Hot-Swapping Analysis and Implementation of Series-Stacked Server Power Delivery Architectures

Current data center power delivery architectures consist of many cascaded power conversion stages, where the system-level power conversion efficiency is reduced each time the power is processed through the individual stages. Recently, series-stacked power delivery architectures have shown how the overall power conversion can be reduced through architectural changes, reporting above 99% system-level power conversion efficiencies for data centers. In this paper, we contribute to the development of the series-stacked power delivery architectures by addressing the important hot-swapping challenge, without sacrificing the high power conversion efficiency. We analyze the hot-swapped operation of the series-stacked architecture, and experimentally validate it on a testbed that includes four series-connected 12 V, 120 W servers and four custom-designed differential converters with associated circuitry for hot-swapping. The results show that continuous operation of the series-stacked servers can be maintained while a server is hot-swapped without a significant reduction in the high power conversion efficiency.