APEC 2023: SiC moving into mainstream, cost major barrier

Silicon carbide (SiC) technology is well into the power electronics mainstream, and it’s been apparent at the APEC 2023 show in Orlando, California. SiC semiconductors, which complement silicon in many applications, are now enabling new solutions by facilitating high power and high switching frequency in the 650 V to 3.3 kV range.

Keynote speakers and seminar presenters at APEC 2023 explained how SiC devices are uniquely positioned to serve the next-generation power electronics. They emphasized that know-how and learning cycles need to be developed and that there is a growing need for a trained workforce to skillfully insert SiC devices into power electronics systems.

There has also been a consensus that cost is a major issue for SiC components. At the same time, however, there is a broad agreement that cost is application-specific, and it can be reduced at the system level via clever engineering. “Meanwhile, SiC technology will continue to decrease cost at the component level,” said Peter Friedrichs, senior director for wide bandgap at Infineon Technologies.

At APEC 2023, Infineon showcased the Aircore EC motor from Infinitum; it replaces heavy iron used in traditional motors with a lightweight PCB. As a result, the air-core motor is 50% smaller and lighter, 10% more efficient, and uses 66% less copper than traditional motors. It’s built around Infineon’s CoolSiC MOSFETs.

STMicroelectronics also showcased a 25-kW dual active bridge reference design for power converters in fast DC charging applications as well as a traction inverter for EVs and HEVs serving up to 800 V battery systems; it’s based on 1,200 V SiC MOSFETs and is accompanied with galvanically isolated gate driver.

Figure 1 STMicro’s fast charger design is based on dual active bridge topology and features bidirectional charging.

However, as noted by Gianluca Aureliano, Americas marketing manager for automotive power transistors at STMicro, the company is developing SiC-based solutions for applications beyond EVs. That includes industrial, solar, and train locomotives.

ST, which unveiled its first SiC diode in 2007 and its first SiC MOSFET in 2014, is now producing the third generation of SiC devices, and they are automotive qualified. Aureliano acknowledged cost as a major issue but noted that it’s because SiC is a new material.

Besides leading power semiconductor players like Infineon and ST, the APEC 2023 was also a host to new SiC aspirants. That’s a testament to SiC’s status as growing technology and its disruptive potential in existing and new applications.

New SiC players

Silicon carbide’s promise in power electronics is attracting new players. Qorvo, the leading supplier of RF semiconductor solutions, is a case in point. Qorvo, aiming to lower its dependence on mobile manufacturers, acquired UnitedSiC in October 2021.

At APEC, Qorvo displayed 750-V SiC FETs that feature on-resistance ranging from 5.4 mΩ to 60 mΩ and come in a surface-mount TO-leadless (TOLL) package. The company is targeting these SiC devices at space-constrained applications such as AC/DC power supplies ranging from several 100s of watts to multiple kilowatts as well as solid-state relays and circuit breakers up to 100 A.

Figure 2 Qorvo demonstrated a circuit breaker reference design at APEC based on its 750-V SiC FETs.

“Qorvo is targeting applications that mandate low resistance for space-constrained designs, squeezing more power in a smaller area,” said Anup Bhalla, chief engineer for Qorvo’s Power Devices business. “The new 750-V SiC FETs improve RDS(ON) by minimizing conduction losses in the end system and facilitate compactness with a small surface-mount package.”

Why low resistance? Because it generates less heat. “But it’s one thing to make the chip smaller and it’s another to take the heat out,” Bhalla added. “Otherwise, while lowering RDSON means high performance, it can also lead to bigger device die.” Qorvo claims that its 750-V SiC FET is half the size of other devices operating in this voltage range.

Another semiconductor supplier, which entered the SiC fray via an acquisition, is onsemi; SiC technology came to onsemi with the Fairchild Semiconductor acquisition in 2016. Next, in 2021, onsemi bought GT Advanced Technologies (GTAT) to bolster its SiC supply chain. GTAT is a SiC materials provider based in New Hampshire.

At APEC, Onsemi launched online simulation tools to boost the development of power designs based on its EliteSiC devices. The simulator lets design engineers virtually test and validate SiC devices through an expansive library of customizable circuit technologies. Moreover, when the simulator is used with advanced PLECS models, designers can gather meaningful insights into the application at a very early stage of the design cycle without relying on hardware fabrication and testing.

Coexistence with silicon

APEC 2023 was packed with power semiconductor suppliers that boast silicon portfolios, and at the same time, are claiming stakes in SiC riches. From Infineon to onsemi to STMicro, power semiconductor players are shifting more resources to SiC technology while keeping the investment alive.

Take Infineon, an early believer in the potential of SiC, which is also the number one supplier of silicon IGBTs. Inevitably, it must perform a balancing act with silicon power while being vigilant about wide bandgap (WBG) technology hype cycles. “Which growth story is sustainable depends on specific power applications,” said Friedrichs.

Silicon constitutes nearly 70% of the automotive power electronics market, but SiC will substitute IGBTs in several applications. That began with SiC’s thrust into mainstream EVs in 2020. However, silicon is likely to remain a major power component in the coming years as both technologies are likely to coexist for their respective characteristics and benefits.

According to Andre Christmann, principal application engineer at Infineon Technologies, silicon will likely remain a major source of power components in the next five years. “But while silicon stays steady, SiC will continue to grow by complementing silicon in many applications and enabling new ones.”

Meanwhile, SiC technology, still at the start of the curve, must bolster the ecosystem encompassing building blocks such as packaging, control, drivers, and sensors. Power electronics applications increasingly demand packaging solutions that maximize SiC performance while facilitating high thermal conductivity, low parasitic inductance, and increased current rating. Gate driver circuits are another important design consideration for SiC devices.

Figure 3 Tools like onsemi’s online simulator aim to replace costly hardware testing for SiC devices.

Last but not least, the critical issue of cost is intertwined with SiC wafers, which calls for new fab models and manufacturing infrastructure. A follow-up article at EDN will delve deeper into wafer-related issues and how they drive up costs.

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