2011
IMAACA 2011 Proceeding
Analytical Redundancy Relations from Bond Graphs of Hybrid System Models
Authors: Wolfgang Borutzky
Abstract
?This paper picks up on one of the ways reported in the literature to represent hybrid models of engineering systems by bond graphs with static causalities. The representation of a switching device by means of a modulated transformer (MTF) controlled by a Boolean variable in conjunction with a resistor has been used so far to build a model for simulation. In this paper, it is shown that it can also constitute an approach to bond graph based quantitative fault detection and isolation in hybrid system models. Advantages are that Analytical Redundancy Relations (ARRs) do not need to be derived again after a switch state has changed. ARRs obtained from the bond graph are valid for all system modes. Furthermore, no adaption of the standard sequential causality assignment procedure (SCAP) with respect to fault detection and isolation (FDI) is needed. It is shown that the approach proposed in this paper can pro- duce the same ARRs given by Low et. al. for a network example reproduced in Fig. 1. Moreover, its usefulness is illustrated in a small case study by application to a switching circuit from the realm of power electronic systems. The approach, however, is not limited to FDI of such systems. Analytically checked simulation results give confidence in the approach.
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