Control of a two stage turbocharger on a Diesel engine

Two stage turbochargers have been developed recently for Diesel engines in order to improve their performances in terms of power, consumption, emissions and dynamic behavior. For this kind of system, the operating conditions are very different than for one stage turbochargers and specific control issues must be considered. In this paper an analysis of single stage turbochargers control issues is extended to two stage systems in order to highlight the specific issues. Two control structures able to cope with these problems are proposed and compared experimentally. A particular focus has been put on industrial constraints such as the number of sensors, the calibration effort, and a robustness analysis. Vehicle results demonstrate the relevance of the strategies proposed and illustrate the analysis.