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Multi-Output Control of a Heavy Duty HCCI Engine Using Variable Valve Actuation and Model Predictive Control

Lund Institute of Technology-Rolf Johansson, Per Tunestål, Bengt Johansson
Volvo Powertrain Corporation-Johan Bengtsson, Petter Strandh
Published 2006-04-03 by SAE International in United States
Autoignition of a homogeneous mixture is very sensitive to operating conditions, therefore fast control is necessary for reliable operation. There exists several means to control the combustion phasing of an Homogeneous Charge Compression Ignition (HCCI) engine, but most of the presented controlled HCCI result has been performed with single-input single-output controllers. In order to fully operate an HCCI engine several output variables need to be controlled simultaneously, for example, load, combustion phasing, cylinder pressure and emissions. As these output variables have an effect on each other, the controller should be of a structure which includes the cross-couplings between the output variables. A Model Predictive Control (MPC) controller is proposed as a solution to the problem of load-torque control with simultaneous minimization of the fuel consumption and emissions, while satisfying the constraints on cylinder pressure. One of the major motivations for using MPC is that it explicitly takes the constraints into account. When operating an HCCI engine there are several contraints present, for example on the cylinder pressure and on the emissions. A drawback of MPC…
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Variable Valve Actuation for Timing Control of a Homogeneous Charge Compression Ignition Engine

Lund Institute of Technology-Petter Strandh, Johan Bengtsson, Rolf Johansson, Per Tunestål, Bengt Johansson
Published 2005-04-11 by SAE International in United States
Autoignition of a homogeneous mixture is very sensitive to operating conditions. Therefore fast combustion phasing control is necessary for reliable operation. There are several means to control the combustion phasing of a Homogeneous Charge Compression Ignition (HCCI) engine. This paper presents cycle-to-cycle cylinder individual control results from a six-cylinder HCCI engine using a Variable Valve Actuation (VVA) system. As feedback signal, the crank angle for 50% burned, based on cylinder pressure, is used. Three control structures are evaluated, Model Predictive Control (MPC), Linear Quadratic Gaussian control (LQG) and PID control. In the control design of the MPC and LQG controller, dynamic models obtained by system identification were used. Successful experiments were performed on a port-injected six-cylinder heavy-duty Diesel engine operating in HCCI mode.
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System Identification of Homogeneous Charge Compression Ignition (HCCI) Engine Dynamics

Lund Univ.-Johan Bengtsson, Petter Strandh, Rolf Johansson, Per Tunestål, Bengt Johansson
  • Technical Paper
  • 2004-35-0135
Published 2004-04-19 by University of Salerno in Italy
Homogeneous Charge Compression Ignition (HCCI) combustion lacks direct ignition timing control, instead the autoignition depends on the operating condition. Since autoignition of a homogeneous mixture is very sensitive to operating condition a fast combustion timing control is necessary for reliable operation, the ignition timing control design requiring appropriate models and system output variables for its feedback design. This paper demonstrates the use of system modelling and identification as a means to find models relevant to the engine control. The identification methods used were various subspace-based methods. An LQG controller was designed based on the estimated models and tested on a six-cylinder, heavy-duty engine running in HCCI operation.
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Cycle-to-Cycle Control of a Dual-Fuel HCCI Engine

Lund Institute of Technology-Petter Strandh, Johan Bengtsson, Rolf Johansson, Per Tunestål, Bengt Johansson
Published 2004-03-08 by SAE International in United States
A known problem of the HCCI engine is its lack of direct control and its requirements of feedback control. Today there exists several different means to control an HCCI engine, such as dual fuels, variable valve actuation, inlet temperature and compression ratio. Independent of actuation method a sensor is needed. In this paper we perform closed-loop control based on two different sensors, pressure and ion current sensor. Results showing that they give similar control performance within their operating range are presented.Also a comparison of two methods of designing HCCI timing controller, manual tuning and model based design is presented. A PID controller is used as an example of a manually tuned controller. A Linear Quadratic Gaussian controller exemplifies model based controller design. The models used in the design were estimated using system identification methods.The system used in this paper performs control on cycle-to-cycle basis. This leads to fast and robust control. Dual fuels with different octane numbers were used to control the combustion timing.The engine was a 12 liter 6 cylinder heavy-duty diesel engine modified…
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Ion Current Sensing for HCCI Combustion Feedback

Dept. of Automatic Control, Lund Institute of Technology-Johan Bengtsson, Rolf Johansson
Div. of Combustion Engines, Lund Institute of Technology-Andreas Vressner, Per Tunestål, Bengt Johansson
Published 2003-10-27 by SAE International in United States
Measurement of ion current signal from HCCI combustion was performed. The aim of the work was to investigate if a measurable ion current signal exists and if it is possible to obtain useful information about the combustion process. Furthermore, influence of mixture quality in terms of air/fuel ratio and EGR on the ion current signal was studied. A conventional spark plug was used as ionization sensor. A DC voltage (85 Volt) was applied across the electrode gap. By measuring the current through the gap the state of the gas can be probed. A comparison between measured pressure and ion current signal was performed, and dynamic models were estimated by using system identification methods.The study shows that an ion current signal can be obtained from HCCI combustion and that the signal level is very sensitive to the fuel/air equivalence ratio. The most important result from this study is that the ion current signal proved to be an excellent indicator of the actual combustion timing which is crucial piece of information for HCCI control.
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