Actuator Limitations in Spatial Temperature Control of SOFC

Abstract

A high performance multiinput multioutput feedback controller has been developed to minimize solid oxide fuel cell (SOFC) spatial temperature variation during load following. Cathode flow rate and its inlet temperature are used to minimize spatial temperature variations in the SOFC electrode electrolyte assembly for significant load perturbations. We focus on control design in the presence of nonideal actuation. This includes the effects of fuel processing delays, cathode inlet thermal delays, and parasitic power associated with the blower supplying air to the cathode. The controller, based on energytopeak minimization synthesis, is applied to a dynamic model of an anodesupported coflow planar SOFC stack. The results indicate that many of the problems associated with realistic and imperfect actuation can be addressed with relatively standard control synthesis modifications, but fuel flow delays can compromise power following significantly. Finally, a strategy that relies primarily on partial internal reformation for power following addresses many of the difficulties associated with reformer delays.