This thesis deals with the design of a permanent-magnet synchronous inner rotor motor for an in-wheel application for the Shell Eco Marathon Urban concept vehicle. First of all, concepts related to permanent magnet motors are studied. Likewise, different features of permanent magnet motors are qualitatively evaluated in order to choose the most suitable. A radial flux motor is selected based on its solid, economic and acceptable characteristics. Next, a detailed study of concentrated windings is carried out. Through this investigation, undesirable configurations of pole and slot numbers due to unbalanced magnetic pull or a low fundamental winding factor will be avoided and how to determine the different winding layouts for different pole and slots configuration will be explained. As well, based on this study, and the magnetic and electric behavior of the machine, an analytical model is created. This model calculates the optimum size and characteristics of a machine in order to obtain lightweight design. After that, the design of a program based on a finite element method that simulates different situations for the machine is accomplished, dealing with the difficulties that entails the concentrated windings. Finally, through the use of this program, the machine calculated by the analytical model is analyzed, specially regarding that it does not surpass some important margin in order not to be demagnetized or not to surpass the maximum phase voltage supplied by the batteries.

The thesis presents deals with the design, analysis, test and control of permanent magnetsynchronous motor(PMSM). An analytical model was carried out based on the d-q frame and the equivalent circuit of PMSM, theanalytical model gives an approximation value of the machine parameters and is carried out byequations from the listed references. this phase includes many iteration steps, once the results wereobtained they were compared with the motor specifications and if they don’t match the requiredspecifications the process must be done again until the desired design is obtained. Once the analytical model is obtained a Finite Element Simulation was carried out using FEMMsoftware to validate the design, in this phase the designed machine in the analytical model isanalyzed and validated, once the simulation is done the results from both models are compared anddiscussed in the results chapter. It’s important to mark that during the design phase some design parameters were affected andlimited by some factors, for example, the air gap length has been magnified due to manufacturinglimits. The manufacturing process and the prototype building have been started once the optimal designwas selected, the manufacturing process was explained and a comparison study was made to selectthe best manufacturing process suitable and available for this thesis.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18788号 / 理博第4046号 / 新制||理||1582(附属図書館) / 31739 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 畑 浩之, 教授 田中 貴浩, 教授 川合 光 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Recent research and development has resulted in a working prototype of an automated process for manufacturing IsoTruss® and other innovative open lattice composite structures which yields faster, and more predictable and consistent parts, while automatically consolidating individual members. This machine is sufficiently versatile to manufacture any type of open lattice structure fabricated from filamentary composite materials. The objectives of the research in this thesis were two-fold: (1) to validate this new process for making IsoTruss structures; and (2) to measure the compression strength and stiffness of specimens produced on the machine. In order to accomplish the first purpose, various parts were manufactured on this prototype machine, including: a six-node IsoTruss structure with single outer longitudinal members, a three-longitudinal member section of an inner longitudinal IsoTruss structure with consolidated members, and a two-bay IsoTruss panel structure. By creating and running patterns to make these parts, the hypothesis that the machine will make any geometry of IsoTruss structure was validated. The second objective of this research was accomplished by testing the compression strength and stiffness of specimens manufactured with this automated process. Buckling versus compression failure of members was examined by varying member aspect ratios. The effect of intersecting helical members was also explored, as was the effect of changing the number of braiding bobbins used to consolidate members. Testing showed that increasing the number of braiders increases consistency of the braided sleeves and reduces scatter in the results. The ratio of helical to longitudinal tows at a joint is directly related to the percent decrease in member strength at the joint. Compression failure of individual members is the preferred method of failure, because this type of failure absorbs significantly more energy. This research proves that the manufacturing process will produce even the most complex IsoTruss geometries, with the necessary consolidation of individual members. Findings also indicate that a few modifications -- such as improved bobbins, more reliable switches, more accurate pulling system, etc. -- will enable this automated process to produce composite lattice structures with superior mechanical properties.

