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Model-Based Fault Diagnosis of the Gas Exchange System in a Turbocharged Gasoline Engine

Salehi, Rasoul | 2014

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 45630 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Alasty, Aria; Vossoughi, Gholamreza
  7. Abstract:
  8. Proper operation of a spark ignition engine is required by comfort demands of a vehicle driver and governmental legislations. Therefore it is essential to monitor, within an online technique, the engine and detect any fault which disrupts its operation. The gas exchange path (including the intake and exhaust subsystems) is an important part of turbocharged engines responsible for accurate control of both engine power and emissions. Monitoring the path for fault detection and isolation (FDI) has been always demanded due to many failures it may face since the turbocharger exasperates the harsh working conditions for components involved in the path. This paper presents a novel model-based algorithm which is able to detect and isolate major faults assigned to the gas exchange path both in the intake and exhaust sides. The FDI system is developed for diagnosis of these faults: air leakage between the compressor and the air throttle, gas leakage in the exhaust manifold upstream the turbine, gain offset in the exhaust manifold pressure sensor, wastegate stuck-closed and wastegate stuck-open. Moreover, the FDI system is able to work on gasoline engines not equipped with a hot-film air-flow meter (HFM). As the first step, the fault effect analysis is performed to find out key engine variables and subsystems (to be monitored) for designing the FDI system. Next, steady-state models are developed for subsystems in both the intake and exhaust path such as compressor, turbine and wastegate. These steady-state models are employed later to design three estimation algorithms including a downstream turbine pressure estimator, a turbocharger observer and an exhaust manifold observer. An asymptotically stable nonlinear Luenberger observer is designed to estimate the turbocharger dynamics whilst a second order sliding mode observer is utilized for estimating the exhaust manifold dynamics. Using estimation errors from the designed observers, a FDI algorithm is proposed and validated with experimental data from a modern TC gasoline engine running in a test cell. Results indicate the FDI system can successfully detect and isolate a 7 mm leakage fault after the compressor, a 6 mm fault in the exhaust manifold, a 3% gain-offset in the pressure sensor, the wastegate stuck-closed and stuck open faults
  9. Keywords:
  10. Model Based Fault Diagnosis ; Spark Ignition Engines ; Gas Exchange ; Turbocharger with Wastegate ; Nonlinear Leunberger Observer ; Second-Order Sliding Mode Observer

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