Silicon is still the dominant technology in power electronics, but wide bandgap (WBG) semiconductors are steadily becoming more popular.
WBG technologies are powering 5G and 6G technologiesWhile there are multiple WBG materials, the two commonly used in power systems are silicon carbide (SiC) and gallium nitride (GaN).
Compared to silicon, WBG devices have some important advantages: improved power efficiency, higher operating temperatures, and a smaller die, to name just a few. Various WBG devices are available, including SiC MOSFETs, SiC Schottky diodes, and GaN FETs, enabling design engineers to choose the right option for their application.
In this article, we’ll examine some of the most popular uses for WBG semiconductors, including automotive, industrial, and telecoms. We’ll also discuss why WBG devices have an advantage over silicon in each case.
Automotive and electric vehicles
The market for power electronics in electric vehicles is large and growing, and will reach US$36 billion by 2035, growing at 17% per year from 2025 to 2035, according to IDTechEx Research.1 The most significant area is the powertrain for electric vehicles (EVs) and hybrids, as environmental legislation drives the electrification of the auto industry.
One of the most important characteristics of an EV is its range — by increasing this, automakers make their cars more appealing to buyers. To boost range without requiring a larger, heavier, more expensive battery, the key is increased efficiency of the vehicle’s power systems. SiC inverters provide this efficiency, as well as the capability to operate at high temperatures and voltages, when compared to silicon.
As well as multiple onboard DC/DC converters, an important part of an EV’s power system is the traction inverter, which handles the conversion of DC power (supplied by the car’s battery) into AC power that the electric motor needs.
While not directly increasing the range of an EV, having a faster and more efficient charging system means the car charges more quickly, and the useful range added by a short charging stops will be appreciated. This includes the onboard charger (OBC), which converts AC power from the grid into DC, or the car’s fast charging system that enables it to use rapid, high-voltage DC chargers.
EV charging infrastructure
As the number of EVs on our roads continues to grow, charging infrastructure must keep up with driver demand. There is a wide range of off-board chargers being deployed, from simple, low-cost versions for the home to super-fast DC chargers delivering 350 kW or more, often found in public locations such as motorway service areas.
For all chargers, high levels of power efficiency are essential. Drivers should only pay for the energy used to charge their EV battery, not the inefficiencies of the charging equipment. The goal is to get as close as possible to this ideal scenario. The high efficiency of SiC makes it well-suited here.
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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 OVERVIEWDrivers need to trust in the charging infrastructure and be confident that a charger will be working when they arrive. Similarly, maintenance must be minimised to keep costs down for the network operator. Power conversion systems must deliver reliably and efficiently. SiC devices meet these demands.
SiC will continue to be at the heart of EV charging infrastructure, as new technologies such as wireless charging and bi-directional vehicle-to-grid (V2G) are deployed.
Industrial
Silicon devices still have many uses in industrial power applications, particularly where low cost is essential, or the system is powered by a three-phase supply.
However, there is an increasing shift to WBG devices. SiC is well suited to uses with high voltages and temperatures, such as industrial uninterruptible power supply (UPS) and motor drive applications. GaN is also finding industrial applications, such as portable robots requiring compact power systems and high efficiency.
Silicon IGBTs are often still the preferred choice in a 3-phase application, the switching frequency is about 20 kHz and the power is up to 3 kW. If the frequency is higher and power requirements are similar (or higher), then a SiC MOSFET becomes an attractive option.
Renewables: solar and wind
Figure 1: Single-phase string inverters become more efficient, smaller, and lighter with GaN switches [Source: Nexperia (from https://my.avnet.com/silica/resources/article/how-wide-bandgap-semiconductors-are-improving-renewable-energy-design/)]
In applications using renewable energy it’s generally more important to minimise losses, so the efficiency of WBG devices is a key benefit. The ability to create compact power systems with high power density is appealing, making solutions lighter, easier to install, and simpler to fit into an overall system.
In solar photovoltaic (PV) applications, such as rooftop solar panels, a common configuration is to connect the PV panels in series as a ‘string inverter’ (Figure 1).
This kind of system is suited to single-phase inverters using GaN FET devices operating at up to 650 V. In higher power (3.5 kW or more) multi-phase systems SiC-based devices are more likely to be used.
Using a GaN FET means the switching frequency can be increased to between 100 kHz and 300 kHz, improving efficiency while also increasing power density and reducing the cost of passive components.
