Simulation Research Of PnG Energy Saving Driving Strategy For Hybrid Vehicles With Discrete Gear Ratio

Under the background of increasing energy scarcity and environmental pollution,hybrid vehicles have become an important development direction for new energy vehicles due to their advantages of high efficiency and low emissions.The Pulse-and-Glide(PnG)energy-saving driving strategy based on periodic control can improve the cruising economy of vehicles.Scholars have theoretically studied the PnG strategy of Continuous Variable Transmission(CVT)hybrid vehicles.The average transmission efficiency of discrete gear ratio transmission like Dual Clutch Transmission(DCT)is higher and widely used.Therefore,this paper takes the P2 Architecture parallel hybrid vehicle equipped with DCT transmission as the research object,considers the difference between theoretical solution and the actual situation,and uses simulation analysis to apply the PnG energy-saving driving strategy to discrete gear hybrid vehicles to improve the fuel economy of hybrid vehicles.The main research contents are as follows:First of all,this paper builds a parallel hybrid vehicle simulation model in AVL Cruise software,designs a rule-based energy management strategy,and conducts dynamic and economic simulation to verify the rationality of the vehicle model,so as to provide a basis for the research and verification of the PnG strategy below.Then the pseudospectral method is used to theoretically solve the PnG strategy,and the optimal control problem of cruise economy is constructed.By applying different speed constraints and gear settings,the two optimal strategies of speed fluctuation(V-PnG)and SOC fluctuation(SOC-PnG)are obtained theoretically.After that,based on the theoretical solution results,Stateflow is used to build the PnG simulation strategy.For the V-PnG simulation strategy,the optimal working curve of the engine is obtained by fitting,and the engine start-up state is added to prevent the slip and wear loss of the clutch.For the SOC-PnG simulation strategy,the optimal charging torque is solved with the goal of the highest total efficiency of the power system in the charging stage.Finally,the simulation verifies the effectiveness and fuel-saving effect of the V-PnG strategy and SOC-PnG strategy.For the V-PnG strategy,different gear settings are selected for simulation,which verifies the rationality of the V-PnG simulation strategy.It is found that there is a difference between the simulation fuel economy results and the theoretical solution results.The reason for this difference is that the theoretical solution ignores the fuel consumption in the engine start-up stage.For the SOC-PnG strategy,the simulation results such as battery SOC and torque meet the requirements of the strategy,which verifies the rationality of the SOC-PnG simulation strategy.Select different average speeds,compare them with constant speed cruising,and simulate and evaluate the fuel-saving effect of the PnG strategy.The results show that the V-PnG strategy has a good fuel-saving effect at average speed,and the use of gear-down acceleration does not improve the fuel economy of the V-PnG strategy.SOC-PnG strategy only has a fuel-saving effect in the low-speed range,and the fuel-saving range is less than that of the V-PnG strategy.Based on the simulation results,the fuel-saving effect of the PnG strategy is analyzed from the perspective of energy loss,and the application scenarios and distance error of the PnG strategy are analyzed to provide preparation for the application of the PnG strategy to the adaptive cruise control system.