Research On Parameter Matching And Shift Strategy Of Transmission Power System For Pure Electric Vehicle

In recent years,with the increase of car ownership,China has begun to focus on the development of pure electric vehicles,so as to achieve overtaking in the automotive industry.The most important part of pure electric vehicle are three electrical systems : They are electric drive system,battery system and motor control system.Due to the current power battery and motor control system technology is weakness,the vehicle mileage,energy consumption rate and other economic problems need to be solved.Compared with traditional vehicles,the power performance of pure electric vehicles also needs to be improved.Base on a survey,the current pure electric vehicles mostly use permanent magnet synchronous motor and fixed gear reducer.So the requirement of driving motor is high.Drive motor has great speed control performance,through a fixed gear reducer can achieve the vehicle speed requirements.When the car is running in climbing or accelerating conditions,the drive motor works in the low efficiency area for a long time,which restricts the driving range of the car.In order to improve the dynamic and economic performance of pure electric vehicles,this paper takes a pure electric vehicle with a fixed gear reducer on the market as the research object.In this paper,the power system and transmission system of the vehicle are re-matched,and the fixed gear ratio reducer is changed to a two-speed transmission,so as to improve the power and economy of the vehicle.The specific research contents of this paper are as follows:1.Taking a pure electric vehicle as the research object,the power layout scheme of two-speed transmission is formulated.Based on the theory of vehicle dynamics,the selection and parameter matching of the driving motor and transmission are carried out.Taking the power performance of the vehicle as the constraint condition and the economic performance of the vehicle as the optimization goal,the matching transmission ratio is optimized by genetic algorithm.2.Taking vehicle speed and accelerator pedal opening as shift control parameters,the dynamic shift schedule,economic shift schedule and comprehensive shift schedule are formulated.Prepare for the following simulation validation.3.The vehicle model of pure electric vehicle is built in the simulation software Matlab /Simulink.The model includes six modules : cycle condition module,driver module,control system module,drive motor module,power battery module and vehicle dynamics module.The results of parameter matching are verified by the vehicle model.The simulation results show that compared with the pure electric vehicle,the power and economic performance of the two-speed transmission pure electric vehicle which parameter matching are improved.Among them,the climbing degree increased by 2.5 %,and the 100 km acceleration time decreased by 3.9 %.The energy consumption per 100 km decreased by 7.1 %,and the driving range increased by 2.17 %.Verify the correctness of the parameter matching.