Experimental analysis of additively manufactured air-cooled splayed end-windings

Abstract

Modern electrical machines for applications including aerospace and automotive need to meet an ever-increasing demand for power density. AC machines are required to operate at high fundamental frequencies, which produce high losses due to the AC skin and proximity effect mechanisms. Machines are limited in power density by the maximum operating temperature of the winding electrical insulation and therefore the ability of a machine to dissipate internally generated losses in the winding and core regions. Additive manufacturing has potential to significantly improve the ability of machines to dissipate heat, whilst reducing AC losses and improving package space by offering the designer unparalleled geometric freedom both in the active length and end-winding. In conjunction, electrical insulation with higher temperature ratings may be used. By forming the endwinding as a heat sink structure, the effective heat transfer coefficient can be substantialy increased, providing new opportunities in end-winding cooling. In this paper, the effect of splayed end-windings are evaluated for their use as a heat sink. The windings are tested experimentally with respect to their splay angle, and air velocity. The paper contains the results of the experimental testing for the convective heat transfer coefficients for electrically uninsulated additively manufactured components.