Methodology for Radiated Noise Refinement of Electrified Drivetrain Systems

Electric drive units (EDU) of battery electric vehicles and electric drivetrain components of hybrid vehicles require significant development effort and planning to ensure that a refined NVH sound quality is achieved. New tools and methods are required to understand the NVH performance throughout the development process and to ensure that NVH risks can be quickly identified and mitigated within the correct EDU subsystems. This paper discusses the development of a methodology (EDSL – Electric Drive Sound Level) aimed at addressing this need. It also outlines how the EDSL tool can be used to address radiated noise issues and understand the NVH performance of the various subsystems within an electrified drivetrain component. The first use of the EDSL methodology is to characterize component-level radiated noise test results and compare the different mechanical and electrical noise sources to targets. The results from this are used to guide EDU development in the appropriate areas. Following the initial characterization, the next stage of the EDSL process is to create detailed mapping that correlates the 3-phase current to the electrical noise shares using 2D electromagnetic simulations and a set of linear transfer functions. This detailed correlation mapping can then be used to generate new radiated noise results for different control strategies and power electronics calibrations. The greatest benefit of this process is the efficiency in being able to quickly generate new radiated noise results directly from new excitation data (3-phase harmonic currents). The use of a correlation map as an alternative to typical multibody and acoustic simulations is fundamental in being able to optimize the e-motor control strategy quickly without the typical time-intensive CAE simulations.