The automotive industry continues to develop new powertrain and vehicle technologies aimed at reducing overall vehicle-level fuel consumption. Specifically, the use of electrified propulsion systems is expected to play an increasingly important role in helping OEM’s meet fleet CO2 reduction targets for 2025 and beyond. This will also include a strong growth in the global demand for electric drive units (EDUs).
The change from conventional vehicles to vehicles propelled by EDUs leads to a reduction in overall vehicle exterior and interior noise levels, especially during low-speed vehicle operation. Despite the overall noise levels being low, the NVH behavior of such vehicles can be objectionable due to the presence of tonal noise coming from electric machines and geartrain components as well as relatively high shares of road/wind noise. In order to ensure customer acceptance of electrically propelled vehicles, it is imperative that these NVH challenges are understood and solved.
This paper discusses various aspects of the EDU NVH development process. This will include a discussion of the NVH target cascading methodologies for EDUs, followed by a description of the EDU development and vehicle NVH integration process. Utilizing examples, specific aspects of EDU design to assure acceptable NVH behavior from the EDU will be discussed. The use of advanced simulation techniques for electric machine noise as well as geartrain-related noise will be demonstrated using examples. Finally, aspects of EDU “source” noise/vibration measurements and integration into the vehicle to assure refined vehicle-level NVH behavior will be illustrated using examples from relevant case studies.