Time to boost analysis of an advanced boosting system for automotive applications

Fun to drive and drivability are important issues in modern vehicles, and propulsion system plays a key role in achieving these goals. Nowadays, most engines are characterized by the presence of a turbocharging system in order to obtain a high level of specific power and efficiency. Unfortunately, turbocharged engines are characterized by a delay in toque delivery, especially at low load, a phenomenon commonly called turbo-lag. In this paper an innovative turbocharging system is studied with the aim of providing a solution to this annoying behavior; a hybrid bosting system consisting of a traditional turbocharger and an electrically assisted compressor is analyzed. This architecture, especially thanks to the good dynamic behavior of the e-compressor, achieves the goal of an important reduction in terms of time-to-boost, providing an important improvement in engine readiness. The experimental campaign is carried out entirely on the test bench for components of the propulsion system of the University of Genoa, and in this article the main results of the electric compressor coupled to the main turbocharger are presented with particular reference to the time required to reach the boost pressure, the path on the compressor characteristic curves to highlight that this technique avoids unstable conditions of the compressor during transient operations and the possibility of improving the efficiency of the propulsion system by using the electrical component instead of the traditional ones.