Design Considerations of Heat Guides Fabricated Using Additive Manufacturing for Enhanced Heat Transfer in Electrical Machines

This paper investigates a new heat extraction approach in application to the high-specific-output electrical machines. The proposed technique employs thermally conductive heat guides (HGs) to provide supplementary heat evacuation paths for the machine regions, which are particularly susceptible to high power loss. Here, the research focus has been placed on the stator-winding assembly. The HGs investigated in this work rely solely on conductive heat transfer, in contrast to the solutions involving working fluid phase change, e.g. heat pipes (HPs). It is intended for the HGs to be an integral part of the stator-winding assembly, e.g. HGs incorporated in the winding active and/or end region. Such arrangement however, imposes several design challenges. These are related with the HGs being a source of additional power loss due to the machine's magnetic flux leakage. The objective of this study is to evaluate a concept of HGs, which are `immune' to the external magnetic field with `good' heat transfer capability. To facilitate that, a combination of detailed multi-physics design-optimization together with modern additive manufacturing, i.e. selective laser melting (SLM) method, has been employed here. The theoretical analysis has been supplemented with experimental body of work. A number of stator-winding hardware exemplars (motorettes) incorporating alternative HGs designs have been fabricated and tested. The research findings show that the optimised HGs allow for 30% improvement in dissipative heat transfer from the winding body and insignificant additional power loss, for the analysed stator-winding assembly.