Due to the price and supply insecurities for rare earth metal-based permanent magnet (PM) materials, a search for new PM materials is ongoing. The properties of a new PM material are not known yet, ...but a span of likely parameters can be studied. This paper presents an investigation on how the remanence and recoil permeability of a PM material affect its usefulness in a low speed, multi-pole, and PM synchronous generator. Demagnetisation is also considered. The investigation is carried out by constrained optimisation of three different rotor topologies for maximum torque production for different PM material parameters and a fixed PM maximum energy. The rotor topologies used are surface mounted PM rotor, spoke type PM rotor and an interior PM rotor with radially magnetised PMs. The three different rotor topologies have their best performance for different kinds of materials. The spoke type PM rotor is the best at utilising low remanence materials as long as they are sufficiently resistant to demagnetisation. The surface mounted PM rotor works best with very demagnetisation resistant PM materials with a high remanence, while the radial interior PM rotor is preferable for high remanence materials with low demagnetisation resistance.
The price of rare-earth metals used in neodymium-iron-boron (NdFeB) permanent magnets (PMs) has fluctuated greatly recently. Replacing the NdFeB PMs with more abundant ferrite PMs will avoid the cost ...insecurity and insecurity of supply. Ferrite PMs have lower performance than NdFeB PMs and for similar performance more PM material has to be used, requiring more support structure. Flux concentration is also necessary, for example, by a spoke-type rotor. In this paper the rotor of a 12 kW NdFeB PM generator was redesigned to use ferrite PMs, reusing the existing stator and experimental setup. Finite element simulations were used to calculate both electromagnetic and mechanical properties of the design. Focus was on mechanical design and feasibility of construction. The result was a design of a ferrite PM rotor to be used with the old stator with some small changes to the generator support structure. The new generator has the same output power at a slightly lower voltage level. It was concluded that it is possible to use the same stator with either a NdFeB PM rotor or a ferrite PM rotor. A ferrite PM generator might require a larger diameter than a NdFeB generator to generate the same voltage.
Low speed, high torque machines are used in wind turbines where the turbine rotor is directly connected to the generator. A permanent magnet synchronous generator using high-energy rare-earth ...permanent magnets (PMs) is one common choice for this application, but rare-earth PMs have supply insecurities and cost risks. A rare-earth free 32-pole PM generator, using ferrite PMs in a spoke-type rotor, for use in a 12 kW experimental wind turbine is built and tested. Voltages and currents at load and no load are measured, as well as the magnetic field in the end regions of the machine. The generator can deliver the required power at nominal speed and has low harmonic content in the output. The electrical measurements are compared to two-dimensional finite element design calculations and the experimental results are lower than expected from simulations. The measured voltage is lower than expected, requiring a higher current than calculated for the rated power. Three-dimensional magnetic field simulations show that there are leakage flux paths in the end-regions that the two-dimensional design calculations overlook, explaining the discrepancy between simulations and measurements.
Ways to utilise ferrite permanent magnets (PMs), in a better way has been in focus the last couple of years since the use of neodymium-iron-boron (NdFeB) PMs has been debated. While ferrite PMs offer ...a low-cost alternative to rare-earth PMs, it is a trade-off for lower energy density. Depending on the type of PM and if the PMs are surface mounted or buried, the risk of demagnetisation during a fault condition can vary significantly between machines. In this study, the demagnetisation risk of two electrically similar generators with identical stators has been studied during several short-circuit faults at different temperatures. The study is simulation-based, and the results show that the generator with the ferrite rotor will suffer from a small but not significant amount of demagnetisation in the worst, three-phase-neutral, short-circuit case at a temperature of 5°C, whereas the NdFeB PMs will suffer from partial demagnetisation if a fault occurs at 120°C. For operational temperatures between 20 and 60°C both generators will sustain a short-circuit event.
When designing permanent magnet (PM) synchronous machines the demagnetizing effect of armature short circuit currents on the PMs needs to be considered. In some cases there can be a need to estimate ...the demagnetizing field from the winding without knowing the winding scheme. To do this, a lumped parameter model of the dynamics of the magnetic field and armature current distribution is proposed. Validation of the model using two different machines shows acceptable agreement. The proposed model is found to be useful for its particular purpose of determining the approximate short circuit current distribution in the armature without knowing the winding design.
Magnetocaloric effects of various materials are getting more and more interesting for the future, as they can significantly contribute towards improving the efficiency of many energy intensive ...applications such as refrigeration, heating, and air conditioning. Accurate characterization of magnetocaloric effects, exhibited by various materials, is an important process for further studies and development of the suitable magnetocaloric heating and cooling solutions. The conventional test facilities have plenty of limitations, as they focus only on the thermodynamic side and use magnetic machines with moving bed of magnetocaloric material or magnet. In this work an entirely new approach for characterization of the magnetocaloric materials is presented, with the main focus on a flexible and efficient power electronic based excitation and a completely static test platform. It can generate a periodically varying magnetic field using superposition of an ac and a dc magnetic field. The scale down prototype uses a customized single phase H-bridge inverter with essential protections and an electromagnet load as actuator. The preliminary simulation and experimental results show good agreement and support the usage of the power electronic test platform for characterizing magnetocaloric materials.
