Search Results

In this paper, a model-based diagnostic system was developed to detect and isolate the dosing fault and the outlet NOx sensor fault for the SCR system. The dosing fault is treated as an actuator additive fault, while the outlet NOx sensor drift and/or offset fault is treated as a sensor additive fault. First, a 0-D SCR model was developed to facilitate the model-based approach. A parity equation residual generator was designed based on the linearized SCR model and the fault transfer function matrix. The diagnostic algorithm is then implemented in the Matlab/Simulink environment for validation. A high fidelity nonlinear 1-D SCR model is used to generate system outputs and to simulate the plant. The simulation results show that the model-based fault diagnosis system succeeds in detecting and isolating the outlet NOx sensor and dosing faults with good sensitivity and robustness

A hot and cold water mixing process with a steam condenser and a chilled water heat exchanger is set up for an engine EGR fouling test. The test rig has water recycled in the loop of a pump, heat exchangers, a three-way mixing valve, and a test EGR unit. The target unit temperature is controlled by a heating, cooling and mixing process with individual valves regulating the flow-rate of saturated steam, chilled water and mixing ratio. The challenges in control design are the dead-time, interaction, nonlinearity and multivariable characteristics of heat exchangers, plus the flow recycle in the system. A systems method is applied to extract a simple linear model for control design. The method avoids the nonlinearity and interaction among different temperatures at inlet, outlet and flow-rate. The test data proves the effectiveness of systems analysis and modeling methodology. As a result, the first-order linear model facilitates the controller design.

This paper describes the advantage of the integrated simulation platform and presents the results of performance simulations and the feed-forward air-fuel ratio (AFR) controller design of a new concept stoichiometric compression ignition (SCI) engine based on this platform. In this integrated simulation environment, the SCI engine was modeled in GT-Power and a simplified production engine control module (ECM) is implemented in Simulink/Matlab for the performance simulation and AFR control. The integrated engine and controller model was used to investigate constant-speed load-acceptance (CSLA) performance. During performance simulation, searching for operating conditions is difficult but critical for performance analysis. Trial and error method would require a long time to do. Based on the integrated simulation, a proportional-integral (PI) controller was designed to find the accurate operating conditions.

Mean value engine model (MVEM) is the basis of control design for advanced internal combustion engines. The engine performance transient process usually takes a few cycles. The MVEM provides an adequate accurate description of the engine dynamics with reasonable approximation by ignoring the heat loss and sub-cycle events. MVEM is very important for engine system control development, especially when the modern engine becomes more and more complicated when equipped with throttle, turbocharger and after-treatment systems. Usually the MVEM is developed based on data from engine tests, which is a costly and time consuming process. In this paper, the air path MVEM modeling method based on the 1D detail model is discussed for a turbocharged diesel engine. Simulation is applied to demonstrate the effectiveness of this new method. This approach could be used to get the MVEM for control design even before the prototype engine is available.