Research On Fault Tolerant Control Of Distributed Drive Electric Vehicle Drive System Based On Full State Observer

As a current research hotspot,distributed-driven electric vehicles(DDEV)represent an important development direction of electric vehicles.Its biggest advantage is that each wheel can be controlled independently and the power output responds quickly compared with traditional vehicles.However,due to DDEV’s unique structure,the increase in the number of actuators increases the probability of failure.When the drive motor fails,if there is no corresponding control strategy,the vehicle will deviate from the expected driving path or even lose its stability,which will threaten the lives of drivers and passengers.Therefore,the faulttolerant control(FTC)strategy of the drive system is particularly important.With the goal of improving the stability of faulty vehicles,this paper takes a certain wheel-driven electric vehicle as the research object,and studies the problem of driving motor fault factor observation and fault tolerance control strategy.The main research contents are as follows:Firstly,the Carsim vehicle dynamics model of the wheel drive electric vehicle was established and verified.Analyzed the fault state of DDEV.According to its fault characteristics and the principles of vehicle dynamics,a seven-degree-of-freedom non-linear vehicle dynamics model including longitudinal,lateral and yaw motion of the vehicle body and four wheel rotations was built.And verify the validity and accuracy of the seven-degreeof-freedom vehicle model.Based on this seven-degree-of-freedom vehicle model and considering the nonlinear characteristics of DDEV,a method for observing faults in distributed-driving vehicles based on extended Kalman filter observer for all states is proposed.The simulation results show that the fault observer established in this paper can operate normally under all vehicle operating conditions(ie,full state),the estimation accuracy basically meets the requirements,and it has the ability to observe vehicle fault information in real time.Secondly,the active and passive fault-tolerant control strategies of vehicles are studied.Judge the credibility of the drive motor’s fault factor,and determine the appropriate current fault-tolerant control method based on the active/passive fault-tolerant control switching module,so as to give full play to the advantages of the active/passive fault-tolerant control method.Among them,the active/passive fault-tolerant control is based on the sliding mode variable structure control theory and the control strategy based on simple rule control,and the active control module is divided into the upper desired yaw moment calculation layer and the lower torque distribution layer;the passive control model passes The rule calculation directly solves the distribution torque.The active/passive fault-tolerant control strategy was simulated under straight-line driving conditions and steering driving conditions.The results show that the active/passive fault-tolerant control strategies designed in this paper can effectively improve the stability of the vehicle when the drive motor fails.And the active control strategy has better control effect than the passive control strategy.At the same time,the active/passive fault-tolerant control switching strategy can also give full play to the advantages of the two kinds of fault-tolerant control,and control the faulty vehicle more scientifically.Finally,a d SPACE hardware-in-the-loop experiment platform was established,and typical operating conditions were selected to verify the real-time and effectiveness of the control strategy.The results show that the fault-tolerant control strategy designed in this paper has excellent performance,can observe the current fault of the vehicle,and effectively improves the safety performance of the faulty vehicle.