Research On Failure Control Of Four-Wheel Independent Drive Electric Vehicle Drive System

Due to the gradual reduction of oil resources,the greenhouse effect and the haze weather,the problems of the automotive industry in various countries around the world have gradually shifted their focus to the research of new energy vehicles.New energy vehicles such as pure electric and hydrogen energy have become the key development directions of the future automotive industry.The power of the four-wheel independent driving electric vehicle with the hub motor as the driving unit is directly derived from the motor installed in the wheel,and the traditional components such as the transmission,differential,and drive train are discarded,which can save more space to expand the seating space or deploy more batteries to increase the range of electric vehicles.Because the Four-wheel independent drive electric vehicle's four drive motors can be controlled separately,it is more accurate,more flexible,and has more degrees of freedom,but it also greatly increases the probability of failure.When the drive motor fails,it cannot provide the desired output torque.At this time,the stability and safe driving of the vehicle can be ensured by reallocating the remaining driving capacity of the drive system.Therefore,it is necessary to research the torque redistribution control strategy after the failure of the drive system of four-wheel independent drive electric vehicle,which is also one of the key technologies for the development of four-wheel independent drive electric vehicle.The force of four-wheel independent driving electric vehicles is analyzed,the mechanism of the failure of the driving system on the stability of the vehicle is analyzed,and the theoretical basis for maintaining the stability and dynamics of the vehicle by redistributing the driving force is described.The in-wheel motor model is established in Simulink,and the Car Sim-Simulink co-simulation platform is established.Considering the situation of partial failure of the hub motor,the failure of the drive system is divided into four categories.By analyzing the failure degree,the number of failures,and the failure location of the four drive motors,the ability of the vehicle to drive in this case is judged.Compared with other failure classification methods,it shows that the failure classification method proposed in this paper can consider more failure situations and greatly improve the drivability of the vehicle.Combined with vehicle stability control theory,based on sliding mode control method,additional yaw moment control is introduced.Taking the yaw rate and the sideslip angle as the control targets,the additional yaw moment is calculated by sliding mode control theory.According to the failure classification method proposed in this paper,the torque redistribution control strategies are designed for the four types of failure modes.The Car Sim-Simulink co-simulation platform was used to verify the failure control strategy of the drive system under straight linear,turning and Sine wave conditions.The simulation results show that the designed failure torque redistribution control strategy can ensure the stability and dynamics of the vehicle.It can improve the drivability of the vehicle and verify the effectiveness of the failure control strategy.