Steady State and 2D Thermal Equivalence Circuit for Winding Heads—A New Modelling Approach

Julien Petitgirard,Jean-Christophe Delmare,Tony Piguet,Eric Fouillien,Didier Chamagne,Philippe Baucour

doi:10.3390/mca25040070

Abstract

The study concerns the winding head thermal design of electrical machines in difficult thermal environments. The new approach is adapted for all basic shapes and solves the thermal behaviour of a random wire layout. The model uses the nodal method but does not use the common homogenization method for the winding slot. The layout impact can be precisely studied to find different hotspots. To achieve this a Delaunay triangulation provides the thermal links between adjoining wires in the slot. Voronoï tessellation gives a cutting to estimate thermal conductance between adjoining wires. This thermal behaviour is simulated in cell cutting and it is simplified with the thermal bridge notion to obtain a simple solving of these thermal conductances. The boundaries are imposed on the slot borders with Dirichlet condition. Then solving with many Dirichlet conditions is described. Some results show different possible applications with rectangular and round shapes, one ore many boundaries, different limit condition values and different layouts. The model can be integrated into a larger model that represents the stator to have best results.

Highlights

The study of increasingly compacted electrical machines in severe thermal environments is today an important tendency in electrical engineering [1,2]
In the second step, we provide two different way to estimate the thermal conductance that will be applied in the network
This study proposes an estimation of thermal resistances which represent the inverse of thermal conductances (Rth = 1/G)

Summary

Introduction

The study of increasingly compacted electrical machines in severe thermal environments is today an important tendency in electrical engineering [1,2]. The electrical machines with concentrated windings exhibit many advantages like high slot-filling factor, short end-winding, high fault tolerance capability, and automated winding process Those advantages allow the high power density applications like electrical vehicles, electric aircraft, and wind turbines [3]. The use of numerical tools, like the finite element method (FEM), to estimate thermal field and find hot spots in coils leads to excessive simulation time. The objective of the present study is to create an adaptable winding model, that reproduces a similar thermal behaviour This model can solve all simple slot shapes with random wire layouts. The advantages of this method are to keep the fast solving from a nodal method with the exact layout of wires in winding in all simple shapes

Objectives

Methods

Conclusion