An ever increasing amount of data is being created, stored and served every day. Social networking, online videos, IoT devices, and automobile advanced driver-assistance systems (ADASs) are among the major contributors of this data onslaught. Referring to ADASs, for example, the data storage consulting firm Coughlin Associates anticipates that self-driving cars will generate one gigabyte of data per second. Though we are years away from fully relying on autonomous vehicles, auto manufacturers such as BMW, Ford and Toyota are planning how to manage and power their future data centers.
Meanwhile, data centers already consume 2% of global power, a number that could reach 5% according to some forecasts. And although they’re more energy efficient today than in the past decade, steps must be taken to greatly improve efficiency.
Let’s review how using GaN (gallium nitride) power-conversion technology offers the best option for designing high-efficiency, compact server power supplies. The resulting system cost and power-saving benefits can equip existing data centers to handle massive amounts of data – and help stave off the need to build new ones.
Data Center Efficiency
New and emerging applications, including IoT (and its cousins IIoT, IoE and so on), as well autonomous vehicles that routinely generate terabytes of data, mean new server installations must increase exponentially. At the same time, National Resources Defense Council (NDC) studies show that many small, midsize, corporate and multitenant data centers actually waste much of the energy they consume. Consequently, a server farm’s efficiency must improve to make maximum use of existing facilities while forestalling the need for new build-outs.
The greatest expense in data centers is the energy to run the servers, which can be as much as 40% of total cost. And typically about 5–10% of that energy is wasted. Additionally, data center energy consumption is projected to increase to roughly 140 billion kilowatt-hours annually by 2020. This amount will require the equivalent annual output of 17 new power plants at the annual cost to U.S. businesses of $13 billion in electricity bills, all while producing nearly 150 million metric tons of carbon emissions.
Advances under way in power-supply design using GaN instead of silicon transistors shave a couple of percentage points off this energy-use projection. In addition to energy-efficiency benefits, these technology advances enable use of fewer and/or smaller power supplies, translating into fewer data centers, as Figure 1 shows. Jim Witham, CEO of GaN Systems, explains the benefits of space savings in a discussion about data center efficiency: “If you can make the server power supplies smaller, you can use less space for power conversion and put more servers in the same space. If you put more servers in the same space, you’re using your assets better. For a data center manager, they’re getting more terabytes per square meter. And with 10x growth we’ve been seeing in data centers, you could also delay actually spending money to build a new data center (through the use of more-efficient power supplies).”
Figure 1. Improving power systems with GaN means more rack space.
GaN Advantages Over Silicon
In today’s data centers, the typical state-of-the-art server power supplies hover around 96% efficiency. Increasing that number often involves optimizing control methods and topologies as well as magnetics, but the most proximate solution for further increasing efficiency is to change from traditional silicon devices to GaN.
For example, typical power supplies employing silicon MOSFET technology have efficiencies of 94–96%. Half the power losses occur in the supply’s power-factor-correction (PFC) stage. The other half is lost in the supply’s power-conversion section. The industry-standard semi-bridgeless PFC based on state-of-the-art MOSFETs is 97.5% efficient. In contrast, owing to the intrinsic qualities of GaN devices, a more advanced totem-pole PFC topology is possible—and it performs this critical function with only 1% power loss. The totem-pole design also reduces the total component count by 30%, as Figure 2 shows.
Figure 2. GaN totem-pole technique offers considerable efficiency advantages over silicon MOSFETs.
The challenges and rewards for power-supply manufacturers in adopting GaN devices is the implementation of faster switching components. Because much of the inefficiency of power-conversion systems is the result of “switching losses,” GaN devices offer efficiency benefits over slower-switching MOSFETs. In addition, the higher switching speeds dramatically reduce the size of magnetic and capacitive circuit components.
GaN’s Impact on the Data Center
The energy consumption of a data center is a complex combination of power losses and cooling. In an average data center, about 30% of power is lost to inefficiencies as it travels through the multiple power conversions from the electrical grid to the microprocessors of an individual server. All of that energy produces heat that must be removed to keep the data center operating properly.
Figure 3. GaN can increase overall data center efficiency to 84%.
GaN devices, used in power conversion from AC to DC and then in converting the DC voltage at the load, can boost the overall efficiency from 77% with silicon to nearly 84%, as Figure 3 shows. According to research by GaN Systems, a Tier One data center operator, GaN devices can reduce energy costs by over $2,300 per rack, an opex savings of more than $240 million. Increasing power density by more than 25%, this operator would have an incremental $1.4 billion in server/storage revenue opportunity while deferring nearly $1.1 billion in capital expenditures by postponing data center construction.
The oncoming flood of data is driving the need for increasingly scalable, efficient and flexible data center infrastructure. Power systems that incorporate GaN devices offer greater power-conversion efficiency. The investment in this high-performance technology means greater energy and space efficiency by enabling the creation of smaller, lighter, lower-cost and more-efficient power systems. GaN technology will enable data center operators to not only reimagine their own business but also, in the end, actually play a role in transforming an energy- and data-dependent world.
About the Author
Paul Wiener is Vice President of Strategic Marketing at GaN Systems.