-The study of thermal behaviour is useful to identify causes of failure in electrical machines. This work details a two dimensional model for computing the magnetic and thermal finite element solution of induction motor using a weak coupling algorithm. In order to improve the accuracy of the adopted numerical formulation, the decrease of the electric conductivity with temperature is taking into account.

Purpose -Designers of electrical machines need a clear understanding of the mechanism of noise generation, in order to be able to reduce the noises which are produced under the influence of forces due to the magnetic field. The purpose of this paper is to develop a new approach to give a best estimation of these forces. Design/methodology/approach -A model is developed to calculate the distribution of local forces using the virtual work principle in finite element context including ferromagnetic hysteresis. The forces are calculated using a formulation based on the energy derivation. The nonlinear behaviour of ferromagnetic material is considered by combining a Jiles-Atherton model and finite element method through the fixed-point iterative technique. Findings -The effects of accurate behaviour of magnetic material are not always taken into account when calculating the local forces in electromagnetic devices. The introduction of hysteresis phenomenon in the analysed device gives a good prediction of magnetic induction. The expression used to compute the force includes an integral which is estimated numerically and not a constant term. Originality/value -The developed approach is more accurate than the classical methods using constant magnetic permeability or a first magnetization curve.