Electromagnetic finite element design of axial flux permanent magnet machines for low speed applications

© 2014 IEEE. The higher torque to volume ratio of Axial Flux Permanent Magnet (AFPM) machines, when compared with their radial flux counterparts, is enhanced in multi pole design, making them suitable for low speed applications. This paper presents a comprehensive approach to the finite element-aided electromagnetic design of a double-sided AFPM machine with internal rotor. The Finite Element (FE) model is included in a coupled electromagnetic-thermal design procedure. Special attention is given to leakage fluxes, synchronous and armature reaction inductances and no-load electromotive force computation. The evaluation of the FE model routine of the design procedure is performed through experimental validation of a prototype machine.info:eu-repo/semantics/publishedVersio

Comprehensive analysis and evaluation of cogging torque in Axial Flux Permanent Magnet machines

Evaluation and minimization of cogging torque in Axial Flux Permanent Magnet (AFPM) machines become essential specially in direct drives for low speed applications. This paper presents a comprehensive analysis of the cogging torque in AFPM machines designed for low speed applications and mitigation methods are proposed. Evaluation methodologies of the cogging torque based on Finite Element Analysis (FEA) computations are discussed and applied to a double-sided, internal rotor, AFPM reference machine. From the performance comparison of Maxwell stress tensor and virtual work methods on the evaluation of cogging torque, it is possible to conclude that the latter overestimates the amplitude of the cogging torque into a considerable extent.info:eu-repo/semantics/publishedVersio

3D Modelling of Large Urban Scenes from Diverse Sources of Information

The complex and extensive nature of urban environments creates difficulties to the task of generating virtual models. Thus a great effort in terms of human resources, time and money is needed. Nevertheless a large number of professionals and institutions devout efforts to gather and analyse data from these urban environments. As data is usually stored in a digital format, it becomes a valuable asset to incorporate it in the modelling process of virtual environments. This paper presents a three-dimensional modelling system with interoperable access to data in diverse formats and digital support, drived by an L-system based modelling process that automatically generates initial solutions for virtual environments, which can be incrementally improved

Prototype of an axial flux permanent magnet generator for wind energy systems applications

Small scale wind power applications require a cost effective and mechanically simple generator in order to be a reliable energy source. The use of direct driven generators, instead of geared machines, reduces the number of drive components, which offers the opportunity to reduce costs and increases system reliability and efficiency. For such applications, characterized by low speed of rotation, the axial flux permanent magnet generator is particularly suited, since it can be designed with a large pole number and high torque density. This paper presents a double-sided axial flux permanent magnet low-speed generator, with internal rotor and slotted stators. Such a structure gives a good compromise between performance characteristics and feasibility of construction. Test results obtained from the prototype are reported.FC

An axial flux permanent magnet synchronous generator for a gearless wind energy system

In low speed applications such as wind energy conversion systems, the use of direct driven generators, instead of geared machines, reduces the number of drive components, which offers the opportunity to reduce costs and increases system reliability and efficiency. The Axial Flux Permanent Magnet (AFPM) generator is particularly suited for such application, since it can be designed with a large pole number and a high torque density. This paper presents the design, construction and experimental validation of a double-sided AFPM synchronous generator prototype, with internal rotor and slotted stators. Design objectives embrace achieving a good compromise between performance characteristics and feasibility of construction, which results in a cost competitive machine

Static Hopfions in the extended Skyrme-Faddeev model

We construct static soliton solutions with non-zero Hopf topological charges to a theory which is an extension of the Skyrme-Faddeev model by the addition of a further quartic term in derivatives. We use an axially symmetric ansatz based on toroidal coordinates, and solve the resulting two coupled non-linear partial differential equations in two variables by a successive over-relaxation (SOR) method. We construct numerical solutions with Hopf charge up to four, and calculate their analytical behavior in some limiting cases. The solutions present an interesting behavior under the changes of a special combination of the coupling constants of the quartic terms. Their energies and sizes tend to zero as that combination approaches a particular special value. We calculate the equivalent of the Vakulenko and Kapitanskii energy bound for the theory and find that it vanishes at that same special value of the coupling constants. In addition, the model presents an integrable sector with an infinite number of local conserved currents which apparently are not related to symmetries of the action. In the intersection of those two special sectors the theory possesses exact vortex solutions (static and time dependent) which were constructed in a previous paper by one of the authors. It is believed that such model describes some aspects of the low energy limit of the pure SU(2) Yang-Mills theory, and our results may be important in identifying important structures in that strong coupling regime.Comment: 22 pages, 42 figures, minor correction

Materiais magnéticos permanentes

Os materiais magnéticos permanentes desempenham um papel preponderante numa vasta gama de produtos industriais e de consumo. O recente desenvolvimento dos ímanes de terras raras e a sua vulgarização introduziram alterações profundas nos dispositivos electromagnéticos e electrónicos com consequências no desempenho, tamanho e configuração, assim como na redução do custo dos produtos finais de uma forma que não era previsível há apenas 30 anos. A proliferação destes materiais tem ainda estimulado o desenvolvimento de novos produtos e mercados. Este trabalho constitui uma sinopse dos principais aspectos relacionados com os materiais magnéticos permanentes: é apresentada uma perspectiva histórica da sua evolução e uma compreensão básica da teoria do magnetismo. As tecnologias de fabrico e as principais classes de ímanes permanentes comerciais encerram a discussão

Cross-fertilization of Ferreira's Hopfions And Electromagnetic Knots

The interrelation between Ferreira's Hopf solitons of a conformal nonlinear $\sigma$ model and the electromagnetic knots found by Ra$\tilde{\rm{n}}$ada et al. is investigated. It is shown that the electromagnetic knots yield exact solutions of the conformal nonlinear $\sigma$ model different from those obtained by Ferreira. Conversely, It is discussed that Ferreira's solutions realize magnetic knots. The energy associated with these two kinds of knots are compared. The structure of the electric charge distribution and the electric current density associated with the magnetic knots is investigated

Test-retest reliability of the Health Literacy Questionnaire (HLQ-Br) in Brazilian carers of older people

The rapid aging of the Brazilian population is seeing people living longer but with comorbidities more common in older people and higher dependence in activities of daily living. Due to these factors, support from formal and informal carers is needed more frequently. Many informal carers are family members who manage the health of the older person they are caring for, including accompanying them to medical appointments and advocating for them when they are hospitalized1,2. As such, carers of older people often have a key role in accessing, understanding and supporting the implementation of health-related recommendations for the older person they provide care for..

Three loop soft running, benchmark points and semi-perturbative unification

We consider three-loop $\beta$-function corrections to the sparticle spectrum in the MSSM, with particular emphasis on Snowmass Benchmark points. The three loop running has little effect on the weakly interacting particle spectrum, but for the squark masses the effect can be comparable to, or greater than, that of two loop running. We extend the analysis to the semi-perturbative unification scenario, where the impact of the three loop corrections becomes even more dramatic.Comment: 12 pages, TeX, Uses Harvmac (big) and epsf. Added references (v2). More emphasis on magnitude of three loop corrections (v3