Power Management Of Fuel Cell/Storage Battery Hybrid System In Vehicle

With the rapid development of our country's economy,energy demand rise sharply.Using of a large amount of fossil energy not only make originally unabundant fossil energy resources shortage in our country,but also caused serious pollution of environment.Study showed that the automobile exhaust had contributed more than 25%in air pollution in our country.The new type of efficient and clean car dynamic system can improve energy utilization and reduce vehicle exhaust pollution to the environment which is the developing direction of automobile power system.Fuel cell/battery hybrid power system which has advantages of high efficiency and cleans is one of the main power systems of new energy automotive.On the basis of reading a large number of domestic and abroad literatures,this thesis summarized the hybrid system energy control strategy research status and development trend,introduced the working principle and structure of fuel cell,and concluded the control strategy of fuel cell/battery hybrid energy principle and implementation method.First of all,using propane tanks,pipelines,valves,humidifier,heater,electronic load,mass flow controller,back pressure valve and system control components build the fuel cell test system,and using the proton exchange membrane,electrode and the flow field plate assembly for proton exchange membrane fuel cell.Then utilizing the good fuel cell system to test the performance of proton exchange membrane fuel cell characteristics.Analyzed the impact of flow,humidification temperature,cell temperature and flow field structure to proton exchange membrane fuel cell volt-ampere characteristic parameters.The study found that the optimal combination of hydrogen flow and air flow and the optimal collocation of battery temperature and humidification temperature were beneficial to improve the performance of proton exchange membrane fuel cell which would be conducive to the application of proton exchange membrane fuel cell.Secondly,according to the characteristics of the batteries and fuel cells,choose a suitable form of hybrid system structure.On the basis of the selected hybrid system structure,established the driver model,energy distribution controller,component model and the vehicle dynamic model and fuel cell/battery hybrid power management forward simulation model.In power management,the fuel cell stack to the bus through the DC/DC converter output power,single direction nickel metal hydride battery as supplementary energy and DC/DC in parallel on the bus,assembly controller do decision-making control and distribution of power output according to the feedback of each component module and the driver's instruction.Based on hybrid structure and control method,analyzes the fuel cell/battery hybrid vehicle operation comfort and various losses.Finally,based on the instantaneous equivalent fuel management strategy,making the hybrid system management mode switching rules,the thesis analyzes the relationship between fuel heat energy and electrical energy conversion,calculation of the equivalent fuel consumption of battery power.Based on factors of hybrid management rules and switching mode,to set the initial values of state charged battery SOC were 0.5,0.6,0.7,0.8,0.9,in CYC_HWFET,CYC_MANHATTAN and CYC_UDDS driving cycle under the condition of traffic real-time simulation test power distribution management system.Study found that when the battery SOC gradually reaching 0.7 was the optimal energy distribution of the hybrid systems;Adjust the fuel cell stack power output distribution range,making the fuel cells to work more in the region of the high efficiency which is beneficial to improve the fuel economy of fuel cell stacks,and better control energy more reasonable distribution of power output.