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Around the world, governments have set themselves the goal of meeting their climate change commitments. To achieve this, they are driving the energy transition to electric vehicles through legislation and financial incentives. Technological research plays a key role in this regard. In fact, the total global market for EV and hybrid-vehicle batteries is expected to grow to almost $1.6 billion by 2030. At the same time, the rapid growth of this sector must be supported by optimizations in automotive design, which must be ready to face this epochal change.
The power of SiC in automotive applications
Silicon carbide is currently the most mature of the current broadband technologies for power semiconductors. SiC has proven in recent times to be a formidable ally for EVs and plug-in hybrid vehicles, becoming their enabling technology thanks to its exceptional thermal and electrical properties. One of the most obvious applications is in power modules for DC/DC power converters and traction inverters, contexts in which the thermal resistance of SiC translates into more efficient heat management. The direct consequence of all this is greater autonomy for EVs and extended battery life.
Furthermore, the use of SiC inverters helps to reduce switching losses and consequently improve the overall efficiency of the traction system. This is particularly relevant for EVs, where every percentage of efficiency gained translates directly into increased range and reduced energy consumption.
SiC’s characteristics, such as its wide bandgap, also enable operation at higher temperatures, which is critical in an automotive environment where heat management is a constant challenge. These features help improve the stability and reliability of the system, ensuring consistent performance even in extreme driving conditions.
SiC also has superior thermal properties and can conduct large amounts of thermal energy. SiC led the introduction of wide-bandgap (WBG) technology into the EV scene, replacing previous silicon MOSFETs or IGBTs in the traction inverter. SiC MOSFETs are known for their superior conductivity and switching performance. By taking advantage of SiC’s favorable characteristics, SiC MOSFETs, with a die area nearly half that of IGBTs, can combine the following desirable characteristics for a power switch:
- High voltage
- Low-resistance RDS(on)
- High switching speed
- Low switching losses
SiC MOSFETs enable automotive system designers to improve efficiency; reduce heatsink size and cost; increase switching frequency to reduce magnetic component size; and decrease design cost, size and weight. In particular, the use of SiC in EVs guarantees greater operating autonomy, smaller battery sizes and faster charging.
SiC offers a higher operating temperature and switching speed than silicon IGBTs, as well as a high breakdown voltage in relation to the size of the device, which allows for greater robustness and power density. These capacities are optimal, for example, in inverter modules of engines for the automotive sector, which must necessarily transfer large quantities of energy to and from the battery. Switching speed is one of the key parameters for the design of automotive systems capable of influencing their efficiency and performance. With an 800-V battery system and large battery capacity, SiC leads to higher efficiency in inverters and thus enables longer runtimes and lower battery costs.
SiC also improves the efficiency and power density of the on-board charger (OBC). The material allows for bidirectional energy flow, from the mains to the battery, and vice versa. It also has a positive impact on battery management: It allows greater vehicle autonomy with the same battery size or smaller and lighter batteries with the same autonomy. Furthermore, charging with the respective infrastructure can be much faster thanks to SiC. Highly efficient vehicles weigh less due to battery capacity, lower cooling effort and optimized wiring. SiC system solutions help improve the overall efficiency of the vehicle, particularly in the transmission, traction inverter and OBC. Finally, a significant advantage is that SiC components can be placed with techniques designed and used for silicon.
The importance of GaN in next-gen automotive design
Gallium nitride is another material that is rapidly gaining ground in the automotive industry, especially in high-frequency power systems. GaN-based MOSFETs are well-suited for applications like DC/DC converters, battery chargers and battery management systems. Thanks to its high switching speed, GaN allows the design of converters that are more compact and lighter, contributing to the reduction of the overall weight of the vehicle and improving the energy efficiency of the overall system. This is particularly important in EVs, where weight is a determining design factor.
The lower conduction resistance of GaN compared with conventional materials helps reduce power losses in fuel systems, further improving overall vehicle efficiency, which is key to ensuring that the energy stored in batteries is used optimally, contributing to maximizing EV autonomy. While SiC devices are mostly popular in high-voltage applications, GaN offers valuable advantages when applied to platforms operating at lower battery voltages up to about 400 V.
Combined SiC and GaN applications for the automotive sector
As we know, the automotive market is a very dynamic sector that presents challenges related to weight and space. Not only must costs be carefully calculated, but voltages vary widely—from about 5 V to over 100 V in vehicles with internal-combustion engines and even higher voltages in EVs or hybrid vehicles. As the EV and hybrid-vehicle market grows and spreads, efficient power conversion is even more critical. As a result, designers are under constant pressure to cost-effectively integrate ever-increasing performance systems into smaller, lighter and more efficient volumes. GaN- and SiC-based power modules can help achieve many of these design goals for EV and hybrid-vehicle systems. Automotive applications that can benefit from improved efficiency and power density are found throughout the vehicle, from the engine to the powertrain to the vehicle control, from the driver console to the infotainment system.
The combined use of SiC and GaN in automotive systems opens up exciting prospects. The way their characteristics complement each other allows the design of highly efficient, reliable and compact electric traction systems. For example, the integration of SiC and GaN in power modules not only maximizes the benefits of both materials but also obtains higher switching frequencies, improving energy efficiency, reducing power losses and optimizing thermal management of components. The benefits of this synergy are particularly important in EVs, where high efficiency is increasingly important to overcome the challenges related to autonomy.
Future trends
As the WBG power semiconductor device market evolves, GaN and SiC drive the future of high power density and weight efficiency. While the commercial adoption of WBG semiconductors still faces small hurdles—for example, in terms of packaging and power-converter design—as the technologies become more mature and sophisticated, more solutions are emerging, with GaN and SiC poised to become more competitive than silicon, thus increasing their strategic importance when evaluating design tradeoffs.
The role of SiC and GaN in the automotive industry is destined to grow over time, pushing innovation toward increasingly efficient electric traction systems that are close to environmental sustainability criteria. The combined use of these advanced materials will not only help reduce emissions and improve energy efficiency but also redefine performance standards in the vehicles of the future. The challenge now is to effectively integrate these technologies into large-scale mass-production vehicles, paving the way for a new era of advanced, sustainable and intelligent mobility.
Ultimately, SiC and GaN mean that design challenges can be successfully addressed by reducing development time. WBG technology ensures lower losses, higher switching frequencies, higher operating temperatures, robustness in harsh environments and high breakdown voltages. As the industry moves toward higher-capacity batteries that operate at high voltages with increasingly shorter required charging times and overall reduced losses, the benefits of these materials promise to revolutionize automotive design.
Reference
1Van Do et al. (2021). “Wide-Bandgap Power Semiconductors for Electric Vehicle Systems: Challenges and Trends.” IEEE Vehicular Technology Magazine, 16(4), pp. 89–98.
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