Simulation of Causally Dynamic Hybrid Bond Graphs, with Application to a Power Converter

Rebecca Margetts, Benjamin Boudon, and Roger F. Ngwompo


Bond graph, hybrid model, switched model, system dynamics


Causally dynamic hybrid bond graphs are generally considered unsuitable for simulation, and causality is therefore often constrained in hybrid bond graph models. This paper demonstrates how a causally dynamic model can be simulated, using a buck converter as a case study. A causally dynamic hybrid bond graph (utilizing controlled junctions) is used to derive a mixed-Boolean state equation. This state equation is transferred to MATLAB, where a simple routine assigns values to the Boolean parameters and then solves the model. Where storage elements are in dynamic causality, the model takes descriptor state form and an implicit solver is used. Solver choice and event detection are discussed. MATLAB was selected as an accessible environment which allows this type of model to be coded and solved, but the technique could be used in an environment of the practitioner’s choice. The power converter is successfully modeled with a fast simulation time, demonstrating that simulating causally dynamic hybrid bond graphs is possible and merits further refinement.

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