Alain Charlet

Parametric optimization of a new hybrid pneumatic-combustion engine concept

Abstract Although internal combustion engines display high overall maximum global efficiencies, this potential cannot be fully exploited in automotive applications: in real conditions, the average engine load (and thus efficiency) is quite low and the kinetic energy during a braking phase is lost. One solution to this problem is to switch to a new hybrid pneumatic-combustion engine concept, which is able to store energy in the form of compressed air. This energy can be issued from a braking phase or from a combustion phase at low power. The potential energy from the air tank can then be restored to start the engine, use the stored air to drive the engine as a pneumatic motor at low load or charge the engine at full load. Optimization of the compressed air tank maximum pressure and volume as well as the operating mode switching strategy provides an improvement in terms of fuel economy as high as 31 per cent if combined with engine downsizing.

On the integration of optimal energy management and thermal management of hybrid electric vehicles

This paper proposes a supervisory control for hybrid electrical vehicle (HEV). It is based on Equivalent Consumption Minimization Strategy (ECMS) extended with a new state reflecting the thermal state of the engine. A new consumption law taking into account the losses due to low engine temperature is therefore included in the optimal control problem. The strategy is tested offline on a regulatory driving cycle, the results show an improvement on the consumption which confirm the relevance of the approach.

A simple method for robust control design, application on a non-linear and delayed system: engine torque control

Abstract This paper presents a simple method for designing a robust controller which can be used on uncertain and non-linear systems. As an extension of the method, the case of delayed systems is examined. The successive steps of the method are: non-linearity analysis and description, system linearization and identification, operating model design by minimization of a weighted frequencies criteria, model uncertainty design, PI and LQ controller design with robust property verification. A Smith predictor is included in the global control scheme to take the delay of the system into account. The application is a design of a robust controller for engine torque control.

Exact and Linearized Neural Predictive Control: A Turbocharged SI Engine Example

This paper describes a real-time control method for non-linear systems based on model predictive control. The model used for the prediction is a neural network because of its ability to represent non-linear systems, its ability to be differentiated, and its simplicity of use. The feasibility and the performance of the method, based on on-line linearization, are demonstrated on a turbocharged spark-ignited engine application, where the simulation models used are very accurate and complex. The results, first in simulation and then on a test bench, show the implementation of the proposed control scheme in real time.

Linearized Neural Predictive Control A Turbocharged SI Engine Application

Nowadays, (engine) downsizing using turbocharging appears as a major way for reducing fuel consumption. With this aim in view, the air actuators (throttle, Turbo WasteGate) control is needed for an efficient engine torque control particularly to reduce pumping losses and to increase efficiency. This work proposes Nonlinear Model Predictive Control (NMPC) of the air actuators for turbocharged SI engines where the predictions are achieved by a neural model. The results obtained from a test bench of a Smart MCC engine show the real time applicability of the proposed method based on on-line linearization and the good control performances (good tracking, no overshoot) for various engine speeds.

Catalytic converter modeling for optimal gasoline-HEV energy management

A simple multi-0D model of a 3-Way Catalytic Converter (3WCC) is built from physical equations, integrating the temperature dynamics and a pollutant emission conversion map. The validated model involves complexity and performances suitable to be integrated in a high fidelity powertrain model of a gasoline-Hybrid Electric Vehicle (HEV). Next, a pollutant constrained optimal energy management is derived from the Pontryagin Minimum Principle. The approach allows the joint minimization of pollution and fuel consumption with only one parameter to tune, by considering all the standardized pollutant emissions. The proposed strategy significantly reduces pollutant emissions with only a slight fuel consumption increase. Using a complex HEV model shows the feasibility of the pollution constraint integration in on-line energy management.

3WCC Temperature Integration in a Gasoline-HEV Optimal Energy Management Strategy

For a gasoline-hybrid electric vehicle (HEV), the energy management strategy (EMS) is the computation of the distribution between electric and gasoline propulsion. Until recently, the EMS objective was to minimize fuel consumption. However, decreasing fuel consumption does not directly minimize the pollutant emissions, and the 3-way catalytic converter (3WCC) must be taken into account. This paper proposes to consider the pollutant emissions in the EMS, by minimizing, with the Pontryagin minimum principle, a tradeoff between pollution and fuel consumption. The integration of the 3WCC temperature in the EMS is discussed and finally a simplification is proposed.

Pollution Constrained Optimal Energy Management of a Gasoline-HEV

In Hybrid Electric Vehicles (HEV), the electrical hybridization offers different ways to reduce the fuel consumption: kinetic energy recuperation during vehicle deceleration, possibility of stopping the engine, and intelligent Energy Management System (EMS). Besides, with the future more stringent standards, there is a need to integrate the pollutant emissions in the EMS, since strictly reducing the fuel consumption can increase the emissions. The paper presents an optimal energy management strategy with constraints on pollutant emissions for gasoline-HEV, taking into account the 3-Way Catalyst Converter (3WCC). Based on a complete model of the powertrain, a mixed fuel consumption / pollutant emissions performance index is minimized with the Pontryaguin Minimum Principle (PMP) and two states, the battery State Of Charge and the 3WCC temperature. Simulation results are presented showing that simply including the 3WCC dynamics in the pollutant emissions leads to a 1-state problem, easier to solve and giving better results for reducing fuel consumption and pollutants emissions, with a lesser use of the battery.

High Dynamic Engine-Dynamometer Identification and Control

In this paper, a high dynamic test-bed control problem for high dynamic vehicle simulation is studied in order to improve the tracking of speed and torque. As the system is nonlinear and square (2x2) with two inputs and two outputs, a multi-input multi-output (MIMO) system-identification problem is discussed. The test-bed data are processed using a fast frequency domain methodology to build a nominal linear plant and a perturbation model. Based on this perturbed plant, the CRONE Control-System Design approach (a fractional order of differentiation based methodology) is used to design a robust MIMO controller, which maintains performance around a wide set of operating points. Finally, experimental results show the relevance of the proposed methodology.

One Dimensional Modeling and Experimental Validation of Single Cylinder Pneumatic Combustion Hybrid Engine

The objective of this paper is to present and to validate a numerical model of a single-cylinder pneumatic-combustion hybrid engine. The model presented in this paper contains 0-D sub-models for non-spatially distributed components: Engine cylinder, Air tank, wall heat losses. 1-D sub-models for spatially distributed components are applied on the compressive gas flows in pipes (intake, exhaust and charging). Each pipe is discretized, using the Two-Steps Lax-Wendroff scheme (LW2) including Davis T.V.D. The boundaries conditions used at pipe ends are Method Of Characteristics (MOC) based. In the specific case of a valve, an original intermediate volume MOC based boundary condition is used. The numerical results provided by the engine model are compared with the experimental data obtained from a single cylinder prototype hybrid engine on a test bench operating in 4-stroke pneumatic pump and 4 stroke pneumatic motor modes. In each mode, the prediction of the mass flow rates, amplitude and timing of the charging pipe waves are satisfactory, without using any discharge coefficient. Indicated work and p-V diagrams are similar between simulation and measurements in the case of pneumatic pump mode. For the pneumatic motor mode the model underestimates cylinder pressure during the charging process.