University of Twente Research Information · 2001 · 33 citations · 4 references
Open access
EngineeringAutomotive EngineeringSystems EngineeringHeat TransferProcess Systems EngineeringSystems ModelingBoundary ConditionsFault DetectionFault IsolationFault ModelingHeat Transfer AnalysisModel FormulationBoundary Condition AnalysisCausal Loop AnalysisCausal Loop ModelingCooling System ArchitectureCooling System DesignEnergy Storage ModelingModel-based Fault IsolationThermal Network Modeling
Many models for fault detection and isolation (FDI) will contain multi-port energy storage and flow-dependencies due to convection. Converting these models into qualitative ones leads to ambiguities that can be eliminated by analysis of boundary conditions. In this study the example of an automotive cooling system is used to demonstrate how these issues can be handled. Furthermore, time constants in the models need to correspond to the bandwidth of the data acquisition system. In order to achieve this, parameters leading to irrelevant time constants can be eliminated by assigning relatively small and large parameters to be zero or infinite respectively. However, this may result in (i) discontinuities and (ii) zero order causal paths ("algebraic loops"). Compensation of qualitative e#ects instead of reversal is shown to be an adequate solution for these problems.
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