First ironless motor pancake stator setup for determining the current density that can be achieved with this design.
Demonstrating a pollution-free aircraft is a NASA 21st century goal. The NASA Glenn Research Center has been investigating, both through feasibility studies and experimental research, the possibility of hydrogen-fueled aircraft that would use fuel cells or turbogenerators to produce electric power to drive the electric motors that turn the aircraft’s propulsive fans or propellers. Conventional electric motors and their electronics are too heavy to use in these new systems, so Glenn is working to make motors lighter and more powerful. One new type of motor that shows promise for flight application is the ironless permanent magnet motor.
The rotating magnetic flux circuit in this device is generated using high-energy-density permanent magnets configured on the rotor in Halbach arrays. The magnets are contained by carbon-fiber composite rings. Two of these arrays working together produce a 1.2-tesla flux density at the center of a 0.5-in. gap. This eliminates the need for iron in the motor, which is heavy, lossy, and potentially very expensive. Different stator design and active cooling concepts will be investigated to obtain higher current densities. The first stator concept was designed and manufactured and is currently being tested. This stator was constructed using Litz wire interlaced with cooling passages for heat removal via forced-convection heat transfer. In addition, a rotating magnet structure is being spun up to verify its structural integrity. This work was supported by the Alternative Energy Foundation Technologies Project.
Basic ironless Halbach permanent magnet motor hardware designed and manufactured in fiscal year 2005. The structural integrity of the rotating magnet structures shown is currently being determined.
Last updated: October 11, 2006
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