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

Abstract

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.

A critical review on thermal management technologies for motors in electric cars

“…However, despite that end winding cooling seems to be a very impressive cooling method to cool the armature conductors it has the main drawback when applied to large length/diameter motor cooling, in which cases the cooling performance for the middle part may not be enough. Another axial cooling method may also be needed in this scenario [181]. Furthermore, due to the annulus shape of the end winding, good temperature uniformity is not easily achieved by simple manifolds, while complex manifold structures will decrease the reliability of the cooling loop to some extent.…”

Modification of the In-Wheel Motor Housing and Its Effect on Temperature Reduction

“…Due to the small working space, temperature increases immediately impact its lifespan and efficiency [15]. Some investigators have looked into ways to cool electric motors, like making grooves on the outside of the motor housing [16], installing heat pipe loops [17], using spiral water jackets [18], and using liquid cooling channels [19]. Oil can be used as a medium to cool electric motors and performs better than water in cooling electric motors [20].…”