<p>This thesis focuses on controller design and analysis for induction motor (IM) drives, flux control for electrically excited synchronous motors with damper windings (EESMs), and to enhance voltage sag ride-through ability and analysis for a wind turbine application with a full-power grid-connected active rectifier. The goal is to be able to use the existing equipment, without altering the hardware. Further, design and analysis of the stabilization of DC-link voltage oscillations for DC systems and inverter drives is studied, for example traction drives with voltage sags in focus.</p><p>The proposed IM controller is based on the field-weakening controller of Kim and Sul [31], which is further developed. Applying the proposed controller to voltage sag ride-through gives a cheap and simple ride-through system.</p><p>The EESM controller is based on setpoint adjustment for the field current controller. The analysis also concerns stability for the proposed flux controller.</p><p>The DC-link stabilization algorithm is designed following Mosskull [38], where a component is added to the current controller. The algorithm is further developed.</p><p>Analysis is the main focus, and concerns the impact of the different parameters involved. Proper parameter selection for the controller, switching frequency, and DC-link capacitor is given.</p><p>The impact of voltage sags is investigated for a power-grid-connected rectifier. Here, we analyze the impact of different types of voltage sags and phase-angle jumps. The analysis gives design rules for the DC-link capacitor and the switching frequency.</p><p>Experimental results and simulations verify the theoretical results.</p>

<p>The Reliability-Centred Asset Maintenance (RCAM) is a structured approach to determine maintenance strategies for electric power system which is developed at KTH School of Electrical Engineering. RCAM focus on reliability aspects of the system and one of the main steps in RCAM in to modeling the relationship between reliability and the elect of maintenance for critical components within the system. The transformer has been identified as a critical component within a power system and in spring 2006 the Ph.D project “<i>Life time modeling and management of</i> <i>transformers</i>” was started within the RCAM group. The overall goal for the project is to develop a quantitative model for the lifetime distribution of a transformer with the final goal to implement the developed model into a maintenance planning.</p><p>Dissolved Gas Analysis (DGA) is a widely used technique to estimate the condition of oil-immersed transformers. Incipient faults within the transformer may be detected by analyzing the gases which are dissolved in the transformer-oil. The objective of this thesis is mainly to analyze available data from DGA, and investigate if this kind of data may be useful in quantitative modeling of the transformers reliability.</p><p>One conclusion from this work is that the difficulty in modeling the transformers reliability lies mainly in the limited availability of adequate data. Transformer is a reliable device and since the number of failures in critical in mathematical modeling of a component´s reliability it becomes very difficult to determine such models. Another aspect is the difficulty to draw conclusions about a transformer´s condition only from the DGA results. Although there are standards available for this purpose the DGA interpretation should also be based on other information about the particular transformed such as size, construction and operation circumstance. During this work no sources have been found from which the correlation between DGA data and probability for transformer failures could be estimated. For this reasons the proposed failure rate function in this work is based on several subjective assumptions and has not been possible to verify.</p>

This thesis focuses on controller design and analysis for induction motor (IM) drives, flux control for electrically excited synchronous motors with damper windings (EESMs), and to enhance voltage sag ride-through ability and analysis for a wind turbine application with a full-power grid-connected active rectifier. The goal is to be able to use the existing equipment, without altering the hardware. Further, design and analysis of the stabilization of DC-link voltage oscillations for DC systems and inverter drives is studied, for example traction drives with voltage sags in focus. The proposed IM controller is based on the field-weakening controller of Kim and Sul [31], which is further developed. Applying the proposed controller to voltage sag ride-through gives a cheap and simple ride-through system. The EESM controller is based on setpoint adjustment for the field current controller. The analysis also concerns stability for the proposed flux controller. The DC-link stabilization algorithm is designed following Mosskull [38], where a component is added to the current controller. The algorithm is further developed. Analysis is the main focus, and concerns the impact of the different parameters involved. Proper parameter selection for the controller, switching frequency, and DC-link capacitor is given. The impact of voltage sags is investigated for a power-grid-connected rectifier. Here, we analyze the impact of different types of voltage sags and phase-angle jumps. The analysis gives design rules for the DC-link capacitor and the switching frequency. Experimental results and simulations verify the theoretical results. / QC 20101012

Bakgrunden till detta arbete är att det saknas riktlinjer från den tekniska avdelningen när vårdavdelningar på Astrid Lindgrens barnsjukhus skall köpa in infusionspumpar. Syftet med arbetet är att rekommendera ett antal pumpar vilka möter de krav och önskemål som ställs på dessa. Krav och önskemål kommer framförallt ifrån sjuksköterskorna men även ifrån rapportskrivarna. I resultatet presenteras sammanfattningar från de intervjuer som hållits med sjuksköterskor. I diskussionen kommenterar vi sjuksköterskornas önskemål och lyfter fram våra egna. Vi spekulerar även om infusionspumpens framtid. I slutsatsen anges vilka pumpmodeller som bäst möter de krav och önskemål som ställts på pumparna och varför vi rekommenderar Brauns pumpar före CareFusions.

