Numerical study of the impact of different cooling arrangements on a high length/diameter ratio motor for electric commercial vehicle

Computational Fluid Dynamics (CFD) was used to carry out a fluid flow and thermal investigation of a high power dense traction machine for electric commercial vehicle. One of the features of the machine design considered is the high Length/Diameter (L/D) ratio; this can represent a further challenge when performing the thermal design; indeed the heat dissipation from the stator core can represent an issue. The aim of this work is to identify an effective cooling configuration capable of enhancing the cooling of the stator and maintaining the operating temperature of the whole machine within the allowable limits. In this paper CFD analyses were therefore used to assess the thermal capability of several cooling arrangements; numerical results of each case are presented and compared. In particular an alternative cooling option, consisting in the implementation of heat pipes between the machine's stator teeth, was considered. Due to their simple structure and high heat transfer coefficients, heat pipes are not invasive but at the same time can dissipate large amount of heat. CFD results show how a significant temperature drop of the machine's core can be achieved.