Modeling And Analysis Of PEMFC Air Supply System

As the main source of power，Proton exchange membrane fuel cell (PEMFC) electricvehicles includes several systems such as cooling system, hydrogen supply system, airsupply system, security system, control system and so on. Air supply system has greatinfluence on the performance of electric pile as an important component of PEMFCsystem. And modeling and control of the air supply system are all relatively difficultbecause of its strong nonlinear characteristics. Models of air supply of PEMFC controlsystem are established in order to improve the response speed which can make sure thefuel cell system working on the best state. The main research contents and results areas follows:At first, the modeling and working principle of PEMFC stack are introduced, andPEMFC stack mechanism model is established. Then simulation of KW level pilebased on mechanism black-boxing model is done by using MATLAB/SIMULINK,analysis results show that the black-boxing model with PID controlling has fasterresponse speed and better anti-jamming ability, which can satisfy the requirement ofthe electric reactor modeling. At the same time, the black-boxing model output voltageand current are tracking on the hardware simulation platform, the simulation resultsshow that the black-boxing model can meet the requirements of realization ofhardware simulation.The air supply system could be driven to run with power generated by PEMFC stackwhile the PEMFC engine running smoothly. The PEMFC engine structure, thehydrogen supply system and the air supply system are all introduced respectively. Theoutput voltage, the equivalent internal resistance, the output power and so on aresimulated using MATLAB, which are the out parameters of KW level PEMFC systemwith traditional air supply system and5KW PEMFC system with mixed charging airsupply system. The results show that the best work pressure of PEMFC system with airsupply system are all in low-pressure area, and the energy consumption of air supplysystem can be significantly improved with the mixed charging system, and maximum equivalent output power point are located at higher utilization rate of exhaust gaspressure. The theoretical analysis of demand for the air supply system and power flowof the air supply system based on conservation of energy are also carried out, theresults show that the control of the air compressor is closely related to the motorcharacteristics, the compressor characteristics and the stack output power, and so on.PEMFC system costs can be reduced by ensuring fuel cells working on maximumpower point as far as possible. In order to solve the problem of maximum power pointtracking of fuel cell power systems, the adaptive MPPT controller is designed, andsimulation analysis was carried out using MATLAN/SIMULINK. The results of theanalysis show that the designed MPPT control system is sensitive, and has a strongrobustness at the same time, which can ensure the system stability and system fastresponse speed while the condition of operating status have rapid and greatly changes.