Pemfc Modeling And Control Method Based On Fractional Order Calculus Study

Energy shortages and environmental pollution has become one of the most important challenges all over the world. As a power generation method, fuel cell is treated to be a revolutionary achievement in the field of electrical energy, because it provides a new solution for energy supply. Among all kinds of fuel cells, PEMFC has a broad application prospects with its unique advantages, such as low operating temperature, high power density, rapid response and good stability. The modeling and the designing of control system is an important branch of PEMFC related technologies. Anvanced technologies of PEMFC modeling and controling will have great siginificance in analyzing system performance, improving power generation efficiency and ensuring a safe operation.It has been shown that, fractional calculus is quite applicable to describe the dynamic performance of the non-rigid motion system such as thermodynamic system and flexible system. Base on the fractional calculus, the method of modeling and control system desiging for PEMFC is studied in this paper, the main achievements and contributions are summarized as follows:(1) A method of designing fractional-order PIλDμ controller is proposed in this paper, while the parameters are identified baseds on the index of error performance. Simulation illustration is presented to show that PIλDμ controller can achieve better adjusting effect than PID for both integral and fractional controlled objects.(2) Depend on the different characteristic between conventional R//C circuit and fractional R//C circuit, the first-order process and fractional-order process are used to describe such two circuits in frequency domain. Simulation illustrates that fractional-order process have much more kinds of curve forms of step response. Corresponding to the characteristic of fractional-order process, the electrical and thermal steady-state models and fractional dynamic models are presented according to the internal working mechanism.(3) After analyzing the effect of stack temperature on each kind of polarization excessive voltage, the fitting formula of the optimum working temperature is obtained and the parameters are identified based on the experimental data. A Simulink model of the fuel cell stack thermal characteristics is constructed, and the fractional PID’s parameters can be optimized with it. Besides, the digital implementation of PIλDμ is accomplished based on GL definition.(4) In the end, a measuring and controlling system of PEMFC designed is introduced, while a detailed description of the PC software is given. The accuracy of the models and the effectiveness of the designed controller are verified by several experimental data curves.