Research On Electronic Differential Control Method Of The Electric Vehicle Driven By Rear Wheel

The energy crisis,environmental pollution is becoming increasingly serious,energy conservation and environmental protection has become the major topic in today's society.With its characteristics of no pollution and low energy consumption,electric vehicle has been rapid development in recent years.Although the rapid development of electric vehicle,but compared with the traditional fuel vehicle,there are some key technologies still relatively backward.Among them,the electronic differential technology is one of the key technologies of electric vehicle.The paper has carried on the certain research based on the domestic and foreign research achievements in the field of the technology of electronic differential.Based on the dynamic structure of electric vehicle,the paper establishes a 9 degree of freedom vehicle model in Matlab/Simulink environment and the related data collected through sensors.Through the linearization and simplification of 9 degree of freedom vehicle model,the state space model of 7 DOF linear system is obtained and the wheel slip ratio is determined as an important factor to measure vehicle differential performance.Firstly,using the standard ??-curve to set the fuzzy rule,a fuzzy controller is constructed to estimate the adhesion coefficient of road and the optimal slip ratio.Then,by following the optimal slip ratio of each wheel and equalizing the slip ratio of both drive wheels as target,electronic differential control strategy designed by sliding mode variable structure control algorithm is adopted to control the driving torque of the two rear wheels to realize the electronic differential function.At the same time,considering the external interference and measurement error and other factors make the system is not accurate enough,the external interference terms would be introduced to the state equation and based on terminal sliding mode algorithm to design electronic differential controller.In order to realize the higher performance of the controller,the genetic algorithm is used to optimize the parameters of the terminal sliding mode.Finally,the paper establishes the CarSim/Simulink joint simulation platform and designs two different simulation conditions.With the simulation comparison between the sliding mode variable structure control strategy and genetic algorithm terminal sliding mode control strategy,it proves that the two kinds of control strategies proposed in this paper are both can achieve the differential function of the vehicle,while the latter has better control performance.