Ett viktigt uppdrag för Svenska kraftnät (SvK) som den systemansvariga myndigheten i Sverige är att driva elnätet på det bästa möjliga sättet. För att kunna garantera den önskade 99,9% tillför- litligheten behövs konstant underhåll och diagnostisering av kraftöverföringssystemets komponenter, varav elkrafttransformatorer är en viktig beståndsdel. Nollföljdsimpedansen behövs för att bestämma hur stora felströmmar som uppkommer när fel inträffar i systemet. Nollföljdsimpedansen är en av tre följder (sekvenser) som används för att analysera trefaskomponenter och är en storhet som inte kan bestämmas analytisk på ett enkelt sätt. Dess värde brukar fås från tester som görs av tillverkaren när transformatorn fabriceras. Denna information saknas dock för flera transformatorer som finns driftsatta i nätet. I detta examensarbete utvecklas empiriska modeller för att estimera nollföljdsimpedansen hos tre- och fembenta elkrafttransformatorer med tre (YY∆) och fyra lindningar (YYY∆), av vilka en av lindningarna är en utjämningslindning. En utjämningslindning är en deltakopplad lindning som icke är åtkomlig och som är avsedd för att minska och balansera nollföljdsimpedansvärdena för intilliggande lindningar. Nollföljdsimpedansen kan endast skattas eftersom en direkt mätning inte är möjlig hos dessa transformatorer. De erhållna modellerna bildar en estimeringsalgoritm, där olika transformatorstorheter kan användas som indata för att skatta nollföljdsimpedansvärdet. Metodiken för att ta fram modellerna bygger på en analys av korrelationen mellan nollföljdsim- pedansen och andra kända och beräknade storheter, där en linjär regression baserad på minsta kvadratmetoden resulterar i en approximativ trendlinje. Approximationen förbättras med en bisquare algoritm, där avvikande värden ges mindre vikt. Denna process utförs för alla transformatorer i stu- dien där generella anpassningsmodeller tas fram. Processen upprepas för särskilda undergrupper med syfte att erhålla modeller med högre anpassningsgrad. Indelning i undergrupper baseras på kopp- lingsart för transformatorernas sekundärlindning som består av antingen fullindad eller autokopplad lindning, samt kärnkonstruktion som består av tre- eller fem ben. Tillförlitligheten för varje modell analyseras med hänsyn till deras anpassningsgrad, statistisk relevans samt kvaliteten av data som användes för att utveckla modellen. Endast modeller med måttlig anpassningsgrad (goodness of fit) och som baseras på ett tillräckligt stor antal enheter för att betraktas som statistisk representativ för målgruppen, inkluderas i algoritmen. Generellt sätt följer data en normalfördelning som tyder på få extrema värden. Följaktligen, anses data ha en bra distribution för att avgöra dess trend. Modellernas prestanda för transformatorer med tre lindningar testades mot ett förväntat värde för nollföljdsimpedansen, baserat på en skattning som för närvarande används av Svk. Testresultaten vissa modeller medan för andra inträffar avvikelser. I detta projekt används LAB som utvecklingsplattform för alla analyser / An important comission for Svenska kraftnät (SvK) as the Swedish authory in charge of the power distribution network is to operate the grid in the most efficient way. In order to ensure 99,9% uptime, constant maintenance and fault diagnostics are required for the entire network of which power transformers are an important component. The zero-sequence impedance is a way to determine the maximum fault currents a transformer can accept before being damaged. The zero- sequence impedance is one of three sequences used to analyze three-phase systems and is a quantity which is not easily obtained analytically. Its value is usually determined in tests carried out during the fabrication process. This information is not available for several transformers currently in service on the power grid. The focus of this thesis is to develop empirical models to estimate the value of the zero-sequence impedance for three- and five limb power transformers with three (YY∆) and four windings (YYY∆) including a stabilizing winding. A stabilizing winding is a delta-connected winding which is not brought out; its purpose is to reduce and balance the zero-sequence impedance in adjacent windings. The value for the zero-sequence impedance can only be estimated since a direct measurement on the winding is not possible for this type of transformers. The resulting models are part of an algorithm where different transformer quantities are used as inputs to estimate the value of the zero-sequence impedance for a given transformer. The method used to obtain these models is based on an analysis of the correlation between the zero-sequence impedance and other known and calculated quantities where a linear regression based on the least-squares method produces an approximative trend line. This approximation is made more robust with a bisquare-weight algorithm where less weight is given to diverging data points. This process is carried out for all the transformers included in this study where general models are obtained. The process is then repeated for specific subgroups of transformers with the goal of deriving more accureate models for these subgroups. The subdivision criteria is based in coupling- and core type which includes an0- and yn0-couplings and three- and four limb cores respectively. The reliability of each model is analayized with respect to their goodness of fit, statistical relevance and the quality of the data used to develop the model. Only models with a substantial goodness of fit and which were based on a sufficiently large number of transformers to be considered statistically representative of the target group are included in the final algorithm. In general, all the data analyzed follows a normal distribution which indicates that there are few extreme values. Consequently, the data used in this study is condsidered to be appropriately distributed to determine its trend. The performance of the models for transformers with three windings was tested against the expected values for the zero-sequence impedance based on the approximation algorithm which is currently being used by Svk. The test results from some of the models match the expected values while oth deviations. MATLAB is used in this projetct as the development platform for all analyses

