Research On The Mechanism Of Vertical Vibration And Vibration Suppression Of Electric Vehicles Driven By In-Wheel-Motor Under Static Eccentric Condition

In light of the pressing concerns surrounding global warming and the energy crisis,the significance of new energy vehicles,particularly electric vehicles,cannot be overstated in the pursuit of sustainable transportation development.Among these vehicles,the In-Wheel-Motor driven electric vehicle(IWMDEV)represents a crucial development direction for future endeavors.However,the integration of the IWM into the vehicle hub as a pivotal dynamic component results in a notable deterioration in its smoothness,owing to its intricate structure,augmented unsprung mass,and multifaceted force coupling.Consequently,investigating the vibration mechanism of the IWMDEV and devising methods to suppress these vibrations hold paramount theoretical significance and engineering value,essential for mitigating the smoothness predicament associated with IWMDEVs.This paper presents the specific research findings in the following manner.Initially,we analyze the characteristics of vertical unbalanced magnetic force(VUMF)exhibited by the permanent magnet synchronous hub motor(PMSHM)in a state of static eccentricity,considering varying eccentricity levels and vehicle speeds.This analysis involves establishing analytical models for the air gap magnetic field and electromagnetic force density of the PMSHM in both eccentricity-free and static eccentricity states.Furthermore,we investigate the frequency and spatial order distribution characteristics and validate the analytical models through corresponding finite element models.The results reveal that the VUMF of the PMSHM increases with eccentricity,with its magnitude and fluctuation range progressively expanding.Moreover,it assumes a quasi-constant force nature,while exhibiting decreased fluctuation range and increased fluctuation frequency with increasing vehicle speed.Subsequently,we establish mathematical and simulation models to examine the vertical vibration of the IWMDEV quarter car under the influence of road surface excitation.Additionally,we introduce the VUMF in the static eccentric state to establish mathematical and simulation models for the vertical vibration of the IWMDEV quarter car under the coupled excitation of the road surface and electromagnetic force.Building upon the aforementioned,we delve into an investigation of the inherent vibration characteristics of the IWMDEV quarter car under the coupled excitation of road surface and VUMF.We analyze its vertical vibration mechanism and characteristics across various levels of road surface conditions and vehicle speeds.Moreover,we comparatively analyze the vibration response indices of the IWMDEV under the coupled excitation of road surface and VUMF in contrast to road surface excitation alone.Our findings indicate notable disparities in the amplitude of unsprung mass acceleration in both the time and frequency domains,whereas body acceleration exhibits marginal differences.Conversely,the amplitude of seat acceleration,suspension dynamic deflection,and body displacement shows insignificant variation across the time and frequency domains.Finally,we employ passive suspension,semi-active suspension based on skyhook damping,and an active suspension control strategy based on reinforcement learning to address the vibration issues associated with the IWMDEV under road excitation and the coupled excitation of road surface and VUMF,respectively.We evaluate the vibration response of each system after implementing the respective control strategies.The results demonstrate that,in terms of controlling vertical vibration in the IWMDEV,the active suspension control strategy based on reinforcement learning outperforms both passive suspension and skyhook semi-active suspension control strategies.Notably,the control effectiveness of the reinforcement learningbased active suspension strategy consistently surpasses that of passive suspension and the semiactive suspension control strategy.In conclusion,this study sheds light on the intricate vibration characteristics of the IWMDEV and proposes effective measures to mitigate these vibrations,fostering advancements in the field of sustainable transportation.