| In order to make full use of the electromechanical coupling driving advantages of the hybrid powertrain to realize high effect vehicle driving and reduce the cost,the 48 V mild hybrid powertrain has become an optimal solution for new energy vehicles.A kind of SUV vehicle in the OEM Great Wall takes the new 48 V P0+P4 system as power source,however,if the control strategy is not appropriate will lead engine start and stop frequently when driving that increases fuel consumption and reduces passenger comfort,so the vehicle performance is depend on the engine start-stop control technology.The engine start-stop control strategy is studied in this paper,main contents are as follows:(1)According to the vehicle system parameters and driving conditions,the driver’s safety,comfort,dynamics and fuel economy are considered,and the control logic of the start-stop control is analyzed and the priority is judged.On this basis,the simulation model of the engine start-stop controller is built,and the control strategy of the model is verified by off-line simulation.(2)Establish the resistance moment model of engine start process,take the numerical solution and the engine inertia moment and value as the BSG motor torque output instruction to carry out the engine idle start-stop feedforward control.The feedback control based on the PID is carried out to realize the closed loop control of the idle start-stop,and the effect of the control strategy of start process is simulated and verified..(3)Based on the powertrain structure of the vehicle,the CRUISE vehicle model is established and the parameters are calculated.The model is combined with the model of the engine start-stop control system to simulate the fuel economy in the NEDC condition,and the start-stop control strategy is verified.(4)Based on DSPACE/MICROAUTOBOX,a prototype platform for rapid start-stop system of engine is built and tested,which verifies the effectiveness of engine start-stop control strategy.On this basis,the vehicle road test is completed based on the real control unit,and the real vehicle validation of the engine start up process is completed.Finally,the feasibility of the proposed control strategy is proved.In this paper,the combination of mathematical modeling,system simulation and experimental verification is used to realize the engine start-stop control of Great Wall Auto’s 48 V P0+P4 drive system,which provides key technical support for improving the drive performance of the entire system control strategy.On this basis,the vehicle road test is completed based on the real control unit,and the real vehicle validation of the engine start up process is completed.Finally,the feasibility of the proposed control strategy is proved. |
