The source-to-wheel efficiency of today's electrified vehicles already far surpasses the efficiency of strictly gasoline vehicles. As sources of electricity become cleaner and more efficient, and as gasoline becomes more scarce, the need for transporation electrification is increasingly economically and environmentally driven. The automotive industry primarily makes use of permanent magnet synchronous machines (PMSMs) and induction machines (IMs), the latter has the cost advantage of containing no rare earth metals. This thesis studies two different induction motors for electrified powertrain applications using a novel optimization algorithm to create efficiency maps and compare the efficiencies of the two motors. Induction motors are difficult to banchmark due to their complicated control schemes. Each point in their operating range can be achieved with an infinite number of current/slip combinations and therefore has infinite potential efficiencies. The proposed algorithm limits the number of simulations needed to benchmark an induction machine, and provides a clear and unbiased way to compare machines based on losses at their most efficient current/slip combinations over their entire operating range. The proposed algorithm is able to calculate losses within 5% error of simulation values for both machines. The first motor studied makes use of stranded windings and geometry parameters from the Tesla Motors patents. The efficiency map created has a peak efficiency of 96% and corresponds closely to an efficiency map for a similar motor found in literature. The second motor makes use of copper bar windings, which are easier to manufacture and have lower material costs. Bar windings, typically have lower resistance and stator copper losses at low speeds, but higher effective resistance and stator losses at high speeds due to eddy effects. The motor modelled was intended simply to compare the stranded and bar windings, and to see the advantages and disadvantages. For this reason, no other changes are made to the winding layout or motor geometry, including changes that would reduce the eddy effect. The resultant efficiency map has a peak efficiency of only 90%, performing worse than the stranded wound motor across most of its operating range. At very low speeds, under 1000 rpm, the efficiency of the bar wound machine is better than that of the stranded machine. The bar wound machine also has the advantage of being over 80\% efficient everywhere. The author suggests that future research focus on applying the proposed benchmarking algorithm to stator bar motors designed to limit eddy effects. Strategies include changing the slot opening shape, increasing the number of stator bars, and moving the stator bars away from the air gap. / Thesis / Master of Applied Science (MASc)

published_or_final_version / Electrical Engineering / Master / Master of Science in Engineering

Thesis--M. Sc.(Eng.), University of Hong Kong. / Mimeographed.

This research focuses on the creation of a thermal estimator to be used in an integrated electromagnetic, thermo-mechanical design tool for the rapid optimal initial sizing of switched reluctance and induction machines. The switched reluctance model includes heat generation in the rotor due to core losses, heat transfer across the air gap through convection, and a heat transfer path through the shaft to ambient. Empirical Nusselt correlations for laminar shear flow, laminar flow with vortices and turbulent flow are used to estimate the convective heat transfer coefficient in the air gap. The induction model adds ohmic heat generation within the rotor bars of the machine as an additional rotor heat source. A parametric, self-segmenting mesh generation tool was created to capture the complex rotor geometries found within switched reluctance or induction machines. Modeling the rotor slot geometries in the R-θ polar coordinate system proved to be a key challenge in the work. Segmentation algorithms were established to model standard slot geometries including radial, rectangular (parallel-sided), circular and kite-shaped features in the polar coordinate system used in the R-θ solution plane. The center-node mesh generation tool was able optimize the size and number of nodes to accurately capture the cross sectional area of the feature, in the solution plane. The algorithms pursue a tradeoff between computational accuracy and computational speed by adopting a hybrid approach to estimate three dimensional effects. A thermal circuits approach links the R-θ finite difference solution to the three dimensional boundary conditions. The thermal estimator was able to accurately capture the temperature distribution in switched reluctance and induction machines as verified with experimental results.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

