Research On Hybrid System Of Marine Fuel Cell

Ship is the main transportation equipment for international logistics while the diesel engine is one of its main power plants,which has caused a series of energy and environment issues.Additionally,considering increasingly strict ship emission regulations,the development of low energy-cost and low-polluting power system has become the main task of current shipbuilding industry.PEMFCs(proton exchange membrane fuel cell),using hydrogen as fuel gas,has the advantages of renewable,non-polluting,high energy density and so on.It shows a potential application and has already been used in vehicles,while its application in the marine field needs more attentions.In this paper,the relevant experiments are carried out based on the application of fuel cells on the ship.Firstly,the structure and related parameters of the experimental ship are designed.The selection of the propeller and the motor is matched for the experimental ship,and then a fuel cell power ship experimental platform is built up.After the experiments,the feasibility of fuel cell application on the ship was verified.However,it was found that the PEMFCs in the existing power system could not be kept in a stable output state,and the utilization of hydrogen fuel was relatively low.In order to ensure a stable output of the fuel cell and achieve a more rational use of hydrogen fuel,a hybrid power system with a 2kW PEM fuel cell and a 1kW Li-ion battery was designed.On the basis of the designed hybrid system in MATLAB,the simulation study was carried out.Firstly,the static model of PEMFCs was built to study the output characteristics of PEMFCs.Compared with the experimental data reported in the literature,it is shown that the PEMFCs model established in this paper can reflect its output characteristics;then further analyses of different operating temperatures and effect of the partial gas pressure on the fuel cell performance were carried out.In order to obtain the input and output characteristics of PEMFCs,the dynamic model of PEMFCs was also established based on the static model.The output voltage and output power of PEMFCs under different input currents were obtained,and the model of DC-DC converter was built so that the output voltage of the PEMFCs could meet the needs of the experimental vessel.Finally,a control strategy based on a Li ion battery auxiliary power source model with a rated power of 1 kilowatt was developed for the hybrid power system.This control strategy uses SOC(stage of charge)of Li ion battery to judge the output power of PEMFCs.When SOC is greater than 0.75,the output power of PEM fuel cell is 1kW wherein the insufficient portion is supported by the Li ion battery through discharge until the SOC less than 0.4.When SOC is less than 0.4,the PEM fuel cell output power is 2kW,which provides both demand of the load and the Li ion battery until the SOC is greater than 0.75.This control mode enables the PEM fuel cell at a stable output,at the same time the overcharge and over discharge of the Li ion battery can be avoided,so that the service life of the primary and secondary power sources is ensured and stable output of the whole power system is obtained.