Study On The Modeling And Control Of Proton Exchange Membrane Fuel Cell

Proton exchange membrance fuel cell converts the chemical energy of hydrogen and oxygen directly into electricity. Their hig efficiency, low emissions and quick startup even at room temperatures have made them a prime candidate for powering the next generation of automobile, electric vehicles and other fields. PEMFC is a muti-variable, stronly coupling and non-linear system, therefor its dynamic and static performance are affected by many factors both from outer environment and inner parameters, which lead to the instability of ouput voltage during run process of PEMFC. So establishing the PEMFC dynamic model based on mechanism method, and adopting a feasible control method to improve the stability of output voltage has the theoretical significance and wide application prospets.Through studies on mechanism operating characteristics of PEMFC, a dynamic model of PEMFC is developed, which incorporates the effects of the temperature, reaction gas flow and double-layer capacitance. Paper analyzes several primary factors that effect to the output voltage, including the electromotive force, activation polarization overvoltage, ohmic polarization overvoltage and density polarization overvoltage. The transient response characteritics are analyzed under the step change of the load current. The simulation results demonstrate that the simulation model can response the stable and dynamic performance of PEMFC well and can be used for the design of control system of PEMFC.What’s more, based on the characteristics of nonlinearity, strong coupling system of PEMFC and instability of output voltage during run process, fuzzy control scheme is proposed to control the reaction gas flow. Through building a reasonable fuzzy control rulers, a fuzzy controller is designed and implementated in this paper. Because there is integration in the fuzzy controller, output voltage will not change with load current.The simulation results show that, the system has no stability error, faster dynamic response, powerful adaptive faculty toward object parameter and better robustness, the model designed can control the output voltage more effectively.