High Power Density Electric Motors for Hybrid Electric Air Platforms

An electric motor is proposed that will achieve a power density of 5 hp/lbm and an efficiency greater than 95%, when delivering 7 hp of mechanical power at a speed of 8400 rpm. This capability, not available from current electric motors, is achieved by arranging high energy-product permanent magnets in a novel configuration expressly designed to deliver highly-concentrated flux densities to the stator windings at minimum weight. The proposed motor will be tailored to the geometry of a ducted fan suitable for rotorcraft, with the aim of providing the key enabling element in a ‘hybrid electric’ rotorcraft drive train, in which an alternator, electric power distribution, and high power density motor(s) deliver power from the gas turbine to the ducted fan(s) (rather than a mechanical transmission and multiple rotating shafts). The potential benefits are reduced maintenance, increased redundancy, reduced vulnerability to ground fire, and rotor speed control. The Phase I design study will undertake (1) motor integration with a specific ducted fan, (2) motor cooling analysis, (3) rotor structural analysis, (4) motor drive analysis, and (5) optimization of the motor design parameters. In Phase II a prototype fan and motor will be tested against the desired power and efficiency goals.