Towards Integrated Powertrain Control for a Mild-Hybrid Urban Vehicle with a Downsized Turbo-Charged CNG Engine

Compressed natural gas (CNG) is considered as one of the most promising alternative fuels for transportation due to its ability to reduce greenhouse gas emissions (CO2 , in particular) and its abundance. An earlier study from IFP has shown that CNG has a considerable potential when used as a fuel for a dedicated downsized turbo-charged SI engine on a small urban vehicle. To take further advantage of CNG assets, this approach can be profitably extended by adding a small secondary (electrical) power source to the CNG engine, thus hybridizing the powertrain. This is precisely the focus of the new IFP project, VEHGAN, which aims to develop a mild-hybrid CNG prototype vehicle based on a MCC Smart car equipped with a reversible starter-alternator and ultra-capacitors (Valeo Starter Alternator Reversible System, StARS). The unfolding of this project has involved and will involve several interesting and challenging issues from an engine control point of view, such as mastering the automatic manual transmission (AMT) control system and integrating a new power source, with its new functions, into the torque-oriented engine control structure.