A Modularized Partial Power Converter Based Uninterruptible Power Supply Scheme for DC Power Feeding Servers in Data Centers

This paper proposes a novel partial power converter based uninterruptible power supply (PPC-UPS) scheme for DC power feeding servers in data centers, in which a server load and its local backup battery are connected in series and compactly integrated to a common DC bus through one PPC. The proposed PPC-UPS scheme is modularized and distributed in multiple DC loads of a data center, with high scalability and reliability. The PPC-UPS scheme can reduce the number of power electronic converters by diverting the battery energy directly to the DC load via the PPC, while power conversion losses can also be significantly reduced as the PPC only undertakes a fraction of the DC load power. A PPC-UPS multi-mode control strategy is designed to autonomously and flexibly secure its continuous operations under various contingencies. Small-signal analysis is carried out to assess the system stability and obtain optimal control parameters. The performances of the PPC-UPS scheme are evaluated through hardware experiments, which illustrate that the PPC-UPS can reliably supply the DC loads under the contingencies of converter or battery outage and facilitate load reconnections.