Control-theoretic cyber-physical system modeling and synthesis: A case study of an active direct methanol fuel cell

A joint optimization of the physical system and the cyber world is one of the key problems in the design of a cyber-physical system (CPS). The major mechanical forces and/or chemical reactions in a plant are commonly modified by actuators in the balance-of-plant (BOP) system. More powerful actuators requires more power, but generally increase the response of the physical system powered by the electrical energy generated by the physical system. To maximize the overall output of a power generating plant therefore requires joint optimization of the physical system and the cyber world, and this is a key factor in the design of a CPS. We introduce a systematic approach to the modeling and synthesis of a CPS that emphasize joint power optimization, using an active direct methanol fuel cell (DMFC) as a case study. Active DMFC systems are superior to passive DMFCs in terms of fuel efficiency thanks to their BOP system, which includes pumps, air blowers, and fans. However, designing a small-scale active DMFC with the best overall system efficiency requires the BOP system to be jointly optimized with the DMFC stack operation, because the BOP components are powered by the stack. Our approach to this synthesis problem involves i) BOP system characterization, ii) integrated DMFC system modeling, iii) configuring a system for the maximum net power output through design space exploration, iv) synthesis of feedback control tasks, and v) implementation.