Silicon Carbide Motor Drive Powers Successful Hybrid Test Flight

A hybrid plane has been flight-tested, equipped with a silicon carbide-based electric motor drive, rather than a traditional silicon system. This development could be used to make aviation lighter, more efficient, and more commercially available.

Alongside the electric engine and conventional gas-powered motor, an experimental silicon-carbide inverter was used in the motor of the hybrid Cessna 337 plane, which has been flight-tested in Southern California. This inverter was designed by the University of Arkansas Power Group,

The test flight demonstrated that the conventional silicon-based motor drive system in a hybrid plane could be replaced with a more compact and effective silicon carbide-based system. The findings of this test flight, which took place in 2023, were published recently in the journal IEEE Transactions on Power Electronics. 

We were the first university to do this for a hybrid electric aircraft. That's a feather in our cap.

Alan Mantooth, Study Lead Researcher and Distinguished Professor, Electrical Engineering and Computer Science, University of Arkansas

The research received funding from the Department of Energy's Advanced Research Projects Agency-Energy, or ARPA-E.

The Advantages of Silicon Carbide

Transistors are the basis of electric circuits, functioning as amplifiers or switches. The microchips in computers and smartphones, for example, include billions of transistors that turn on and off to generate the binary language of ones and zeros. Today, most transistors are composed of silicon, which is formed by heating purified sand.

Transistors, however, cannot turn on and off instantly. Energy is wasted during the transition between the two states, although this occurs in only a fraction of a second. This lost energy generates heat.

Silicon carbide transistors can switch 1000 times quicker than those made of silicon. The quicker switching speed increases the transistor's efficiency, allowing all other components, such as inductors, transformers, and capacitors, to be significantly smaller and lighter.

Imagine a race car with a big 350 engine that weighs hundreds of pounds. What if you had that same power, but I gave you something that would fit in your hand?

Chris Farnell, Assistant Professor, Electrical Engineering and Computer Science, University of Arkansas

The University of Arkansas Power Group is a recognized leader in silicon carbide research and application. Despite its improved performance, the higher cost of silicon carbide has limited its widespread adoption.

“Silicon is made from dirt, and nothing is cheaper than dirt,” Mantooth added.

The cost of making silicon carbide, however, has been decreasing. Furthermore, the overall system cost is lower when using silicon carbide systems since they require fewer supporting components.

If the overall system gets cheaper, then Ford cares, Toyota cares. That's why it ends up in cars.

Alan Mantooth, Study Lead Researcher and Distinguished Professor, Electrical Engineering and Computer Science, University of Arkansas

Current silicon carbide production techniques, however, are not yet advanced enough to economically produce the nanometer-scale devices necessary for creating computer microchips. The UA Power Group is set to establish the Multi-User Silicon Carbide Research and Fabrication Laboratory to advance research on silicon-carbide microchip creation and connect university researchers with manufacturers.

The Challenges of Aviation

For the airplane trial, the UA Power Group developed a silicon carbide-based inverter that converts a battery's direct current into the alternating current needed to power a motor. A silicon carbide-based system's smaller size is especially useful aboard a smaller airplane with limited room.

“You're able to remove stuff and give passengers more legroom,” Farnell stated.

The reduced weight of a silicon-carbide system also means that the plane requires less energy to take off and cruise.

Electrical engineers have unique challenges while working on planes. To survive vibrations and landing stress, electrical systems must be mechanically supported. 

At higher elevations, drier air increases partial discharge, which can weaken insulation and produce electrostatic problems. Additionally, other aviation systems may be affected by the increased electromagnetic interference resulting from silicon carbide's faster switching speed.

The Cessna 337's successful test flight demonstrated that the UA Power Group team was able to deal with these challenges.

Video Credit: University of Arkansas

Journal Reference:

Farnell, C. et.al. (2025) Development, Integration, and Flight Testing of a Silicon Carbide Propulsion Drive for a Hybrid Electric Aerospace Application. IEEE Transactions on Power Electronics. doi.org/10.1109/TPEL.2025.3597905