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The automotive industry continues to develop new powertrain and vehicle technologies aimed at reducing overall vehicle-level fuel consumption. Specifically, the use of innovative drivetrain technologies including conventional and electrified propulsion systems is expected to play an increasingly important role in helping OEMs meet fleet CO2 reduction targets for 2025 and beyond. NVH development for vehicles with electrified powertrains introduces new challenges, which need to be understood and solved. The electrified vehicle space spans variants from micro and mild hybrids all the way through plug-in hybrids and fully electric vehicles. In addition to conventional NVH development methodologies, active sound design (ASD) can play a crucial role to enhance the interior sound perception of such vehicles and hence, improve customer acceptance of new technologies. This paper will begin with an introduction to the NVH challenges posed by electrified vehicles.

In modern vehicle acoustics, Active Sound Design (ASD) is a popular method to enhance the interior sound perception of a vehicle. In vehicles with a traditional internal combustion engine, the load dependency of the sound can be increased to give a positive dynamic feedback. Irritating small band resonances can be attenuated by boosting the surrounding frequency content, and downsized-engines with a small number of cylinders can be made to sound like the larger ones from former days. However, once a characteristic sound is designed for a specific vehicle, it is a tedious process to transfer this lead-sound to derivatives (e.g. same model but different exhaust system). So far, sound designers must adapt the ASD dataset manually - usually this takes several loops of measuring the vehicles interior sound on a track and adjusting the ASD settings back in the office.

The most appreciated driving characteristics of electric vehicles are the quietness and spontaneous torque rise of the powertrain. The application of range extenders (REX) with internal combustion engines (ICE) to increase the driving range is a favourable solution regarding costs and weight, especially in comparison with larger battery capacities. However, the NVH integration of a REX is challenging, if the generally silent driving characteristics of electric vehicles shall remain preserved. This paper analyses key NVH aspects for a REX design and integration to fulfil the high expectations regarding noise and vibration comfort in an electric vehicle environment. The ICE for a REX is typically dimensioned for lower power outputs, incorporating a low number of cylinder units, which is even more challenging concerning the NVH integration. It will be explained that sophisticated, innovative technologies are required on component and vehicle side to ensure best possible NVH comfort.