The impact of manufacturing tolerances on the performance of a permanent magnet synchronous generator is investigated. A generator with a flux concentrating spoke-type rotor, with ferrite permanent ...magnets, is used in the investigation. Measurements of the air gap magnetic flux density, the air gap length, as well as the magnetization and size of the permanent magnets have been performed. Correlations are calculated and causalities are discussed. It is found that the permanent magnets used are below tolerance in remanent magnetic flux density, that the air gap length is smaller than specified, and that the resulting air gap magnetic flux density is lower than specified. From the results it can be concluded that the design should be made with tolerances in mind and that quality control of parts, especially of PM magnetization, is important for machine performance.
Examensarbetet utgörs av en sammanfattning av tre genomförda nybyggnadsprojekt. Foton, ritningar och skisser visar hur arkitektoniska koncept omsatts från vision till verklighet. Gemensamt för ...projekten är att målbilden varit inriktad på nytta, identitet och mervärde. Kanal 5 i Stockholm är en mindre glasbyggnad som blivit en symbol för omvandlingen av ett helt innerstadskvarter, där verksamheterna ändrats från industri och hantverk till arbetsplats för idéprojekt och mediaproduktion. Byggnaden fungerar som huvudentré till äldre lokaler som renoverats. Stadsutveckling. Kommunikation. Landmärke. Canon i Solna är ett medelstort kontorshus som i sitt utförande förenar en värdeneutral prefabriceringsestetik med det globala hightech-företagets krav på attraktiv arbetsmiljö, representativitet och profilering. Kontakt, öppenhet och överblick präglar byggnadens inre organisation. Effektivitet. Varumärke. Gränssnitt. Swedbank Stadion i Malmö är resultatet av en hel regions långsiktiga uppslutning kring det lokala fotbollslaget, Malmö FF. Ett renodlat fotbollsstadion, en teaterscen för utpräglad fankultur, en intäktsmaskin för klubben i dess strävan mot etablering i det internationella finrummet. Interaktivitet. Historia. Intäkter.
The thesis consists of a summary of three completed projects. Photographs, drawings and sketches demonstrate how architectural concepts have been carried through into real buildings. Common to these projects is the clear focus on utility, identity and added value. Kanal 5 in Stockholm is a small glass building. It has become a symbol of the transformation of an entire city block, where operations have changed from industry and crafts to work on conceptual content and media production. The building serves as the main entrance to the older renovated premises. Urban development. Communications. Landmark. Canon in Solna is a medium-sized office building. Its design combines the anonymous aesthetics of prefabrication with the global high-tech company's requirement for an attractive working environment, hospitality and profiling. Connection, transparency and visibility characterize the building's interior organization. Efficiency. Branding. Interface. Swedbank Stadion in Malmö is the result of an entire region's long-term commitment to the local football team, Malmö FF. A genuine football stadium, a theatre for a devoted fan culture, a cash machine for the club in its ambition to establish itself in the international community. Interactivity. History. Revenue.
Due to the insecurity of the supply of raw materials needed for neodymium-iron-boron magnets, typically used in permanent magnet generators, the use of ferrite magnets as an alternative was ...investigated. The investigation was conducted by attempting to redesign a generator that previously used neodymium-iron-boron magnets for use with ferrite magnets. The major part of the redesign was to find an alternate rotor design with an electromagnetic design adapted to the characteristics of the ferrite magnets.It was found that ferrite magnets can be used to replace neodymium-iron-boron magnets with changes to the electromagnetic design of the rotor. The changes of the electromagnetic design increase the amount of magnetically active material in the rotor and, therefore, require the mechanical design of the rotor to be changed. The new rotor design also requires some changes to the generator support structure. A design for a replacement rotor, using ferrite magnets, along with the required changes to the support structure, is presented.
Aktörer inom fastighetsbranschen har visat stort intresse att möta den nya Generation Y och söka kunskap inom marknadsföring mot dessa. Aktörerna efterfrågar kunskap för att bygga långsiktiga ...kundrelationer, där bostadsbristen inte är lika utbredd som i storstäderna. Syftet med denna studie är att analysera om engagemang, förtroende och lojalitet är avgörande faktorer vid skapandet av långsiktiga kundrelationer med Generation Y. Vidare presenteras teori angående vad som ligger till grund för långsiktiga kundrelationer. 103 respondenter har medverkat i en internetbaserad enkätundersökning där svaren har analyserats i det statistiska analysverktyget SPSS. Följande analyser har genomförts: korrelationsanalys, faktoranalys, regressionsanalys samt klusteranalys. Resultaten visar att Generation Y har en positiv inställning till relationsmarknadsföring där de anser att engagemang och förtroende är avgörande faktorer hos en hyresvärd. Studien visar även att Generation Y har en neutral inställning till Customer Relationship Management, vilket gör att fastighetsbolag bör överväga användandet av detta verktyg. Väletablerade kundrelationer kan förbättras av detta verktyg medan de relationer som är under uppbyggnad kan försämras. Studien bidrar med information till beslutsfattare inom fastighetsbranschen som är aktiva i kommuner inom glesbefolkade regioner och glesbygdskommuner. Kunskap om de framtagna faktorerna är avgörande vid skapandet av långsiktiga kundrelationer och kan bidra till minskade omflyttningskostnader och stabila inkomster under längre tid.
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