Study Of Mode Switching Torque Coordination Strategy For P3 Commercial Hybrid Powertrain System

The development of traditional internal combustion engine vehicles has been significantly restricted due to the strong advocacy of environmental protection in countries around the world,and hybrid vehicles have gradually emerged in the automotive industry due to their advantages of low emission pollution and high power performance.The key to the advantages of hybrid vehicles is the ability to switch between multiple drive modes,but the torque shock generated during the mode switching process is a problem that needs to be solved.In this study,the P3 parallel commercial hybrid system is used to coordinate the torque fluctuations during mode switching by designing an optimization strategy based on a model predictive control algorithm to improve the driving quality of hybrid vehicles.Firstly,for the first time,the system structure of a P3 parallel commercial hybrid vehicle is taken as the control object,and a detailed analysis of the relevant components of the whole system is made to establish a dynamics model with clutch control as the main focus.The list of each operation mode of the hybrid vehicle is organized,and the torque fluctuation generated by the typical mode switching process from pure electric drive to combined drive is mainly coordinated.In addition,evaluation indexes for mode switching smoothness are developed with reference to the control of the shifting process,and the control effect is analyzed from several perspectives.Secondly,switching rules are developed for the selected typical mode switching process.Starting from the demand torque,real-time status of the engine and drive motor,and battery power,the switching rules are developed with the control objective of continuous engine and battery operation in the high efficiency zone.Then,the principles of the model predictive control algorithm are described.The optimization strategy is designed based on the model predictive control algorithm to plan the output of the main component torque during the mode switching transient.The strategy process of construction mainly includes: establishing a prediction model based on the kinetic equations of the clutch slip-grinding phase by discrete integration,considering the influence of the transmission resistance in the establishment process,and optimizing the matrix coefficients of the prediction model;establishing a reference model targeting the speed response under separate motor drive;designing the objective function and solving to obtain the control quantity in the prediction time domain;the output quantities and errors of the system are iteratively optimized by feedback correction to achieve optimal output values.Finally,the simulation is based on the AMESim-Simulink co-simulation technology.The main components of the hybrid system are physically modeled in AMESim software to determine the utility of the whole vehicle model,the simulation model of the control strategy is built with Simulink module,the joint simulation environment is configured and the parameter configuration is refined.The effectiveness of the designed control strategy is determined by verifying whether the simulation results are within the set evaluation index.A conventional motor torque compensation control strategy was also built based on the same platform and simulated in relation to the designed control strategy,so that the control effect can be more obviously derived.The simulation results show that under the control strategy designed in this thesis,the shock degree and slip work during vehicle mode switching are in accordance with the evaluation index,and compared with the traditional motor torque compensation control strategy,the shock degree and slip work were further reduced and the control effect is more excellent,which improves the quality of vehicle drive mode switching and ensures the smoothness of vehicle driving.