Research On Energy Management Strategy For The Hydrogen Fuel Cell Vehicle

The power system of hydrogen fuel cell vehicle provides the required power(vehicle demand power)for the driving of hydrogen fuel cell vehicle,and the energy management strategy plays a role in power distribution in this process.The energy management strategy requires to consider the power source’s working efficiency and the influence of the actual complex working conditions on the hydrogen fuel cell.At the same time,it is necessary to prolong the service life of the hydrogen fuel cell.However,the existing rule-based energy management strategies could not meet this requirement.Therefore,to improve the efficiency of power source and prolong the service life of the hydrogen fuel cell system,the rule-based energy management strategy is optimized.The main research work and results are as follows:(1)The hydrogen fuel cell vehicle power system was taken as the research object.Based on the analysis of the current situation of its power system structure,the advantages and disadvantages of the current power system structure were compared and analyzed.According to the requirements of power system,the power system structure of hydrogen fuel cell vehicle was constructed.The power distribution method of the power source of the hydrogen fuel cell vehicle was given.According to the performance requirements of the actual operation of hydrogen fuel cell vehicle,the requirements of energy management strategy were put forward.(2)Based on the structure of hydrogen fuel cell power system,the component types of hydrogen fuel cell vehicle power system were compared and analyzed.The selection of hydrogen fuel cell system components was determined.As well as,the modeling of hydrogen fuel cell system,lithium battery,DC / DC converter,motor and vehicle dynamics was completed.(3)In the energy management strategy based on power following,the principle of the energy management strategy is introduced.The work flow of the four parts of the hydrogen fuel cell demand power calculation,power correction,on-off state determination and demand power limitation in this energy management strategy is expounded.In view of the problem that the energy management strategy based on power following did not consider the efficiency of the power source,the fuzzy correction was introduced to adjust the working range of the hydrogen fuel cell.Combined with the energy management strategy based on power following,an energy management strategy based on fuzzy optimization is proposed.After simulation and comparative analysis,it was concluded that the energy management strategy based on fuzzy optimization could improve the power source efficiency of hydrogen fuel cell vehicle.(4)Aiming at the problem that the service life of hydrogen fuel cell was affected by four adverse working conditions: start and stop,idle speed,large load change and overload,EMS based on driving mode division was proposed.In this strategy,fuzzy control was introduced to initially limit the output power and output power change rate of the hydrogen fuel cell.At the same time,the power distribution was adjusted according to the different driving mode.At the same time,according to the real-time working conditions of hydrogen fuel cell,the strategy was adjusted by the power distribution.The typical working conditions of Chinese passenger cars were divided into six driving modes: start,low-speed constant speed,ordinary acceleration,high-speed constant speed,fast acceleration and deceleration.Then the power limit standard was set in different driving modes to limit the required power of the hydrogen fuel cell output by the fuzzy control.To achieve the purpose of minimum hydrogen consumption,the multi Island genetic algorithm was used to optimize the driving mode division parameters based on experience.Comparing the simulation results of the energy management strategy before and after the introduction of the driving mode division,it is verified that the energy management strategy based on the driving mode division can reduce the operation time of hydrogen fuel cell under adverse working conditions significantly.Multi Island genetic algorithm was used to optimize the standard of driving mode division.The consumption of hydrogen is reduced and the working conditions of hydrogen fuel cell system was further optimized.At the same time,hydrogen consumption decreased by 3.2%To sum up,improving the efficiency of power source and prolonging the service life of hydrogen fuel cell were the research objectives in the thesis.EMS based on fuzzy optimization and driving mode division were deeply studied and proposed.And its effectiveness was verified by simulation.The research results in this paper had certain theoretical significance and engineering practical value in improving power source efficiency,prolonging the service life of hydrogen fuel cells,and reducing hydrogen consumption.