On the improvement of the thermal behavior of electric motors

The objective of this work is the improvement of the heat dissipation and the cooling of electric motors of great power intended for the traction of urban vehicles. Two ways of improvement are proposed. The first one consists in replacing the air surrounding the stator windings by resins of higher thermal conductivity. The second way consists in using the spray cooling technique to cool the hottest parts (coil windings) of an electric motor. The two solutions are tested independently and simultaneously. Results show that filling the coil windings with resin allows better heat dissipation in the case of basic cooling by free air convection. On the contrary, the lowest temperatures are obtained with traditional coil winding without resin and by using spray cooling. In that case, the liquid part of the spray may infiltrate inside the coil and the evaporation takes place at the hottest point.