Verification of loss segregation in electrical machines through inverse thermal modelling

Abstract

This paper aims to validate the loss components in the net electromagnetic losses in electrical machines through an inverse thermal modelling approach. The specific focus is on the stator core losses, which can be physically divided into yoke and tooth losses. A method to thermally map the three dimensional heat distribution in the 3-D stator core domain from noisy temperature measurements of the stator lamination surface using constrained least square minimization is presented. Preconditioned conjugate gradient method is also introduced as an alternative method and is shown to be a faster, and more accurate choice. The 3-D finite element model was built for a 37 kW induction motor which served to generate the numerical forward thermal solution. Different measurement data from the yoke and tooth surface, with different levels of simulated noise were used to test the inverse loss approximation.