Hot-Swappable Grid-Connected Multilevel Converter for Battery Energy Storage System

The objective of this brief is to propose a hot-swappable grid-connected multilevel converter (HGM-converter) for the battery energy storage system (BESS). The proposed HGM-converter is composed of series-connected bi-directional H-bridge sub-converters and a LCL filter. Advantages of the proposed HGM-converter include: hot-swappable capability, single-stage power conversion, low dc-bus voltage, and individual power control for each battery module. Therefore, the equalization, lifetime extension, and capacity flexibility of the BESS can be achieved. Based on the equivalent model, the power flow of the battery module can be estimated without the need of input current sensor. Also, with the interleaved operation between the sub-converters, the current ripple of the output inductor can be reduced too. The computer simulations and hardware experimental results are shown to verify the performance of the proposed HGM-converter.