Design Of The Scale-down Fuel Cell Hybrid System For Locomotive

Currently,people have paid close attention to some questions,such as environmental pollution,energy crisis,and greenhouse effect and so on.In order to solve energy and environment question effectively,many countries are studying the development of green energy and the application of renewable energy sources.Among the numerous renewable energy sources,hydrogen energy is a safe,reliable and clean energy.Meanwhile,among the application domain of hydrogen energy,fuel cell is a classical hydrogen energy conversion device which could make the hydrogen energy into electrical energy efficiently through the electrochemical reaction.Hence,fuel cell has been widely applied to many energy fields,such as Micro DC-Grid,rail traffic,military industry and so on.At present,some countries have developed the fuel cell hybrid locomotive.Due to those researcher were limited by the development of technology,the developed fuel cell hybrid locomotive did not consider too much about the question of system optimization,and the developed locomotive employed theory relatively simple.Moreover,there are few papers which present the way of locomotive modeling and optimization.However,the technical scheme of way is difficult to achieve in real locomotive system,and those methods are not suitable for the practical locomotive application.Therefore,this paper set up a scale-down fuel cell hybrid system for locomotive,besides that,the practical parameters of each power source were measured and analyzed through hardware experiment,such as the efficiency of unidirectional DC/DC converter and bidirectional DC/DC converter,internal resistance of battery,the efficiency of fuel cell system and so on.Energy management strategy has important influence on the whole performance of hybrid system.According to the actual data measured in previous and the practical drive cycle of locomotive,this paper has done the theoretical derivation of equivalent minimum hydrogen consumption energy management strategy(ECMS),and has done the theory verification through the Matlab programming.Because of the braking energy of actual locomotive are relatively more than conventional vehicles.The battery will absorb more energy that makes ECMS could not control the state of charge(SOC)variation of battery reasonably.Therefore,this paper proposed an energy management strategy based on dynamic power factor(EMS_DPF)which could effectively control the SOC within a certain range.Moreover,this paper has done the theoretical derivation of energy management strategy based on Pontriagin's minimum principle(PMP).The results reveal that EMS_DPF and PMP could decrease the hydrogen consumption of system effectively and improve the efficiency of system.Besides that,EMS_DPF and PMP could maintain the SOC of battery which could extend the life time of battery.In order to verify the effectiveness of energy management strategy proposed by this paper,this paper did the hardware experiment in the scale-down fuel cell hybrid locomotive system and analyzed the experiment results.The experiment results demonstrate that EMS_DPF and PMP are more suitable for the fuel cell hybrid locomotive.EMS_DPF and PMP could meet the dynamic demand of fuel cell hybrid locomotive and effectively decrease the system hydrogen consumption which ensures the economy of fuel.Moreover,EMS_DPF and PMP could improve the durability of fuel cell and extend the life time of battery.