Electric motor and transmission coupled vibro-acoustics of electric powertrains

英国处于大规模使用零排放（电动）汽车（EV）的最前沿，因为根据最近的政府公告，新内燃机驱动的汽车和货车的销售计划到2030年结束。与流行的观点相反，电动汽车的动力传动系统并不安静。电动汽车运行期间（主要是在中高速）产生的噪音（来自电动机和传动系统）由于缺乏内燃机的掩蔽噪音而被放大。因此，汽车原始设备制造商必须迅速调整其噪声、振动和声振粗糙度（NVH）设计方法，以应对电动动力系统带来的新挑战。电动汽车中最突出的NVH问题是电动机（转子速度谐波，即啸叫噪声）和机械传动装置（齿轮啮合频率谐波，即啸叫噪声）辐射的音调噪声。在前者中，电动机电磁力起着关键作用，激励结构，通过减小电动机的尺寸（和重量）来放大。在后者中，到达变速器的扭矩变化与系统不对准（在齿轮、轴和壳体中）相结合，激励传动系统，导致齿轮啮合振荡。上述NVH问题通常被宽范围的EV操作条件和高功率传输放大，这在耦合系统动力学（在电动机和变速器之间）中引入不稳定性。一个耦合的多物理场调查，包括哨声和抱怨NVH需要同时考虑各种学科，如电磁学，组件的灵活性，瞬态动力学和噪声产生。目的是确定上述NVH行为背后的主要根本原因。因此，将在开发过程的早期提出新型设计解决方案，以降低电动汽车动力总成NVH的严重程度。研究将集中在以下方面：i）电动机和变速箱瞬态动力学之间的耦合; ii）新型降阶方法来模拟上述NVH行为。

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.