Proposal of Battery Back-up Unit (BBU) Configuration for Data Centers

This paper proposes a modular configuration of battery back-up unit (BBU) for data centers. The proposed configuration is based on the concept of battery power module (BPM) where the battery cells are decoupled from each other by connecting each cell with a low bi-directional DC-DC power converter. The proposed configuration respects the requirements specified by the latest issued Open Compute Project-open rack (OCP-OR v3). This is achieved through connecting the BPMs in strings. Thus, during charging mode, the strings can be charged sequentially at their rated power. On the other hand, during discharge mode, all the strings can be simultaneously operated at their rated power to feed the data center racks. Simulation and experimental results are introduced to verify the proper operation of the proposed configuration.