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1 Turbocharging plays an important role in the downsizing of engines. Model-based approaches for boost control are going to increasing the necessity for controlling the wastegate flow more accurately. In today’s cars, the wastegate is usually only controlled with a duty cycle and without position feedback. Due to nonlinearities and varying disturbances a duty cycle does not correspond to a certain position. Currently the most frequently used feedback controller strategy is to use the boost pressure as the controller reference. This means that there is a large time constant from actuation command to effect in boost pressure, which can impair dynamic performance. In this paper, the performance of an electrically controlled vacuum-actuated waste-gate, subsequently referred to as vacuum wastegate, is compared to an electrical servo-controlled wastegate, also referred to as electric wastegate.

With stricter emission legislations and customer demands on low fuel consumption, good control strategies are necessary. This may involve control of variables that are hard, or even impossible, to measure with real physical sensors. By applying estimators or observers, these variables can be made available. The quality of a real sensor is determined by e.g. accuracy, drift and aging, but assessing the quality of an estimator is a more subtle task. An estimator is the result of a design work and hence, connected to factors like application, model, control error and robustness. The air mass-flow in a diesel engine is a very important quantity that has a direct impact on many control and diagnosis functions. The quality of the air mass-flow sensor in a diesel engine is analyzed with respect to day-to-day variations, aging, and differences in engine configurations. The investigation highlights the necessity of continuous monitoring and adaption of the air mass-flow.

Heat release analysis by using a pressure sensor signal is a well recognized technique for evaluation of the combustion event, and also for combustion diagnostics. The analysis includes tuning of several parameters in order to accurately explain measured data. This work presents and investigates a systematic method for estimating parameters in heat release models and minimizing the arbitrary choices. In order for the procedure to be systematic there are also the requirements on the model, that it includes no inherent ambiguities, like over-parameterization with respect to the parameters and to the information contained in the measurements. The fundamental question is which parameters, in the heat release model, that can be identified by using only cylinder pressure data. The parameter estimation is based on established techniques, that constructs a predictor for the model and then minimizes a least-squares objective function of the prediction error.

The main result of this paper is a real-time closed loop demonstration of spark advance control by interpretation of ionization current signals. The advantages of such a system is quantified. The ionization current, obtained by using the spark plug as a sensor, is rich on information, but the signal is also complex. A key step in our method is to use parameterized functions to describe the ionization current [1]. The results are validated on a SAAB 2.3 1, normally aspirated, production engine, showing that the placement of the pressure trace relative to TDC is controlled using only the ionization current for feedback.