Frequency domain solution for distributed drive automotive vibration systems considering motor excitation

Vibrations of distributed drive electric vehicles (DDEVs) are simultaneously influenced by road and motor excitations. Traditional time-domain approaches struggle to quantify the coupled contributions of these two excitation sources in the frequency spectrum. This paper proposes a frequency-domain decoupling analysis method that separates the coupling effects of motor and road excitations. Analytical expressions for the fundamental and harmonic frequencies are derived based on the motor excitation mechanism. The power spectral density (PSD) of the motor excitation is estimated using an autoregressive (AR) model optimised with the Pearson correlation coefficient. By quantifying the spectral characteristics of road and motor excitations and their frequency-domain coupling with vehicle vibrations, a dual-excitation vibration model of DDEVs is developed, enabling direct computation of the frequency response function and statistical characteristics of vibration response variables. Simulations show that at low vehicle speeds, the motor fundamental frequency closely aligns with the vehicle's natural frequency, causing resonance and a significant PSD increase around 10 Hz. Motor excitation strongly affects wheel-related responses across all speeds, but other responses only at low speeds. Suspension and wheel responses are affected only by same-side motor eccentric excitation. The proposed method provides a novel framework for suppressing coupled multi-excitation vibrations in DDEVs.