Dr. Andrew Woodworth is currently a Hybrid Electric Aircraft Materials Technical Lead in the Materials and Structures Division at the NASA Glenn Research Center. In this programmatic position he advises on a portfolio of work developing megawatt scale powertrain technologies for electric aircraft propulsion. Beyond programmatic duties, Dr Woodworth leads a team developing new material approaches for megawatt scale electric machines. He has also been engaged in hardening SiC based power devices to cosmic radiation. Dr. Woodworth earned a Ph.D. in Physics from West Virginia University. He has also worked as a Physical Scientist National Institute for the Occupational Safety and Health, and a Staff Scientist with the West Virginia Nano Initiative.
Aircraft are the last major mode of transportation to undergo electrification for many reasons, where the underlying reason is the sensitivity of aircraft performance to mass. This sensitivity demands that efficient, megawatt (MW)-scale high specific power density powertrains be developed to impact regional, single aisle and larger aircraft that account for the majority of fuel burn in commercial aviation. Developing MW-scale high specific power density electric powertrains (machines, cables/busbars, power electronics, etc.) remains a significant challenge. While advanced power semiconductors have enabled higher voltages, densities, and operational frequencies this also leads to passing high current through smaller volumes in applications such as electric machines and power electronics. This poses significant thermal challenges due to joule heating. This is particularly true for electric machines that strive to surpass 13 kW/kg, which studies have shown to be desirable for electric aircraft propulsion. The necessity of handling high current densities to achieve MW power levels dictates that greater than 10kW of waste heat will be generated. Moreover, most of the heat is generated in the stator winding which is a mixture of electrical conductor (copper or aluminum), potting material, magnet wire (electrical) insulation and high voltage electrical insulation. Although the electrical conductor is a fantastic thermal conductor, it is also the source of the heat (carrying the electrical current) and is thermally isolated by the other materials. Simply letting the machine run at increased temperatures is an attractive idea, however the reality is that most of the suitable electric insulations and potting material candidates are not likely to satisfactorily operate at higher temperatures with reasonable life expectancies. The likelihood of developing new polymers that can satisfy the necessary functions (mechanical and electrical), operate at higher temperatures with acceptable lifetime in the near term is small. This has led the researchers at the NASA Glenn Research Center to examine electrically insulative materials in high power destiny electric machines, their thermal environment, and what solutions are realistic from a materials point of view. This presentation will touch on both the thermal challenges of electric machines and NASA Glenn’s research into material solutions.
This presentation will touch on both the thermal challenges of megawatt scale electric machines for electric aircraft propulsion applications and material solutions with a specific emphasis on machines’ stators.
