Research On Fault Tolerant Performance Of Active Suspension Control Of In-wheel Motor Electric Vehicle

With the increasingly serious environmental pollution,energy crisis and increasing attention to green energy vehicles at home and abroad,the electric vehicle market is gradually increasing.In-wheel motor electric vehicles have become a research hot spot because of their energy-saving,high-efficiency,environment-friendly,compact structure and independent control of individual wheels.However,the introduction of in-wheel motors has a certain negative impact on vehicle ride comfort.A variety of improvement methods have been proposed to relieve the negative impact of the in-wheel motor on the ride comfort of vehicles.Among them,improvement through suspension control is an effective method.However,previous studies have seldom considered the influence of in-wheel motor eccentric excitation on the suspension control effect.The study considers the influence of motor eccentric suspension on the improvement of in-wheel motor electric vehicle ride comfort,which has theoretical value and practical application significance.Active suspension can be used to improve car ride comfort,the model or parameter uncertainty,external disturbance,measurement error,actuator failure and sensor failure should be considered during the application process.These phenomena will affect the active suspension Control fault tolerance performance affects.Aiming at the problem of fault-tolerant performance of in-wheel electric vehicle active suspension control,this paper considers the combined effect of the road disturbance and the in-wheel motor vibration.Based on the plane model,the passive suspension modeling and performance analysis of the in-wheel electric vehicle are carried out.Research work on the design and performance analysis of frame state feedback H_∞control,active suspension state estimation feedback H_∞control and performance analysis,fault-tolerant performance analysis considering the state of active suspension actuators.The main contents of the study are as follows:(1)Aiming at the influence of motor introduction on in-wheel motor electric vehicle,the four free plane performance model of passive suspension of hub motor electric vehicle is established,and the suspension performance indexes of random road and pulse road are determined.Based on filtered white noise and Pade approximation,the front and rear wheel excitation model of random road disturbance is established,the front and rear wheel excitation model of pulse road disturbance model is established based on national standard,and the eccentric excitation model of typical four phase 8/6 pole switched reluctance motor is established based on motor stator and rotor eccentricity.The simulation model of the performance of the passive suspension of the hub motor electric vehicle is developed by MATALB/SIMULINK.The performance of the in-wheel motor electric vehicle passive suspension on random road and pulse road is analyzed without eccentric,front wheel eccentric,rear wheel eccentricity and double wheel eccentric at the same time.The results show that the rotor eccentricity of the motor has an important influence on the performance of the passive suspension of the in-wheel b motor vehicle.(2)The linear matrix inequality(LMI)and Schur complement lemma are explained,and the MATLAB solution method of LMI is given.The standard state feedback H_∞control and constrained state feedback H_∞control are summarized to overcome the problem of too complex description in the past.The four free plane performance model of the active suspension of the in-wheel motor electric vehicle is established,and the constrained H_∞state feedback control is applied to design and realize the control design of the active suspension of the in-wheel motor electric vehicle.This paper presents a method to determine two state feedback H_∞control parameters by simulation.The control performance simulation model of in-wheel motor electric vehicle active suspension is developed by using MATALB/SIMULINK.The effectiveness of the H_∞state feedback controller is illustrated by the simulation results of random road and pulse road.(3)Considering the control term of measurement equation and external disturbance,the expression of discrete linear system of Kalman filter algorithm and its derivation process,matters needing attention and the implementation of SIMULINK are given.The discrete program of linear continuous system is realized by MATALB command.The discrete simulation model of active suspension performance of in-wheel motor electric vehicle is developed by MATALB/SIMULINK.The results of continuous and discrete simulation models of active suspension performance of in-wheel motor electric vehicle on random road and pulse road are compared,which shows the effectiveness of the discrete simulation model.Using four responses that can be measured by sensors,the system state estimation is realized by combining the discrete simulation model of active suspension performance of in-wheel motor electric vehicle and Kalman filter algorithm.The state estimation feedback H_∞control simulation model of active suspension of wheel motor electric vehicle is developed by MATALB/SIMULINK.In the case of no motor eccentricity and front and rear motor eccentricity,the effects of state estimation and state feedback on random road and pulse road are compared respectively,and the effect of H_∞feedback control based on Kalman filter state estimation is illustrated.The state model of actuator which can consider the normal state and main failure state of actuator is established.Based on this,the active suspension actuator state model considering the state of front and rear suspension actuators is established.Combining the active suspension actuator model with the in-wheel motor electric vehicle,a state feedback H_∞control performance model of the active suspension of the in-wheel motor electric vehicle considering the state of the front and rear suspension actuators is developed by using MATALB/SIMULINK.In the case of constant gain fault and constant deviation fault of active suspension actuator,the theoretical output force of fault free suspension on random road and pulse road is compared with the actual output force and its difference when both front and rear actuators fail at the same time.The fault compensation control method is designed by combining Kalman filter with actuator fault.The corresponding simulation model of active suspension fault compensation control of in-wheel motor electric vehicle is developed by MATALB/SIMULINK.In the case of constant gain fault and constant deviation fault,the fault tolerance performance of active suspension is analyzed for random road and pulse road respectively.The results show that the fault compensation control based on Kalman filter and actuator state can eliminate the influence of actuator fault to a certain extent.The above research shows that motor eccentricity has an important impact on vehicle ride comfort,and the negative effect caused by motor eccentricity should be considered in-wheel motor electric vehicle;vehicle ride comfort can be improved by active suspension control design,state estimation can be realized by using Kalman filter,and wheel stability can be realized by combining H_∞control,Kalman filter and actuator state model Fault tolerant performance of active suspension control for in-wheel motor electric vehicle.