Study On Drive Control Strategy Of Four-wheel Independent Drive Electric Vehicle

Four-wheel independent drive as an ideal of drive mode of the electric vehicle hasbecome an unique development direction. In this paper, Four-wheel independent driveelectric vehicle drive control systems is the object of study. We analyzed the domestic andforeign research present situation of four-wheel independent drive electric vehiclesechnology and they key technologies. We take the ASR(Acceleration Slip Regulation)and TCC(Torque Coordinate Control) as entry point,and studied the drive control strategyof four independent driving electric vehicle.Firstly, according to the difference of the four electric-drive electric vehicles with theconventional internal combustion engine vehicles,we have established7degrees-of-freedom vehicle model, that included vehicle longitudinal, lateral and yawmovement around the z-axis and four wheels rotation freedom.We used Dugoff tiremodel,that Can easily calculate the tire longitudinal force and lateral force.Secondly,we analyzed the factors influencing the stability,that include wheel slip rate,sideslip angle and yaw rate,and then formulated Acceleration Slip Regulation whosecontrol target was the optimal slip rate and Torque Coordinate Control whose controlparameters were Sideslip angle and yaw rate.We also showed Integrated control programto protect the vehicle stability.Again, we have designed ASR controller and TCC controller. The method of roadstatus automatic identification was used to Identify optima slip ratio of the different roadsin the ASR controller, and then use the fuzzy-PID compound control algorithm to controlthe tire slip rate to keep it at the optimum slip ratio. Torque coordination controllers usingfuzzy neural network control algorithm to achieve the coordinated distribution of thevehicle driving force，In order to meet the power performance and stability when thevehicle goes straight or turn.Finally,we simulated and analyzed drive control system with Matlab/Simulink. Theresults showed that:(1) The ASR control system based on road Identification can remainthe tire slip rate near the optimum slip ratio to get better traction control effect whenvehicles driving in bad road conditions.(2) The TCC control system can achieve thecoordinated distribution of the vehicle driving force, and enabling the vehicle to havebetter starting performance as well as straight-line driving stability. In turning conditions, the TCC has electronic differential function to assist driver in steering to ensure that thevehicle cornering stability and driving safety.