Boosting the Efficiency of Low Voltage Modular Multilevel Converters beyond 99

摘要

The Modular Multilevel Converter (MMC) is an upcoming topology for high efficiency power conversion not only in the high voltage range but also for low voltage applications. This contribution presents several improvements in the hardware design, control and modulation of a low voltage MMC to increase the efficiency over 99%. Simply standard Silicon-MOSFETs and no SiC- or GaN-transistors are used as semiconductor switches in the prototype converter. The detailed analysis of the efficiency also shows an excellent performance in the low power range, which yields to a very flat efficiency curve. Therefore, the MMC is especially suited for grid connected inverters, e. g. in applications like DC microgrids, photovoltaics etc.