Electro-thermal design and optimization of high-specific-power slotless PM machine for aircraft applications

A 1 MW high-frequency air-core permanent-magnet (PM) motor, with power density over 13 kW/kg (8 hp/lb) and efficiency over 96\%, is proposed for NASA hybrid-electric aircraft application. In order to maximize power density of the proposed motor topology, a large-scale multi-physics optimization, which is not favorable for current electrical machine software, is needed to obtain the best design candidates, which is not favorable for current electrical machine software. Therefore, developing electromagnetic (EM) and thermal analytical methods with computational efficiency and satisfactory accuracy is a key enabling factor for future multi-physics optimization of motor power density. This dissertation summarizes the efforts of developing an electro-thermal analysis and optimization scheme of the proposed motor for aircraft applications. Component hardware tests including windage loss, fan performance, full-scale stator temperature and litz-wire were conducted to validate the proposed prediction methods and provide calibrations in the motor design analysis. Furthermore, slotless litz wire winding geometry and strand size are optimized with the developed electro-thermal modeling including transposition effects. After gaining confidence in the developed electro-thermal models, an optimization design toolbox is built for the hybrid-electric engine systems study. The first application study is in partnership with Rolls Royce's Electrically Variable Engine Project to study thermal management system integration effects on motor sizing. The second study is in collaboration with Raytheon Technologies to study motor transient performance with phase change materials integration, which can be tailored to a hybrid-electric engine mission profile