Air-gap Electrical Windings for Light-weighting of Future Electric Propulsion Systems.

Future electric propulsion systems in aircraft must meet ambitious power density targets to drive the adoption of hybrid- and all-electric air-transport. The Aerospace Technology Institute technology roadmap seeks electrical machines achieving 20kW/kg by 2035 in stark contrast to the 3kW/kg available today. With improvements in permanent magnet technology and the potential for superconducting electrical conductors, the magnetic field strength within future electrical machines may exceed that of the saturation flux density of the most capable electrical steels. Hence, light-weight electrical machine topologies with air-gap windings and minimal electrical steel become increasingly attractive, however, the air-gap winding must be designed to provide the reaction torque which would conventionally be borne by electrical steel teeth. As such, this project focuses on the design, implementation and experimental test of composite electrical machine windings which incorporate structural elements such as glass- and carbon- fibre along with electrical conductors to yield a mechanically robust, highly electrically conductive winding. The primary challenges are the winding/weaving of such a component along with the thermal management of the DC Joule and AC losses exhibited by the conductors.