Development and Validation of a “Crank-angle” Model of an Automotive Turbocharged Engine for HiL Applications

Management and diagnostic functions are playing a key role in the improvement of engines performance and in the reduction of fuel consumption and pollutant emissions especially in automotive applications. As widely documented in the open literature, design, validation, and testing of control systems take actually advantage of theoretical models to a great extent, due to their capabilities to reduce development time and costs. However, the increasing complexity of present engines and related management systems give rise to challenging issues in the development and applications of mathematical models. The paper describes the improvements introduced in the original Library set up by the authors in Simulink® for “control- oriented” simulation of Internal Combustion Engines (ICE) and powertrains. The tool has been initially developed to build up Mean Value Models (MVMs) of automotive engines for “real-time” simulations, and in that version has been used in several HiL applications. Due to the enhancing requirements in engine control functions, the Library has been recently improved to allow for “crank-angle” simulation of the engine. To this extent models of intake and exhaust valves and of in-cylinder processes have been built up (where combustion process is described following a classic single-zone approach based on a proper Heat Release Rate, HRR). An original algorithm has been developed to run the model at a computational speed comparable with real time even with a resolution of 1 degree CA for in-cylinder calculation. Modeling tools have been applied to the simulation of a four-cylinder turbocharged Diesel engine with Exhaust Gas Recirculation. Through a specific calibration procedure, the model was fitted on a typical layout of an automotive Diesel engine and then validated comparing simulation results with experimental data measured by the OEM on a test bench. With a very low computational time, the model showed interesting capabilities in the simulation of the behavior of automotive engines with “crank-angle” resolution and therefore has been used in an original HiL application developed by the authors.