Modeling And Control Of Cathode System Of Fuel Cell For Locomotive

Proton Exchange Membrane Fuel Cell (PEMFC) which has advantages of high energy density, little pollution, lower operating temperature and starting fast has attracted much attentions. And proton exchange membrane fuel cell (PEMFC) is suitable as power source for locomotives and other vehicles. The characteristics of the stack can be well reflected by an accurate dynamic model of the fuel cell system which is convenient for the design of control system. Cathode system which provides proton exchange membrane fuel cell (PEMFC) with air is important. And the performance of air compressor of cathode system has significant impact on the operation of power reactor. However, most of the existing air compressor model directly fit with the experimental data with low accuracy, while the simulation speed is slow and it is difficult to deal with boundary data. Therefore, it is necessary to design appropriate controller to ensure the stack operating stable, safe and efficient.In this paper, considering the overall design modeling and control strategy of the cathode of the fuel cell system, the dynamic model cell and control strategy of high-power proton exchange membrane fuel at home and abroad are analyzed. A stack’s model is proposed based on the analysis of the working theory of Proton Exchange Membrane Fuel Cell. A cathode system model is built based on the fuel cell cathode system of the 150KW electric locomotive developed by laboratory, which is suitable for ROTREX C15 compressor by improving the centrifugal air compressors model.Additionally, the auxiliary components, namely manifolds, flow channels and back pressure valve are all composed in this model.Simulation analysis of cathode system is conducted, which proves the impact of environment on the compressor and the impact of rotating speed and demanding current on the system. Moreover, the "oxygen starvation" phenomenon occurs.On the basis of the dynamic model of fuel cell, the flow pressure independent bicyclic PID controller is designed to control the compressor, by which could realize the controlling of output voltage and power of fuel cell, and then the output voltage of the fuel cell could be controlled. The simulation results show that the Bicyclic PID control can effectively regulate the flow and pressure of compressor, which could ensure stable and efficient operation of the system.Finally, a brief introduction of fuzzy control theory is provide in this paper. The piping system model is simplified, and then the relationship between current and pressure is obtained by polynomial fit technique, lastly the control of the compressor voltage is realized by the fuzzy controller. The results show that the fuzzy control is more suitable for nonlinear system than PID control.The two control methods designed in this paper have important guiding significance for the design of the actual control system.