Challenges in Electric Vehicle NVH

Abstract

The quest for reducing CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> footprint by nations worldwide has propelled the automotive industry in taking the turn towards new energy sources. Electric vehicles (EV) are at the helm of this revolution. There have been many hurdles in development of EVs. Vehicle NVH tends to be one of these areas. The change in fundamental source of noise and vibration in a vehicle combined with efforts to increase range by using lighter materials has produced new challenges for NVH engineers. This paper tries to identify the disparities brought about in NVH performance of vehicle with introduction of electric powertrains. A subjective as well as objective approach using state of art is used and methodology elaborated in this paper. Henceforth providing an original and unique contribution to NVH testing of electric vehicles. The core of this work is to analyze the shift in noise and vibration trend with the introduction of electric powertrains thereby finding the challenges in NVH analysis. A multitude of test conditions are performed at vehicle level for acquiring NVH data which is further thoroughly analyzed to bring about the shift in trends observed in electric vehicles. It is observed that a huge reduction in noise levels is observed at idle conditions whereas the difference diminishes as vehicle accelerates to higher speeds. Also mount vibration ranges have significantly reduced with introduction of electric powertrains. Yet there are peculiar phenomena observed in EVs related to switching frequencies of inverter which are visible at higher frequencies. The whole work has been organized into four sections: Noise, tactile vibrations, mount vibrations and noise/vibration transfer functions.