Research On Efficiency Characteristics Of Fuel Cell Engine System And Vehicle Energy Management Strategy

Due to the increasingly serious energy and climate issues,the Chinese government has clearly put forward the strategic goals of energy conservation,emission reduction and green development to achieve “emission peaking” by 2030 and “carbon neutrality” by 2060 in2020.Vigorously developing new energy vehicles is an important measure in the field of transportation to implement the national "dual carbon" goal.Hydrogen fuel cell vehicles have become an important development direction of new energy vehicles due to their advantages of fast refueling,long range,high efficiency,and zero emissions.With the continuous deepening of hydrogen fuel cell vehicle technology research and product demonstration and promotion,how to improve the working efficiency of the fuel cell power system,the core of hydrogen fuel cell vehicles,has also become one of the key common technical problems to be solved urgently to accelerate the industrialization of fuel cell vehicles.Relying on an industry-university-research cooperation project,this paper aims to further improve the efficiency of the fuel cell engine system,and conduct research on the efficiency characteristics of the fuel cell engine system and the vehicle energy management strategy.In terms of the system,the optimal operating point sequence of the fuel cell engine system is obtained through experiments and simulations.In terms of the vehicle,an adaptive PMP energy management strategy based on FLC is proposed.The simulation results show that the proposed strategy has significant improvements in fuel economy and SOC maintenance compared with the power following strategy.The specific research contents are as follows:In the aspect of the fuel cell system,starting from the system structure and working principle,the simulation model of fuel cell system is built by adopting the model-building method combining mechanism and experience.The output performance experiment of the stack was carried out on the fuel cell system bench in the laboratory,and the accuracy of the built model was verified according to the experimental results.Electrical efficiency and system efficiency are defined,the variation of electrical efficiency under different working cases is analyzed,and the difference of the influence of working pressure on electrical efficiency and system efficiency is studied.Finally,the operating point sequence for optimum efficiency of the fuel cell engine system and the corresponding system efficiency and net power are obtained through simulation.In terms of vehicle energy management strategies,first,according to the analysis results of the fuel cell vehicle topology and vehicle performance indicators,perform forward matching calculation of parameters for key vehicle components.The mathematical model of each component is built and integrated into the vehicle model,and the dynamic simulation is carried out to verify that the parameter matching results meet the performance requirements.Then,according to the control objective of the energy management strategy,the applicability of two typical energy management strategies to the vehicle in this paper is analyzed,and a power following strategy is established based on the finite state machine theory.The method of using the optimization algorithm to resolve the energy management problem is also analyzed,and an energy management strategy(offline PMP)based on the minimum value principle is established.Finally,the influence of co-state variables on the solution of the minimum value principle is analyzed,and a scheme of on-line adjustment of co-state value using fuzzy controller(APMP-FLC)comprehensively considering SOC and fuel cell system efficiency is proposed.The simulation results of different strategies are compared and analyzed.Among them,the APMP-FLC strategy has better distribution of fuel cell operating points,and the economy is closer to the global optimal offline PMP strategy,which verifies the effectiveness of the proposed strategy.