With growing concerns about global warming, there is a need to develop pollution-free aircraft. One approach is to use hydrogen-fueled aircraft that use fuel cells or turbogenerators to produce electric power to drive the electric motors that turn the aircraft’s propulsive fans. Hydrogen fuel would be carried as a liquid, stored at its boiling point of 20.5 K (-422.5 °F). Conventional electric motors, however, are too heavy to use on an aircraft. We need to develop high-power, lightweight electric motors (high-power-density motors).
At the NASA Glenn Research Center, our approach is first to improve the heat removal from the stator, by using forced-convection heat transfer, and second to improve the magnetic flux circuit with a Halbach Array. This will eliminate the need for an iron core. The last improvement will be to increase the speed of the motor while containing the permanent magnets with a carbon fiber ring.
Left: Ironless permanent magnet brushless direct-current motor (all dimensions given in inches). Right: Halbach magnet array.
Long description of figure.
An ironless motor was designed to have a 5.6-in.-mean-diameter cylindrical Halbach Array with nominally 1 in.3 permanent magnets. It is brushless and can run at speeds up to 15,000 rpm. The motor is being manufactured and will be used to test different stator designs. The stators use vacuum-potted, epoxied Litz wire, with molded cooling channels. This work was supported by the Alternate Energy Foundation Technologies (AEFT) Project.
U.S. Army Research Laboratory, Vehicle Technology Directorate at Glenn contact: Albert F. Kascak, 216-433-6024, Albert.F.Kascak@grc.nasa.gov
Glenn contacts: Dr. Gerald V. Brown, 216-433-6047, Gerald.V.Brown@nasa.gov; and Jeffrey J. Trudell, 216-433-5303, Jeffrey.J.Trudell@nasa.gov
Authors: Albert F. Kascak, Jeffrey J. Trudell, and Dr. Gerald V. Brown
Headquarters program office: OAT
Programs/Projects: AEFT
Last updated: July 21, 2005 2:38 PM
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