The world’s data centers currently consume about 480 to 660 TWh of electricity annually, accounting for 1.7% to 2.2% of the world's electricity generation. Traditional power delivery architectures in data centers are bulky and inefficient. About 40% of the data center energy consumption comes from the losses in power conversion. Such high energy consumption and the related carbon emission have raised public concerns about their economic and environmental impact.
There is a long path to convert electricity from the utility grid to the onboard CPUs, including multiple AC-DC, DC-AC, DC-DC stages from 10 kVac to ~ 1Vdc. This tutorial will introduce the current status of ICT industry on both digital and energy aspects, provide an overview of the state-of-the-art of power supply architecture and topology in data centers, and discuss the key principles on designing and implementing these power electronics technologies for data center energy saving and decarbonization.
Three topics will be discussed: zero-voltage-switching (ZVS) three-phase/single-phase AC-DC/DCAC/ BTB converters as grid interface, Super-UPS/Multicell MIMO energy router for renewable integration, and 48-V voltage regulator modules (VRM) for high current CPU and GPU. The ZVS AC-DC/DC-AC/BTB converters aim to solve the switching loss issue and improve the efficiency and power density of the grid interface of data centers. Based on the resonant dc link concept, a family of three-phase/single-phase ZVS AC-DC/DC-AC/BTB converters and a unified modulation strategy (Edge Aligned-PWM) will be introduced. The engineering challenges, practical details of this approach, and the impact of wide bandgap (WBG) devices tech will be discussed.
The second topic introduces two architectures for renewable integration in data center: the Super-UPS and Multicell MIMO (Multi-Input Multi-Output) energy router. Super-UPS is the evolution of UPS by adding natural gas, PV and Hydrogen fuel cell to the DC bus by multiple bi-directional DC-DC converters and DC-AC converters. This architecture not only reduce the carbon emission but also increases the system reliability significantly. Multicell MIMO energy router is a modular design in which a large number of cells are coupled by a single magnetic core. The conversion stages are reduced whereas the power flow control is more complicated compared to the Super-UPS with DC bus. The operation principle and the comparison of two architectures will be presented in detail in this tutorial.
The 48V architecture is now becoming the mainstream choice for powering the high current microprocessors in data centers. Meanwhile the power consumption and transient current of microprocessor is also increasing with the improvement of performance. The 48-V VRM aims to address the challenge of very high voltage conversion ratio for high performance microprocessors. A family of hybrid switched-capacitor topologies leveraging the low voltage device, the high energy density of capacitor, and precise regulation of inductor will be introduced. The magnetic design and fast dynamic control will also be introduced.
.jpg "Yenan Chen, PhD photo")