Experimental validation of interval-based sliding mode control for solid oxide fuel cell systems

The utilization of solid oxide fuel cells (SOFCs) as well as other high-temperature fuel cells for a decentralized power supply demands for reliable and guaranteed stabilizing control strategies, that are capable of providing electrical and thermal energy. Moreover, it is essential to increase the number of possible thermal cycles of SOFCs by means of control laws which reduce temperature gradients in the space coordinates of a stack module during transient operating conditions. For this purpose, suitable control-oriented system models have been identified in previous work and parameterized reliably by means of both local and global optimization procedures. By exploiting these models, which can be extended to account for parameters that are subject to bounded uncertainty, interval-based sliding mode controllers can be derived. These controllers simultaneously adjust the mass flow and temperature of air supplied to the cathode of the SOFC. In this paper, a real-time capable implementation of the corresponding interval-based sliding mode controller and selected experimental results are presented for an SOFC test rig available at the Chair of Mechatronics at the University of Rostock.