Highly Thermally Conductive Insulation for High Power Density Electric Machines

Electric machines are integral parts of a hybrid-electric propulsion system for an aircraft to achieve higher fuel-saving and lower carbon emission. Poor heat transfer efficiency from the winding and the magnetic core limits the power density of motors and generators. To address this issue, a high-performance ceramic composite dielectric coating is developed for motors and generators. The coating has substantially higher thermal conductivity and temperature stability than conventional insulation and can be applied directly onto the magnetic core as slot insulation and onto the copper conductor as winding insulation by electrophoretic deposition (EPD). The thermal resistance between the copper winding and the stator/rotor core can be reduced by an order of magnitude in comparison to traditional slot liner and winding insulation. This can increase machine power density by 1.5-2X depending on machine design. This paper will discuss the feasibility and initial results of using EPD technology to make highly thermally conductive, high temperature, and high dielectric strength insulation materials for high power density electric machines.