Analysis of current distribution and circulating currents in a permanent magnet synchronous machine with parallel coils

In this thesis the current distribution among parallel coils and the presence of circulating currents in an electric machine is investigated. Differences in induced voltage and in impedance between the parallel coils might lead to an uneven current distribution, which may cause the temperature of a single turn to become too high. To determine the flow of current in the machine it is necessary to model the machine in sufficient detail. For this research the coils in the machine have been modelled as a series connection of a voltage source, and inductance (with mutual coupling to other coils) and a resistance. This was made possible by the machine designer, who provided these parameters for every copper turn in the machine. The most important result of this research is that the difference in amplitude of the currents through parallel wires is very small, for this specific machine. The phase difference between the currents is larger, but the impact of this is still insignificant. Furthermore, the investigation on circulating currents has shown that the magnitude of these currents mainly depends on the difference in induced voltage between parallel wires and the resistance of the wires. The inductance of the coils was found to have negligible influence on the magnitude due to very good magnetic coupling between the parallel coils.Electrical Power EngineeringElectrical Engineering, Mathematics and Computer Scienc

Coastal zone management around the southern North Sea

The Southern North Sea is bordered by Great-Britain, France, Belgium, The Netherlands, Germany and Denmark. The North Sea basin and its adjacent shorelines are intensively used. Management of the basin and the coastal zone is therefore essential. Because of the small scale of the area, the dense population and the big scale of the interactions, international cooperation is vital. In this paper an overview is given of both the morphologic-physical interactions and the administrative interactions between the bordering governments. A complicating factor in Coastal Zone Management around the Southern North Sea is that CZM is highly connected to national spatial planning and to sea defence policy. In several of the bordering countries this is not a subject of the national government, but is handled on a regional level. This makes that we are dealing with more authorities involved. At this moment international agreement exists on most aspects of active use of the North Sea basin itself (navigation, oil and gas mining, fishery, cables, etc) and its major coastal shallow areas (like the Waddensea). However in the field of passive use (pollution by inflowing rivers, air contamination by heavy industry, risk by transport and processing of hazardous goods) still much has to be done. International agreement on the recreation along the coastal strip does not yet exist. Also the standards for coastal protection against flooding by storm surges and against chronic erosion vary in each country.Hydraulic EngineeringCivil Engineering and Geoscience

De stad en de rand: Een interdisciplinaire studie naar een gespannen verhouding

UrbanismArchitectur

Advanced Nano Telescope: A cornerstone solution in Earth Observation

Recent developments in satellite industry gaining strong attention are so called nanosatellites. These small satellites, with sizes of about a milk carton, are easy to build and much more adordable, promising great advantages for future space missions. Up until today no reliable mid-resolution Earth observation instrument has been build that can be operated on such a small, low cost satellite. In light of these events this years Design Synthesis Exercise group 9 developed such a camera system which is called the Advanced Nano Telescope (ANT) providing a novel instrument that can be carried as payload by nanosatellites. The novelty lies in the applied principles of miniaturization and intelligent distribution in order to compete with a single large scale instrument. The strength of the instrument developed lies in the fact that it can take images with 7.5 meter resolution, requiring a volume of only 10 x 10 x 15 cm at an estimated cost about EUR 100,000. The small dimensions allow it to ft into half a standard 3 unit CubeSat such as the Delfi-n3Xt. The resolution is achieved by limiting the system to sense a narrow band around a single color, making use of a well designed combination of lenses and mirrors folding the light path enabling a long focal length. The thermo-mechanical design is designed such that the instrument functions in the hostile space environment from altitudes of 540 to 1440 km altitude. ANT has a smart modular structure that allows a mission designer to simply purchase the instrument and plug it into a satellite. Since all required electronic components are already present in the instrument the host satellite only needs to provide power and pointing capability to be able to achieve a fully functional system. One ANT by itself can take mid-resolution mono-chromatic images, but its real value will show when it is launched in a constellation, something which the low cost per unit allows. Multiple constellations of ANT's can outperform single satellites systems with similar ground resolutions in terms of development time, construction costs, operating costs and revisit time, enabling color composite imagery and promising improved availability at a lower price per image. Furthermore dedicated relay satellites can be added to achieve higher data rates. Overall catastrophic failures are eliminated as multiple satellites performing independent tasks are present offering redundancy and the possibility of replacement. The conclusion is that the system developed holds a promising future with a wide range of possible applications. The instrument itself is striking due to its apparently simple but intelligent and robust design enabling Earth observation without the need of expensive large scale satellites. For future work it is recommended to further develop the concept in order to prototype and test the actual performance of the ANT instrument.Bachelor Aerospace EngineeringSpace EngineeringAerospace Engineerin