Optimization Design Of Fuel Cell Vehicle With Life Cycle Performance

In the process of transitioning and upgrading traditional fossil fuels to renewable and clean energy,the development and commercialization of multi-energy source fuel cell vehicles,as a branch and an important supplementary form of new energy vehicles,has received attention within the automotive industry.Multi-energy source fuel cell vehicles mixed with auxiliary energy sources such as battery or/and supercapacitor can effectively overcome the shortcomings of insufficient dynamic response capability of fuel cells,long start-stop time and inability to recover braking energy,and have good application prospects.However,the multienergy source system has multiple control degrees of freedom,multiple operating modes and complex coupling relationships.In order to realize the advantages of its configuration,it needs to make an optimal design including both component parameter and energy management strategy(EMS).In addition,the lifetime degradation of fuel cells increases their cost of use and becomes a limitation for their large-scale deployment,therefore,it is necessary to focus on the whole life cycle of fuel cell for its optimal design.In this paper,the optimal design of a three-energy source fuel cell vehicle is taken as the target,and the details of the study are as follows.Firstly,a simulation platform is built to evaluate the economy of the vehicle,including the simulation of the energy consumption simulation model and the fuel cell and battery lifetime degradation model for discrete time domain control,to evaluate the economy of vehicle in terms of energy consumption cost and component lifetime degradation cost,which provides a simulation verification basis for the optimization design later on.Secondly,the performance index requirements of the energy source from the vehicle design requirements and driving cycle data statistics,as well as the constraints of the acquisition cost of the energy source,are integrated,and the feasible domain of the parameter design of the energy source components is completed.The dynamic planning algorithm is used to decouple the combined problem of parameter optimization and EMS optimization,and the optimization of parameter design is carried out independently under the condition that the EMS is guaranteed to reach the global optimum.For the three configurations of multi-energy source fuel cells that can exist,discrete parameter design scenarios are divided in their respective parameter design feasible domains,and the global optimal economy of the vehicle under each scenario is calculated using the dynamic programming algorithm.The results verify that the three-energy source configuration has the optimal ultimate economic capability,and its parameter design extrema are selected as the energy source parameters for the threeenergy source configuration in the later section.Finally,a two-dimensional ECMS(d ECMS)based on a rule-based(RB)framework is designed,aiming to obtain a composite EMS that takes into account implement ability,system stability and better control effects by complementing the advantages of rules and algorithms.Among them,the RB EMS achieves the distribution of demand power through a series of filtering methods,working mode division,logical variable calculation and logical relationship setting on the framework of primary and auxiliary energy source control.The simulation results show that the strategy has good adaptability to working conditions and component states,and also verifies the role of supercapacitor to improve the economy of the whole vehicle.The two-dimensional ECMS based on the rule framework,on the other hand,uses the ECMS algorithm instead of the filter module to form two power allocation routes,which are the threeenergy source power allocation based on the two-dimensional ECMS and the fuel cell power allocation based on the rule plus the auxiliary energy source power allocation based on the one-dimensional ECMS,according to whether the fuel cell is in a specific mode of RB EMS to decide allocation route is used.Simulation results show that this strategy has better optimization performance in terms of reducing operating costs compared to the RB EMS.