News: Microelectronics
12 September 2025
NREL’s silicon carbide-based ULIS power module claims record efficiency, power density, and low-cost manufacturability
The US National Renewable Energy Laboratory (NREL) has created a silicon carbide (SiC)-based power module with what is claimed to be record efficiency, power density, and low-cost manufacturability.
The 1200V, 400A Ultra-Low Inductance Smart (ULIS) power module is capable of achieving five times greater energy density than predecessor designs in a smaller package, making it possible for manufacturers to build and power more efficient, compact and lighter technologies, suitable for use in data centers, power grids, micro-reactors, and even heavy-duty vehicles such as next-generation aircraft and military vehicles.
Most importantly, ULIS boasts parasitic inductance 7–9 times lower than any existing state-of-the-art SiC power module, it is reckoned. Its ultrafast, ultra-efficient switching allows it to get more usable power out of the electricity supply.
Picture: ULIS features record low parasitic inductance. Image by NREL.
“It’s a future-proofed, ultra-fast power module that will make the next generation of power converters more affordable, efficient, and compact,” says chief power electronics researcher Faisal Khan, the principal investigator for the project.
Furthermore, ULIS is uniquely suited for high-intensity applications (like aviation and military operations), because the powerful, lightweight module also monitors its own state of health and can predict component failure before it occurs, says Khan. For planes flying 30,000ft above sea level or military vehicles traveling through combat zones, that level of reliability can mean the difference between life and death, it is noted.
Entirely new, low-cost design
Many of ULIS’ features are made possible by its wholly new design. Unlike typical power modules, which assemble semiconductor devices inside a brick-like package, ULIS winds its circuits around a flat, octagonal design. The disk-like shape allows more devices to be housed in a smaller area, making the overall package smaller and lighter. At the same time, novel current routing allows for maximum magnetic flux cancellation, contributing to the power module’s clean, low-loss electrical output, i.e. ultra-high efficiency.
“Our biggest concern was that the device switches off and on very quickly, and we needed a layout that wouldn’t create a chokepoint within the design,” says Shuofeng Zhao, an NREL power electronics researcher who designed ULIS’ flux cancellation architecture.
One of the original layouts looked like a flower with a semiconductor at the tip of each petal, says Zhao. Another idea was to create a hollow cylinder with components wired to the inside. Every idea was either too expensive or too difficult to fabricate — until the team stopped thinking in three dimensions and flattened the design into nearly two dimensions. Sarwar Islam (another NREL power electronics researcher on the ULIS team) came up with the 2D structure, which made it possible to build the module balancing complexity with cost and performance. “Suddenly we had a low-cost, high-performing design that was much easier to fabricate,” says Zhao.
Picture: NREL’s Ultra-Low Inductance Smart (ULIS) power module. Photo by Brooke Buchan, NREL.
NREL power electronics researcher Joshua Major devised several fabrication innovations to build ULIS’ intricate architecture inexpensively using only NREL tools and lab facilities.
The balance that the team found between the high electrical performance of a 3D design and a flat, fabrication-friendly layout unlocked ULIS’ full potential.
Second, where conventional power modules rely on bulky and inflexible materials, ULIS takes a new approach. Traditional designs call for power modules to conduct electricity and dissipate excess heat by bonding copper sheets directly to a ceramic base — an effective, but rigid, solution. ULIS bonds copper to the flexible polymer Temprion to create a thinner, lighter, more configurable design.
Because the material bonds easily to copper using just pressure and heat, and because its parts can be machined using widely available equipment, ULIS can be fabricated quickly and inexpensively. Manufacturing costs total hundreds, rather than thousands, of dollars.
A third breakthrough allows ULIS to function wirelessly, as an isolated unit that can be controlled and monitored without external cables. That modular nature means that it can slot into machines as different as data-center servers, advanced aircraft, and military vehicles. The patent for this low-latency wireless communication protocol is pending.
Finally, while the silicon carbide powering ULIS represents the existing state of the art, the ULIS team has intentionally ‘future proofed’ the design. ULIS can scale to accommodate advances in semiconductor devices using silicon carbide, gallium nitride and even gallium oxide.
In pursuit of steadier, lower-cost electricity, high-performance artificial intelligence, and advanced vehicle technologies, ULIS is now available to license.
NREL to design silicon carbide-based power inverters for US ground combat vehicles
NREL’s thermal management design boosts power density of SiC inverters for heavy-duty vehicles
