Research Scientist CG Cantemir develops lightweight motor concept for NASA electric aircraft
NASA is investing in Electrified Air Propulsion (EAP) research to lessen the environmental impact caused by commercial aircraft.
These aircraft are highly efficient, require less energy and allow for cheaper air travel.
One factor that plays a critical role in these aircraft is the electric motor. NASA sought the expertise of Dr. Codrin-Gruie (CG) Cantemir, a research scientist at Ohio State’s Center for Automotive Research, to develop a 10 Megawatt Ring Motor concept.
The electric motor developed in this project is powerful enough to be used in large transport aircraft such as a Boeing 737.
Cantemir says it’s important to note that this motor, which has already set four world records, is based on a continuous power rating, rather than peak performance, the number that is most often advertised for electric machines. In on-highway applications such as passenger cars and light trucks, peak performance is a key factor. The motors can develop very large amounts of power for 10 to 30 seconds, but after that the power must be drastically reduced. The motors developed for aircraft and marine applications require full power for longer periods of time, in many cases continuously.
As a result of this project, Cantemir developed a new theory called the Tuned Coil Theory which allows him to implement a solid conductor winding, which can operate very well at high frequency.
“Once the theory was developed, its implementation was unique because no conventional implementation was adequate,” said Cantemir. “We needed to use unconventional materials for an unconventional motor. We came up with some new solutions that had never been tested before. We took risks and they worked.”
To keep the motor lightweight, the number of phases increased from a conventional three-phase system to a nonconventional, asymmetric six-phase system made entirely of conventional, American-made materials. This specific motor has only one circuit per stator slot and several enabling fabrication technologies were also developed to bring this design to fruition.
Cantemir developed a new, simpler, more efficient control technique for the motor because its electromagnetic behavior makes a conventional “Vector Control” obsolete.
Cantemir found that power electronics utilizing asynchronous modulation to be a severe limitation for this application, so the team developed their own modulation technique known as synchronous modulation. They were able to make this synchronous modulation work from zero to the max RPM, another first for this project.
“There are over 20 unique and creative steps that must all take place at once for this project to be a success,” said Cantemir. “What we are currently listening to is just the draft of the overture and now we have to master the symphony.”