A coupled thermal-electromagnetic analysis for a rapid and accurate prediction of IM performance

Abstract—The design of electrical machines for extreme oper- ating conditions must include a thermal analysis coupled with the magnetic analysis. However, the traditional coupling of the thermal and the magnetic models can result in an unacceptable increase in computation time, particularly if finite elements (FEs) are used for the machine analysis. This paper proposes a coupled thermal–magnetic analysis of an induction motor (IM) with the primary goal of achieving a rapid and accurate prediction of the IM performance. Only a minimum set of FE magnetic analyses is carried out so as to determine the parameters of the IM equivalent circuit. These parameters are nonlinear and are adjusted on the basis of the operating point. Then, this equivalent circuit is coupled with a lumped-parameter thermal network to predict the temper- ature in each part of the IM. Since both the equivalent circuit and thermal network solutions are analytic, the analysis converges very rapidly. At the same time, the FE analysis yields a precise estimation of the IM parameters used in the equivalent circuit. Some experimental results are reported, showing the accurate prediction of the proposed methodology.