Before I begin discussing data center power management solutions for 2019, I would like to briefly take a general overview of data centers. In 2016, I wrote about power supply solutions for improved efficiency; much has changed since then.

Figure 1 Data Center Frontier discussed trends in data centers for 2019 (Image of a data hall at a LinkedIn facility in Hillsboro, Oregon, courtesy of LinkedIn)

It is expected that there will be more than 175 zettabytes of data by 2025. Data center construction and deployment, as well as upgrading efforts in existing older ones, is booming with the advent of 5G, starting in earnest at the 2020 Olympics in Japan (6G is already being discussed for future development) and the growth of artificial intelligence (AI) and machine learning (ML).


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There will be numerous connected technologies that will want to use the advantages of 5G. Their challenge is one of processing the high volumes of data at high speeds. Enter edge computing. This may be the next major technology trend after the cloud; edge computing describes an environment where data processing takes place as close as possible to the data source. This will ensure speed and low latency, helping to meet 5G’s performance goals. However, there will still be a need for central data centers, to handle applications’ less latency-critical needs.

What we will see is the development of next generation central offices (NGCOs). These are edge cloud data centers that can support both fixed and mobile traffic. Serving on average 35,000 subscribers per central office, compared with approximately 5,000 today, they will be located between the radio access network (RAN) and the central core.

Wherever data is stored or processed – be it on the edge, in regional centers known as metros, or centrally – there will be a growing demand for capacity. This is set to increase significantly from late 2019, and service providers will need to refine or transform their architecture to support 5G. Much of the data that will move through 5G networks will exist in the cloud, underlining the vital role that data centers must play.

The power challenge
Preventing disruption to the systems in the data center building is critical; downtime means dollars lost and unhappy customers. The operator can rely on uninterruptible power supply systems and power distribution units that safely and reliably control the flow of electricity to sensitive equipment. Small to mid-sized businesses and residential buildings with back-up power generation may also be candidates for load management programs. Surpassing 10kW per rack is the norm, which will make in-rack power protection less viable. The usage of end-of-row UPS systems is coming.

Intelligent power management (IPM)
IPM is a combination of hardware and software that optimizes the distribution and use of electrical power in computer systems and data centers. While the installation of IPM involves up-front cost and ongoing maintenance, the technology can save money in the long term as a result of reduced electric bills, reduced downtime, and prolonged hardware life.

Most effective IPM solutions incorporate temperature monitoring and regulation, voltage regulation, current limiting, and load distribution. Advanced IPM technology deploys branch circuit protection (each group of outlets has its own breaker or fuse), centralized/integrated management to enable administrators to monitor all data center hardware so they can isolate problems and resolve them quickly. Smart load shedding is also used to methodically shut down non-essential devices under specified conditions.

Three-phase power
The use of three-phase power will typically balance power loads and maximize the available current for each load. Using zoned cooling can prevent isolated overheating incidents with a minimum of wasted energy. System redundancy will ensure uninterrupted operation in cases of localized hardware or software failure, and coordinated management of power-supply hardware from multiple vendors can keep Data Centers up and running continuously.

Cooling
New cooling techniques such as direct liquid cooling are beginning to get noticed. The market is exploring multiple options for this technology, with everything from direct water-to-chip to fully submerged servers on the table (see Submerge your power supply, and other options).

Schneider Electric’s data center division is looking at direct liquid cooling as its next big growth area. Hyperscale data center operators, the cloud platforms, should drive most of that demand. Even direct-to-chip and full immersion are being discussed.

Efficient Power Conversion’s eGaN thermal enhancements will be covered later in this article.

Lithium-ion batteries are now taking over for lead-acid batteries in data center UPS systems for battery backup.

Higher-voltage distribution of power reduces I2R losses. Moving to a 48V vs. 12V power distribution scheme creates a 16× in power loss reduction.

Now let’s look at what some of the top power IC companies have for solutions that range from 48V conversion down to the extreme low voltage/high current needs of the graphics processor (GPU). I love these choices because, looking through the eyes of a power designer, they present such great options to create a power supply architecture in the increasingly challenging data server realm.

One of the key things that I learned during my 40 years as a circuit design engineer was that not all circuit architectures are created equal. One architecture may fit perfectly in a particular design where another different architecture might fit better in a different scenario. Keep an open mind with the following solutions; your particular project will have specific needs for power management as there is no ‘cookie cutter’ design for power. Especially pay attention to your customer ‘care abouts’ and then use your power design expertise to guide and advise the final customer toward what you feel is the best design. Communication and discussion are imperative when choosing the best power solution for any project.

That said, I really, really like solutions with GaN as the power element—that’s my personal first preference in my designer opinion and experience. The final particular power architecture in which GaN is employed is many and varied—choose wisely.

In Reference 5, Alex Lidow from EPC examines the cases for isolation vs. no isolation and regulation vs. no regulation architectures. The idea is that first stage may not need to be regulated while operating as a DC transformer (DCX). In these cases Lidow's article goes on to look at four different solutions with intermediate buses:

  1. Isolated and regulated brick converter
  2. Non-isolated DC-DC converters
  3. 48 V step down LLC DC transformer
  4. 48V-to-1V hybrid converter

It was determined that the best efficiency was achieved with either the dual inductor hybrid converter (DIHC) or the LLC with a 6 VOUT.  The DIHC topology, however, is relatively new and has yet to be widely adopted.  The 48 VIN – 6 VOUT LLC, coupled with a 6 VIN – 1 VOUT buck converter is being quickly adopted in new AI and gaming applications due to its high efficiency, high power density, and low cost. 

In all the topologies with 48 VIN, the highest efficiency was achieved with GaN devices.  This is due to their lower capacitance and smaller size.

[Continue reading on EDN US: EPC and STMicroelectronics]

Steve Taranovich is a senior technical editor at EDN with 45 years of experience in the electronics industry.