Structural and Micro-Geometry Optimization of an Electric drive unit for Whine Noise Reduction

The noise generated by pure electric vehicles (EVs) has become a significant area of research, particularly due to the increasing adoption of electrified propulsion systems aimed at meeting OEM fleet CO₂ reduction targets. Unlike internal combustion engines, which mask many drivetrain noises, EVs expose new challenges due to the quieter operation of electric motors. In this context, the transmission system and gear structures have emerged as primary contributors to noise, vibration, and harshness (NVH) in EVs. The present study provides an NVH study that focuses on the gear whine noise issue that is seen at the vehicle level and cascades to the powertrain level. Comprehensive root cause identification, focusing on the transmission system's structural and dynamic behavior. The research emphasizes modifications to both the gearbox housing and gear structures to reduce noise level, and model validation was all part of the study, which was accompanied by physical test results. Using MBS software, the multibody simulation model of the two-stage reducer is developed. At several reducer locations, the fidelity of the reducer model with test data is validated. Gear tooth microgeometry parameters are optimized to reduce the surface vibration of the gearbox. Finally, the whine noise from the gearbox was attenuated.