A systematic experimental approach in deriving stator-winding heat transfer

This work is devoted to providing a more systematic approach to thermal design and analysis of electrical machines with the research focused on heat transfer from the winding body to the stator core pack/machine periphery. The heat transfer from the winding body is notoriously difficult to predict theoretically due to the multi-material composite structure of the stator-winding assembly. Together with numerous manufacture and assembly factors, the heat transfer is usually informed empirically. Further to this, the stator-winding assembly frequently constitutes the main source of power loss within a machine assembly. Both the heat transfer and power loss effects have a significant impact on the machine’s overall power output capability.

A common approach when quantifying the heat transfer across the stator-winding is based on an equivalent thermal resistance. This method provides reliable information regarding the capability of the dissipative heat transfer. However, as the thermal resistance data is related to a particular machine and stator-winding assembly, the results are difficult to transfer and compare across different machine designs. Especially if no supplementary stator-winding construction data is available. Here, a method utilising an equivalent thermal conductance has been proposed to enable data transfer for the alternative machine builds and topologies. This allows for a relatively simple comparison among alternative stator-winding assemblies. Both the experimental and theoretical findings are presented in the paper to illustrate the proposed approach.