Due to the lack of masking effect from the engine, noise and vibration from the
drivetrain system have become a critical issue in electric vehicles. To address
this problem, this study aims at proposing a comprehensive optimization method
with respect to multiple internal excitation sources to reduce the noise and
vibration of the electric drivetrain system (EDS). A rigid-flexible coupling
dynamic (RFCD) model is first proposed by incorporating the elements of electric
motors, gear pairs, bearings, shafts, and housing. Based on the proposed model,
optimizations concerning multiple internal excitations are carried out by
designing the notch width of the stator core and optimizing the modification
parameters of the tooth surface along the flank and lead direction. Meanwhile,
multiple operating conditions are considered in the optimization of the tooth
surface to cover a complete working condition of the EDS. The results show that
the torque ripple of the electric motor and the transmission error (TE)
fluctuation of the gear pair is effectively reduced. Besides, the dynamic
vibrations on the gearbox housing are also significantly decreased, which
verifies the validity of the proposed optimization method. Then, focusing on the
resonance phenomenon on the housing, a strengthened design by adding reinforced
ribs in critical positions is developed to reduce the resonance vibration. At
last, an experiment test is performed to verify the validity of the proposed
method. In general, this study proposes a comprehensive noise and vibration
reduction method for EDS, which can shed light upon the design of EDS with lower
noise and vibration for engineers.