwise limit the MMC applicability in low voltage, variable frequency electric drives. This article introduces the design procedure and the analytical modeling of this novel topology together with the validation of the theoretical claims via simulations and experimental tests.