Electric Motor Thermal Management Using 3D-Printed Hollow Liner

In this article, a novel in-slot cooling concept using 3D-printable hollow liners (HLs) has been introduced. Using a 25-kW motor topology as a base case, 3D-printable HLs with lofted inlets and outlets were designed. Inline circular pin-fins were incorporated inside the HLs to enhance the convection heat transfer area and mechanical strength. Coupled electrothermal analyses were performed to investigate the effect of wall thickness and materials used for the HLs. The numerical results show that 1.5-mm-thick ceramic HLs can significantly reduce motor temperature by reducing the thermal resistance between the winding and the coolant and can sustain 47% more current before reaching the winding insulation’s temperature limit, compared to conventional jacket cooling (JC). The designed HLs were 3D-printed using a ceramic-like high-temperature material, and a 3-kW dc motorette testbed was developed to demonstrate the applicability of the cooling concept. The analysis of this motorette shows that HLs can maintain a transient current density of 27.95 A/mm², within the temperature limit of class F insulation (155 °C).