Research On Coordinated Torque Control For Drive Mode-Switch Of Hybrid Powertrain Based On P2 Configuration

With the increasing depletion of oil resources and national emission regulations for cars increasingly demanding,the car companies are committed to the development of new energy vehicles,hybrid electric vehicles is one of the hotspot.There are many kinds of work modes in hybrid electric vehicle,and the mode switching often occurs in different driving conditions and driver requirements.Due to the different dynamic response characteristics of the engine and the motor,it is easy to affect the ride comfort of the vehicle when the mode is switched.Therefore,it is necessary to control the mode switching process of hybrid electric vehicle to improve the driver's comfort.In this paper,the hybrid powertrain based on P2 configuration is studied,and the torque coordination control strategy for dynamic process of drive mode switching is analyzed and researched on,the main research contents can be summarized as follows:?The structural characteristics of hybrid powertrain based on P2 configuration are analyzed,based on the analysis of the steady state characteristics,dynamic characteristics and starting resistance moment of the engine,the throttle opening model and the engine model based on the experimental data modeling method are established.The structure and work principle of wet multi disc clutch are introduced,based on the analysis of the clutch engagement process and the torque characteristics,the simulation model is established.According to the characteristics of the motor torque response and the relevant test data,the first order response of the motor model is established.An internal resistance battery model is established by using the test data of lithium ion batteries.On the basis of theoretical analysis,the double mass flywheel and dry DCT transmission model are established.According to the classical vehicle dynamics equation,the vehicle longitudinal dynamics model is established.?According to the work mode area divided,the power supply torque and clutch state are determined in different drive modes.Based on the simplification of the powertrain,the dynamic analysis is carried out for the work mode in the driving state.The evaluation index of switching quality uses the jerk,based on the definition of the jerk,the jerk equation of hybrid powertrain is derived.The stage of EV to engine only,engine only to EV and engine only to hybrid are divided,the dynamic equations of different stages and jerk equation and the feasible region of torque change rate are obtained.According to theoretical analysis,clutch engagement process,clutch separation process,no clutch action process are divided.?According to the dynamic process control of drive mode switching,the control methods of engine,motor and clutch are presented,the engine is mainly based on throttle opening rate of change and PID control,the motor uses vector control to control,and the control of the transmission torque of clutch sliding stage is realized by controlling the oil pressure of the first stage and the change rate of the oil pressure.The control flow of drive mode switching is established,and the influence of different ignition modes on the ride comfort is analyzed,according to three types of mode switching process,torque coordination control strategies are made separately.?Torque coordination control strategy model and other control strategy model are established.The top level control module of the hybrid powertrain system is established,and the whole vehicle mode switching control module are listed.The engine starting process is simulated,the results show that the use of engine target speed and same torque ignition method is more stable.The simulation and analysis of the control strategy for the clutch engagement,separation and no action are carried out respectively,the results show that the torque coordinated control strategy can effectively reduce the jerk and improve the ride comfort.The simulation results and analysis of coordinated control strategy with or without feasible region limits show that coordinated control strategy with feasible region limits can effectively control the jerk of switching mode and meet national regulatory requirements.