Research On Vibration Control Method Of Electric Vehicle Suspension System Driven By In-Wheel Motors

Vehicle has become one of the most important modes of transportation in today's society.In recent years,mankind is faced with severe energy,environment and climate challenges with the rapid growth of automobile production and possession.New energy vehicles represented by electric vehicles are the best choices for sustainable traffic development.In-wheel motor has characteristics that the torque response of the motor is faster than the internal combustion engine,and can realize the independent control of the driving and braking force of each wheel directly through the wire control technology.It has been regarded as the ultimate drive form of electric vehicle.However,on the one hand,unsprung mass of the vehicle is increased,and on the other hand,ground excitation is acted on in-wheel motor directly,both of which affect dynamic characteristics of electric vehicle.In this paper,this research includes as follows:Fristly,the dynamic model of 1/4 the electric vehicle linear suspension system is established and dynamic characteristics of the system are analyzed.Linear dynamic vibration absorber is attached to sprung and unsprung mass separately,and differential equations of suspension-linear vibration absorber system are established and solved.Dynamic characteristics of the suspension-absorber system are obtained and parameter influence analysis is carried out.The results show that the linear vibration absorber can effectively suppress the vibration of the sprung and unsprung masses near their natural frequencies.Moreover,the nonlinear dynamic vibration absorber(NES)with cubic stiffness is added to sprung mass.Differential equations of the electric vehicle suspension-nonlinear dynamic vibration absorber system are established.The Complexification-averaging method is used to solve the equations,and bifurcation and stability of the equilibrium point are analyzed.The parameter interval of strongly modulated responses can be obtained,and dynamic characteristics of the suspension-nonlinear dynamic vibration absorber system are obtained.The results show that the nonlinear vibration absorber can reduce the vibration of the sprung mass near its resonance region.Additionally,introducing the control action into the electric vehicle linear dynamic absorber,the differential equation of the suspension-active vibration absorption system is established.The state equation of the control system is obtained.Based on the quadratic linear optimal control theory,the active dynamic vibration absorber is designed.The dynamic characteristics of the suspension-active vibration absorption system are analyzed under the sine and stochastic excitations.The influences of the system parameters are discussed.Finally,introducing the control effect directly on the suspension system,the differential equation of the electric vehicle active suspension system is established.The state equation of the control system is obtained.The active suspension system is designed based on the quadratic linear optimal control theory.The dynamic characteristics and the influences of the system parameters are analyzed under the sine and stochastic excitations.Additionally,some experiments are conducted to verify the designed controller.