Research content -Multi-level converter-
A multilevel inverter can reduce the output voltage fluctuation to 1/(n-1) (n:number of levels) of the DC bus voltage. In the case of 3-level converter, the voltage stress can be decreased to 1/2 compared with a conventional 2-level converter. For this reason, a multilevel inverter is applied to a medium voltage motor drive.
In our laboratory, we are aiming to propose a novel circuit configuration for higher efficiency and more compact size of multilevel converter, and to establish quantitative design methods for them.
Modular Multilevel Converter (MMC)
MMC is configured by cascading cells in which each arm combines multiple switching devices and DC-link capacitor. Moreover, it is possible to easily increase the withstand voltage of the system by increasing the number of connected cells.
Solid-State Transformer (SST)
SST uses a high-frequency transformer instead of the conventional low-frequency transformer for the isolation part. Thus, it is possible to greatly reduce the size of transformer compared with the low-frequency transformer.
