Double Stage Turbocharger Control Strategies Development

A major issue in the development of the future engines (diesel or gasoline) 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... For these new architectures, the engine control strategies need to be modified in order to address the specific issues related either to the new system in itself or to its integration in the global engine. Renault and IFP have studied together, from a control point of view, the integration of a double stage turbocharger in a diesel engine. This paper presents the works undertaken during this study. The structure of the paper follows the different stages of the project. The functioning of the system was first analyzed in simulation, leading to the adaptation of existing turbocharger control strategies and the development of new specific ones. In a second stage, the algorithms were implemented on an engine and validated online. Simulation as well as real test results are exposed in the different sections, demonstrating a good correlation between online and offline tests and proving the validity of the approach based on the utilization of simulation tools.