In this thesis the compounds Fe5SiB2 and Fe5PB2 have beensynthesized via high temperature synthesis, including arc melting anddrop synthesis. The structure for both compounds are of Cr5B3 typewith the space group I4/mcm. The cell parameters were refined toa = 5.5533 Å and c = 10.3405 Å for Fe5SiB2 and a = 5.4903 Å andc = 10.3527 Å for Fe5PB2. The saturation magnetization at roomtemperature for Fe5SiB2 has been measured to 138.8 Am2/kg and theanisotropy constant has been estimated to 79 kJ/m3. Theferromagnetic properties and the high anisotropy constant makesthese materials promising as permanent magnet materials, but moreinvestigations are necessary.

In this thesis, two selected topics in magnetism are studied using theoretical modelling and computational methods. The first of these is the magnetocrystalline anisotropy energy (MAE) of transition metal based magnets. In particular, ways of finding 3d transition metal based materials with large MAE are considered. This is motivated by the need for new permanent magnet materials, not containing rare-earth elements, but is also of interest for other technological applications, where the MAE is a key quantity. The mechanisms of the MAE in the relevant materials are reviewed and approaches to increasing this quantity are discussed. Computational methods, largely based on density functional theory (DFT), are applied to guide the search for relevant materials. The computational work suggests that the MAE of Fe1-xCox alloys can be significantly enhanced by introducing a tetragonality with interstitial B or C impurities. This is also experimentally corroborated. Alloying is considered as a method of tuning the electronic structure around the Fermi energy and thus also the MAE, for example in the tetragonal compound (Fe1-xCox)2B. Additionally, it is shown that small amounts (2.5-5 at.%) of various 5d dopants on the Fe/Co-site can enhance the MAE of this material with as much as 70%. The magnetic properties of several technologically interesting, chemically ordered, L10 structured binary compounds, tetragonal Fe5Si1-xPxB2 and Hexagonal Laves phase Fe2Ta1-xWx are also investigated. The second topic studied is that of magnetic effects on the elastic scattering of fast electrons, in the context of transmission electron microscopy (TEM). A multislice solution is implemented for a paraxial version of the Pauli equation. Simulations require the magnetic fields in the sample as input. A realistic description of magnetism in a solid, for this purpose, is derived in a scheme starting from a DFT calculation of the spin density or density matrix. Calculations are performed for electron vortex beams passing through magnetic solids and a magnetic signal, defined as a difference in intensity for opposite orbital angular momentum beams, integrated over a disk in the diffraction plane, is observed. For nanometer sized electron vortex beams carrying orbital angular momentum of a few tens of ħ, a relative magnetic signal of order 10-3 is found. This is considered realistic to be observed in experiments. In addition to electron vortex beams, spin polarised and phase aberrated electron beams are considered and also for these a magnetic signal, albeit weaker than that of the vortex beams, can be obtained. / <p>Felaktigt ISBN i den tryckta versionen: 9789155497149</p><p></p>

In the recent decades, an increased interest into multiphase machines has developed due to certain beneficial properties they have over the standard three- phase machines. Proper modelling of a multiphase machine allows access to higher degrees of freedom given by the ability to control higher order harmonic frames. This feature is of particular interest in the area of parameter estimation as it may provide an opportunity to implement methods that are not feasible in three- phase machines. Modelling of a real six- phase machine meant for marine application with a functioning control structure is carried out on MATLAB/Simulink; considering nonlinear relations, cross coupling and saturation effects, the model includes the machine’s behavior in the fundamental frame as well as the next two higher order harmonic frames. Stator resistances and permanent magnet flux linkage are estimated online and simultaneously during various operating points. It is shown that stator resistance may be accurately estimated by means of DC test signal injections into the highest order harmonic frame; thus, minimizing torque ripple and additional loss generation. Permanent magnet flux linkage is accurately estimated via reactive power calculations on the fundamental frame which remains undisturbed by the aforementioned test signals. / Under de senaste decennierna har intresset för flerfasmaskiner ökat, på grund av i vissa avseenden, fördelaktiga egenskaper i jämförelse med traditionella trefasmaskiner. En väl genomförd modellering av flerfasmaskiner möjliggör högre grader av frihet givet förmågan att kontrollera frekvensplan av högre ordning. Denna funktion är av särskilt intresse inom parameteruppskattning, då det kan ge möjligheter att implementera metoder som är omöjliga i trefas maskiner. En modell av en verklig sexfasmaskin, byggd för en marin tillämpning och med ett givet styrsystem, har skapats i MATLAB/Simulink. Modellen tar hänsyn till ickelinjära förhållanden, korskopplingar och mättning. Den inkluderar även maskinens egenskaper i det fundamentala frekvensplanet och de två nästkommande frekvensplanen av högre ordning. Statorresistansen och permanentmagneternas sammanlänkade flöden uppskattas i realtid för olika driftsförhållanden. Det visar sig att statorresistansen kan uppskattas noggrant genom inmatning av en DC testsignal i högsta ordningens frekvensplan vilket minimerar momentrippel och extra förluster. Permanentmagneternas flöden kan uppskattas noggrant genom beräkning av den reaktiva effekten i det fundamentala frekvensplanet som är opåverkat av de ovan nämnda testsignalerna.

