Exergy/energy dynamics-based integrative modeling and control for difficult hybrid aircraft missions

This paper introduces a new modeling approach to complex Turbo-electric Distributed Propulsion (TeDP) aircraft systems, by viewing them as dynamically interacting interconnected modules. Each module comprises group of components in which dynamics of physical variables are modeled first in dynamic state space, generally used for control design. Then a recently proposed transformed state space modeling is used to represent the dynamics of stored energy and its rate in each of these modules. The interaction variables, key to modeling and controlling mutual effects of components are shown to be instantaneous real and instantaneous reactive power. The interconnected dynamic model is systematically derived by writing conservation of both real power and rate of change of reactive power. Notably, the notions of instantaneous real and reactive power are common to all modules, and are defined for all types of energy conversion modules the same way. These models provide great physical intuition about the dynamics of energy conversion in these complex systems, as the proposed model in transformed state space has a straightforward interpretation in terms of exergy and anergy. Both efficiency and stability conditions become apparent. Based on these concepts, it becomes possible to understand potential benefits from new technologies. As an example, in this paper the case is made for utilizing fast electric storage control for purposes of eliminating engine stall and surge problems. In closing, future extensions of these concepts to modeling and controlling complex aircrafts and other vehicles are discussed.