Enhanced Thermal Model of a Totally Enclosed Fan Cooled Squirrel Cage Induction Machine

Thermal simulations are a very important tool for optimizing the design of electric machines. In this paper, two thermal simulation models for totally enclosed fan cooled (TEFC) induction machines are compared with thermal measurement results. For both one dimensional models of the induction machine a thermal equivalent circuit of the machine is presented. The enhanced model was built with the possibility to split the middle part into equal sized parts to model a more detailed axial temperature distribution in the machine. For modelling the circuits, MODELICA language was used in combination with the simulation tool DYMOLA. Simulation results are obtained for both thermal models at the thermal equilibrium. For a comparison between simulated and measured results two measurements on an 18.5 kW four pole induction machine have been accomplished. With iron-copper-nickel sensors embedded in the winding, the housing and between the ribs of the machine temperatures have been determined.