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Supervisory Controller for a Light Duty Diesel Engine with an LNT-SCR After-Treatment System

Chalmers University of Technology-Tomas McKelvey
Volvo Car Corp.-Dhinesh Velmurugan, Daniel Lundberg
Published 2018-09-10 by SAE International in United States
Look ahead information can be used to improve the powertrain’s fuel consumption while efficiently controlling exhaust emissions. A passenger car propelled by a Euro 6d capable diesel engine is studied.In the conventional approach, the diesel powertrain subsystem control is rule based. It uses no information of future load requests but is operated with the objective of low engine out exhaust emission species until the Exhaust After-Treatment System (EATS) light off has occurred, even if fuel economy is compromised greatly. Upon EATS light off, the engine is operated more fuel efficiently since the EATS system is able to treat emissions effectively.This paper presents a supervisory control structure with the intended purpose to operate the complete powertrain using a minimum of fuel while improving the robustness of exhaust emissions. A supervisory controller assisted by look ahead information, and using a supervisory control interface that works in concert with low level local controllers, can make subsystems operate near optimal. The look ahead parametrized supervisory control calculates the set-points for the subsystems: Internal Combustion Engine (ICE), Lean NOx Trap…
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Comparing Dynamic Programming Optimal Control Strategies for a Series Hybrid Drivetrain

Chalmers University of Technology-Tomas McKelvey
Volvo Car Corporation-Rickard Arvidsson
Published 2017-10-08 by SAE International in United States
A two-state forward dynamic programming algorithm is evaluated in a series hybrid drive-train application with the objective to minimize fuel consumption when look-ahead information is available. The states in the new method are battery state-of-charge and engine speed. The new method is compared to one-state dynamic programming optimization methods where the requested generator power is found such that the fuel consumption is minimized and engine speed is given by the optimum power-speed efficiency line. The other method compared is to run the engine at a given operating point where the system efficiency is highest, finding the combination of engine run requests over the drive-cycle that minimizes the fuel consumption. The work has included the engine torque and generator power as control signals and is evaluated in a full vehicle-simulation model based on the Volvo Car Corporation VSIM tool. Lowest fuel consumption is obtained by the new two-state method, with 12 % less fuel consumed compared to operating the engine in the system efficiency sweet spot.
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Battery Parameter Estimation from Recorded Fleet Data

Chalmers University of Technology-Tomas McKelvey
Volvo Car Corporation-Rickard Arvidsson
Published 2016-10-17 by SAE International in United States
Existing battery parameter model structures are evaluated by estimating model parameters on real driving data applying standard system identification methods. Models are then evaluated on the test data in terms of goodness of fit and RMSE in voltage predictions. This is different from previous battery model evaluations where a common approach is to train parameters using standardized tests, e.g. hybrid pulse-power capability (HPPC), with predetermined charge and discharge sequences. Equivalent linear circuit models of different complexity were tested and evaluated in order to identify parameter dependencies at different state of charge levels and temperatures. Models are then used to create voltage output given a current, state of charge and temperature. The average accuracy of modelling the DC bus voltage provides a model goodness of fit average higher than 90% for a single RC circuit model. Both single RC equivalent circuit model and R-equivalent circuit model produce goodness of fit at average 75 % or higher. The dual RC equivalent circuit model experienced larger errors in voltage estimations compared to single R and RC equivalent circuit…
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A Structure and Calibration Method for Data-Driven Modeling of NOX and Soot Emissions from a Diesel Engine

Chalmers University of Technology-Tomas McKelvey
Volvo Car Corporation-Markus Grahn, Krister Johansson, Christian Vartia
Published 2012-04-16 by SAE International in United States
The development and implementation of a new structure for data-driven models for NOX and soot emissions is described. The model structure is a linear regression model, where physically relevant input signals are used as regressors, and all the regression parameters are defined as grid-maps in the engine speed/injected fuel domain.The method of using grid-maps in the engine speed/injected fuel domain for all the regression parameters enables the models to be valid for changes in physical parameters that affect the emissions, without having to include these parameters as input signals to the models. This is possible for parameters that are dependent only on the engine speed and the amount of injected fuel. This means that models can handle changes for different parameters in the complete working range of the engine, without having to include all signals that actually effect the emissions into the models.The approach possibly also enables for the model to handle the main differences between steady-state engine operation and transient engine operation, thus possibly being able to use steady-state engine measurement data to calibrate…
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Parameterized Diesel Engine Combustion Modeling for Torque Based Combustion Property Estimation

