NVH Analysis of Integrated Motor and Two-Speed Gearbox System for Electric Vehicles

The market penetration rate of electric vehicles has boosted very rapidly in China and worldwide this year. Most of e-powertrain systems nowadays in passengers’ vehicle consists of electric traction motor, inverter and single speed gearbox. Compared to the traditional single speed system, integrated motor and two-speed gearbox system has been developed with higher overall efficiency, higher power density and better noise, vibration and harshness (NVH) performance. This paper presents NVH analysis and optimization of the two-speed e-powertrain system under electromagnetic and mechanical excitations. The simulation model with both e-motor and gear excitations is established. The order interference analysis is conducted at the very beginning to avoid system resonance. Modal, vibration and radiated noise analysis are done in a systematic way to analyze and optimize the original design. System NVH tests are completed in the semi-anechoic chamber. A-weighed system sound pressure level is verified to be less than 80 dBA.