Research On Electrical Characteristics And Control For Electrical Auxiliary System Of Proton Exchange Membrane Fuel Cell Engine

Nowadays,development issues,such as environmental pollution and energy crisis,are becoming increasingly serious.Fuel cell,with the advantage of zero pollution,environmental protection,high efficiency and safety,is recognized as one of the ways to shape the strategic development of human energy development in the new era.The development of new energy vehicles is obviously the inevitable trend in the automotive industry.The industrialization of fuel cell vehicles has also been regarded as the development goal in the world.High demands have been made on the performance of fuel cell vehicles.Researches on and rational control of electrical characteristics in fuel cell engine system are conducive to improving its response performance and system efficiency.However,the research in this area is still in its infancy.In this paper,firstly,comparative analysis on the advantages and disadvantages of different configurations of fuel cell engine power system is conducted,thus to identify the indirect hybrid power system of fuel cell which is most suitable for vehicle use as the research object.Then,it is clear that the electrical auxiliary system mentioned in this paper mainly refers to DC/DC converter and three-phase inverter at the air compressor end.Relying on the project of "Research and Platform Development of Key Technologies for High Specific Power Fuel Cell Engine",co-constructed by research groups of provincial schools,a centralized parameterized fuel cell model is built under the environment of MATLAB/SINMULINK.A fuel cell experimental platform is built and experiments are carried out to identify the parameters of the model and verify the validity of the model.The results show that the proton exchange membrane fuel cell model has high stability and accuracy.The overall model of the fuel engine system is further built to prepare for the future research.In this paper,with the starting point of the efficiency of fuel cell engine system,the electrical coupling relationship between DC/DC converter and three-phase inverters at air compressor end is studied.The current and voltage ripple at system bus bar and fuel cell output end are mainly considered.That is to say,because the main components of the two converters are power devices,the system will cause large low-frequency voltage and current ripple.However,voltage ripple at the system bus bar is actually equivalent to loads with periodical breaks.On the one hand,the regulation of the gas supply system has a lag,which leads to the fuel flow rate reaching the corresponding flow value of peak power,which will inevitably lead to the decrease of hydrogen efficiency and consequently reduce the fuel cell efficiency.On the other hand,current and voltage ripple will also increase the energy consumption of the auxiliary system and reduce the efficiency of fuel cell engine system.Therefore,the electric auxiliary system must be controlled.In order to improve the efficiency of fuel cell engine system,DC/DC converter and three-phase inverters at air compressor end are used as control objects.For DC/DC converter,the output ripple suppression strategy of ftuel cell based on harmonic injection method and bus voltage ripple suppression strategy based on power feedback are proposed.A decoupling control strategy of d and q axes is proposed for three-phase inverters at air compressor terminals.The simulation results show that this control strategy can effectively reduce the voltage and current ripple and improve the efficiency of the engine system.