Investigation of SC faults in 3300 V SiC MOSFET based Half Bridge Submodules for HVDC Converters

Inhalt:
The content of this work presents the failure robustness of 3.3 kV Silicon carbide (SiC) MOSFETs in the use of Modular Multilevel Converter (MMC) half bridge submodules. The focus of investigation is on the application specific short circuit (SC) failure types of HV SiC MOSFETs within a half bridge (HB) cell of a HVDC MMC. First, various SC types are executed in a double pulse test setup to characterize the SC behavior and the required save turn off conditions. A system loss simulation is executed to investigate the influence of potential soft turnoff. The second part of this work will focus on system DC link SC failures in a 3.3 kV SiC based HB submodule using the intrinsic bodydiodes of the devices. For this purpose, surge current tests of discrete SiC MOSFETs were executed to investigate the maximum ratings. Finally, a system simulation of a DC link SC failure with a fictive scaled SiC HB module is simulated to obtain the stress on the body diode in the application.