Examensarbete Model-based turbocharger controla common approach for SI and CI engines

In this master’s thesis, a turbine model and a common control structure for the turbocharger for SI and CI-engines is developed. To design the control structure, simulations are done on an existing diesel engine model with VGT. In order to be able to make simulations for engines with a wastegated turbine, the model is extended to include mass flow and turbine efficiency for that configuration. The developed model has a mean absolute relative error of 3.6 % for the turbine mass flow and 7.4 % for the turbine efficiency. The aim was to control the intake manifold pressure with good transients and to use the same control structure for VGT and wastegate. By using a common structure, development and calibration time can be reduced. The non-linearities have been reduced by using an inverted turbine model in the control structure, which consists of a PI-controller with feedforward. The controller can be tuned to give a fast response for CI engines and a slower response but with less overshoot for SI engines, which is preferable.