Aim of the diploma thesis is set to present a new method for evaluation of the friction coefficient of the wastegate valve system. A test fixture was designed and manufactured for this purpose. Simulations in ANSYS and MSC Adams support test results. The developed method provides an accurate and affordable solution for investigating of friction coefficient for various valves of turbochargers wastegate.

This diploma thesis is focused on performance options for turbocharged 1.2 litre spark ignition engine. First of all, couple of engine variants are compared and the most suitable one is chosen. Production turbocharger is determined upon the calculation of compressor parameters. Simulation in Lotus Engine Simulation and GT-Power is done to confirm co-operation of turbocharger with engine. Two stage serial turbochargers are also compared and the most effective pair is chosen for simulation. Research through the possibilities for increase the power output and the detail focus on turbochargers is also part of this thesis.

Engine control becomes increasingly important in newer cars. It is therefore interesting to investigate if a relatively new control method as Model Predictive Control (MPC) can be useful in engine control in the future. One of the advantages of MPC is that it can handle contraints explicitly. In this thesis basics on turbocharged engines and the underlying theory of MPC is presented. Based on a nonlinear mean value engine model, linearized at multiple operating points, we then implement both a linear and a nonlinearMPC strategy and highlight implementation issues. The implemented MPC controllers calculate optimal wastegate position in order to track a requested torque curve and still make sure that the constraints on turbocharger speed and minimum and maximum opening of the wastegate are fulfilled.

In this master’s thesis, a turbine model and a common control structure for theturbocharger 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 tobe able to make simulations for engines with a wastegated turbine, the model isextended to include mass flow and turbine efficiency for that configuration. Thedeveloped model has a mean absolute relative error of 3.6 % for the turbine massflow and 7.4 % for the turbine efficiency. The aim was to control the intake manifoldpressure with good transients and to use the same control structure for VGTand wastegate. By using a common structure, development and calibration timecan be reduced. The non-linearities have been reduced by using an inverted turbinemodel 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 slowerresponse but with less overshoot for SI engines, which is preferable.

The diploma thesis deals with the calculation of thermodynamic parameters of a turbocharged petrol engine with Miller cycle. A drive unit from Volkswagen, the EA211EVO model line, was chosen as the engine. The engine has a displacement of 1498 cm3 and engine power reaches 110kW at 5000 to 6000 RPM. In this work, a basic description of the thermodynamics of cycles of spark ignition engines is performed, then the problem of turbocharging and methods of its control are presented. The following are the created engine models in GTSuite environment in variants with WasteGate and Variable Turbine Geometry. Finally, operation optimizations with various valve timing changes are presented. The individual variants are the compared.