Research On Energy Management Strategy Of Parallel-Series Hybrid Electric Vehicle Based On Fuzzy PI Control

Nowadays,with the increase of cars,environmental problems and the shortage of oil resources,researchers have attracted more attention.The world’s major car companies and experts have researched new energy vehicles and energy-saving vehicles.The hybrid electric vehicle has the advantages of long driving range of traditional internal combustion engine vehicle,and zero-emission of the pure electric vehicle,which is the best way to improve the conventional fuel vehicle.The hybrid electric vehicle compound type configuration power split on fuel consumption and emissions performance superior to the performance of series and parallel hybrid electric vehicle.It can achieve more work mode while the engine can remain in the best condition to run,In this paper,according to the power-diverting hybrid electric vehicle characteristics,the energy management strategy was formulated and optimized that verified by the vehicle dynamics model built by ourselves.The specific contents are as follows:(1)A brief introduction and comparative analysis of the configuration and working mode energy flow of series-parallel and power-split hybrids.The results show that both power split and series-parallel hybrids systems use the electric drive system as the main driving force for medium and low loads to avoid the engine working in an area with poor fuel economy.In addition,it can realize common modes such as direct motor drive,engine-driven charging,or braking energy recovery.However,the power split type mainly uses a planetary gear train without a clutch to couple the engine,motor and generator.Therefore,compared with the seriesparallel hybrid with a clutch,the coordination and switching between the three are smoother.(2)For the power-split hybrid electric vehicle,establish a vehicle dynamics model,formulate and build a rule-based control strategy,and verify the rationality of the strategy through simulation.The results show that: under CLTC-P conditions,the vehicle has better comfortability and less vehicle speed error.The energy management strategy developed can achieve a reasonable distribution of vehicle power sources.The switching of different working modes can meet the engine’s requirements with a minimum fuel consumption curve.(3)Optimize the driver model based on PID,adopt the preview optimal control model,and analyze the optimization results through simulation.The results show that the speed errors of the two driver models are within ±2.5km/h,and there is no large speed error in the rapid acceleration and rapid deceleration conditions.Furthermore,compared with the classic PID driver model,the preview is used when controlling the driver model,and the vehicle speed error is significantly reduced about 40%.(4)Optimize the generator PI control model,introduce fuzzy PI control and establish the model,and verify its optimization effect through simulation analysis.The results show that:values compared with PI control,after using fuzzy PI control,the engine operating point is more concentrated near the lowest fuel consumption operating point,and HC emissions,CO emissions and NOx are reduced to varying degrees.Furthermore,regardless of SOC,under CLTC-P conditions,fuel consumption per 100 kilometers is reduced by 5.5%,and under WLTC conditions,fuel consumption per 100 kilometers is reduced by 2.9%,which significantly improves form of fuel economy.