Electric Vehicle Powertrain Multiphysics NVH Simulation

Abstract

This paper presents in-depth understanding and approach to simulate NVH performance of electric vehicle powertrain. The powertrain assembly contains two main components - a synchronous motor and a gearbox. Excitations in motor's casing comes from vibration of stator and rotor, while excitation of gear box casing comes from vibration due to transmission error, gear backlash and misalignments. Motor excitation are solved in time domain using electromagnetic analysis and transferred to structure of motor to perform harmonic analysis in frequency domain. Similarly, gear vibrations are calculated using transient gear multibody dynamics (gear whine excitations)and then gear box vibration are applied in frequency domain in harmonic analysis. At the end combined motor and gearbox casing's vibration induced noise is measured at receiver location in frequency domain using Harmonic acoustic analysis. This process requires multiphysics capability and ability of accurate data mapping from time domain to frequency domain. The work presented here is an enhancement to the previous work [1]. The study presented in [1] is enhanced by; 1. 3D electromagnetic analysis to increase accuracy of load transfer from electromagnetics to harmonic analysis over 2D method mentioned earlier; 2. Including gear-train transmission error induced excitations on the gear box housing using full 3D transient multibody dynamics simulation. Study is going to address major requirements of analysts to design electric vehicle powertrain for NVH performance at constant RPM of motor. Further enhancements are underway to incorporate multiple RPM of motor without increasing manual effort of analysts.