Control of a heat-integrated co-ionic-conducting solid oxide fuel cell system

A control study of a heat-integrated solid oxide fuel cell system with a BaCe_1-xSm_xO_3-α. type electrolyte is presented. This type of electrolytes exhibit both proton and oxygen-anion conductivity, and the fuel cell has multiple steady states in some operating regions. A multi-loop control system consisting of four proportional-integral (PI) controllers with two coordination rules is used to adjust four manipulated inputs to control the cell solid temperature and outlet voltage. For the temperature control two secondary PI controllers that adjust the duties of an air and a fuel inlet temperature conditioner are used. The set-points of the secondary PI controllers are set by a primary PI controller. Simulation results show that the control system can operate the cell at all steady states, whether stable or unstable. They also indicate that the control system is capable of tracking step changes in the set-points and rejecting piece-wise constant external load disturbances.