An effective temperature controller for steam reformers is critical to ensure a high performance reforming process in the connection of Solid Oxide Fuel Cell (SOFC). The establishment of a control-orienteddynamic mod...
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An effective temperature controller for steam reformers is critical to ensure a high performance reforming process in the connection of Solid Oxide Fuel Cell (SOFC). The establishment of a control-oriented dynamic model plays an important role in the development of a control system. In this work, a high-fidelity lumped parameter model for a steam reformer is constructed based on physical and chemical laws. In order to fit simulated data to experimental data, such as flow rate and temperature characteristics, a new identification method based on a breed particle swarm optimization (Breed PSO) algorithm is introduced for parameter identification. The results show that the identified model can achieve an accurate description of the actual plant and can be used to replace it for the development of a control system. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
In this study, a novel discrete pulse frequency modulation with sliding-mode control (SMC) implementation of LLC resonant converter is proposed. SMC is employed to cope with the variable dynamic characteristics of LLC...
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In this study, a novel discrete pulse frequency modulation with sliding-mode control (SMC) implementation of LLC resonant converter is proposed. SMC is employed to cope with the variable dynamic characteristics of LLC resonant converter. The control-oriented dynamic model is first developed by extended describing function method. In order to achieve an optimised output voltage dynamic response, the sliding surface is derived based on the input-output linearisation concept. The proposed sliding-mode controller provides inherent strong robustness against the dynamic drift issues. Meanwhile, the digital SMC signal is insensitive to the non-linear parasitic capacitor of optocoupler. Furthermore, the dynamic performances are significantly improved for the applications of strict dynamic requirements. The theoretical analysis and the attractive dynamic performance are verified by simulation and experimental results.
Given the complicated mechanisms associated with the operation of the solid oxide fuel cell (SOFC), mathematical models developed to capture the SOFC's dynamic characteristics often result in high order and comple...
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Given the complicated mechanisms associated with the operation of the solid oxide fuel cell (SOFC), mathematical models developed to capture the SOFC's dynamic characteristics often result in high order and complex dynamics that make the model unsuitable for control design and analysis. In this paper, the minimum Gibbs free energy (MGFE) method is exploited to simplify the calculation of the mass balance dynamics of the fuel flow in the SOFC in an effort to develop a controlorientedmodel that achieves appropriate trade-off between model accuracy and simplicity. The simplified model is compared with a baseline model where dynamic governing equations are derived for the mass balance of each of the six gas species in the fuel flow. The implications of the MGFE method on the modeling performance are investigated through numerical simulations and frequency domain analysis. The MGFE method leads to the elimination of 5 out of 11 states in the baseline model, thereby resulting in a significantly lower order model. Critical parameters that may influence the accuracy of the simplified model are also identified. The study concludes that the accuracy of the reduced-order model is acceptable at normal conditions for both steady-state and transient operations. Noticeable model errors are only observed in steady-state responses at extreme conditions, where the fuel inlet has a high fraction of CH4 and the fuel cell has low fuel utilization, and in transient when the inputs change at high frequency. (c) 2006 Elsevier B.V. All rights reserved.
A lumped, non-linear control-oriented dynamic model for the solid oxide fuel cell has been developed. The exponential decay function and the exponential associate function are introduced to fit the distribution charac...
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A lumped, non-linear control-oriented dynamic model for the solid oxide fuel cell has been developed. The exponential decay function and the exponential associate function are introduced to fit the distribution characteristics of fuel cell state variables in the flow direction of the gases in order to account for the effect of spatial variation of fuel cell parameters in the dynamicmodel. It is integrated into the dynamicmodel by three characteristic parameters of the fitting function, which are determined via numerical simulations. A planar solid oxide fuel cell with co-flow has been used to evaluate the accuracy and applicability of the current dynamicmodel. The dynamicmodel is programmed and implemented using the SIMULINK software. The simulation results indicate the model has good service quality to predict the state variables and the performance of the solid oxide fuel cell. (c) 2006 Elsevier B.V. All rights reserved.
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