Chalmers University of Technology-Mikael Thor, Bo Egardt, Tomas McKelvey, Ingemar Andersson
Published 2012-04-16 by SAE International in United States
Combustion model structures based on Vibe functions are outlined and investigated in this work. The focus of the study is the use of such model structures for estimation of diesel combustion properties by reconstructing in-cylinder pressure from measurements of crankshaft torque. Investigated combustion properties include the start and phasing of the combustion as well as maximum values of the in-cylinder pressure and its derivative. The accuracy associated with the proposed estimation method is evaluated using ideal torque data, i.e. torque calculated from in-cylinder pressure, that is generated using both simulations and experiments. The results indicate that the uncertainty associated with the estimation of a selected combustion property tends to increase if that property is located close to TDC, where the signal-to-noise ratio is low for a torque signal. The results also show that the ideal torque based estimation of combustion phasing and maximum in-cylinder pressure generally is very accurate while the estimation of start of combustion and the maximum in-cylinder pressure derivative suffers more from disturbances and model imperfections.
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Modeling, Identification, and Separation of Crankshaft Dynamics in a Light-Duty Diesel Engine

Chalmers University of Technology-Mikael Thor, Ingemar Andersson, Tomas McKelvey
Published 2009-06-15 by SAE International in United States
Mathematical models of a torque sensor equipped crankshaft in a light-duty diesel engine are identified, validated, and compared. The models are based on in-cylinder pressure and crankshaft torque data collected from a 5-cylinder common-rail diesel engine running at multiple operating points. The work is motivated by the need of a crankshaft model in a closed-loop combustion control system based on crankshaft torque measurements. In such a system a crankshaft model is used in order to separate the measured crankshaft torque into cylinder individual torque contributions. A method for this is described and used for IMEP estimation.Not surprisingly, the results indicate that higher order models are able to estimate crankshaft torque more accurately than lower order models, even if the differences are small. For IMEP estimation using the cylinder separation method however, these differences have large effects on accuracy. Here, the performance of higher order models is significantly better than for lower order models. Also, models of odd model order perform better than models of even model order. On average, a 9th order model estimates IMEP…
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Parameterized Diesel Engine Heat Release Modeling for Combustion Phasing Analysis

Chalmers University of Technology-Mikael Thor, Ingemar Andersson, Tomas McKelvey
Published 2009-04-20 by SAE International in United States
Different Vibe function model structures for parameterized diesel engine heat release models are investigated. The work is motivated by the need of such models when closed-loop combustion control is implemented based on torque domain combustion phasing analysis.Starting from the studied model structures, models are created by estimating the model parameters using a separable least squares approach. After this, the models are evaluated according to two different performance criteria. The first criterion rates the ability of the estimated models to describe reference mass fraction burned traces. The second criterion assesses how accurately the models estimate the reference combustion phasing measure.As expected, the analysis shows that the models based on the most flexible model structure achieve the best results, both regarding mass fraction burned estimation and combustion phasing estimation. However, even if the less complex models describe the mass fraction burned traces with lower accuracy, these models are able to estimate the combustion phasing measure surprisingly well.
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Instantaneous Crankshaft Torque Measurements - Modeling and Validation

Chalmers University of Technology-Stefan Schagerberg, Tomas McKelvey
Published 2003-03-03 by SAE International in United States
A simulation model for the dynamic properties of multi-cylinder engines is developed. Specifically, the model is used to describe the relation between the individual cylinder pressures and the resulting torque in the crankshaft. The model is validated against a 5-cylinder SI-engine equipped with a crankshaft integrated torque sensor. The simulation model developed is based on a system of first order nonlinear differential equations where the crankshaft dynamics are expressed as interconnected mass-spring-damper elements. The motivation is to investigate how instantaneous crankshaft torque measurements can be used to deduce information on the combustion process, cylinder by cylinder, for the purpose of engine control. Therefore, a computationally simple simulation method is introduced. For the model validation, an engine testbed has been developed which includes a standard production engine equipped with a crankshaft integrated magneto-elastic based torque sensor and cylinder pressure sensors. The torque sensor provides a crank-angle resolved measurement signal. The model was validated against measurements collected during engine tests at several load cases. The cylinder pressure signals acquired were used as input to the simulation model…
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