Research On Driving Force Distribution Control Strategy Of Four-motor Independently Driven FSEC Racing Car

The problem of environmental pollution is becoming increasingly prominent,and the electrification of automobiles is considered an important measure to alleviate this problem in the world now.In order to cultivate relevant talents,the China SAE launched the Formula Student Electric China(FSEC)in 2013.In the past,electric racing cars were driven by a single motor.This arrangement has a single structure,and only the motor is used instead of the engine.The four-motor independently driven formula racing car fully utilizes the characteristics of compact structure,flexible layout,and independent controllable driving force of the electric drive assembly,showing a trend of popularization.But the resulting four-motor driving force control problem requires a new solution.Relying on the National Natural Science Foundation of China(51675257)and the Liaoning Provincial Department of Science and Technology Key R&D Program(2017106020),the thesis conducts research on the driving force distribution control strategy of the four-motor independently driven FSEC racing car,aiming to establish a safe and efficient driving force that meets the needs of the event Allocation strategy.The thesis conducts research on the following parts:Firstly,the drive system of the racing car is analyzed and a racing simulation model is established.The layout and power distribution characteristics of the racing drive system are analyzed,and put forward the driving force distribution requirements.Using CarSim and Matlab/Simulink to build a simulation model of the racing car.Based on CarSim software,the system models of racing car body,braking,aerodynamics,suspension and steering are built,the model I/O interface is defined,and the drive system model is built using Matlab/Simulink software.Secondly,racing car drive state estimation algorithm is researched.Using the Cubature Kalman filtering theory,construct the estimation algorithm framework,select the three-degree-of-freedom vehicle dynamics model as the estimation model,design a lateral force look-up table module based on tire data,combine longitudinal and lateral acceleration,yaw rate,and driving torque,the front wheel angle,etc.are jointly used as the input parameters of the estimation algorithm to obtain the state prediction value and the error covariance matrix.After the measurement and correction of the Kalman gain,the longitudinal and lateral velocity estimates and the yaw and acceleration correction values can be finally obtained.Thirdly,the driving force distribution control strategy is researched.Considering the control requirements comprehensively,an electronic differential speed control strategy,an efficiency optimal drive control strategy and a failure stability control strategy has been developed.The electronic differential control strategy calculates the vertical load of the four wheels and calculates the peak value of the longitudinal force in combination with the tire data,and allocates the tire attachment utilization rate to the driving torque required by the driver,and limit the wheel slip rate under low adhesion conditions to maintain the lateral stability of the vehicle.The efficiency optimal driving force control strategy constructs the driving efficiency objective function according to the motor driving efficiency MAP,and combines the grid traversal method to search for the optimal driving force distribution scheme under the current input conditions.The failure stability control strategy comprehensively analyzes the working status of the four motors.In the failure mode,according to the linear two-degree-of-freedom model,the yaw stability is taken as the control target for driving force distribution.Finally,the experimental verification of the developed control strategy is carried out.Integrate the racing simulation model and the control strategy model to build a test scene that meets the competition conditions.Using software-in-the-loop simulation to verify the effectiveness and real-time performance of the control algorithm,and use the driver’s hardware-in-the-loop to verify the practicality of the algorithm after real physical signal input and model generation code.The research indicates that the state estimation algorithm proposed in the paper can better estimate the state of the vehicle,and the driving force distribution algorithm can effectively improve the vehicle handling and stability under corresponding conditions.