Cooling of Windings in Electric Machines via 3-D Printed Heat Exchanger

This article presents a novel use of three-dimensional printed direct winding heat exchangers (3-D-DWHX) to improve the thermal management of the stator in high power density electric machines. The 3-D-DWHX is in direct contact with the stator windings, enabling high continuous current densities. The use of dielectric polymer for the heat exchanger allows direct contact with the windings without an additional insulation material. By occupying the otherwise unused space between double layer concentrated windings, there is no significant impact on the electromagnetic design, and a smaller machine can be realized. The result is an increased continuous power rating and power density of electric machines. The polycarbonate-aluminum flake 3-D-DWHX was validated in a nonencapsulated motorette test, achieving a continuous current density of 20.4 A
_RMS
/mm
²
for a hotspot temperature of 148 °C. Finite element analysis shows that the same design, when encapsulated, can achieve 33.3 A
_RMS
/mm
²
current density with a hotspot temperature of 195 °C, corresponding to a continuous specific power of 11.8 kW/kg.