Parametric Study of Thermal Performance of BMW I3 Electric Motor
Advanced thermal management of electric motors is an obligatory prerequisite for the next generation electric vehicle (EV) design. To meet the enhanced thermal management demands of electric motor, first benchmarking strategy should be the identification of geometrical and thermo-physical parameters of electric motors most significantly influencing the overall temperature distribution within the motor. Moreover, to ensure functionality and durability of the electric motor, selection of the proper embedded thermal management approach is also crucial. A series of parametric studies have been performed to decouple the effect of winding power density, winding liner thermal conductivity, effective thermal conductivity of the air gap between stator and rotor on the overall thermal performance of BMW i3 Permanent Magnet Synchronous Motor (PMSM). To perform a parametric study, a 3D Computational Fluid Dynamics (CFD) model has been developed using ANSYS Fluent®. A jacket cooled thermal management system has been investigated and a sensitivity analysis has been performed to explore the effect of coolant flow rate, i.e., forced convection heat transfer coefficient on the overall temperature distribution of the PMSM. Sensitivity analysis has also been performed over a wide range of convection heat transfer coefficients from the stator. The numerical results indicate that winding liner thermal conductivity, and forced convection heat transfer coefficient have significant effects on the thermal map of the PMSM. On the contrary, effective thermal conductivity of the air gap and natural convection heat transfer coefficient have negligible effect on the overall thermal performance of the PMSM. Keywords - Electric Vehicle, Permanent Magnet Synchronous Motor (PMSM), Thermal Management, Jacket Cooling, Computational Fluid Dynamics (CFD).