NVH Optimization Methods Applied to E-Motors

Noise-vibration-harshness (NVH) is now playing an important role in electric vehicle development process. Experience shows that the NVH criteria must be considered at the very early stages of the concept design phase. Finite Elements (FE) models are widely used to simulate the vehicle design. To achieve a correct accuracy of a FE model, the results of an experimental modal analysis (EMA) are commonly applied to a FE model via correlation and updating processes. Thus, different kinds of optimization might be used throughout the concept design duration. This paper describes, first, the use of a parametric optimization to tune a FE model in high frequencies relying on the results of the EMA test. Then the frequency response analysis is conducted to detect the critical frequencies for the NVH performance. Based on the results of this analysis, a topographic optimization is performed. The aim of this optimization is to improve the NVH behavior by mitigating the resonance peaks in specified frequency range and to produce a shape which can be stamped with required constraints. Both parametric and topography optimizations are carried out with a help of a dedicated FE software. The study shows two main aspects of optimization: the speed-up of the updating time of a FE model and the reducing of an e-motor noise and vibration by implementing new optimized shapes.