Thermal management is always difficult but the lower switching losses of SiC MOSFETs (including reduced turn-on, turn-off, and conduction losses) mean they typically achieve lower losses through heat than an equivalent silicon IGBT device. The result is lighter, smaller solutions can be used to handle dissipated heat, which may be particularly important in offshore wind turbines where space is at a premium.
Green energy
Looking beyond wind and solar, WBG devices have multiple other uses in green energy and renewables – typically, wherever efficient power conversion is required.
For example, local energy storage systems (ESSs) are an essential part of the renewables infrastructure, enabling power to be stored where it is generated, and used later when needed. Moving energy in and out of an ESS adds extra stages of conversion, and therefore high efficiency is needed to avoid excessive power losses — both for large-scale ESSs and smaller home versions. These requirements are being addressed by SiC devices, as well as SiC/Si hybrids.
Also, while traditional heat pumps may have a simple, fixed output (on or off), more advanced inverter heat pumps feature a variable speed compressor. By more closely providing the power needed efficiency is improved and the pump’s lifetime extended.
For heat pumps, using GaN and SiC-based inverters can deliver higher conversion efficiency and better power density, due to reduced switching losses, better thermal conductivity, and greater power density.
More generally, microgrids with multiple, distributed generation sources are becoming increasingly important to maximise the impact of renewables. Again, the high efficiency and compactness of WBG devices make them ideal — particularly SiC components that can handle high voltages.
Data centres
With the boom in artificial intelligence (AI), power demanded by data centres and data transmission networks is skyrocketing. It is estimated to become 2–3% of global electricity.2
Energy efficiency is crucial for their power supplies and back-up systems. Architectures such as intermediate bus conversion (IBC) optimise power delivery to reduce losses — for example, stepping down the mains supply to 48 V DC, which is then converted within a server rack to the low voltages needed.
These multi-stage architectures provide an excellent mix of efficiency, flexibility, and reliability. However, conversion efficiency is extremely important, and heat dissipation must be minimised, particularly as the power demands of data centres is only going up.
The solution is SiC inverters, with their high efficiency to minimise losses. This is a win-win situation because any waste heat must be handled by the data centre’s cooling systems. Therefore, reducing losses in power conversion means that less power is needed for cooling, and the cooling systems can be smaller and lower cost.
Consumer
Cost-sensitive consumer applications have, understandably, lagged other areas in their adoption of WBG, but it’s happening. In particular, the high charging frequencies and excellent efficiency delivered by GaN are making it a popular choice in chargers for smartphones and other portable devices.
GaN technology can enable AC/DC converters to deliver more power. As well as requiring more power, electronic devices charge significantly faster, which is an important benefit for consumers. The same advantages apply for wired and wireless/contactless chargers.
Telecoms
Telecoms base stations are another area where efficient power handling is vital. Their design commonly uses multiple RF power amplifiers, which must operate efficiently to reduce power consumption. Additionally, reliability is paramount. Any outage will cause a loss of service for consumers, and as they are often in remote locations, repairs can be difficult, slow, and expensive to carry out.
Due to its high efficiency, GaN is becoming the technology of choice in base stations. This applies both to 4G systems, and the more recent rollout of 5G infrastructure – which now dominates the demand for GaN in telecoms. With the use of multiple antennas in 5G base stations, the efficiency and high power density of GaN devices help minimise heat dissipation in compact spaces.
Design considerations
Whatever the application, WBG devices present multiple design challenges that must be considered. For example, the high switching frequencies employed mean that noise and EMI will be an issue, and suitable filtering is needed.
Gate drivers for SiC or GaN devices are different from the equivalents used with silicon components. A dedicated driver can be best, with digital drivers providing more precise control, for example, to minimise conduction losses and avoid unintended turn-on.
Thermal management is also important. Thermal stress in WBG devices is a significant factor impacting reliability. The high power density of WBG-based solutions creates new thermal challenges that must be handled carefully.
Choosing the right technology
For any application, Avnet Silica’s FAEs and power engineers can provide the information and guidance that will help you choose the best technology, the right devices, and the optimal design.
Moving from silicon to SiC or GaN is not normally a simple drop-in replacement, and there are multiple factors to consider. Having an expert on your side, like Avnet Silica, will help you get it right.
References
2. https://www.iea.org/energy-system/buildings/data-centres-and-data-transmission-networks
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