Model-based turbocharged diesel engine control and diagnostics using nonlinear sliding control and observers.

摘要

Sliding mode control and observers are used to develop turbocharged diesel engine control and diagnostics based on representative nonlinear dynamic engine models. Both a mean torque production and a cylinder-by-cylinder turbocharged diesel engine model are presented. The sliding observer and global linearized observer are applied to reconstruct cylinder pressure from the varying engine speed measurement. This is the first model-based nonlinear observer approach that has been designed for cylinder pressure estimation. The strengths of adding cylinder pressure dynamics to varying crankshaft dynamics and the use of sliding observer are shown. Engine misfire can be detected by using the observer correcting terms, cylinder pressure estimate, fuel burning rate estimate, or estimated heat release.; The intake manifold pressure observer is used to reconstruct the manifold pressure that has sensor delay and noise problems. An engine load observer is outlined by using the engine mean speed dynamics and a simple step load change assumption. A similar approach is applied to estimate the average fuel-air equivalence ratio. Sliding mode theory is used in the design process to guarantee the engine observers' convergence and robustness.; Several nonlinear diesel engine controllers including four variations of sliding mode controls, PI control, and PI control with feedforward are discussed. Sliding mode and PI feedforward controls are used to formulate diesel engine controllers and indicated torque input observers. An interesting and fair comparison is done by including nonlinear dynamic terms in both indicated torque input observers. Cylinder pressure and indicated torque estimates which come from these model-based observers are analyzed and related to combustion faults. The cylinder pressure centroid location can be easily used for misfire detection. Derivations of cylinder pressure difference approaches are discussed. Advanced automotive powertrain systems will benefit from using these model-based observers and controllers inside their electronic control modules.