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New challenges arise for engineers with the emergence of Hybrid Electrical Vehicles (HEV) and Battery Electrical Vehicles (BEV). As an electric motor has a lower overall noise emission compared to an Internal Combustion Engine (ICE), the overall noise level inside an EM driven car’s cabin is more colored by road noise and windnoise. That being said, the EM can still be very audible because of its prominent high-pitched tonal content, linked to the machine design (number of slots, poles). Hence, in view of driver and passenger comfort, reduction of cabin noise also involves optimizing the noise mission of electric motors. The noise produced by an electrical machine in operation can be assessed early on in the design process using simulation methods. This paper presents currently available approaches for assessing during the ideation phase the noise induced by a brushless Permanent Magnet Synchronous Machine (PMSM) which are widely used in electrical vehicles.

Fan noise can form a significant part of the vehicle noise signature and needs hence to be optimized in view of exterior noise and operator exposure. Putting together unsteady CFD simulation with acoustic FEM modeling, tonal and broadband fan noise can be accurately predicted, accounting for the sound propagation through engine compartment and vehicle frame structure. This paper focuses on method development and validation in view of the practical vehicle design process. In a step by-step approach, the model has been validated against a dedicated test-set-up, so that good accuracy of operational fan noise prediction could be achieved. Main focus was on the acoustic transfer through the engine compartment. The equivalent acoustic transfer through radiators/heat exchangers is modeled based on separate detailed acoustic models. The updating process revealed the sensitivity of various components in the engine compartment.