Cette convention s'inscrit dans un programme de l'Association nationale pour la recherche et la technologie (ANRT), coordonné par le Centre national de la recherche scientifique (CNRS). Les recherches du Gipsa-lab portent sur les domaines de l'automatisme, du contrôle, du signal, de l'image et de la voix.
Objectif de l’etude
Cette thèse se concentre sur la modélisation 0D, notamment sur une description plus détaillée du processus de combustion et l'estimation des masses incluses dans la chambre de combustion d'un moteur Spark Ignited (SI). Ce modèle permet de prendre en compte la géométrie de la chambre de combustion et la proportion de flamme brûlant à proximité des parois du cylindre.
Index du manuscrit
Chapitre 3: Modélisation moteur
Des développements pour le contrôle Common Rail ont été réalisés pour les moteurs diesel Renault. Cependant, il est possible d'appliquer les stratégies proposées aux moteurs à allumage commandé car l'architecture du système à rampe commune est très similaire dans les deux cas.
Chapitre 4: Observateurs pour l’estimation des masses enfermées
Ce chapitre se concentre sur le développement du contrôleur pour le système d'injection à rampe commune. L'objectif est de synthétiser un contrôleur de moteur à allumage commandé basé sur les mêmes principes physiques que le système d'injection à rampe commune pour un moteur diesel.
Publications
Nowadays, the research and development of engine model-based control takes place in zero-dimensional-one-dimensional (0D-1D) engine models. In a 0D model, only the temporal variations of the variables involved in the model are taken into account, without spatial references.
Objective of the study
This thesis focuses on modeling a more detailed description of the 0D combustion process and estimating the mass enclosed in the combustion chamber for a spark ignition (SI) engine. A final point considered in this thesis is related to the control of the common rail injection system.
Manuscript outline
Chapter 3: Engine modeling
However, it is possible to apply them to the SI engine because the common rail architecture in both cases is very similar.
Chapter 4: Observers for enclosed mass estimation in the combus-
Chapter 5: Common rail injection system controller using input-
To maintain the performance of the engine, a more accurate engine modeling is essential. Different levels of modeling were used to represent the behavior of the engine.
Four strokes SI engine: operating cycle
In this thesis it is assumed that the combustion chamber and piston are cylindrical bodies. The piston head is assumed to have a disk shape, with the same radius as the combustion chamber.
Two zones 0D thermodynamical engine modeling
Vibe’s law combustion model
A common way to model the combustion process with a parametric approach is what is referred to as Vibe's law [Vibe, 1956]. Sl(t) is the gas laminar speed of the flame, derived from experimental measurements in [Metghalchi & Keck, 1982] as:. 1−2.21Xegr where p(t) is the cylinder pressure, Tu(t) is the unburned gas temperature, po and T0 are the atmospheric pressure and temperature respectively.
Fractal theory based wrinkling coefficient
For these reasons, the fractal approximation of the ripple coefficient presented below is retained to model the combustion model in this thesis. In the fractal model it is assumed that the ripple phenomenon can be represented by a fractal dimension D3(t) for a range of turbulence length scales Lmin and Lmax.
Flame surface: laminar flame area geometric model
If the gases in the combustion chamber are moving quickly, this will "fan" the flame and help it to propagate much faster. Including this result in Equation (3.5.7), the production term is only related to the non-isentropic speed as:. The non-isentropic production term represents the turbulent kinetic energy produced by the various turbulent sources: the swirl, the squish, the spray and the tumble. For an SI engine, the effects of swirl, squish, and spray on turbulence can be neglected [ Lafossas et al ., 2005 ]. The tumbling energy is then the only turbulence source for the production term:. 3.5.13) The turbulent kinetic energy due to the tumble can be obtained by assuming a linear decrease of the tumble motion from the intake valve closure (IVC) to the top dead center (TDC) as suggested in [Richard et al . ., 2009] (Note that there are several approaches for the tumbling motion modelling), (The temporal dependence of the variables is introduced from here on where Hp(t) is the piston height, m(t) is the gas mass in the combustion chamber, ωe the engine speed in rad/s and Ntumble(t) is the tumble number.
K-k turbulence model
The fourth term in equation (3.5.20) corresponds to the turbulence caused by compression, and the fifth term represents the reduction of turbulence at the end of the cycle. The third term represents the effect of compression and relaxation, and the fourth term represents the extinction of turbulence at the end of the cycle.
Tumble motion
The tumble phenomenon occurs due to the mass rotation of the gases around the cylinder diameter. The K−k based turbulence model was tested with 3D calculations of the turbulence intensity u0(t) in an SI engine as a reference.
Validation and application of a new 0D flame-wall interaction model for
Flame-wall interaction models review
When lu(t) < li(t), the effective intensity of near-wall turbulence changes when compared to that of the free stream. In order to propose a more realistic approximation of the behavior of the combustion process near the cylinder walls than the global approach, the shape of the cylinder and the flame surface distribution in the combustion chamber must be taken into account.
Flame/wall interaction model: local approach
With this information, a distribution of the flame surface in relation to the cylinder walls during combustion is obtained. Fext is defined as a function of the distance from the flame surface to the cylinder walls.
Flame-wall interaction local approach: Model validation and results 82
When Ψ(t) is included, the heat release rate decreases due to the slowing down of the burning rate. To test the validity of the flame-wall interaction model with respect to changes in combustion chamber geometry, two spark plug positions and two different spark plug types were tested.
