Modelling three-way catalytic converter oriented to engine cold-start conditions

This is the author¿s version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419853145[EN] This article introduces a physical model of a three-way catalytic converter oriented to engine cold-start conditions. Computational cost is an important factor, particularly when the modelling is oriented to the development of engine control strategies. That is why a one-dimensional one-channel real-time capable model is proposed. The present model accounts for two phases, gas and solid, respectively, considering not only the heat transfer by convection between both, but also the water vapour condensation and evaporation in the catalyst brick, which plays a key role during engine cold-start. Moreover, the model addresses the conductive heat flow, heat losses to the environment and exothermic reactions in the solid phase, as well as the convective heat flow in the gas phase. Regarding the chemical model, the oxidation of hydrocarbons and carbon monoxide is considered by means of the Langmuir-Hinshelwood mechanism. Three layers make up the model structure from a kinetic point of view, bulk gas, washcoat pores and noble metal in the catalyst surface. The model takes fuel-to-air ratio, exhaust gas mass flow, temperature, pressure and gas composition as inputs, providing the thermal distribution as well as the species concentration along the converter.Real, M.; Hedinger, R.; Pla Moreno, B.; Onder, C. (2021). Modelling three-way catalytic converter oriented to engine cold-start conditions. International Journal of Engine Research. 22(2):640-651. https://doi.org/10.1177/1468087419853145S64065122

EduBal: An open balancing robot platform for teaching control and system theory

In this work we present EduBal, an educational open-source hardware and software platform for a balancing robot. The robot is designed to be low-cost, safe and easy to use by students for control education. Along with the robot we present example tasks from system identification as well as SISO and MIMO control. Using Simulink, students can quickly implement their control algorithms on the robot. Individual control parameters can be tuned online while analyzing the resulting behavior in live signal plots. At RWTH Aachen University and ETH Zurich 28 units have so far been built and used in control classes. In first laboratory experiences students show high intrinsic motivation and creativity to apply the studied concepts of control theory to the real system.Comment: Accepted for publication at the 21st IFAC World Congress 202

Optimal Cold-Start Control Strategies for Gasoline Engines

In the first part of this thesis, generally valid rules for optimal control strategies during the catalyst heating phase at a high value of ignition retardation are identified experimentally. To this end, the effects of variations in control strategies are analyzed. Specifically, variations are analyzed in the center of combustion $\theta_{\mathrm{50}}$, in the air-to-fuel ratio $\lambda$ and in maldistributions in both quantities among individual cylinders on the behavior of the engine in idling conditions after a cold start. This behavior includes the fuel consumption, the heat-up behavior of the three-way catalytic converter, and the cumulative tailpipe emission of HC, CO, and NO$_\mathrm{x}$. A dedicated cylinder-individual, model-based, multi-variable controller is developed and used in experiments in order to isolate the effects of the individual control strategy variations as much as possible. An optimal control problem for a gasoline engine at a cold start is formulated which is used to interpret the experimental data obtained. The corresponding goal is to minimize the fuel consumption during an initial idling phase of a fixed duration while guaranteeing that the three-way catalytic converter reaches a sufficiently high final temperature and at the same time ensuring that the cumulative emissions stay below a given limit. The experimental data indicates that the engine should be operated with a maximum ignition retardation and at an air-to-fuel ratio of 5\%-10\% lean in order to reach any temperature inside the three-way catalytic converter as quickly as possible concurrently with minimum tailpipe emissions and at a minimum possible fuel consumption. In the second part of this thesis, trajectory tracking algorithms for gasoline engines are devised. Specifically, a simultaneous and precise reference tracking in engine speed, air-to-fuel ratio, and center of combustion is enabled. Such a tracking of multiple reference trajectories requires a coordinated control action for the air path, the fuel path, and the ignition timing actuators. Combining a dedicated feedforward and feedback controller structure and multivariable model-based norm-optimal parallel iterative learning control strategies, feedforward control trajectories are generated that enable a precise tracking of desired reference trajectories. Experimental results show the effectiveness of the proposed methodology

Optimal Cold-Start Control of a Gasoline Engine

This article analyzes the influence of the ignition retardation on the fuel consumption, the cumulative tailpipe hydrocarbon emissions, and the temperature inside the three-way catalytic converter in a gasoline direct injection engine operated under idling conditions. A dedicated cylinder-individual, model-based, multivariable controller was used in experiments in order to isolate the effect of the ignition retardation on the hydrocarbon emissions as much as possible. An optimal control problem for a gasoline engine at a cold-start is formulated, which is used to interpret the experimental data obtained. The corresponding goal is to minimize the fuel consumption during an initial idling phase of a fixed duration while guaranteeing that the three-way catalytic converter reaches a sufficiently high final temperature and at the same time making sure that the cumulative hydrocarbon emissions stay below a given limit. The experimental data indicates that the engine should be operated with maximum ignition retardation in order to reach any temperature inside the three-way catalytic converter as quickly as possible concurrently with minimum tailpipe emissions and with the minimum possible fuel consumption.ISSN:1996-107

EduBal: An open balancing robot platform for teaching control and system theory

In this work we present EduBal, an educational open-source hardware and software platform for a balancing robot. The robot is designed to be low-cost, safe and easy to use by students for control education. Along with the robot we present example tasks from system identification as well as SISO and MIMO control. Using Simulink, students can quickly implement their control algorithms on the robot. Individual control parameters can be tuned online while analyzing the resulting behavior in live signal plots. At RWTH Aachen University and ETH Zurich 28 units have so far been built and used in control classes. In first laboratory experiences students show high intrinsic motivation and creativity to apply the studied concepts of control theory to the real system

EduBal: An open balancing robot platform for teaching control and system theory

In this work we present EduBal, an educational open-source hardware and software platform for a balancing robot. The robot is designed to be low-cost, safe and easy to use by students for control education. Along with the robot we present example tasks from system identification as well as SISO and MIMO control. Using Simulink, students can quickly implement their control algorithms on the robot. Individual control parameters can be tuned online while analyzing the resulting behavior in live signal plots. At RWTH Aachen University and ETH Zurich 28 units have so far been built and used in control classes. In first laboratory experiences students show high intrinsic motivation and creativity to apply the studied concepts of control theory to the real system.ISSN:2405-896