48 V mains supply technology is the future direction of data centers (1)

48 V mains supply technology is the future direction of data centers (1)

With the large-scale construction of data centers, users pay more attention to energy costs and efficiency. The future direction of the power supply technology of data centers must be the municipal direct power supply technology, while saving the investment and Site Occupation of traditional UPS equipment and reducing the initial cost, it also reduces the operation cost by reducing the conversion level and improving the power supply efficiency. In addition, the efficiency improvement mentioned here not only refers to the high efficiency of the power supply path from the power grid side to the IT equipment input side, it is an efficient and environmentally friendly way from the energy side to the CPU. Although the traditional PUE value may increase, the Unit Computing Energy consumption is reduced. 1. In the future, the overall development trend of data center power supply technology is the development of high-voltage/centralized/ac ups to low-voltage/distributed/DC small UPS, from centralized lead-acid batteries in data centers to distributed small (Lithium) Batteries embedded in IT cabinets and even servers, from contaminated fossil energy to environmentally friendly green energy.

The core of the data center Power Supply uninterrupted technology lies in the uninterruptible power supply and its battery technology. Therefore, different battery connection locations also determine different power supply architectures. Currently, the industry's mainstream backup battery voltage ranges from high to low, from over 400 volts of UPS to 380 V, 240 V, and 48 V of DC power supply, even 12 V batteries embedded in IT devices. There are even medium voltage UPS using flywheel or smaller UPS with lower voltage such as 5 V, which will not be listed here due to a small number of applications. Figure 2 shows the industry's main technical solutions for power supply in data centers. First, from the traditional UPS with a centralized 400 + V lead-acid battery, second, the standard server does not need to be customized, V battery directly mounted output bus V high-voltage DC technology, followed by servers using custom 48 V or V input power 48 v dc or V high-voltage DC battery direct mounting technology, finally, go to Google and other 12 V batteries to directly mount the server motherboard input solution. The closer the battery is to the end server motherboard or CPU, the more scattered the power supply system is, the more distributed the IT system is. The closer the battery is to the end, the higher the customization of the power supply system, the larger the scale of common users, the closer the battery is to the end, and the higher the IT Power Supply and battery control and management level. At last, the closer the battery is to the end, the conversion level from the power grid to the CPU power supply path is also reduced, resulting in higher conversion efficiency, but the transmission loss may increase at the low voltage side. Therefore, to compare the centralized and distributed power supply architectures, such as high voltage, low voltage, AC, and DC, different power supply architectures will greatly affect the reliability, power supply efficiency, and cost of the power supply system, there are also the maturity of technology, ecology, and application flexibility.

In addition, with the development of battery technology and the introduction of green energy such as wind energy, solar energy, and fuel cells in the data center, more opportunities and challenges will be brought to the data center. In a sense, the uninterrupted power supply technology of the data center will ultimately depend on the development of the battery technology, and the battery innovation will also bring about changes in the power supply architecture of the data center, for example, from the development of the traditional low density lead-acid battery to the high energy density lithium battery technology, IT is likely to place the backup battery from the Battery room to the IT cabinet, or even inside the IT equipment. The development of the same battery technology makes it possible for fluctuating green energy such as wind energy and solar energy to realize energy storage, and will also change the traditional data center from a single power grid power supply mode. These further discussions will not be discussed here. This article focuses on the mainstream technologies used in the industry for the time being, so that you can further explore the future development direction of data center power supply technology.

Hierarchical Data Center Granularity

Before the official start of this article, we can also consider the UPS application scenarios from the top-down to different levels of the data center, typical data centers can be divided into different granularities, such as the whole park, single building, data center module, micromodule, Cabinet, and server. Because the scale of the whole park and single building is too large, there is basically no UPS to cover the entire level, so we will not discuss it here. The typical practice at the data center module level is to use the traditional centralized sub-cabinet level UPS. The typical practice at the micro-module level is to use a semi-Distributed Integrated cabinet level UPS, the typical practice at the Cabinet layer is distributed DPS power-in-box UPS, and the typical practice at the server layer is to use the component-level embedded battery UPS, respectively 3 (a) to (d). Similarly, in these four application architectures, the placement of batteries varies greatly, from centralized power battery rooms at the data center module level to semi-distributed battery cabinets at the micromodule level, go to the distributed battery BBU at the cabinet level, and then to the component-level lithium battery package at the server level. The Construction Scale of UPS and battery at different levels is from large to small, from centralized installation to scattered placement, from one-time investment to phased investment, the impact of the fault is also from the entire data center module to a single server.

 

From the previous analysis, the adoption of distributed UPS can bring some benefits, such as the construction of phased development while investment, which can reduce the one-time investment in the early stage; in addition, many data centers often do not have high load rates, or it takes a long time to fill up servers. In this way, the inefficiency of centralized UPS under long-term low load can be effectively reduced when distributed small UPS is used; in addition, the distributed small UPS built in installments can flexibly match future technical upgrades or business changes, or be configured as needed based on different reliability levels to bring more flexibility. Therefore, distributed architecture has some advantages over centralized architecture, but is the distribution better?

The answer is clearly no. we will analyze the difficulty and other aspects of the ecosystem or industrial chain. The first is the traditional UPS architecture shown in Figure 3 (, after decades of development, both the technical maturity and the upstream and downstream industrial chains are very mature, with the lowest difficulty. Secondly, Figure 3 (B) micro-module UPS, IT can be an integrated modular UPS, an integrated V high-voltage DC, or even a 48 V Communication Power Supply System. Because IT does not need to be customized or transformed for the existing server and other IT equipment, IT is relatively easy to carry out; next, Figure 3 (c) shows the power plug box + Battery BBU solution for the entire cabinet layer, OCP, Google, Microsoft, and Scorpio cabinets outside China have accumulated technical expertise and industrial chain support, as well as large-scale application requirements for Internet users, however, IT is difficult. In the end, the battery package solution is directly mounted on the Main Board of the IT equipment. Because of the embedded battery servers, IT equipment must be fully customized. In addition, the battery package direct mounting solution of IT equipment is not mature enough, and involves many upstream and downstream manufacturers and different models and other products, so IT is the most difficult to carry out.