Evaluation of a Medium-Voltage Grid-Tied Cascaded H-Bridge for Energy Storage Systems Using SiC Switching Devices

This paper presents the study and evaluation of a medium-voltage grid-tied cascaded H-bridge (CHB) three-phase inverter for battery energy storage systems using SiC devices as an enabling technology. The high breakdown voltage capability of SiC devices provide the advantage to significantly minimize the complexity of the CHB multilevel converter, with less power loss compared to when Silicon (Si) devices are used. The topology in this study has been selected based on high voltage SiC devices. In order to reach 13.8 kV, a nine-level CHB is needed when using 6.5 kV SiC MO Stns. However, if 10 kV SiC MOSFETs are used, only five-levels of the CHB are required. The controls were developed, simulated and verified through an experimental prototype. The results from the scaled-down prototype proved the controls and the verification of the performance of the-level CHB three-phase inverter. For the system reliability, both open-loop and short-circuit faults are analyzed.