Evaluation of an Existing Thermal Model of an Induction Motor and its Further Application to an Advanced Cooling Topology

In this paper, an existing lumped-parameter thermal model is analyzed and evaluated using experimental results. In order to verify the validity and effectiveness of the thermal model a 10 hp machine was dismantled, physically measured and reassembled inserting thermal probes in it at different locations to test their temperatures. The model is simulated using PSPICE schematics for finding temperatures at different locations. The simulated results match with the experimental results. The model is further modified to fit a new direct lamination cooling (DLC) topology, characterized by coolant flowing through tubes inserted into the back iron and by modified dimensions to make the active cooling more effective. The flow within the tubes inserted in the back iron of a DLC motor is modeled using lumped parameter approach. The parameters are formulated from purely dimensional data and thermal constants for convection and conduction. The heat that is pulled out by the circulating liquid in the holes is modeled by adding a lumped heat sink which is represented as a current sink at the stator iron node in the model. The model is simulated for 30% and 60% cooling using PSPICE Schematics for finding temperatures at different locations. An empirical 10 hp DLC model is simulated inferring the data from AeroVironment. A comparative study between the two models shows the effectiveness in cooling technique employed.