Direct Conductor Cooling of Outer-Rotor Machine Enabled by Additive Manufacturing

Most of the heat in electrical machines is generated in the windings, which is why cooling them directly can give the largest gains in thermal performance. Normally this is complicated, especially in an outer-rotor machine, where the stator windings are not easily accessible. Although, with additive manufacturing, the conductor’s geometry can be freely modelled and optimized for thermal performance. Therefore, this paper presents additively manufactured windings with integrated heatsinks, which are cooled by a centrifugal fan attached to an outer-rotor machine. The aluminum alloy windings achieved a current density of 9.3 A/mm2 with a hotspot temperature of 85 °C.