Stator inter-turn short circuit (ITSC) faults are one of the common sources for induction machine failure affecting their reliable operation. In this thesis, a finite element (FE) model is developed to study the ITSC fault. The FE model is developed for a prototype induction machine that has the potential to emulate an ITSC fault in the stator. With the developed FE model of the prototype machine, a simulation study is performed to understand the behaviour of various electrical and magnetic quantities in time- and frequency-domain. The investigated quantities are potentially good signatures of the stator winding faults and they are therefore suitable to use in a condition monitoring system. The prototype machine with ITSC faults has been tested in an experimental setup and the results are compared to the simulation and also to analytical results. For the fault current it was found a good agreement between analytical results, FE simulations and experimental results. Moreover, the FE simulation results of the negative-sequence stator current amplitude present a minor mismatch with the analytical and experimental results. The reason for this mismatch is due to an inaccurate knowledge of the prototype machine geometrical parameters. / Kortslutning mellan varven i en asynkronmotors statorlindning (ITSC) är en av de vanligaste källorna för fel som påverkar dess drifttillförlitlighet. I detta examensarbete utvecklas en finit-element (FE) modell för att studera ITSC- fel. FE-modellen är utvecklad för en asynkronmotorprototyp som kan emulera ITSC-fel. Med den utvecklade modellen utförs en simuleringsstudie för att förstå beteendet hos olika elektriska och magnetiska egenskaper både i tids- och frekvensdomän. Dessa egenskaper är goda indikatorer av statorlindningsfel och kan därför med fördel användas i ett tillståndsövervakningssystem. Prototypmaskinen har testats experimentellt och de erhållna resultaten jämförs med FE-simuleringen och analysresultaten. Det analytiska resultatet, FEM- simuleringarna och den experimentella utvärderingen uppvisade god överrensstämmelse vad gäller felströmmen. Dock finns det en mindre avvikelse när det gäller amplituden hos statorströmmens negativa fasföljd. Orsaken till denna avvikelse är att prototypmaskinens geometri inte är helt känd.

Condition monitoring techniques can be employed to enhance reliability of electric machinery. The stator winding fault is one of the dominant causes for the failure of induction machines. In this work, the condition monitoring of an inverter-fed induction machine using high-frequency signal injection based technique is investigated. Initially, an analytical model of the induction machine with a stator inter-turn fault is developed. Subsequently, the behaviour of the induction machine in the presence of stator inter-turn fault is analyzed using the symmetrical component theory. Because of their use for fault diagnosis purposes, the analytical expressions for the fundamental and high-frequency symmetrical component currents are derived. The high-frequency signal injection is performed by adding a balanced three-phase high-frequency low-magnitude voltage to the fundamental excitation voltage. The resulting high-frequency negative-sequence current component can be used as reliable fault indicator to detect stator inter-turn faults. The effectiveness of the high-frequency negative-sequence current as a fault indicator is compared with the fundamental negative-sequence current, which is one of the traditionally used fault indicators for detecting these faults. The high-frequency signal injection technique proposed in this work is tested experimentally on a prototype machine in a laboratory set-up. The use of the proposed fault indicator is found to be advantageous when compared to the use of the traditional fault indicator for variable-frequency drives. In particular, it is shown that the proposed fault indicator is less dependent from the drive operating conditions than the traditional fault indicator. / Tillståndsövervakning är en teknik som kan användas för att förbättra tillförlitligheten hos elektriska maskiner. För asynkronmaskiner är fel i statorlindningen en av de dominerande orsakerna som leder till problem. I detta arbete undersöks tillståndsövervakning av en omriktarmatad asynkronmotor med hjälp av en högfrekvent signalinjektionsbaserad teknik. Inledningsvis utvecklas en analytisk modell av en asynkronmaskin med korsslutningsfel mellan varven i statorn. Därefter analyseras beteendet hos maskinen med hjälp av teorin för symmetriska komponenter. Analytiska uttryck för både grund- och övertoner härleds för de symmetriska komponenterna. Den högfrekventa signalinjektionen utförs genom att addera en liten högfrekvent trefasspänning till den matningsspänningen. Den resulterande högfrekventa negativa strömkomponenten kan användas som en tillförlitlig indikator för att upptäcka eventuella kortslutningar i statorlindningen. Förmågan som felindikator hos den högfrekventa negativa sekvensströmmen jämförs med den grundläggande negativa strömkomponentens förmåga, vilken är den traditionella indikatorn för att detektera dessa fel. Den högfrekventa signalinjiceringsmetoden som föreslås i detta arbete undersöks experimentellt på en prototypmaskin. Den föreslagna felindikatorn har visat sig vara fördelaktig jämfört med användningen av den traditionella felindikatorn för frekvensomriktare. I synnerhet visas att den föreslagna felindikatorn är mindre beroende av frekvensomriktarens driftsförhållanden än den traditionella felindikatorn.

