Numerical Verification and Experimental Validation of Sliding Mode Control Design for Uncertain Thermal SOFC Models

The design of reliable and robust control strategies for the automatized operation of SOFC systems in a decentralized power grid demands for the use of nonlinear dynamic system models with a large number of physical parameters. These models have to cover the most dominant nonlinear effects and include knowledge about the uncertainty of specic parameters. In this paper, interval variables are taken into account to represent imperfect system knowledge during modeling on the one hand and to account for possible ambiguities in the system parameterization on the other hand. As soon as point values are chosen from parameter intervals identied by means of global optimization techniques in previous work, it becomes necessary to determine control laws which compensate the remaining uncertainties as well as non-modeled disturbances in a reliable way. For this purpose, guaranteed stabilizing control strategies are derived in this paper using the principle of sliding mode design. This methodology is extended towards a reliable interval-based implementation that can be evaluated in real-time environments. In such a way, it is possible not only to validate the resulting control strategies oine by means of simulations but also to use the same program code online on a real-life test rig. Corresponding experimental results are presented in this paper for an SOFC system that is available at the Chair of Mechatronics at the University of Rostock.

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