Innovators at NASA Glenn Research Center have designed a High-Efficiency Megawatt Motor (HEMM), a wound-field partially superconducting machine. The HEMM implements a combination of superconducting and non-superconducting elements, along with an integrated cryocooler, to achieve some of the benefits of a superconducting motor without the need for an external cryogenic system.
The motor essentially operates like any other motor when viewed as a black box but substantially enhanced performance can be achieved. The incorporation of superconductors on the rotor to create a high-level magnetic field results in a specific power and efficiency that could not be achieved any other way. The HEMM can achieve over 98% efficiency in a lightweight electric machine with an operating power greater than 1.4 MW, a specific power greater than 16 kW/kg (ratio to electromagnetic mass), and a rated operating speed of 6800 RPM.
While the HEMM is designed for propulsion systems for hybrid electric aircraft, the technology could be broadly applied to transportation markets including electric trains, hybrid cars, and turboelectric ships or as a generator system for wind turbines, power plants, or motors for other industrial machinery.