Man has always included some form of sugar in his diet. Only in the past two centuries has sugar been developed as an individual food. During that time vast amounts of money and time have gone into the development and improvement of sugar. In 1747, a German chemist by the name of Andreas Marggraf proved that sugar beets contained sugar. One of his pupils, Franz Karl Achard, in 1799 gave further evidence of this fact by his experiments.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2006. / Härtill 4 uppsatser.

The permanent magnet synchronous machines have been attracting more and more attention due to the advantages of high torque density, outstanding efficiency and maturing technologies. Under the urges of mandatory energy efficiency requirements, they are considered as the most potential candidates to replace the comparatively low-efficient induction machines which dominate the industrial market. However, most of the high performance permanent magnet machines are based on high cost rare-earth materials. Thus, there will be huge demands for low-cost high-performance permanent magnet machines. Ferrite magnet is inexpensive and abundant in supply, and is considered as the most promising alternative to achieve the goal of low cost and high performance. In consideration of the low magnetic energy, this thesis explored the recent developments and possible ideas of ferrite machines, and proposed a novel multi-layer spoke-type interior permanent magnet configuration combining the advantages of flux focusing technique and multi-layer structure. With comparable material cost to induction machines, the proposed ferrite magnet design could deliver 27% higher power with 2-4% higher efficiency with exactly the same frame size. Based on the data base of International Energy Agency (IEA), electricity consumed by electric machines reached 7.1PWh in 2006 [1]. Considering that induction machines take up 90% of the overall industrial installation, the potential energy savings is enormous. This thesis contributes in five key aspects towards the investigation and design of low-cost high-performance ferrite permanent magnet machines. Firstly, accurate analytical models for the multi-layer configurations were developed with the consideration of spatial harmonics, and provided effective yet simple way for preliminary design. Secondly, the influence of key design parameters on performance of the multi-layer ferrite machines were comprehensively investigated, and optimal design could be carried out based on the insightful knowledge revealed. Thirdly, systematic investigation of the demagnetization mechanism was carried out, focusing on the three key factors: armature MMF, intrinsic coercivity and working temperature. Anti-demagnetization designs were presented accordingly to reduce the risk of performance degradation and guarantee the safe operation under various loading conditions. Then, comparative study was carried out with a commercial induction machine for verification of the superior performance of the proposed ferrite machine. Without loss of generality, the two machines had identical stator cores, same rotor diameter and stacking length. Under the operating condition of same stator copper loss, the results confirmed the superior performance of the ferrite machine in terms of torque density, power factor and efficiency. Lastly, mechanical design was discussed to reduce the cost of mass production, and the experimental effort on the prototype machine validates the advantageous performance as well as the analytical and FEA predictions.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This thesis presents a new optimization design methodology for power electronics converters with volume, cost and efficiency objectives. The optimization methodology, achieved by mathematical interactions, is based on the concept of the converter integrated design. In other words, the main physical converter components are designed simultaneously in the function of a common variable. The integrated design provides for the reduction of cost and time of the system design and also gives complete and matched solutions with the objective of the proposed optimization. The proposed methodology is illustrated with the help of a case study of a Boost Power Factor Correction converter (PFC) including an input EMI filter. In this case study, three different magnetic materials are used in both inductors designs (Boost and EMI filter), different semiconductors technologies and heat sink profile are also analyzed, aiming to demonstrate how technology affects the volume, cost and efficiency of the converter. Furthermore, switching auxiliary circuits (snubber and ZVT) are designed and its volume, cost and efficiency results are compared to the converter with hard switching. To confirm the models and theoretical analysis that was carried out, the experimental mechanical, electrical and thermal measurements are presented. / Esta tese apresenta uma nova metodologia de projetos para conversores eletrônicos de potência, com otimização de volume, custo e rendimento. A metodologia de otimização, desenvolvida através de interações matemáticas, é baseada no conceito de projeto integrado do conversor, em outras palavras, os principais componentes do sistema são projetados simultaneamente em função de uma variável comum. O projeto integrado disponibiliza redução de tempo e custo do projeto fornecendo uma solução completa de acordo com o objetivo de otimização. A metodologia proposta é ilustrada com a ajuda do estudo de caso do conversor Boost com correção do fator de potência (do inglês power factor corrector - PFC), com a inclusão de um filtro de EMI. Para este estudo de caso, três diferentes tecnologias de materiais magnéticos são utilizadas nos projetos do indutor Boost e dos indutores de filtro, diferentes tecnologias de semicondutores e perfis de dissipadores também são analisadas, objetivando avaliar o impacto de cada diferente tecnologia no volume, custo e rendimento do conversor. Além disso, circuitos de auxílio à comutação (snubber e ZVT) são projetados e os resultados de seu volume, custo e rendimento comparados aos do conversor com comutação forçada. Para validar os modelos adotados e as analises teóricas, medidas elétricas, térmicas e mecânicas são obtidas experimentalmente.

In this dissertation, a novel two-phase switched reluctance machine (SRM) with a stator comprised of E-core structure having minimum stator core iron is presented for low-cost high-performance applications. In addition, three new magnetic structures for the E-core SRM comprising two segmented stator cores or a monolithic stator core are proposed for good manufacturability, mechanically robustness, ease of assembly, and electromagnetic performance improvement. Each E-core stator in the segmented structure has three poles with two small poles at the ends having windings and a large center pole containing no copper windings. The common stator pole at the centers in the segmented E-core is shared by both phases during operation. Other benefits of the common poles contributing to performance enhancement are short flux paths, mostly flux-reversal-free-stator, constant minimum reluctance around air gap, and wide pole arc equal to one rotor pole pitch. Therefore, two additional common poles in the monolithic E-core configuration are able to significantly improve efficiency due to more positive torque and less core loss by the unique design. Using a full MEC analysis, the effect of the common-pole structure on torque enhancement is analytically verified. Efficiency estimated from the dynamic simulation is higher by 7% and 12% at 2000 rpm and by 3% and 7 % at 3000 rpm for the segmented and single-body SRMs, respectively, compared to a conventional SRM with four stator poles and two rotor poles. The new E-core SRMs are suitable for low-cost high-performance applications which are strongly cost competitive since all the new E-core SRMs have 20% cost savings on copper and the segmented E-core SRMs have 20% steel savings as well. Strong correlation between simulated and experimentally measured results validates the feasibility of the E-core common-pole structure and its performance. A simple step-by-step analytical design procedure suited for iterative optimization with small computational effort is developed with the information of the monolithic E-core SRM, and the proposed design approach can be applied for other SRM configurations as well. For investigating thermal characteristics in the two-phase single-body E-core SRM, the machine is modeled by a simplified lumped-parameter thermal network in which there are nine major parts of the motor assembly. / Ph. D.