| With the worsening of global resource shortage and environmental pollution,electric vehicles have attracted more and more public attention due to zero emission and low noise.However,due to the bottleneck of battery technology,electric vehicles cannot meet users’ longdistance driving needs.Reducing the energy consumption of the vehicle is an important way to improve the range of electric vehicles.How to reduce the power consumption of the vehicle is an important problem.The two-speed transmission system can adjust the efficiency of the driving motor under different working conditions and improve the working efficiency of the motor,it has become an important scheme to reduce the power consumption of the whole vehicle.In this paper,taking power performance and economy into consideration,the power parameter matching optimization,shifting strategy and control strategy are studied.On the premise of ensuring the power performance of the vehicle,the energy utilization rate of the vehicle is improved,and the driving range of the vehicle is increased.Firstly,the two-speed transmission system is preliminarily matched according to the NEDC(New European Driving Cycle).Then,based on the traditional dynamic shift strategy,the cycle power consumption is calculated by ADVISOR(Advanced VehIcle SimulitOR)with a speed ratio of two gears as the optimization variable,and the optimization model is solved by calling the calculation function by genetic algorithm.Secondly,after analyzing the transmission shifting strategy,the maximum acceleration dynamic shifting strategy and the best economy shifting strategy is respectively established,then simulation analysis was taken,the result proves that the two shifting strategy can meet the needs of drivers’ different scenarios.Then,according to the driving mode selection information,the electric vehicle drive model was changed,the basic driving torque was got for different mode,and torque compensation strategy based on fuzzy control algorithm was put forward after considering the vehicle impact,the control strategy of vehicle was composed of shifting strategy and drving strategy.Finally,the drive control strategy and shift control strategy model was built by MATLAB/Simulink,electric vehicle model was also built by AVL_Cruise.Maximum speed,maximum gradability,accelerate ability were used in dynamic performance simulation and the NEDC cycle condition power consumption and motor efficiency and vehicle fuel economy were used in ecnomic simulation.The results show that the two-speed electric vehicle is better than the fixed speed electric vehicle in economy because of the more reasonable working point of the motor.The maximum gradient,in situ start acceleration time,the maximum speed is also slightly better than the fixed speed ratio of pure electric vehicles. |