- / -

Orientador: José Antenor Pomilio / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-25T15:20:15Z (GMT). No. of bitstreams: 1 PerezParedes_MarinaGabrielaSadith_M.pdf: 3442654 bytes, checksum: 6edc07da0803fe3dff86c9aa224d8ee3 (MD5) Previous issue date: 2013 / Resumo: Esta dissertação estuda a aplicação de frenagem regenerativa em veículos elétricos, em ação conjunta com freio de atrito. Considera-se o caso de um veículo leve com um motor de indução acionado por inversor. O processo de regeneração ocorre sempre que a velocidade comandada pelo inversor for menor do que a velocidade mecânica. O fluxo reverso de energia é absorvido pela fonte presente no lado CC do inversor. A partir de um único comando de frenagem o sistema é capaz de utilizar os freios elétrico e mecânico de acordo com o melhor procedimento para a recuperação da energia cinética do veículo, respeitando as limitações dos dispositivos eletrônicos e garantindo a frenagem, de acordo com a desaceleração determinada pelo condutor do veículo. Resultados de simulação computacional e em um arranjo experimental permitem analisar e verificar a sistemática proposta / Abstract: This thesis studies the application of regenerative braking in electric vehicles in joint action with friction brake. It is considered the case of a light vehicle with an induction motor driven by an inverter. The regeneration process occurs whenever the commanded speed to the inverter is less than the mechanical speed. The reverse flow of energy was able to be absorbed by the source available on the inverter DC side. From a single braking command, the system was able to use the electrical and mechanical brakes according to the best procedure for recovering the vehicle's kinetic energy, respecting the limitations of electronic devices and ensuring the braking according to the deceleration determined by the vehicle driver. Results of computer simulation and in an experimental setup allows to analyze and validate the methodology / Mestrado / Energia Eletrica / Mestra em Engenharia Elétrica

M.Ing. / The synchronous reluctance machine is a reasonably unknown type of machine. Recent developments have made it possible to deliver more power than an induction machine of similar size. It must, however, be noted that to accomplish this, the rotor profile design becomes complex and also expensive to manufacture. The aim of this project is to explore the possibility of controlling a synchronous reluctance machine `sensorlessly' (with no speed or position feedback sensors). The specific synchronous reluctance machine was made from an induction machine by machining a profile into the rotor cage of the induction machine. The required profile was designed using finite element analysis of the magnetic structure of the machine. A model of the machine was developed through using the direct and quadrature axis approach. With a model of the machine an estimator could be designed. This estimator was used to calculate the load angle of the machine by measuring the phase voltages and line currents and then estimating from these measurements the actual load angle. The estimator was designed for steady state conditions and gave sufficiently accurate values for the load angle under these conditions. The estimator was used as feedback in the torque control of the machine and it was shown that better results could be achieved with a better rotor profile. The partial cage of the induction machine present in the rotor made the machine more robust to changes in load. More research can be done on the modelling of the partial cage as well as the influence it has on the synchronous reluctance machine. Torque control and speed control were achieved with step changes in load of up to eighty percent of rated value. The performance of the machine was poor compared to an induction machine, but should improve with improvement in rotor profile design.

Electric machines are being deployed in industrial applications where previously only mechanical systems were considered, as environmental concerns from burning fossil fuels and energy costs are becoming a more dominant factor in system design considerations. Electric machines offer greater operational flexibility and typically higher efficiencies. There has therefore been a growing demand to develop electric machines to replace traditional mechanical systems in a number of industrial applications. One such suitable electric machine topology is the 'direct-drive' machine. These machines can be used where implementation does not require a high operating speed, therefore eliminating the necessity of a gearbox. Furthermore, direct-drive machines offer a number of advantages including reductions in through-life costs, noise and vibration, and overall system volume. This thesis explores the development of direct-drive rim-driven machines, constructed by integrating a propeller with the electric machine that is driving it, by mounting the machine directly around the outside of the propeller. A novel machine topology was developed by integrating a conducting-can onto the rotor structure capable of producing induction torque, to create a motor that can start directly from the main electric supply. This eliminated the need for a power electronic converter, gearbox and complicated drive shafts arrangement, for use in applications where only a low duty cycle of operation was required such as secondary propulsion systems for marine applications or where safety and reliability is of significant importance. A number of other industrial applications that may benefit from this canned rim-driven topology were also identified including seal-less pumps and 'run-of-the-river' generators. Permanent-magnet and induction motor topologies operating in fluid environments were investigated, using finite element analysis and thermal analysis techniques, to examine and optimise the design of the rim-driven topology for a specific operational requirement, in each industrial application area identified. A 30 kW canned line-start rim-drive induction motor was designed and developed for use as a bi-directional thruster on-board a tidal stream turbine. A novel induction motor topology was developed utilising only a conducting-can on the rotor, which eliminated the need for a traditional squirrel-cage, due to the ratio of the relatively large mean air-gap diameter to the small output power requirement; creating a simple yet reliable direct-drive canned induction motor. The design of this motor was manufactured and successfully tested to validate the design process.

