Electrical Characteristics of Additively Manufactured Hollow Conductor Coils with Integrated Heat Pipes for Electric Aircraft Applications

This paper presents an extensive study on the characterization of AlSi 10 Mg additively manufactured coils for a 250 kW, 5,000 rpm aircraft surface permanent magnet machine. This study includes DC tests up to 70 A and AC tests up to 100 Arms for frequencies up to 1200 Hz. The experimental results were compared to one of the vendors' test results which shows promising match with less than 4.6% error in electrical resistivity. Moreover, electrical resistivity temperature coefficient of the coils was extracted which enables more accurate analysis at nominal temperatures of the machine. The FEA simulation results further demonstrate the accuracy of the test results with errors within 0.5% in losses. This paper also investigates the effects of heat pipes and their placements in the coil under six different scenarios. Different thermal interfaces were used to examine the thermal management system that shows the effectiveness of the heat pipes used in hollow conductors. Furthermore, FEA results show the effects of heat pipes and a magnetic core on the AM coil losses. Among the most important conclusions of this study are that the heat pipes seem not to cause significant electrical short circuits in the coils and using thermal paste on heat pipes has significant effect on extracting heat from the coils.