Multiphase machines have gained a lot of popularity during the recent years, as they offer certain benefits over their three- phase counterparts. This work investigates the losses of a six- phase drive system for a marine application when supplied by four different switching patterns (also referred to as modulators). Using MATLAB/SIMULINK, a model was built for the machine featuring three independent frames and a nonlinear, cross coupled flux relation. It has been connected with the corresponding modulator models, where two carrier based modulators have been developed as well as two space vector modulators. The simulation data was then fed into the loss model to calculate the corresponding losses in both machine and converter. This work shows that control of the harmonics – mainly the fifth – is beneficial to reduce losses, mainly in the machine. Without control, harmonic currents cause unnecessary losses. As none of the investigated modulators strictly dominates all others, this work suggests a combination of the two carrier based methods to create a simple and robust modulator, which offers both a high voltage magnitude and control over the fifth harmonic. / Flerfasmaskiner har blivit mycket populära under dem sestate åren, då de erbjuder specifika fördelar jämfört med trefasmaskiner. Denna avhandling undersöker förlusterna för en sexfasmakin för en maritim applikation när den är kopplad med fyra olika modulatorer. En modell för maskinen byggdes i MATLAB/SIMULINK som innehåller tre oberoende nivåer samt en ickelinjär och korskopplad flödesrelation. Maskinmodellen har blivit kopplad till de fyra korresponderande modulatormodellerna, där två är baserade på bärvågor samt de resterande två är baserade på rymdvektormodulation. Data erhållen från den simulerade maskinmodellen var sedan inmatad in i en förlustmodell för att beräkna de korresponderande förlusterna för både maskinen och omvandlare. Denna avhandling visar att kontroll av övertoner – i huvudsak den femte övertonen – är fördelaktigt för att minimera förluster, främst i maskinen. Eftersom ingen av de modulatorerna som undersöktes i avhandlingen är bäst i alla funktioner, föreslår avhandlingen en kombination av de två bärvågsberoende metoderna. Den nya modulatorn antas vara bra både i kontrol över den femte övertonen men också erbjuda en hög spänning tack vare hamonisk injektion. Dessutom är modulatorn enkelt och robust, eftersom det är bärvågberoende.

