Riassunto analitico
Nowadays, the stringent environment regulations, together with the need to reduce dependence on fossil fuels, have brought automotive engineering to an extensive electrification. In this context, the electric motor carries out a key role, as it can achieve exceptional efficiency values compared to internal combustion engines in the ”tank-to-wheel” energy path. Electrified powertrains allow employing less components and permit to have wider room for improvements due to the ongoing progress in material engineering.
Additionally, electric motors performance has been constantly improving: electric powertrains permit a fine control of the torque delivered to wheels and out-
standing acceleration capabilities, as well as a great reliability and torque density.
One of the most suitable motor type able to meet the above mentioned characteristics is the Internal Permanent Magnet (IPM) configuration. Besides featuring high efficiency and torque density, this motor type has a wide speed range that often permits to avoid the employment of a multiple-stage gearbox. One of the challenges associated to electric motor remains the power loss: copper losses within windings, iron losses in rotor and stator cores and mechanical losses unleash a certain amount of thermal energy which has to be properly managed so to keep the overall operating temperature under certain limits.\\
This thesis proposes a thermal analysis of an IPM motor intended for high-performance automotive applications, focusing on the optimum design of the water jacket surrounding the stator core. The aim is to validate, and eventually to enhance, the cooling system capability to subtract heat in every possible
operating condition while maintaining a good concentrated and distributed hydraulic losses in its path. To do so, a comparison is made between various types of inlets, evaluating the impact that each of them has on the pressure drop. Furthermore, a parametric study on the channel geometry is performed considering different section dimensions and varying the number of “turns” of the water jacket. Finally, by modulating the value of the passage area, the effect of increasing the speed of
the fluid is analyzed: the results show a good effect on the subtracted heat but at the cost of increased losses. All the calculations and simulations are carried out using a computational fluid dynamics (CFD) software (star-ccm+), with which a complete Conjugate Heat Transfer simulation of the motor is lastly performed: the original geometry of the channels proves to be suitable for good heat disposal and low hydraulic losses while a more tangential inlet arrangement reduces the losses concentrated at the entrances.
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