Research And Development Of Stright Line Driving Control Strategy For Four-wheel-drive Electric Bus

As an important development direction of electric vehicles,distributed drive electric vehicles have key technologies such as vehicle motion control and optimal driving force distribution.This study designs the drive control strategy of a four-wheel-drive electric bus,which based on the longitudinal motion control of the vehicle under straight-line driving conditions.In order to meet the power requirements,reasonable selection and matching of power components is required to meet the design indicators;to meet the driver’s operating intentions,a reasonable analysis of the accelerator pedal signal is required;to meet the different driving conditions,reasonable distribution of torque is required.The research contents are as follows:Firstly,the motor is matched and selected according to the dynamic index of the passenger car,and the vehicle dynamics model and related components such as vehicle model,motor model,battery model,tire model and driver model are established by AVL Cruise vehicle simulation software.The model is validated by real vehicle data to establish the basis for subsequent research.Secondly,processing the accelerator pedal signal: if accelerator pedal signal is large,on the basis of ensuring the real-time response of the torque,the jerk constraint is added to ensure the passenger’s comfort;if accelerator pedal signal is small,smoothing the accelerator pedal signal,in order to suppress frequent fluctuations of the pedal.Then,distribution of driving torque: On the asphalt road,driving torque distribution is based optimal torque distribution method which is based on motor electric efficiency MAP chart;on the slippery road,the fuzzy-PI control method is used to adjust the driving torque,in order to reduce the slip rate.Lastly,the drive torque control algorithm is based on modeling thought,which building the model through the Matlab/Simulink platform,including an accelerator pedal analysis model,an optimal torque distribution model,and a Acceleration Slip Regulation model.At the software simulation stage,setting cycle run,constant speed,and slow acceleration working conditions,in order to analyze the impact of economy by using the optimal torque distribution control strategy and the slow accelerator pedal strategy;On the asphalt road,analyze the effects of dynamic and comfort by using rapid acceleration pedal strategy in rapid acceleration working conditions;On the slippery road,analyze the impact of the dynamics by using acceleration slip regulation strategy.At the hardware in loop stage,thereal-time performance of the control algorithm is verified by the dSPACE platform,and the last stage is real vehicle test the control strategy which designed before is downloaded in vehicle controller to do some real vehicle test.Based on the above research,this paper simulates the normal working conditions,such as rapid acceleration,slow acceleration and constant speed working conditions by using simulation software,HIL platform,and doing some real vehicle test.The results show: Slow accelerator pedal strategy can improve vehicle economy in constant speed working condition;the rapid accelerator pedal analysis can effectively reduce the jerk of the vehicle in rapid acceleration working condition;the optimal torque distribution control strategy can improve vehicle economy in cycle run or good road conditions;the fuzzy-PI acceleration slip regulation control strategy can ensure vehicle dynamics and reduce the slip rate on the slippery road.