This dissertation contains a comprehensive analysis of both non-coupled and mutually coupled switched reluctance motors with concentrated windings for an electric bicycle traction application. Multiple pole configurations are analyzed and compared for each motor type. Includes magnetic design, thermal analysis, and structural analysis. A prototype is designed, manufactured, and validated. / This thesis discusses the design of both a conventional non-coupled switched reluctance motor (CSRM) and a mutually-coupled SRM (MCSRM) for an exterior rotor e-bike application. Several novel pole configurations were analyzed for each machine type, and the performance of the final CSRM and MCSRM designs were compared for this application. A commercially available e-bike permanent magnet synchronous motor (PMSM) was purchased, reverse engineered, and validated to define the geometry constraints and performance targets for the designs. Since switched reluctance motors do not use rare-earth permanent magnets, they are often seen as a potential low-cost alternative to permanent magnet machines. The goal of this research is to explain the relative advantages of CSRMs and MCSRMs when compared to PMSM machines for a direct-drive e-bike application. The final CSRM and MCSRM designs are analyzed in detail; electromagnetic, controls, thermal, and structural considerations are all studied. A prototype of the final CSRM design was manufactured and validated experimentally, using a dynamometer setup. The finalized CSRM design is shown to be competitive with the PMSM machine when considering torque output, and is superior in terms of peak efficiency, and high speed torque performance. However, the CSRM noise output and torque ripple were not compared to the PMSM, and a less-common asymmetric-bridge converter is required for the CSRM, which may hinder the ability for the machine to be implemented into existing e-bike packages. The high speed torque performance of the MCSRM is shown to be inferior to both the CSRM and PMSM, as is the torque quality and efficiency. The MCSRM is shown to be highly resistant to saturation which gives it the potential for high torque output at low speed (if thermal limits are not breached), though low saturation levels also contribute to low machine power factor. The MCSRM may be better suited to lower speed, high torque applications, for this reason. / Thesis / Doctor of Philosophy (PhD) / This thesis studies the design process and analysis of two different motor types, for an electric bicycle application. They are designed to replace a commercially available permanent magnet synchronous motor (PMSM). This type of motor is typically expensive due to the rare-earth magnet material it requires. The two motors discussed in this thesis are switched reluctance motors (SRMs), which do not require magnet material, and thus have the potential to save cost (in addition to other benefits). One of the SRMs has magnetic fields that are independently controlled (CSRM), and one has fields that are controlled together to produce torque (MCSRM). The magnetics, control, thermal, and structural aspects of the CSRM and MCSRM are studied in detail. Novel geometry considerations (i.e. novel pole configurations) which impact the magnetics of each machine are compared to find the best-performing configuration for each machine type.

The passive components such as inductors and capacitors are bulky parts on circuit boards. Researchers in academia, government, and industry have been searching for ways to improve the magnetic energy density and reduce the package size of magnetic parts. The "constant-flux" concept discussed herein is leveraged to achieve high magnetic-energy density by distributing the magnetic flux uniformly, leading to inductor geometries with a volume significantly lower than that of conventional products. A relatively constant flux distribution is advantageous not only from the density standpoint, but also from the thermal standpoint via the reduction of hot spots, and from the reliability standpoint via the suppression of flux crowding. For toroidal inductors, adding concentric toroidal cells of magnetic material and distributing the windings properly can successfully make the flux density distribution uniform and thus significantly improve the power density. Compared with a conventional toroidal inductor, the constant-flux inductor introduced herein has an enclosed-winding geometry. The winding layout inside the core is configured to distribute the magnetic flux relatively uniformly throughout the magnetic volume to obtain a higher energy density and smaller package volume than those of a conventional toroidal inductor. Techniques to shape the core and to distribute the winding turns to form a desirable field profile is described for one class of magnetic geometries with the winding enclosed by the core. For a given set of input parameters such as the inductor's footprint and thickness, permeability of the magnetic material, maximum permissible magnetic flux density for the allowed core loss, and current rating, the winding geometry can be designed and optimized to achieve the highest time constant, which is the inductance divided by resistance (L/Rdc). The design procedure is delineated for the constant-flux inductor design together with an example with three winding windows, an inductance of 1.6 µH, and a resistance of 7 mΩ. The constant-flux inductor designed has the same inductance, dc resistance, and footprint area as a commercial counterpart, but half the height. The uniformity factor α is defined to reflect the uniformity level inside the core volume. For each given magnetic material and given volume, an optimal uniformity factor exists, which has the highest time constant. The time constant varies with the footprint area, inductor thickness, relative permeability of the magnetic material, and uniformity factor. Therefore, the objective for the constant-flux inductor design is to seek the highest possible time constant, so that the constant-flux inductor gives a higher inductance or lower resistance than commercial products of the same volume. The calculated time-constant-density of the constant-flux inductor designed is 4008 s/m3, which is more than two times larger than the 1463 s/m3 of a commercial product. To validate the concept of constant-flux inductor, various ways of fabrication for the core and the winding were explored in the lab, including the routing process, lasing process on the core, etching technique on copper, and screen printing with silver paste. The most successful results were obtained from the routing process on both the core and the winding. The core from Micrometals has a relative permeability of around 22, and the winding is made of copper sheets 0.5 mm thick. The fabricated inductor prototype shows a significant improvement in energy density: at the same inductance and resistance, the volume of the constant-flux inductor is two times smaller than that of the commercial counterpart. The constant-flux inductor shows great improvement in energy density and the shrinking of the total size of the inductor below that of the commercial products. Reducing the volume of the magnetic component is beneficial to most power. The study of the constant-flux inductor is currently focused on the dc analysis, and the ac analysis is the next step in the research. / Master of Science