The Research Of Shift Control Strategy For Automated Mechanical Transmission Of Electric Vehicles

As the car ownership and sales continue to rise of China,the auto industry's reliance on oil is increasing.The environmental problems brought about by the burning of petroleum have become a major problem in modern life.In order to control environmental pollution and mitigate energy crisis,on the one hand,the government has implemented a more stringent “National 6” emission standard to control the emission of pollutants from automobile exhaust;on the other hand,the government has introduced a series of policies to support the development of new energy vehicles,especially pure electric vehicles.As one of the core control technologies of pure electric vehicles,transmission shift control technology has also received increasing attention from the world's major automotive manufacturers and research institutions at home and abroad.With proper shift control strategies,the power economy of pure electric vehicles can be ensured while improving the energy economy and improving driving comfort.Since the drive motor of a pure electric vehicle has characteristics of fast torque rise and wide speed range,most of the pure electric vehicles currently available on the market use fixed speed ratio reducers,but this type of structure loses the gear shift effect of the transmission for the drive motor.The performance requirements are high,and the cost of the motor is also greatly increased.Researchers at home and abroad are now focusing on two-speed transmissions.For purely electric buses,off-road vehicles,long-distance buses,trucks and other vehicles with complex operating conditions and requiring more gear,the two-speed transmission obviously cannot meet the requirements.The focus of this article is the shift control strategy of the four-speed AMT transmission of pure electric vehicles.The proposed shift control strategy is also applicable to AMT transmissions with more gears.The main research contents of this article are as follows:1.Analyzed the layout methods adopted by pure electric vehicles.Based on the basic parameters and design requirements,the target models were matched with suitable drive motors and mechanical automatic transmissions,and the principle of maximizing the power performance and economic performance of automobiles was designed for shifting rules of the target model.2.The models were established to simulate the change of the state from the first gear to the fourth gear of the pure electric vehicle and to simulate the change of the state of active-driven parts of the clutch and impact during the shift from the low gear to the high gear.3.According to the linear quadratic performance index's optimal control method,the control strategy of the drive motor and the clutch state in the torque recovery process is formulated.The evaluation function is constructed to improve the car shift quality,the optimal trajectory of the speed and torque state of the drive motor and clutch under control is solved.4.Based on the optimal control results,in order to improve the performance of the entire system to adapt to external disturbances,the model predictive control(MPC)method is used to accurately follow the optimal control trajectory,and the advantages of the optimal control and the model predictive control are integrated to achieve the optimal control of the shift process.5.The characteristics of AMT shifting for pure electric vehicles without clutch and direct drive are studied.According to the different dynamic modes,the shifting procedures are divided into different execution stages,and the state of the synchronizer and the shift are simulated during the whole shift process.The impact of changes and analyzed.