Research On Control Strategy Of Parallel P2.5 Hybrid Vehicle Based On AMT

With the depletion of fossil energy and the growing problem of environmental pollution,safety and environmental protection have become the two major themes of today's automotive development.Hybrid electric vehicles are one of the technical directions for the development of automobiles towards cleanliness and electrification.They are equipped with two sets of power systems,engine and motor.According to the combination of different working states of the two power sources,there are various working modes of the vehicle's power system.In a parallel AMT hybrid system,the switching between different working modes will affect the ride comfort and power of the vehicle.When the AMT parallel hybrid vehicle switches,there is power output interruption and shift shock.Seriously affect the driving comfort and power of the vehicle.So,this paper chooses to study the mode switching and power shift control strategy of AMT parallel hybrid system to solve the above problems.This topic comes from the actual project of engineering,that is,the development of parallel P2.5 hybrid system based on AMT,mainly for the development of vehicle control unit(VCU)and transmission control unit(TCU)for the new P2.5 hybrid system.The research content of this paper is part of the project development,mainly researching the mode switching control strategy and power shift control strategy of P2.5 system.Firstly,this paper introduces the structure of the P2.5 system and analyzes its power coupling device.The hybrid motor can be connected to the AMT input shaft through a twospeed electric gearbox,or it can be connected to the output shaft.The single motor realizes the function of “P2+P3” configuration,so P2.5 The working mode of the system is more than that of the traditional parallel system,and the main modes of the system are analyzed.In order to optimize the engine fuel interval,the vehicle torque demand,mode division and power source target torque distribution of P2.5 system were studied according to the torque distribution strategy.Aiming at the switching process between different modes of division,four representative mode switching are selected and analyzed,and a mode switching control strategy based on motor dynamic coordination is proposed.In order to evaluate the quality of mode switching,an evaluation index of impact degree and switching time is proposed.Secondly,using the structural characteristics of P2.5 system,a power shift control strategy for optimizing AMT shift quality is proposed.Aiming at the problem of power interruption and shifting shock during the AMT shifting process,the dynamic characteristics of the clutch transmission torque and the control strategy of the motor dynamic compensation are solved.The dynamic characteristics of the clutch transmission torque are realized by an adaptive control algorithm based on the Kalman filter algorithm estimation and the clutch transmission torque characteristic curve.Combined with clutch transmission torque characteristics,the power shift control strategy dynamically compensates the reduced output torque of the engine in the initial stage of the shifting clutch disengagement to ensure the stability of the vehicle output power;After the clutch is completely disengaged,the motor separately outputs power,so that the driver's demand torque is maintained constant,and the gear shift is completed;After the gear shift is completed,the clutch is closed and the motor is used to adjust the output torque to maintain the stability of the total output torque.Finally,according to the theoretical model and test data of each component of P2.5 system,the simulation model is built in Matlab/Simulink software,and the control strategy is standardized modeling in accordance with the software development specification.After setting up the completed simulation model,different test cases are created to simulate the mode switching and power shift control strategies.The simulation results show that the proposed mode switching control strategy can significantly improve the smoothness of the output torque of the P2.5 system during mode switching.The power shift control strategy avoids the power interruption during the AMT shifting process and significantly reduces the shift shock.Then the bench test is carried out,and the mode switching and power shift control strategies are verified by the bench.The test results are in good agreement with the simulation results,which further verifies the accuracy and effectiveness of the proposed control strategy.