Cold start modelling of spark ignition engines

The ability of mean value models to replicate the key characteristics of automotive powertrains has been well established over the past four decades. There has been considerable success in the application of these models to controller design, with improved emissions and performance of the primary benefits. However, these low order models typically must make certain assumptions about the engine—with constant temperature operation a standard approximation. As economy and emissions at every point in the drive cycle become scrutinised, the cold start operation of the engine becomes more critical and the constant temperature assumption is limiting. This paper seeks to develop a model framework for capturing the temperature transients and gaseous concentrations throughout the engine. A methodology for calibrating the model is also presented, and uses a combination of steady state and transient testing. Finally, certain states in the full model are eliminated to produce a family of reduced order models, with the intention of outlining the minimum complexity required for control and optimisation studies with differing objectives.