Evaluation of steering wheel vibration in electric vehicles and application to Dynamic Motor Drive

Eliminating steering wheel vibration is a key in refining vehicle Noise, Vibration, and Harshness (NVH). The absence of masking engine noise and vibration makes this challenge harder in a pure electric vehicle. This paper provides three key insights with regards to the evaluation of steering wheel vibration in EVs using on-road test data. First, we explore the effects of steering wheel grip variation in the measured accelerometer response. Second, we identify the limitations of evaluating powertrain induced vibration in a noisy environment and propose a post-processing technique to reject irregular road-induced perturbations from the measured data. Third, we evaluate a tuned mass absorber as a localized mitigation tool for steering wheel vibration. Finally, we describe how the above techniques were brought together to deliver a refined NVH experience while integrating Dynamic Motor Drive (DMD) technology as a software-only solution which has been shown to improve EV range by 0.4% on IPM and 3% on EESM based vehicles.