Modeling and Multi-time Scale Analysis of Railway Traction Systems Using Bond Graphs

The unified and global formalism of bond graph is suitable for modeling complex heterogeneous systems. Besides, direct application of the singular perturbation method to bond graphs can reduce or simplify the obtained models. In this paper, we take two different railway traction systems as case study. The first one consisting of a DC motor coupled with a mechanical load is relatively simple in order to show the advantages of these methods. The second corresponds to an actual railway traction system (the BB 36000 locomotive) composed of an asynchronous motor with direct field oriented control. By using the singular perturbation method, the bond graphs of these systems are simplified and reduced. To validate these simplifications, numerical simulations are carried out in both of the normal operating mode and the short-circuit mode. The analysis of couplings on the simplified bond graph allows us to find the dynamic elements associated to the main phenomena, such as resonance, which disturbs the system