A Series-Stacked Power Delivery Architecture With Isolated Differential Power Conversion for Data Centers

In this paper, an alternative method to achieve more efficient dc power distribution and voltage regulation for future data centers is presented. This paper describes a series-stacked power delivery architecture, where servers are connected electrically in series, thereby, providing inherent step down of voltage. Server voltage regulation is performed by differential power converters, which only process the mismatch power between servers. The bulk power flows with no power processing, yielding greatly increased system efficiency compared to conventional architectures. We demonstrate the series-connected architecture with an experimental proof of concept and compare the proposed architecture with a conventional dc power delivery architecture employing a best-in-class power supply unit for servers. The proposed power delivery architecture is validated with a series-stacked server rack consisting of four 12 V servers, powered from a 48 V dc bus, performing two different real-world operations: web traffic management and computation. Through experimental measurements, we demonstrate up to a 40x reduction in power conversion losses compared to state-of-the-art hardware, and an overall best-case system conversion efficiency of 99.89%.