In-Cylinder Oxygen Concentration Estimation Based on Virtual Measurement and Data Fusion Algorithm for Turbocharged Diesel Engines  
[PERSON]  
1 School of Transportation Science and Engineering, Beihang University, Beijing 100191, China; [EMAIL_ADDRESS] (Q.Z. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (K.W. ); [EMAIL_ADDRESS] (X.W.) [PERSON]  
1 School of Transportation Science and Engineering, Beihang University, Beijing 100191, China; [EMAIL_ADDRESS] (Q.Z. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (K.W. ); [EMAIL_ADDRESS] (X.W.) [PERSON]  
1 School of Transportation Science and Engineering, Beihang University, Beijing 100191, China; [EMAIL_ADDRESS] (Q.Z. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (K.W. ); [EMAIL_ADDRESS] (X.W.) [PERSON]  
1 School of Transportation Science and Engineering, Beihang University, Beijing 100191, China; [EMAIL_ADDRESS] (Q.Z. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (K.W. ); [EMAIL_ADDRESS] (X.W.) [PERSON]  
2 Intelligent Network R&D Institute, China FAW Group Co., Ltd., Changchun 130011, China; [EMAIL_ADDRESS]; [EMAIL_ADDRESS]; xinyu_wu@faw. The ICOC can hardly be directly measured in commercial applications. Model-based observer is thus developed to estimate it. In [14], linear parameter-varying model is utilized for the estimation of the ICOC at intake valve closing (IVC). In [15], the robustness of three observers for in-cylinder oxygen fraction is analyzed based on input to state stable (ISS) theory. In [16], the author outlines a physics-based time-varying transport delay model for oxygen concentration estimation for dual-loop EGR engine, which revealing the oxygen concentration relation between exhaust and intake manifold. Literature [17] proposes a model based on plug flow, which applied the effects of the time-varying transport delay. The method possesses an estimation error within 0.2% (RMS value). However, these model-based methods are mostly derived based on mass/energy conservation and vulnerable to uncertainties, such as the inaccuracy of volumetric efficiency [18] or the error of orifice geometry [19], etc. Additionally, semi-model based or numerical-based approaches are also developed. In [20], a semi-empirical model is presented for NOx emission prediction, which combine dynamical model and empirical data to develop the relation between the NOx emission and intake oxygen concentration. In [21], a numerical approach is developed to study the engine performance and emission for various blend fuels under various oxygen concentration. Despite of its accuracy, it cannot be implemented to combustion control. In this paper, the concept called \"virtual measurement\" is introduced. Virtual measurement means not physically measured by sensors but obtained by mathematical models or other relations, such as looking up tables, etc. Combining the virtual measurement with the information that calculated from dynamical equations by data association algorithm, the concerned information is supposed to be refined better. Back to the oxygen concentration estimation, as for the virtual measurement, we modeled the oxygen concentration as a function of ignition delay, which can be captured by the in-cylinder pressure trace. Once the ignition delay obtained, the in-cylinder oxygen information can be obtained accordingly. Thus, the virtual measurement is actually related to the in-cylinder pressure which is independent with the existing dynamical model-based strategy (on the basis of mass/energy conservation). To improve the overall robustness and accuracy, Kalman filter is utilized to fuse the data from in-cylinder pressure trace and the conventional dynamical model. Therefore, the virtual measurement (by in-cylinder pressure trace) of ICOC combines with the predicted one by the dynamical model to enable the ICOC to be estimated in a predictor-corrector fashion. The proposed method is validated through a calibrated GT-power model, the simulation results reveal the improved estimation accuracy and robustness. Figure 1: Engine architecture with air-path system.