Operation of Cascaded H-bridge-Based Split-Battery Energy Storage System With Reduced Sensors

In the conventional cascaded H-bridge-based splitbattery energy storage (CHB-SBES) system, the dc-bus voltages are measured for state-of-charge (SoC) balancing and charge/discharge control of battery packs, and multilevel voltages are sensed for open-circuit (OC) fault detection in the submodules. In this paper, a new control approach is proposed where the multilevel voltage measurement of the CHB-SBES system alone is utilized for control (i.e., SoC balancing and charge/discharge control) as well as fault detection. The dc-bus voltage of each submodule is estimated from the measured multilevel voltages, gating signals and grid currents for control purposes. Further, to localize OC faults within a fundamental line cycle, a simplified fault detection method is proposed using the estimated dc-bus voltages. The proposed method eliminates n dc-bus voltage sensors per phase and the associated sensor power supplies in CHB-SBES system, where n is the number of submodules per phase. Results from MATLAB-Simulink model are presented to validate the proposed method.