Research On Multi-actuator Fault Tolerant Control Of Distributed Drive Electric Vehicle Drive System

As a series of problems such as the energy crisis and environmental pollution have become increasingly severe,electric vehicles have gradually become a trendy means of transportation.The distributed drive electric vehicle drive system has four independently controllable executive motors.Its unique drive mode has attracted widespread attention,but the increase in the number of actuators has led to an increase in the failure rate.The failure of the drive system of the distributed drive electric vehicle during driving will cause the vehicle to produce yaw deviation,cause vehicle instability,and even cause serious traffic accidents to threaten the lives of passengers and passengers.Therefore,the research on fault-tolerant control of vehicles is of great significance.This article combines the research content of the national key research and development plan project "Study on the key basic issues of perception,decision-making and control of smart electric vehicles"(2016YFB0100905).Aiming at the problem of multi-actuator failure in the drive system of distributed drive electric vehicles,the multiactuator of the drive system is carried out.Active fault-tolerant control research.The main research contents are as follows:(1)Reliability analysis of distributed drive electric vehicle drive system.Considering the impact of reliability on vehicle driving safety,based on the fault tree analysis method FTA(Fault Tree Analysis),the structure principle of the drive system is analyzed,the drive system actuator fault logic tree is established,and the failure mechanism of the main components of the drive system is analyzed.In this way,the reliability evaluation model of each component is established to evaluate the reliability of the drive system and identify the weak links of the drive system and the main factors of the drive system failure.Select one of them to carry out the study of the motor failure problem,establish a motor failure model,introduce the motor failure characteristic parameter f to describe the degree of failure,and clarify the drive system to implement the motor failure mode.(2)Distributed drive electric vehicle drive system executive motor failure characteristics research.Establish a three-degree-of-freedom model of the vehicle body(including longitudinal,lateral and yaw),a wheel motor model and a nonlinear tire model to form a seven-degree-of-freedom vehicle dynamic model that includes the drive system and the tire to describe the actual vehicle driving state.Considering the strong nonlinear characteristics of distributed-driven electric vehicles,using Unscented Kalman Filter(UKF)algorithm,a research method of motor failure characteristics based on vehicle status is proposed.Combined with the established motor failure model,the motor failure characteristic parameter f is transformed into the vehicle state variable by using the random walk model.By real-time estimation of the failure characteristic parameter,the study of the motor failure characteristic is realized,and the accuracy and real-time performance of the algorithm are verified.(3)Research on Multi-actuator Failure and Fault Tolerant Control of Distributed Drive Electric Vehicle Drive System.Aiming at the problem of motor failure in the drive system,considering the limitation of only relying on torque distribution control to cope with the failure mode,a collaborative fault-tolerant control method based on rotation angle compensation and torque distribution is proposed.With the goal of tracking the desired longitudinal vehicle speed,the longitudinal speed following PI controller is designed to compensate for the loss of power due to motor failure;then based on the second-order sliding mode control(SSMC)theory,the yaw rate error for the control input,the expected yaw moment and the front wheel compensation angle that satisfy the stability are solved.The steady state of the vehicle is analyzed based on the phase plane method,and the control switch is realized according to the state of the vehicle.Combined with the motor failure characteristic parameter f after binarization,the average distribution algorithm is used to redistribute the driving torque under the control constraints of motor capacity/increment and road adhesion coefficient.The simulation results show that the algorithm can deal with multiple failure modes,has strong robustness,can ensure the stability of the vehicle when it fails,and make the vehicle have good fault tolerance.