Research On Coordinated Control Strategy For The Engine Starting Of HEV

The dynamic coordination of the mode switching process is the hotspot of the power split hybrid vehicle research.In this paper,the electro-mechanical transmission system was taken as the research object.The subjects of in-situ engine starting control and vehicle in-motion engine starting coordinated control were researched.The engine starting coordinated control strategy was obtained and verified by simulation and experiment.First of all,the models of the key components of electro-mechanical transmission system,namely,engine and permanent magnet synchronous motor,were finely built.Based on the Matlab/Simulink platform,the mean value model of the engine was established by using the modular modeling method and the bench test data.The motor controller models in speed and torque control mode were established by the motor mathematical model in the dq coordinate system.The simulation platform of the electro-mechanical transmission system was established and verified by the integrated coupling mechanism and the vehicle dynamics model,which was the foundation for the study of engine starting characteristic and control strategy.Then,the dynamic performance index of engine starting is defined,and the concept of total equivalent fuel consumption of hybrid vehicle engine starting was proposed.The simulation of engine starting process drgagging by motor in speed control and torque control mode was carried out,and the motor drag strategy of reduction of torque control was designed.A fuzzy controller was designed to control the engine idling speed adjustment.Compared with the traditional controller,the rotation speed overshoot of the idle speed adjustment controlling result by this fuzzy controller is reduced by 54%and the equivalent fuel consumption is reduced from 2.75mL to 2.35mL.In addition,the influence of different ignition rotation speed of engines on the starting characteristics was studied,and the results show that increasing the ignition speed can reduce the speed overshot amout and engine starting time.The simulation for the transition from in-situ engine starting to the parked electricity generation and hybrid drive mode starting conditions was carried out to verify the feasibility of the control startegy.Aiming at the problem of engine starting coordinated control during the process of vehicle moving,the dynamics model of engine starting process was established,and the multi-stage coordinated control strategy of engine starting was designed.In the engine reverse dragging process,the coordinated control strategy was transformed into a optimal speed tracker problem,and the problem of the tracker under different boundary conditions was off-line solved.In order to obtain the unknown value,namely,the ground load torque,a reduced order system observer was designed.The convergence rate of the observer was adjusted through designing pole position of the observer.Basing on the established simulation platform of electro-mechanical transmission,the simulation verification of engine starting coordinated control strategy was carried out under four driving conditions.The simulation results showed that the maximum jerk of the vehicle during engine stating was reduced from 30m/s~3 to 6.3m/s~3 or less.Finally,the engine start controller was developed based on the rapid prototype of Rapid ECU controller,the hardware in-loop simulation was carried out.The engine start-up test bench was set up,and the bench test was carried out for the engine start-up,which further proved the effectiveness of the starting control strategy.