Thermal and Manufacturing Aspects of Traction Motors Potting: A Deep Experimental Evaluation

Thermal effects and manufacturing processes of different potting strategies are studied in this paper. In the first small prototype, winding is impregnated traditionally with a standard epoxy-based material and then potted using a thermally conductive epoxy. In the motor with global potting, a single material and process is used to enhance heat transfer from the copper conductors in the winding to the housing where the cooling ducts are located. The potted motors are then compared to a reference motor without potting and traditionally impregnated using standard resins. Steady-state and transient thermal measurements are done and a comparative investigation is performed on the built prototypes. Moreover, influences of traction motor designs on thermal effects of potting are studied and presented in this paper. Using the results achieved on the tested prototypes, end winding potting is applied to a real-size traction motor designed and built for electric off-road vehicles and thermal effects are investigated in a test setup where the potted and unpotted motor are placed back-to-back running in an identical operating point and under the same cooling conditions. Moreover, measurements on the duty cycles are run with the aim of investigating the potting thermal performance in the real operating condition.