Research On Parameters Optimization And Control Strategy Of A Two-speed Electric Vehicle Powertrain For Energy Consumption

With the shortage of resources and environmental problems become more and more serious,pure electric vehicles attracts more and more attention with its zero emissions and low noise advantages.But the problem of short mileage has been an important factor restricting the development of electric vehicles.Reducing energy consumption of electric vehicles can improve the vehicle mileage effectively.The main drive system as the main energy consuming components of electric vehicles,how to reduce the energy consumption of main drive system to improve the electric vehicle mileage is an important problem to be solved urgently.A two-speed automatic transmission system is proposed in this paper.To improve the energy efficiency of the vehicle under the premise of ensuring the dynamic performance,dynamic parameters of the system are optimized and control strategy is studied,thereby the mileage of the vehicle is improved.First,characteristic of EV energy consumption is analysis,the main driving system is the main energy consuming components of electric vehicles is pointed,and the energy consumption model of the main driving system is established;then the energy saving potential of two-speed transmission system is illustrated through the analysis of real-time working efficiency of the motor.Secondly,the parameters of two-speed transmission system are preliminary matched based on the New European Driving Cycle(NEDC).Then a multi-objective optimization model is established based on the control strategy and real-time efficiency of motor,which takes power and speed of motor,and gear ratio as the variables,specific energy consumption and acceleration time from 0 to 100km/h as the optimization objectives.The model is solved by multi-objective particle swarm optimization algorithm,and the results show that the optimized parameters of the powertrain could improve the dynamic and economic performance of electric vehicle.Thirdly,the motor torque output curves under different driving modes are determined according to the accelerator pedal information,and torque compensation strategy for low-energy consumption is put forward considering the driver,motor,battery and other information.Based on that,the dynamic shift schedule and economic shift schedule are developed,and the optimization model of shift schedule considering economic and dynamic characteristics is established,then the comprehensive performance shift schedule curve is obtained.Finally,the economic performance simulation model and dynamic performance simulation model are established by MATLAB/Simulink.Compared with the simulation results of the fixed speed ratio reducer,both the dynamic performance and the economy of the two-speed transmission system are improved.