Electric motor and transmission coupled vibro-acoustics of electric powertrains

点击翻译按钮获取中文摘要

The UK is at the forefront of utilising zero-emission (electric) vehicles (EVs) in a large scale, since the sale of new internal combustion engine driven cars and vans is planned to end by 2030 according to recent government announcements. Opposing to the prevalent views, the powertrains of EVs are not silent.The generated noises (from the electric motor and the drivetrain) during the EV operation (predominantly at medium to high speeds) are amplified by the lack of masking noise from the internal combustion engine. Thus, Automotive OEMs will have to quickly adapt their Noise, Vibration and Harshness (NVH) design approaches to the new challenges imposed by electric powertrains.The most prominent NVH issues in Evs are the tonal noises radiated from the electric motor (at harmonics of the rotor speed, namely whistling noise) and from the mechanical transmission (at harmonics of the gear meshing frequency, namely whining noise). In the former, the electric motor electromagnetic force plays a key role, exciting the structure, amplified by the reduced size (and weight) of the motor. In the latter, the torque variation reaching the transmission combined with system misalignments (in gears, shafts and the housing) ae exciting the drivetrain, leading to gear meshing oscillations.The above NVH issues are often amplified by the wide range of EV operating conditions and high power transmitted, which introduces instabilities in the coupled system dynamics (between the electric motor and the transmission). A coupled multiphysics investigation involving whistling and whining NVH requires the simultaneous consideration of various disciplines, such as electromagnetics, component flexibility, transient dynamics and noise generation. The aim is to identify the principal root-causes behind the above NVH behaviour. As a result, novel design solutions will be proposed to reduce the powertrain NVH severity in EVs early in the development process.The research will focus on the following aspects: i) the coupling between the e-motor and transmission transient dynamics and ii) novel reduced-order methods to simulate the above NVH behaviour.