|Title:||Control of miniature proton exchange fuel cells based on fuzzy logic|
|Authors :||Schumacher, Jürgen|
|Published in :||Journal of power sources|
|Publisher / Ed. Institution :||Elsevier|
|License (according to publishing contract) :||Licence according to publishing contract|
|Type of review:||Peer review (Publication)|
|Subjects :||Fuzzy logic; Control; Fuel cells|
|Subject (DDC) :||621.3: Electrical engineering and electronics|
|Abstract:||A control strategy is presented in this paper which is suitable for miniature hydrogen/air proton-exchange membrane (PEM) fuel cells.The control approach is based on process modelling using fuzzy logic and tested using a PEM stack consisting of 15 cells with parallel channels on the cathode side and a meander-shaped flow-field on the anode side.The active area per cell is 8 cm^2. Commercially available materials are used for the bipolar plates,gas diffusion layers and the membrane-electrode assembly. It is concluded from basic thermodynamic principles that water management at different temperatures can be achieved by controlling the air stoichiometry. This is achieved by varying the fan voltage for the air supply of the PEM stack. A control strategy of the Takagi Sugeno Kang (TSK) type, based on fuzzy logic, is presented. The TSK-type controller offers the advantage that the system output can be computed in an efficient way: the rule consequents of the controller combine the system variables in linear equations. It is shown experimentally that drying out of the membrane at high temperatures can be monitored by measuring the AC impedance of the fuel cell stack at a frequency of 1kHz. Flooding of single cells leads to an abrupt drop of the corresponding single-cell voltage.Therefore, the fuzzy rule base consists of the AC impedance at 1kHz and all single-cell voltages. The parameters of the fuzzy rule base are determined by plotting characteristic diagrams of the fuel cell stack at constant temperatures. Stable system operation is achieved at T=60°C for a power level of 7.5 W. The fuel cell stack is controlled successfully even when the external electric load changes. The maximum power level for stable system operation was found to be 8 W at T=65°C. A decrease of the maximum power level is observed for higher temperatures.|
|Departement:||School of Engineering|
|Organisational Unit:||Institute of Computational Physics (ICP)|
|Publication type:||Article in scientific Journal|
|Appears in Collections:||Publikationen School of Engineering|
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