Bond-graph-based model simplification for system analysis: application to a railway traction device

Heterogeneous and multifield systems can be homogeneously modelled using bond graphs. Even if this formalism contributes to making the system analysis easier, simplifying the device modelling as much as possible is also required in order to obtain the 'just accurate enough model' with respect to the design objectives. Two simplification methods are investigated in this paper: the model order reduction algorithm (MORA), depending on the energetic transfers in the systems, and the singular perturbation method (SPM), based on element dynamics. Each method is directly applied on bond graphs. To illustrate their application, a railway traction device is considered as an example. The results obtained by both methods are compared and the conditions of use are analysed. Finally, these two processes have proved their efficiency to reduce the computation time and to simplify the system analysis.