Enclosed mass in a SI engine: estimation strategies review
- Hart, Ziegler and Loffeld: Adaptive model for the cylinder air mass
- Mladek and Onder: Inducted air mass and residual gas fraction
- Colin, Giansetti, Chamaillard and Higelin: In cylinder mass esti-
- Leroy, Alix, Chauvin, Duparchy and Le Berr: Modeling Fresh Air
These two variables are used to obtain different physical variables which are used to calculate the air mass, the IGR mass fraction Xigr and the total mass in the cylinder mtot. In the algorithm, the cylinder volume V is first calculated based on the engine geometry, and the cylinder pressure p and the intake manifold pressure pint are recorded.
One zone thermodynamical model for observers design
Intake valve flow: if mass flow goes from the intake manifold to the cylinder (positive intake mass flow), then Tint(t) = Tcol, where Tcol is the temperature of the intake manifold, if the gas goes from the cylinder to the manifold of intake (negative intake mass flow) Tint(t) = T(t), where T(t) is the cylinder temperature. Exhaust valve flow: if the mass flow goes from the cylinder to the exhaust manifold (positive exhaust mass flow), then Texh(t) =T(t), if the gas goes from the exhaust manifold to the cylinder (positive mass flow of negative exhaust) , Texh(t) = Tech, where Tech is the exhaust manifold temperature.
A sliding model observer for estimating the wall losses during the valves
Brief background on sliding mode observers
The condition V˙1(z)<0 must be satisfied to guarantee observer stability and convergence of e1 to 0. As the function is used and the Lyapunov function decreases, convergence to the sliding surface S = e1 eventually. time t0 is gained.
Sliding mode observer application
To ensure convergence of the observer, the initial conditions xˆ10 and xˆ20 must belong to the observer's area of attraction. These values were chosen taking into account the observer convergence conditions, the familiarity of the system and the reference model simulations.
Observer results
This result is shown in Figure 4.7, a zoom of Figure 4.6 during valve closing. Therefore, the enthalpy flow xˆ2(t) shown in Figure 4.7b corresponds to the heat wall losses δQˆth(t) during valve closing and the effectiveness of the sliding mode strategy proposed in equation (4.4.11) to obtain this variable has been proven. . b) Estimation of the enthalpy flow during compression and combustion strokes, ˆ.
One zone engine model reduction
The cylinder pressure x1(t) is a known measurement, but it is necessary to estimate the cylinder temperature x2(t) from Equation (4.5.5) to derive the mass using Equation (4.5.6).
A high gain observer for estimating the enclosed mass in the combustion
- Brief background on high gain nonlinear observers
- High gain nonlinear observer application
- Engine compression model
- Parameter varying polytopic system representation
- High gain observer for LPV systems
To use a high gain nonlinear observer such as (4.6.3) for system (4.5.5), the state space system must be transformed to fit the triangular additive form of system (4.6.1). The observer gain is written as a function of the estimated state and the high gain observer is calculated using Linear Matrix Inequalities (LMI) techniques.
High gain nonlinear observer for LPV systems application
Simulation results
As depicted in the figure, the observer is able to recover the mass estimate in the presence of the perturbation. Experiments with respect to changes in the initial pressure state of the observer xˆ10 have also been investigated and the result is presented in Figure 4.22a.
Chapter Summary
Besides, the PID does not guarantee the robustness and stability of the common rail system. A 0D model of the common rail system is designed based on experimental data map and is presented in Section 5.4.
Common rail injection system
When the pressure in the pump cavity is greater than the pressure in the rail, the pump opens the discharge side and the fuel flows to the HP circuit. The fuel flow passing through the IMV is the variable that controls the pressure in the rail.
Common rail injection control strategies review
- Gauthier, Sename, Dugard and Meissonnier: An LFT approach to
- An and Shao: Common Rail Pressure Control Based on Neuron
- Chatlatanagulchai and Yaovaja: Gain-scheduling integrator-augmented
- Balluchi, Bicchi, Mazzi, Sangiovanni-Vincentelli and Serra: Hybrid
- di Gaetaai, Montanaroa, Fiengob, Palladinob and Giglioa: A model-
An hybrid model of the common rail system is developed and validated with respect to experimental measurements. Both of the proposed strategies can be implemented for the common rail injection system of gasoline engines.
Rail pressure control
- Fundamentals on Input-State Linearization
- Common rail model transformation
- Linear Quadratic Regulator (LQR)
- LQR controllers application
- LQR controller results
As it can be seen in Equation (5.5.4), the final system has the form of a classic linear system. The LQR tracking controller has a faster response with respect to abrupt changes in the reference when compared to the LQR controller and the PI.
Chapter Summary
A new model has been proposed, the so-called local approach, which models the impact of the cylinder walls on the combustion rate. 2005], “Fractal approach to the evaluation of the combustion rate near the piston in a spark-ignition engine”, Combustion and Flame.
Mass balance between the intake manifold and the cylinder
Senecal, Xin and Reitz. Residual gas fraction in IC engines
Cavina, Siveiro and Suglia residual mass fraction estimation
Koehler and Bargende: In-cylinder residual mass model
Two zones thermodynamic model
Unburned zone energy balance
Burned zone energy balance
Combustion chamber energy balance
Geometric flame surface model
Reynolds stress tensor