NVH Performance Improvement Method of the Three-in-one Electric Drive System Based on Structural Topology Optimization

In order to improve the NVH performance of a three-in-one electric drive system, the structural transmission path is designed and optimized. Firstly, the weak components with the highest NVH contribution to the electric drive assembly were identified by analytical method, frequency positioning method and plate contribution analysis method. Then, the material distribution of the controller cover plate （the weak component with the highest NVH contribution） was optimized with the modal frequency as the optimization goal and the volume fraction as the constraint. The simulation results show that the frequency of each mode of the optimized cover plate is increased, the first mode is increased by 34%, and the sound power level under unit excitation is reduced by 2-7 dB. Finally, NVH bench performance test was carried out on the electric drive assembly with optimized cover plate. The test results show that compared with the original electric drive assembly, the total sound pressure level of the electric drive assembly optimized cover plate has a certain reduction in different frequency ranges, especially in the middle and high frequency band, and the reduction effect is more significant, reducing 2-4 dB.