NVH Improvement of BEV transmission using housing modal analysis co-relation and design optimization

Battery Electric Vehicles (BEVs) are extremely sensitive in terms of NVH requirements. While the engine is being replaced with an almost silent electric motor, the transmission noise appears persistent and demands more silent transmission. This has raised demand for improvement in design as well as manufacturing quality. Various innovations are being made to drive an improvement in the NVH. The following paper will discuss the improvement in NVH achieved through a design optimization of the housing using modal analysis. Firstly, the NVH results were co-related with the modal analysis and the cause for the dominant peak in amplitude of the NVH graph associated with the housing modes were mapped. A simple Excel based correlation matrix is used to map the list of all Eigenfrequencies of housing and its corresponding gear tooth frequency. Further optimization is done in housing design to defer the modal frequencies and another NVH test was run. It was proven that housing design optimization using modal analysis can solve NVH issues and improve the overall performance of the transmission. It was demonstrated that the electric vehicle NVH is not only critically dependent upon gear geometry and accuracy but also equally impacted by housing design. The best engineered housing design can enhance overall NVH performance of vehicles as well as customer satisfaction.