Bond Graph Representations of Hybrid System Models

2 Bond Graph Representations of Hybrid System Models 

One approach is to combine the advantages of established graphical representations by capturing physically feasible system modes and discrete transitions between them in a Petri net (PN) and by modelling the dynamic behaviour in each system mode by a bond graph or set of disjoint bond graphs composed of standard elements [6, 7]. 

Switching Off and On Degrees of Freedom by Means of Switched Residual Sinks 

One way to keep computational causalities time-invariant as proposed in [8] is to use sinks of invariant causality in conjunction with a modulated transformer MTF b t) that switches off and on degrees of freedom. 

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Section 1.2 gives a literature review of various approaches to a bond graph representation of hybrid system models. In particular, the section discusses the representation of fast switching devices by means of non-ideal switches with fixed mode-independent causality and addresses the equation formulation as a DAE system. 

In this book, a bond graph representation of hybrid system models is chosen as basis for bond graph model-based EDI in Chap. 4. The representation is system mode independent with regard to computational causalities and allows for deriving a set of... 

The book briefly recalls various bond graph representations of hybrid system models proposed in the literature. The development of hybrid models for the purpose of fault detection and isolation, in this book, makes use of conceptual nonideal switches representing devices for which it is justified to abstract their fast state transitions into instantaneous discrete state switches and accounts for stmctural model changes by special sources that are switched on or off at the advent of a discrete event. As other possible approaches, this approach has its pros and cons. For illustration, the presented method is applied in a number of elaborated case studies that consider fault scenarios for switched power electronic systems that are commonly used in a variety of applications. Power electronic systems have been chosen because they may be appropriately described by a hybrid model and are well suited for application of the presented bond graph model-based approach to fault detection and isolation. The approach, however, is not limited to this kind of systems. 

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