Analysis of a DC Data Center Power Supply with Series-Connected Active and Passive Rectifiers

• Main Authors: Cervone, Andrea, Arbogast, Louis, Dujic, Drazen
• Format: Conference Proceeding
• Language: English
• Subjects: Active-Front-End (AFE); Data Center DC power supply; Diode-Rectifier (DR); Loading; Partial Power Processing; Performance evaluation; Pollution; Power system harmonics; Reactive power; Rectifiers; Transformers
• ISSN: 2835-8457
• DOI: 10.1109/SPEEDAM61530.2024.10609127

In future Data Centers with DC power distribution, unidirectional rectification is required to provide a constant DC voltage from the AC grid. Given the unidirectionality requirement, an inverter-based Active Front End (AFE) solution could be ideally replaced by a passive Diode Rectifier (DR) unit, leading to a simpler, more robust and cheaper solution. However, a purely passive solution would not be able to provide the DC-bus voltage stabilization in spite of the ±10% AC voltage fluctuations in the supplying grid, and would also lead to operation at non-unitary power factor and to harmonic current pollution. Therefore, this work analyzes a hybrid solution relying on the simultaneous utilization of an AFE and of a DR unit, whose DC outputs are connected in series with one another. By employing both a passive and an active rectifier, this solution could potentially reduce the sizing requirements for the AFE while achieving at the same time the desired target requirements in terms of DC-bus voltage stabilization and unitary power factor operation. The potential benefits and limitations of this approach are analyzed in this work. From an idealized design it is shown that, at the expense of a increased system complexity, the analyzed hybrid solution would theoretically achieve a 37.5% reduction in the sizing requirements of the AFE, but that in practical designs this ideal optimum might not be compatible with the voltage class of available semiconductor devices, in which case a sub-optimal solution could be instead designed, with a potential 25 ÷ 28% reduction in the AFE sizing requirements, while achieving similar control and efficiency performances as in a full-AFE solution.