  Satellite power system is a complex, highly interconnected hybrid system that
exhibit nonlinear and mode switching behaviors. Directed factor graph is an
inference model for fault diagnosis using probabilistic reasoning techniques. A
novel approach for constructing the directed factor graph structure based on
hybrid bond graph model is proposed. The system components status and their
fault symptoms are treated as hypothesis and evidences respectively. The
cause-effect relations between hypothesis and evidences are identified and
concluded though qualitative equations and causal path analysis on hybrid bond
graph model. A power supply module of a satellite power system is provided as
case study to show the feasibility and validity of the proposed method.
