| The development of new energy vehicles has been a global trend.The future development of vehicles is a combination of energy saving,green environmental protection,safety and efficiency.Four wheel drive electric vehicles are gradually widely concerned because of their simple mechanical structure and efficient four-wheel independent drive mode.However,the handling stability of four wheel drive electric vehicle is determined by the operation condition of four wheel motor.When motor failure occurs in the process of vehicle operation,if there is no corresponding control strategy,the vehicle will lose stability and deviate from the original path,which is likely to cause traffic accidents.Therefore,the fault-tolerant control of the four wheel drive electric vehicle is very important.In order to ensure the driving stability of the vehicle,this paper proposes a double-layer fault-tolerant control strategy for the four wheel drive vehicle when the motor breaks down suddenly.①The vehicle multi freedom model and tire magic formula model are established.For vehicle kinematics modeling,the 7-DOF vehicle model and the 2-DOF model which are more conducive to stability research are considered.For wheel modeling,based on the analysis of wheel load and sideslip angle,the "magic tire" model is established,and the relationship between transverse and longitudinal forces and slip rate under different working conditions is analyzed according to tire sideslip characteristics.②Aiming at the single motor control,a improved beetle antennae algorithm is proposed and applied to the intelligent control of motor.The motor adopts double closed-loop control system of current and speed,and optimizes the speed loop controller by using improved beetle antennae algorithm to obtain the best PID parameters.Based on Simulink,the simulation model of motor control system with beetle antennae algorithm is built,and the control results of traditional PI algorithm,beetle antennae algorithm and improved beetle antennae algorithm under three working conditions of no-load,speed step and sudden load are analyzed.The control model based on TMS32F28335 is established chip motor experimental platform,through two means of experiment and simulation,verify that the improved algorithm can effectively improve the motor control performance.③Aiming at the vehicle stability control of four motor drive vehicle,a double-layer fault-tolerant control strategy is proposed.Firstly,the motor failure mode is divided,and different failure modes are simulated;Secondly,the motor fault detection method based on fuzzy control is proposed to determine,the fault motor and output the motor operation factor;Finally,a double-layer fault-tolerant control strategy is proposed to ensure the stability of the whole vehicle after motor failure,and the upper layer is determined by the yaw rate and mass center sideslip angle.The sliding mode controller is designed to obtain the yaw moment to maintain the stable operation of the vehicle,and the ordinary PI controller is used to obtain the longitudinal moment.Two fault-tolerant control strategies are proposed in the lower layer to redistribute the motor torque.One is the quadratic programming algorithm with motor operation factor,and the other is the torque distribution algorithm based on fuzzy control law.④The simulation and experimental verification of fault tolerant control for vehicle driving fault behavior are carried out.According to the fault-tolerant control strategy proposed above,the CarSim and Simulink are combined to simulate and analyze different working conditions,different fault motors and different fault time according to the joint model,and the control effect curves of different strategies are obtained;According to STM32F407ZGT6,the simulation and experimental results show that the double-layer fault-tolerant control strategy designed in this paper redistributes the motor torque and effectively increases the vehicle driving stability when the motor fails. |
PDF Full Text Request