In this thesis , a theoretical model of a humidifier of Proton Exchange Membrane (PEM) fuel cell systems is developed and analyzed first. The model shows that there exists a strong nonlinearity in the system. Then, the system is identified using a wavelet networks method. To avoid the curse-of-dimensionality problem, a class of wavelet networks proposed by Billings is employed. Next, a model of the thermal system of a PEM fuel cell is proposed, based on the theory of energy conversation and the theory of mass conversation. Finally, an expert PID control algorithm is applied to the temperature control of the humidifier and a fuzzy algorithm is employed to the temperature control of the fuel cell stack, respectively. The main contributions of this thesis include: Firstly, a theoretical model of a PEM fuel cell humidifier is proposed on the basis of the principles of energy conservation and mass conservation, and the theory of heat transfer and mass transfer. Secondly, the model of a PEM fuel cell humidifier is identified using a wavelet networks method. To avoid the curse-of-dimensionality problem, a class of wavelet networks proposed by Billings is employed. The experimental data acquired from the test bench are used for identification. The one-step-ahead predictions and the five-step-ahead predictions are compared with the real measurements, respectively. It shows that the identified model can effectively describe the real system. Thirdly, a dynamical model of a fuel cell stack is developed, based on the theories of conservation of energy conservation and mass conservation. This model can predict the performance of the stack. Fourthly, an expert PID algorithm is applied to the temperature control of the PEM fuel cell humidifier. The simulation and experimental results show the effectiveness of the algorithm. Finally, a fuzzy logic algorithm on the temperature control of the fuel cell stack is developed, based on the knowledge of the thermal property of the PEM fuel cell. It is shown that the algorithm can meet the needs of the stack control.
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