<p>Since measurements in engine test cells are closely coupled with high costs it is of interest to use physically interpretable engine models instead of engine maps. Such engine models can also be used to do off-line tests of how new or altered components affects engine performance.</p><p>In the thesis an existing mean value engine model will be extended with a model of a compressor bypass valve. A controller for that valve will also be developed. The purpose with that controller is to save torque and boost pressure but at the same time avoid having the compressor entering surge during fast closing transients in the throttle position.</p><p>Both the extension and controller is successfully developed and implemented. The extension lowers the pressure after the compressor and increases the pressure before the compressor when the bypass valve is being opened and the controller shows better results in simulations than the controller used in the research lab. By using the proposed controller, as much as 5 percent higher torque can be achieved in simulations.</p><p>Finally there is a discussion on wastegate control alternatives and the use of TOMOC for optimization of wastegate control.</p>

<p>Mean Value Engine Modeling (MVEM) is used to make engine control development less expensive. With more and more cars equipped with turbocharged engines good turbo MVEM models are needed. A turbocharger consists of two major parts: turbine and compressor. Whereas the turbine is relatively durable, there exist phenomenons on the compressor that can destroy the turbocharger. One of these is surge.</p><p>Several compressor models are developed in this thesis. Methods to determine the compressor model parameters are proposed and discussed both for the stable operating range as well as for the surge region of a compressor map. For the stationary region methods to automatically parameterize the compressor model are developed. For the unstable surge region methods to get good agreement for desired surge properties are discussed. The parameter sensitivity of the different surge properties is also discussed. A validation of the compressor model shows that it gives good agreement to data, both for the stationary region as well as the surge region.</p><p>Different open loop and closed loop controllers as well as different performance variables are developed and discussed. A benchmark is developed, based on a measured vehicle acceleration, and the control approaches are compared using this benchmark. The best controller is found to be a open loop controller based on throttle and surge valve mass flow.</p>

Since measurements in engine test cells are closely coupled with high costs it is of interest to use physically interpretable engine models instead of engine maps. Such engine models can also be used to do off-line tests of how new or altered components affects engine performance. In the thesis an existing mean value engine model will be extended with a model of a compressor bypass valve. A controller for that valve will also be developed. The purpose with that controller is to save torque and boost pressure but at the same time avoid having the compressor entering surge during fast closing transients in the throttle position. Both the extension and controller is successfully developed and implemented. The extension lowers the pressure after the compressor and increases the pressure before the compressor when the bypass valve is being opened and the controller shows better results in simulations than the controller used in the research lab. By using the proposed controller, as much as 5 percent higher torque can be achieved in simulations. Finally there is a discussion on wastegate control alternatives and the use of TOMOC for optimization of wastegate control.

Modern engines are faced with increasingly stringent requirements for reduced fuel consumptionand lower emissions. A technique which can partly be used to reduce emissionsof nitrogen oxides is recirculation of combusted gases (Exhaust Gas Recirculation, EGR). Ingasoline engines, it also has the advantage that it can save fuel by reducing pumping losses.To large mixture of EGR in the air to the cylinders will however affect the combustion stabilitynegatively. To investigate EGR rate and dynamics with respect to different actuatorinputs, the thesis develops an engine model that includes EGR. The model focus on the airflow in the engine and extends an existing mean value engine model. Two types of EGRsystemare investigated. They are short-route EGR which is implemented between intakemanifold and exhaust manifold and long-route EGR which is implemented between compressorand turbine. The work provides a simulation study that compares both stationaryand transient properties of the two EGR-systems, such as fuel consumption, maximum EGR,and rise time with respect to different actuators.

Mean Value Engine Modeling (MVEM) is used to make engine control development less expensive. With more and more cars equipped with turbocharged engines good turbo MVEM models are needed. A turbocharger consists of two major parts: turbine and compressor. Whereas the turbine is relatively durable, there exist phenomenons on the compressor that can destroy the turbocharger. One of these is surge. Several compressor models are developed in this thesis. Methods to determine the compressor model parameters are proposed and discussed both for the stable operating range as well as for the surge region of a compressor map. For the stationary region methods to automatically parameterize the compressor model are developed. For the unstable surge region methods to get good agreement for desired surge properties are discussed. The parameter sensitivity of the different surge properties is also discussed. A validation of the compressor model shows that it gives good agreement to data, both for the stationary region as well as the surge region. Different open loop and closed loop controllers as well as different performance variables are developed and discussed. A benchmark is developed, based on a measured vehicle acceleration, and the control approaches are compared using this benchmark. The best controller is found to be a open loop controller based on throttle and surge valve mass flow.

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.