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<p>The objective of this thesis work was to implement all the hardware and software necessary to simulate the functionality of a Vector Network Analyzer (VNA). With equipment that is already available, and is common in a measurement station, the most common functions of a VNA were implemented, using an Vector Signal Generator, that provide the signal for testing, and a Vector Signal Analyzer, to make all the amplitude and phase measurements. With these instruments and the appropriate software that control them, the basic functionality of a Vector Network Analyzer can be achieved with a reasonable accuracy. With this system, we can reduce costs, avoiding the need of a real VNA and take advantage off instruments that are already available in a laboratory. A Complete measurement system of all four scattering parameters is proposed at the end of the report for future implementation. With this implementation all the different S-parameter measurements were made with an acceptable accuracy that can be comparable to a commercial VNA.</p>

<p>This thesis is a project carried out at the “Centre for RF Measurements Technology of Gävle”. The first aim of this work was basically to develop an EMI measurement system, to that purpose, it has been used an EMI Tester receiver, Spectrum Analyzer and a broadband antenna. Tables and graphics are shown to provide the values of the different detectors utilized.</p><p>Using this measurement system, an interference file was recorded and then inserted in a Bluetooth communication model. The interference file was simulated with Matlab Simulink, to check how the interference affected the communication; the effects of the signal degradation are presented in a graphic.</p><p>Finally a real Bluetooth communication was established using two Bluetooth modules from Free2Move Company, to prove that the effect of microwave oven interferences produces the increase of transmission time and therefore decrease the Throughput.</p>

<p>Tjockleksmätning av rör med ultraljud görs typiskt genom att mäta tiden mellan två efterföljande ekon av en utsänd puls. Detta är ofta en svår process som är känslig för störningar och påverkan utifrån. Denna rapport beskriver hur detta i stället kan göras i frekvensdomänen för att minska effekterna av dessa problem.</p><p>För att göra detta härleds en signalmodell som beskriver de effekter som är nödvändiga för att utföra mätningarna. Utifrån signalmodellen togs metoder fram för att analysera och fastställa tjockleken på den uppmätta signalen.</p><p>En av metoderna fungerar så bra att den skulle kunna användas.</p> / <p>Ultrasonic thickness gauging of steel tubes is typically performed by observing the time difference between two following echoes. This process is often connected to various problems regarding interference. This thesis describes how to avoid these problems by using signal processing and analyzing the signals in the frequency domain.</p><p>To achieve these results a signal model that describes the necessary effects is derived. From this model different measurement methods to analyze and determine the thickness are developed.</p><p>One of the methods proved to be useful.</p>

The objective of this thesis work was to implement all the hardware and software necessary to simulate the functionality of a Vector Network Analyzer (VNA). With equipment that is already available, and is common in a measurement station, the most common functions of a VNA were implemented, using an Vector Signal Generator, that provide the signal for testing, and a Vector Signal Analyzer, to make all the amplitude and phase measurements. With these instruments and the appropriate software that control them, the basic functionality of a Vector Network Analyzer can be achieved with a reasonable accuracy. With this system, we can reduce costs, avoiding the need of a real VNA and take advantage off instruments that are already available in a laboratory. A Complete measurement system of all four scattering parameters is proposed at the end of the report for future implementation. With this implementation all the different S-parameter measurements were made with an acceptable accuracy that can be comparable to a commercial VNA.

This thesis is a project carried out at the “Centre for RF Measurements Technology of Gävle”. The first aim of this work was basically to develop an EMI measurement system, to that purpose, it has been used an EMI Tester receiver, Spectrum Analyzer and a broadband antenna. Tables and graphics are shown to provide the values of the different detectors utilized. Using this measurement system, an interference file was recorded and then inserted in a Bluetooth communication model. The interference file was simulated with Matlab Simulink, to check how the interference affected the communication; the effects of the signal degradation are presented in a graphic. Finally a real Bluetooth communication was established using two Bluetooth modules from Free2Move Company, to prove that the effect of microwave oven interferences produces the increase of transmission time and therefore decrease the Throughput.