| With the rapid development of social industrialization,petroleum,coal and other fossil energy continue to consume and environmental pollution continues to intensify.Pure electric vehicle(EV)is called a feasible method to solve global environmental pollution and energy exhaustion because of its unique energy consumption and driving force.Hub-driven electric vehicles adopt more advanced driving mode,which is more simple and reliable in structure,more efficient in power transmission and has obvious advantages in handling and stability.But there are also some drawbacks,including the increase of hub motor deteriorates the ride comfort of vehicles,and the steering control characteristics are different from those of ordinary vehicles.Therefore,it is necessary to study the vertical vibration characteristics of vehicles and the stability of steering control.This paper mainly carries on the following researches:(1)Detailed information of road spectrum and classification of road grade are introduced.Pavement excitation is described by filtering white noise method and Simulink model is established.General evaluation methods and main performance evaluation indexes of ride comfort of electric vehicles are analyzed.(2)The 1/4 vehicle suspension dynamics model of the wheel-driven electric vehicle is established,and the vertical vibration characteristics of the wheel-driven electric vehicle are systematically studied.The research is mainly carried out from four aspects: analyzing the wheel-driven electric vehicle based on rigid connection under different conditions The vertical vibration characteristics;the spring-damped hub motor suspension structure is studied,and the vibration characteristics of the rigidly connected hub motor suspension structure are compared;the characteristics of the hub motor structure based on the elastic connection are discussed,and the new The vibration characteristics of the hub motor suspension structure are studied.A new type of hub motor suspension structure is designed for the integrated motor suspension and vehicle suspension,and the vertical vibration performance of the improved structure isdiscussed.(3)A six-degree-of-freedom 1/2 hub motor suspension model is established and simulated.The characteristics of the two models are analyzed by comparing with the1/4 hub motor suspension model.(4)A two-degree-of-freedom 1/4 vehicle model of hub-driven electric vehicle is established,and the vibration characteristics of vehicle driving process are analyzed by random vibration virtual excitation method.The response changes of three vehicle ride comfort evaluation indexes,namely,the vertical acceleration power spectral density of vehicle body under different road grades,different non-spring loads and different speeds,are studied.(5)By establishing the vehicle two-degree-of-freedom dynamic model and the steering system control model,the four-wheel steering system with the front-wheel proportional control of the all-wheel steering system,the traditional front-wheel steering system and the yaw rate feedback is studied in the vehicle yaw motion and side. |
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