From the smallest wearable to the biggest hyperscale data centre, everything that uses electricity needs power components.
Regardless of what the end-product looks like, most power system engineers need similar features from their power supplies: small, reliable, efficient, and able to provide excellent power density and thermal performance.
Stating the requirements for power supplies is easy, but meeting these requirements can be extremely difficult. Consumers are always looking for improvements in their devices, such as the latest AI-driven features but with longer battery life. The ever-growing demands on power systems come from booming applications — such as AI and electric vehicles (EVs).
In this article, we’ll look at some of the technology megatrends that are moulding the world around us, including:
- EV charging
- AI, data centres and high-performance computing (HPC)
- Renewables
- Industrial automation/robotics
We’ll discuss how these applications create new requirements for power systems, and how the semiconductor industry is responding with innovation and novel technologies, and specifically how compound semiconductors are overtaking silicon in high-performance use cases.
What are compound semiconductors?
Over many years, innovation in power semiconductors has kept pace with the applications. Now, new demands are being placed on them, specifically significant improvements in efficiency, power density, and thermal performance. While silicon devices have been the mainstay of power systems for decades, many of these improvements are being delivered by wide bandgap devices, made from compounds of other semiconductor elements — primarily, silicon carbide (SiC), gallium nitride (GaN), and gallium arsenide (GaAs).
These compound semiconductors are displacing silicon in many applications as the material of choice. This is largely due to their superior properties; they can be used at higher frequencies, which in turn improves efficiency as well as power density. Compound semiconductors continue to outperform silicon at higher operating temperatures (such as 175ºC to 200ºC), with simpler heat dissipation demands, enabling smaller power supplies.
Figure 1: GaN, Si, and SiC compared. Source: Avnet Silica whitepaper, “Selecting GaN or SiC devices in high voltage switching technologies"
Compound semiconductors do have some drawbacks, though: they are more complicated than silicon to produce in large numbers and are typically more expensive. This is partly because their manufacturing processes are less developed than silicon, plus SiC is physically harder than silicon, making SiC wafers more difficult to cut, grind, and polish. But, for many new applications that can only succeed with corresponding improvements in power, compound semiconductors can offer dramatically improved power efficiency, making the extra investment well worth the cost.
There are differences between compound semiconductor materials to consider. For example, currently power transistors manufactured using GaN can only be used up to voltages of 650V, limiting their usage in applications such as high-power inverters in renewables. SiC devices can go beyond this limit, to 1200V and higher. Silicon devices operate at similarly high voltages but lack the other advantages wide bandgap brings.
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With the ongoing shift to renewable energy and the electrification of transport and industry, the demand for higher power and greater energy efficiency in electronics is increasing. Wide bandgap technologies including SiC and GaN bring many advantages.
WBG OVERVIEWFigure 1 shows, in simplified form, which type of device is best suited for different use cases (looking only at voltage and switching frequency). In general, silicon is best suited to applications with lower switching frequencies, while GaN and SiC are better at higher frequencies. ‘FOM’ refers to ‘figure of merit’, a metric that can be calculated to compare different alternatives — multiple semiconductor technologies may suit applications in this area and specific comparisons are needed to find the best option in each use case.
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Matching megatrends with wide bandgap technologies
So, where are these compound semiconductors finding the most usage? And which megatrends are most important for driving demand in power system innovation with these new materials?
It’s no surprise that one of the main sectors is automotive, as the industry undergoes large-scale electrification and a seismic shift towards EVs. The excellent efficiency, better thermal performance and compact size that can be achieved with compound semiconductors are essential for EV charging, both for charging stations and onboard chargers (OBCs) in the vehicles themselves. The most commonly used material is SiC, first used in an EV in 2017, by Tesla for the main inverter in its Model 31.
