Research On Energy Management And Control Of Hybrid Power System For Electric Vehicles

In recent years,with the state’s strong support for the new energy vehicle industry,the sales of pure electric vehicles are growing,but the problems of short range and low battery power density restrict the further development of the pure electric vehicle industry.Combining high Energy density lithium battery with high power density super capacitor to form Composite Energy Storage System(CESS),giving full play to their respective advantages,is of great significance to improve the dynamic performance of vehicles and increase the driving range.Therefore,this paper will study the energy management and control of the composite power system according to the running characteristics of the vehicle and the working characteristics of the composite power system.First of all,this paper establishes the vehicle dynamics model and deduces the calculation formulas of vehicle demand power and braking intensity,which are respectively brought into three different types of working conditions of NEDC,Ftp75 and Highway for simulation calculation and data analysis.In order to improve the simulation accuracy of the lithium battery model,the improved equivalent model based on the PNGV model is adopted in this paper,and the parameter calculation methods of the energy storage components are summarized,which provides a theoretical basis for the development of the improved energy management strategy.Then,the advantages and disadvantages of the four traditional composite power supply topologies are summarized,and the active composite power supply topology is selected for research.Based on the analysis of the existing energy management strategies of the composite power supply,in order to improve the working participation rate of the supercapacitor,the lithium battery is proposed to charge the supercapacitor when the vehicle stops and waits,and the working mode of the composite power system is specifically divided to develop an improved energy management strategy.Based on the traditional braking force distribution strategy,in order to recover as much braking energy as possible,an improved braking force distribution control strategy was developed to improve the efficiency of recovery braking energy.Finally,aiming at the control of energy input and output of the complex power system,in order to reduce the influence of unknown disturbance on the control effect,the sliding mode surface and controller of the sliding mode control are redesigned,and the state observer is added to obtain the adaptive sliding mode controller.A complete composite power system is built and simulated one by one.In order to verify the performance of the improved composite power system in the actual operating environment,a single lithium battery power system,a passive composite power system,a traditional composite power system and an active composite power system with improved energy management and control strategy were selected,and the vehicle simulation models were respectively built in AVL CRUISE simulation software.Simulation and comparison were carried out respectively in three different types of conditions,including 100 km acceleration,maximum climb,range,and simulation results verify the effectiveness of the composite power system with improved energy management and control strategy.Figure [72] Table [4] Reference [82]...