The aim of this master thesis is to design and analyse a FSCW PMaSynRM (Permanent Magnet assisted Synchronous Reluctance Motor) for industrial applications. The design process includes analytical calculations (initial design and PM amount minimization) and nite element method (FEM) based design optimization. An overcompensated design is proved to be advantageous for a 10-pole reluctance motor. A comparative analysis with other rotor topologies was made, where motor performance, temperature e ects and production costs are taken into account. Detailed curves which describe eciency, power factor and current with respect to ambient temperature are studied for the proposed motor designs at di erent working points. The demagnetization risk is also taken into account and the safe working temperature ranges have been dened for all the considered motors. The results show that the initial motor design with 10 poles/12 slots PMaSynRM with NdFeB magnets has poor performance in terms of eciency and power factor, with huge amount of PM inserted. This is mainly due to the lack of reluctance torque for this relatively higher number of poles solution. Moreover, it has been found in literature and conrmed in this investigation that this negative e ect for the 10-pole motor is amplied due to the presence of the concentrated winding. Indeed, it is shown by simulations that the motor performance is improved by employing 8 poles/12 slots PMaSynRM conguration with a relatively lower NdFeB magnet amount, thanks to the improved rotor anisotropy. The 10 poles/12 slots interior permanent magnet (IPM) and surface mounted permanent magnet (SMPM) topologies present higher performance due to the e ective utilization of PM, mainly or completely producing the torque. Hence, IPM and SMPM do not su er the lack of anisotropy. / Syftet med detta examensarbete ar att utforma och analysera en FSCW PMaSynRM (Permanent Magnet assisted Synchronous Reluctance Motor) for industriella applikationer. Designprocessen omfattar analytiska berakningar (ursprungliga konstruktion och PM belopp minimering) och nita elementmetoden (FEM) baserad design optimering. En overkompenserad design visat sig vara fordelaktigt for en 10-polig reluktansmotor. En jamforande analys med andra rotor topologier gjordes, dar motor prestanda, temperature ekter och produktionskostnader beaktas. Detaljerade kurvor som beskriver e ektivitet, e ektfaktor och strom med avseende pa omgivningstemperatur studeras for de foreslagna motorn for vid olika arbetspunkter. Den avmagnetisering risken ocksa beaktas och sakerhetstemperaturomraden har denierats for alla ansag motorerna. Resultaten visar att den initiala motordesign med 10-polig/12 spar PMaSynRM med NdFeB magneter har daliga e ektivitet och e ektfaktor, med enorma mangder PM insatt. Detta ar framst pa grund av bristen pa reluktansvridmomentet for denna relativt hogre poltal losning. Dessutom har man funnit i litteraturen och bekraftat i denna unders okning att denna negativa e ekt for 10-polig motorn forstarks pa grund av narvaron av den koncentrerade lindningen. Faktum ar att det framgar av simuleringar att motorprestanda forbattras med en 8-polig/12 spar PMaSynRM konguration med en relativt lagre NdFeB magnet belopp, tack vare den forbattrade rotor anisotropi. Den 10-polig/12 spar interior permanentmagnet (IPM) och ytmonterade permanent magnet (SMPM) topologier presentera hogre prestanda tack vare ett e ektivt utnyttjande av PM och deras produktion vridmoment, huvudsakligen eller helt anfortrotts PM effekten.