Modeling And Optimal Control During Fast Filling Process Of Fuel Cell Vehicle

With the gradual commercialization of fuel cell vehicles,the development of hydrogen refueling stations(HRSs)has gained more and more attention.Governments around the world begin to support the construction of HRSs for their currently high capital and operating costs.Currently,high pressure hydrogen storage in refueling stations are mostly considered,as more practical,reliable,durable and so acceptable.Although the compressed hydrogen approach has advantage of technical simplicity and high filling rates,the fast filling speeds and the high states of charge(SOC)bring to new challenges for the on-board cylinders.The rapid increase of hydrogen temperature during the fast filling process could lead to the failure and safety hazards of cylinders.In order to effectively reduce temperature rise and shorten filling time,a series of studies have been carried out in this paper.The main contents are as follows:(1)The types and working modes of hydrogen refueling stations have been researched.The cascade storage system which applied on a large scale due to its lower power consumption,appreciable when high hydrogen utilization occur is taken as the research object.The modeling scheme of hydrogen refueling station and on-board cylinder is proposed.(2)The thermodynamic principle of temperature rise within cylinder during hydrogen filling process is studied.Based on the revised real gas equation,mass conservation equation and energy conservation equation,the theoretical model of hydrogen filling process was established.The calculation methods of pre-cooling and compression energy consumption in the working process of hydrogen refueling station are proposed.Finally,the effects of different parameters on hydrogen refueling process is studied with the model above,which provides a theoretical basis for the development of hydrogen fast filling control strategy.(3)The design and processing of 140L-35MPA-III hydrogen cylinder and multi-point temperature measuring device inside the cylinder are carried out.Relying on the demonstration operation hydrogen refueling station,high pressure hydrogen/nitrogen charging and discharging experiments have been completed.The internal hydrogen and external temperature of cylinder have been recorded and analyzed.Results show that experiments data could validate simulation model effectively;(4)The definition of pressure switching coefficient(PSC)is presented for the cascade hydrogen storage system and the model of three-stage refueling system is established.Results show that PSC and hydrogen precooling temperature have great effects on the temperature rise during fast filling process.Therefore,The PSC and pre-cooling temperature are taken as the optimization parameters and the total energy consumption,filling time and SOC are considered as optimization objectives.The optimization model was established.The sequence search algorithm is proposed to solve the simulation model considering the calculation efficiency and accuracy.Pre-cooling system real-time control strategy is proposed due to the complexity of hydrogen refueling station working condition and model error.