A Modular Multilevel DC-DC Converter With Auxiliary Inductor Circuits for Cell Voltage Balancing and Fast Output Response

Battery-equipped apparatuses, such as electric vehicles (EVs), renewable energy generations, and mobile devices, are widely used still being developed. For the design evaluation of these there is a growing demand for dc power supplies to test charge-discharge characteristics lifetimes batteries. As voltage performance batteries increase, battery must be able handle higher voltages have faster output transient response. To high voltage, multilevel converters that use multiple devices with lower ratings often been in recent years, addition using single device high-voltage ratings. Among various circuit topologies, modular (MMCs) actively studied However, unlike dc-ac ac-dc conversions, dc-dc conversion MMCs has problem cell capacitor cannot balanced principle because less redundancy operation states. Therefore, most MMC-based achieve balancing control by combining conversion, isolation transformer or inductor, conversion. configurations tend large equivalent inductance unsuitable achieving fast In this study, we analyze its problems MMC circuit. Based on analysis, topology auxiliary inductor circuits method suitable converter proposed. A prototype 6-cell SiC-MOSFETs was designed implemented, it demonstrated response could realized.