Model Based Control of Turbochargers: Application to a Diesel HCCI Engine

The recent developments in Diesel engines tend towards new types of combustion, such as Homogeneous Charge Compression Ignition (HCCI) which looks promising with respect to the pollutant emissions. However, these new technologies require a faster and more accurate control of the gas mixture in the cylinder due to its higher sensitivity to thermodynamic conditions and composition. A major issue in the development of these new types of Diesel engines lies in the architecture and the control of the air intake system. In this context many setups are envisaged, and in particular the turbocharging systems are becoming more and more complex: variable geometry turbines, double stage turbochargers, variable geometry compressors. The associated control laws have to be modified: the conventional strategies based on steady static maps and proportional integral controllers have to be improved in order to address the new challenges. This paper proposes a model based control strategy for a variable geometry turbocharger. This strategy is based on a physical representation of the system (turbocharger, intake and exhaust manifolds). The approach has two main advantages: it is easy to calibrate, and it can be adapted to other types of architecture. The first part of this paper describes the architecture of the system and its model. The second part details the strategies designed and the results carried out in simulation and on an engine test bed.