System interactions affecting NVH performance of an Electric Vehicle drivetrain 2019-01-1545

The paper will present an integrated approach to system NVH analysis, which gives an insight into the system response in an EV driveline due to electrical and mechanical excitations; namely gear transmission error, rotor mechanical imbalance, electrical machine torque ripple, and stator radial force shapes. The paper will address the fact that, as part of a practical design exercise, different subsystems and components may achieve design maturity at different times. It is therefore important to understand to what extent various drivetrain components may be considered in isolation, and at what point it becomes necessary to consider the interactions present in the full system. The paper will compare predicted NVH performance of a representative EV traction motor when different boundary conditions are considered; for example, when considering the motor in isolation, when being tested in a representative test setup, and when included in a representative drivetrain. For each configuration, the response to mechanical and electro-mechanical noise mechanisms will be assessed. In each case, the fidelity of simulation required to achieve an appropriate engineering insight will be considered. From these studies, the best practice for the assessment of NVH as part of a holistic design process will be discussed. Consideration will be made of the factors which may influence the choice of simulation approach; for example, the level of design maturity, the availability and reliability of system data, and the design targets which are to be addressed.