Orientador: João Sinézio de Carvalho Campos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-27T19:06:13Z (GMT). No. of bitstreams: 1 Conceicao_RafaelNovaesda_M.pdf: 10111957 bytes, checksum: 9168b5514bd29d6ead99888af5052aab (MD5) Previous issue date: 2015 / Resumo: É bem conhecida a necessidade de energia elétrica para o bem estar e desenvolvimento tecnológico da população em nosso planeta. Ao lado dos avanços científicos de novas tecnologias para geração, existem interesses na melhoria do transporte da energia. Dentre estes se encontram materiais para isolação elétrica de barras estatóricas, quer sejam para melhorar a isolação ou mesmo para reduzir custos. Assim, o presente trabalho visa apresentar resultados da aplicação de uma nova resina epóxi bisfenólica (DGEBF) (RN) à base de nanopartículas de sílica e comparar suas propriedades com a resina epóxi bisfenólica (DGEBA) (RE), atualmente utilizada para a isolação de hidrogeradores. Neste sentido, fabricaram-se protótipos de barras estatóricas, destinadas a hidrogeradores, sendo as resinas impregnadas em sistema VPI (Vácuo-Pressão-Impregnação) e avaliaram-se as propriedades físico-químicas pelas técnicas de viscosimetria, TGA, DSC, MEV e EDS. As propriedades elétricas foram avaliadas pelas técnicas de fator de dissipação (tan delta), descargas parciais, envelhecimento acelerado (VET) e tensão de ruptura. Dentre os resultados das propriedades físico-químicas pode-se comprovar um aumento inicial de três vezes o valor de viscosidade para resina RN em comparação com RE. Entretanto, não houve detrimento das características dielétricas em função da viscosidade, o que foi comprovado através dos resultados de tan delta e VET. Obteve-se um valor de Tg de 116°C e 145°C para RN e RE, respectivamente, o que limitaria a aplicação da resina em geradores por estar abaixo da temperatura de operação. Dentre os resultados dos testes elétricos para as resinas observou-se que: (i) o fator de dissipação e de envelhecimento são praticamente os mesmos para ambas as resinas; (ii) o valor de tip-up resultaram em 0,014 % para RE e 0,020 % para a resina RN, sendo que a norma EN 50209 exige que seja inferior a 0,25% e (iii) a estimativa do tempo de vida útil obtida foi de cerca de 40 anos para os dois tipos de resina, o que é aplicável para maioria dos enrolamentos em operação. Neste sentido sugere-se que a resina RN pode ser uma boa alternativa a resina RE, com um desempenho elétrico equivalente, desde que ajustadas suas condições de processamento e temperatura de aplicação / Abstract: It is well know the demand of electrical energy for the wellbeing and technological development of the population in our planet. Among the scientific development of new technologies for generation, are interests to optimize the energy transport. Among them are materials for electrical insulation of stator bars, whether for improving the insulation or even to reduce the costs. Therefore, the present work aim to present the results of the employment of a new bisphenolic epoxy resin (DGEBF) (RN) containing silica nanoparticles and compare its properties with the bisphenolic epoxy resin (DGEBA) (RE) currently used for the insulation of hydrogenerators. In this context, it was manufactured prototype stator bars, designed for hydrogenerators, being the resins impregnated through VPI (Vacuum-Pressure-Impregnation) system and their physicochemical properties evaluated with the technics of viscosimetry, TGA, DSC, MEV and EDS. The electrical properties were evaluated with the tests of dissipation factor (tan delta), partial discharges, voltage endurance test (VET) and breakdown. Among the results of the physicochemical properties it was possible to verify an initial increase of three times the value of viscosity for RN resin compared to RE. However there was no detriment of the dielectric characteristics depending on the viscosity, what was proven with the results of dissipation factor and VET. It was obtained a value of Tg of 116°C and 145°C for RN and RE respectively, what could limit its employment for hydrogenerators as being below the operational temperature. Among the results of electrical tests for the resins it was observed that: (i) the dissipation factor and VET are practically the same for both resins; (ii) the tip-up value resulted in 0,014% for RE and 0,020% for RN, being required lower than 0,25% according to the norm EN 50209 and (iii) the estimating lifecycle was approximately 40 years for both types of resin, what is applicable for most windings under operation. In this context it is suggested that the RN resin can be a good alternative for RE resin with an equivalent performance once the process conditions and employment temperature are adjusted / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química