When converting electric power from AC to DC, a 12-pulse converter is often used. Unfortunately, the converter creates harmonics superimposed on the DC voltage. These are removed by filters. A passive filter is normally used, but active filters may be added for improved performance. However, the drift in component values due to fluctuations in temperature and the change in load, makes it difficult

This is a presentation of automatic weight control of a submarine, where the use of nonlinear system components has been considered. The work was done at Lund Institute of Technology, Department of Automatic Control, with Kockums Marine, Malmö as sponsoring organization. The nonlinearities are due to the use of OnOff pump in the controller. This presentation consists of five different controllers.

The report refers to a master thesis project which has been done at SattControl AB and the Institute of Technology in Lund. The purpose of the project was to implement a fuzzy controller in SattLine, a new system of SattControl.

Window based interactive software systems can be used to create very user friendly interface e.g. to image processing libraries, and hence to image processing hardware. A system has been implemented, where standard "off the shelf" products that are commercially available from different companies have been used. The use of readily available components greatly simplifies the implementation

The purpose of this thesis has been to study different types of control strategies for an Electrohydraulic position servo in a Fuel metering valve. The Servo needs a high accuracy and fast response controller. Unlinearlities cause the system dynamics to vary with different operating conditions. A mathematical model implemented in the simulation tool ACSL is used in design and analysis. The System

This master thesis is about the regulation of temperature and flow of a steaming fluid when it passes through a heater. There are problems with the present regulation of temperature when the flow rate varies. The study has dealt with two control methods to regulate temperature and flow of the infusion fluid. These methods are different from the method to date. The first method is based on the fa

The purpose of this work was to investigate if the choice of frequency, on a pulse width modulated control signal to a DC motor, might influence the behaviour of the system, as wall as to see how the system reacts in connection with the controlling by means of such a signal. I came to the conclusion that the frequency was not critical seen from the system's point of view, but should be chosen

In this report heat quantity measuring and temperature regulation of smaller heating networks have been studied. At lower flows, as well as at lower difference temperatures, the accuracy of the measurement is very low. Today's control of a heating plant endeavour to let the temperature of the water into the heating network follow the heat requirement. This control strategy leads to small heat