Electric motor and transmission coupled vibro-acoustics of electric powertrains

英国在大规模使用零排放(电动)汽车(EVS)方面走在了前列，因为根据最近的政府公告，新内燃机驱动的轿车和货车的销售计划在2030年结束。与流行的观点相反，电动汽车的动力系统并不是静音的。电动汽车运行期间(主要是在中高速)产生的噪音(来自电机和传动系统)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将不得不迅速调整他们的噪声、振动和粗糙度(NVH)设计方法，以适应电力系统带来的新挑战。电动汽车中最突出的NVH问题是来自电机(转子速度的谐波，即哨声噪声)和机械传动(在齿轮啮合频率的谐波，即哀鸣噪声)发出的音调噪声。在前者中，电机的电磁力起着关键作用，通过减小电机的尺寸(和重量)放大结构，从而激励结构。在后一种情况下，到达变速器的扭矩变化与系统(齿轮、轴和壳体中的)不对中相结合，会激励传动系统，导致齿轮啮合振荡。上述NVH问题经常因电动汽车运行条件的广泛和传输的高功率而放大，这引入了耦合系统动力学(电机和变速器之间)的不稳定性。涉及哨声和哀鸣的NVH的耦合多物理研究需要同时考虑各种学科，如电磁学、元件灵活性、暂态动力学和噪声产生。目的是找出上述NVH行为背后的主要根源。因此，在电动汽车开发初期，将提出新的设计方案来降低电动汽车动力总成NVH的严重性。研究将集中在以下几个方面：i)电动马达和变速器暂态动力学之间的耦合；ii)用新的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.