Research On Parameter Matching And Conltrol Strategy Of Composite Power Supply For Pure Electric Bus

As energy crisis and environmental issues intensified,governments and automobile companies have their sights on high efficient and environmental electric vehicles.But for the reason of low power density and short cycle life etc,battery has restricted commercial development of PEV.The composite power supply based on battery and ultra-capacitor has the advantages of the two,which has become the main direction of the current electric vehicle research.In this dissertation,the parameter matching and the control strategy of energy management in composite power supply are researched in the target of pure electric bus.In this paper,compare the advantages and disadvantages of commonly used batteries,determine the Lithium iron phosphate batteries as the main energy source of the composite power supply,and analyze the characteristics of the lithium iron phosphate batteries,ultra-capacitor and DC / DC converter in detail.Introduce and analyze four composite power supply structure which are commonly used,determine the optimal structure of composite power supply is the ultra capacitor and bidirectional DC/DC converters in series and in parallel with the battery.The simulation model of the battery,ultra-capacitor,bidirectional DC/DC converter and power bus are established in the Matlab/Simulink environment.On the base of this,composite power supply module is also established.Combine the actual vehicle driving condition,design the logic threshold control and fuzzy control strategy for pure electric bus composite power supply,and make a detailed description of both the overall scheme and control rules,the simulation model is established respectively in the Matlab/Simulink environment.According to the relevant national standards of pure electric vehicles,put forward the reasonable dynamic index requirements of the pure electric bus,matching drive motor parameters,parameters of the battery and ultra-capacitor of pure electric bus,then the power supply of pure electric bus which meets the performance requirements is designed.Introduces the working principle of Advisor,and complete the secondary development,embed the model of composite power supply and control strategy in the Advisor,make the simulated analysis in suitable condition,verify the rationality of vehicle dynamic parameters and the effectiveness of the control strategy.The simulation results show that,ultra-capacitor functions as peak load shifting in the composite power supply,avoid the battery charge and discharge in large current,protect the battery and at the same time effective recovery the braking energy;compared withsingle battery,the composite power supply has a huge advantage on the performance of fuel economy;compared with the logic threshold control strategy,the energy saving effect of composite power supply for pure electric bus which using fuzzy control strategy is better.