The successful design of various electrical devices and machines is not only a matter of electromagnetic field analysis and optimization; it increasingly requires multi-physics consideration [1, 2]. Thermal performance is one design characteristic that sometimes trumps the electromagnetic performance and requires careful attention. Not only is thermal behavior important for determining cooling requirements and dimensioning heat sinks when needed, it is often strictly regulated by international standards and norms, such as the various UL standards, and can make the difference to wether a not a product is certified

In this paper, we discuss the multi-physics problem involving current flow and the resulting heat dissipation as well as the fluid mechanics implications for air forced cooling. We focus on the electrothermal simulation of various devices involving current flow, with particular emphasis on motors and transformers. We present the numerical formulation of the coupled physics problem involving the rigorous solution of Maxwell’s equations and the heat equation. The Finite Element Method is chosen for the numerical solution of these equations since it offers the highest level of flexibility and generality by accommodating arbitrarily complex geometrical models with a range of material properties. Several examples are considered to illustrate the power and accuracy of this simulation technique as well as how electromagnetic and thermal design objectives can be met through judicious optimization.

[1] So Noguchi; Inaba, Y.; Igarashi, H.; "An Optimal Configuration Design Method for HTS-SMES Coils Taking Account of Thermal and Electromagnetic Characteristics," IEEE Transactions on Applied Superconductivity, Vol. 18, No. 2, Jun. 2008 pp. 762 – 765

[2] Zhu, H.; Morton, C.; Cherukupalli, S.; "Quality evaluation of stator coils and bars under thermal cycling stress," Conference Record of the 2006 IEEE International Symposium on Electrical Insulation, June 2006, pp. 384 - 387