The other megatrend pushing power supply innovation is AI. As more products and applications add AI capabilities, demand for high-performance computing (HPC) and ever-larger data centres is mushrooming. This sector’s requirements are mostly around two key factors: minimising excess heat dissipation, achieved through better efficiency, and keeping power supplies as small as possible. Reducing the amount of heat produced means less electricity is needed to keep the data centre cooled, which can lead to significant cost savings.
In a typical hyperscale data centre, there are an estimated 4,500 power supply units (PSUs) converting the incoming alternating current (AC) to direct current (DC) — and there are more than 10,000 data centres around the globe2. Today’s data centre PSUs are typically based around SiC, maximising efficiency and minimising the physical space required. With high-performance components such as Nvidia’s ‘Blackwell’ chips requiring up to 1200W, the power demands are huge, and SiC’s efficiency is invaluable.
Beyond automotive and AI, the demand for power efficiency is a common theme supporting other applications that align with megatrends and high growth. For a start, consumer devices are always pushing for better efficiency, and today’s smartphone power adapters are shifting to GaN to enable the use of smaller chargers.
In the renewables sector, to get the most electricity from photovoltaic (PV) solar cells, every stage must be as efficient as possible. For example, SiC-based inverters provide excellent efficiency for both DC/DC and DC/AC conversion. GaN devices are also finding uses in smaller solar inverters.
On the industrial side, the rise of the Internet of Things (IoT) and the growing usage of robots means that there is also a burgeoning demand for efficient power supplies. Similarly, medical electronics innovation is dependent on better power systems.
Let’s look at one example — the automotive sector and EVs — in more detail.
Compound semiconductors in automotive
Governments around the world are increasingly demanding the automotive industry reduce its emissions, including legislation to ban sales of petrol and diesel vehicles in the near future. At the same time, as the charging infrastructure improves and EVs become more affordable, they are becoming increasingly popular with consumers.
Figure 2: Building blocks of an EV charger
Source: https://my.avnet.com/silica/solutions/markets/smart-city/ev-charging/
One of the most important factors for buyers of EVs is range — how far can their car drive between charging stops? Many consumers have expressed fears and so-called ‘range anxiety’, worrying about their vehicle not reaching their planned charging station in time.
Increasing the battery size is the most straightforward way for car manufacturers to increase range. But bigger batteries add substantially to a vehicle’s cost, plus they are heavy and bulky — therefore, less efficient.
Instead, car manufacturers can squeeze the most range out of their existing batteries by maximising the efficiency of the car’s power systems. SiC power devices are the key to these efficiency improvements, offering greater range (or the same range from a smaller, cheaper battery). SiC power electronics in an EV can lead to an increase in battery range of 5–10%, as well as weight savings and shorter charging times3.
As well as the cars themselves, there’s a huge growth in demand for EV charging stations. The EV charging infrastructure market is expected to grow at more than 30% compound annual growth rate (CAGR) through to 2030, requiring at least six million new chargers to be in operation4. EV chargers must be reliable, efficient, and capable of delivering the high power needed to minimise charging time for drivers. SiC, again, is the material that can enable these demands to be met.
Design support maximises benefits
Creating a power system is not just about the power devices themselves — there’s a wide range of other components needed, such as microcontrollers (MCUs), sensors, wireless communications, and electro-mechanical devices (see Figure 2).
As well as components, Avnet Silica provides design services such as hardware, firmware, and software development through to cloud services. This gives design engineers the support they need to make the right choices and to maximise the benefits they can achieve by adopting compound semiconductors.
Reference
[1] https://www.pntpower.com/tesla-model-3-powered-by-st-microelectronics-sic-mosfets/
[2] https://csa.catapult.org.uk/news-insights/insights/compound-semiconductors-the-uks-answer-to-cleaner-and-greener-data-centres/
[3] https://csa.catapult.org.uk/wp-content/uploads/2024/06/12-June-CSA-Catapult-Silicon-Carbide-in-Electric-Vehicles-Report.pdf
[4] https://my.avnet.com/silica/solutions/markets/smart-city/ev-charging/
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