Distribution And Control Of Driving Force In Distributed Drive Electric Vehicle Based On Optimal Energy Consumption

With the increasing awareness of automobile energy conservation and emission reduction,and the rapid development of battery,electric motor and electronic control technology,electric vehicles have gradually become the research focus of manufacturers and experts.The distributed drive electric vehicle,which is driven directly by four in-wheel motors,has been strongly supported by the government and researchers for its flexible layout and control advantages.In this paper,a four in-wheel motors driven electric vehicle is taken as the research object,and the strategy of optimal energy-saving torque allocation for distributed drive electric vehicle is studied.Firstly,a distributed drive electric vehicle has been modified from a pure electric vehicle by rebuilding the mechanical structure and control system.The D2 P rapid prototyping has been used as vehicle controller to build the control system of the vehicle.Based on the parameter of the real vehicle,a co-simulation platform of the vehicle has been built based on Matlab/Simulink and CarSim.The simulation platform mainly includes the CarSim vehicle model,the in-wheel motor model based on the bench test data,the driver model and the power battery model.Secondly,after the analysis of the driving structure of the distributed drive electric vehicle and the driving efficiency of the in-wheel motor,the feasibility of reducing the energy consumption of the whole vehicle through optimal torque distribution has been demonstrated.When the drive cycle is given,the optimal control problem which takes the ripple of the motor output torque and the optimal energy consumption of the vehicle as the comprehensive goal has been studied,and the dynamic programming has been used to carry out the strategy of torque distribution.The simulations of the FTP drive cycle and the NEDC urban drive cycle have been carried out.The energy consumption of the vehicle under different torque distribution algorithm has been compared.The final energy consumption results show that the energy consumption of the vehicle is reduced by 14.5% in the FTP drive cycle,and9.7% in the NEDC urban drive cycle.The results show that the optimal torquedistribution strategy can save energy and has an good adaptability.Finally,in order to realize the optimal torque allocation in real time,a vehicle road test has been carried out.After collecting and counting the road driving cycles,the maximum likelihood estimation method has been used to achieve the transfer probability matrix of the driver's demand power,so as to establish the Markov model of the driver's demand power.Based on the analysis of stochastic dynamic programming,combined with the characteristics of distributed drive electric vehicle driving system,an optimal control model according to the characteristics of the system has been established.After solving the optimal control model,the results of optimization algorithm have been imported into the vehicle controller to verify the control strategy.After the statistical calculation of data of the road drive cycle,the experimental results show that the energy consumption of the vehicle under the torque optimization algorithm is 5.4% less than that of the average torque distributed.The designed torque optimization algorithm can effectively reduce the energy consumption of vehicles.