The bio-inspired algorithms are novel, modern, and efficient tools for the design of electrical machines. However, from the mathematical point of view, these problems belong to the most general ...branch of non-linear optimization problems, where these tools cannot guarantee that a global minimum is found. The numerical cost and the accuracy of these algorithms depend on the initialization of their internal parameters, which may themselves be the subject of parameter tuning according to the application. In practice, these optimization problems are even more challenging, because engineers are looking for robust designs, which are not sensitive to the tolerances and the manufacturing uncertainties. These criteria further increase these computationally expensive problems due to the additional evaluations of the goal function. The goal of this paper is to give an overview of the widely used optimization techniques in electrical machinery and to summarize the challenges and open problems in the applications of the robust design optimization and the prospects in the case of the newly emerging technologies.
The degradation of electrical insulating materials has been a subject of interest for decades as they are commonly applied in many fields of electrical engineering. Suitably modeling such a process ...is important since the known and well-described degradation process reveals the effect of ambient conditions, and this allows us to possibly estimate a material’s remaining useful life. However, not many studies are dealing with the effect of the hygrothermal degradation of impregnating mono-component epoxy resins in the context of electrical engineering. Therefore, this study deals with this issue and discusses both the dielectric response (based on the measurement of relative permittivity, dissipation factor, and dielectric strength) and the mechanical response (based on measurements of tensile strength and Shore D hardness) to a hygrothermal degradation experiment. In addition, the results of thermal analyses are presented for the evaluation of the pristine specimen manufacturing process and possible post-curing processes. Furthermore, this study presents several methodologies for modeling the degradation process, including a novel methodology in this area based on Bayesian experimental design. As an outcome, mechanical parameters are proven to be specific in terms of the actual condition of the material and the Bayesian enhanced degradation model seems to be superior to the conventional evaluation methods in this particular study.
The operational reliability and high efficiency of modern electrical machines depend on the ability to transfer heat in the construction parts of the machine. Therefore, many authors study various ...thermal models and work on the development of effective heat dissipation. New insights and methods lead to improved techniques for the thermal design of electrical machines. This paper presents an experimentally validated thermal model of a permanent magnet synchronous motor (PMSM) with an improved slot winding model. It also deals with various approaches to homogenization and equivalent material properties of a tooth-coil winding sub-model. First, an algorithm for building a lumped-parameter thermal network (LPTN) of PMSM is described and its properties and problems are discussed. Subsequently, a sub-model of a slot with a winding based on the finite element method (FEM) is introduced. This sub-model is able to generate different conductor distributions based on probabilistic methods for a specified fill factor. This allows the verification of various homogenization approaches and at the same time it is a tool that automatically calculates thermal resistances for the LPTN.
This paper presents a novel approach to design of highly time-consuming aging experiments of electrical insulation system (EIS) materials, specifically epoxy resin, through Bayesian methods. The aim ...is to find a suitable model with as few experiments as possible. This is achieved by evaluation the information gain for each potential new experimental condition, and select the most informative conditions for measurement. If a model structure is not entirely known, multiple candidate models can be designed and the experiment design procedure quickly discriminates between them. The method is compared with the conventional approach of factorial experiment design and Response Surface Methodology (RMS). The aging of the epoxy samples is then hygrothermal, using temperature and humidity as two factors. This aging setup is not well studied, as the experiments are very demanding, but of high importance for the diagnostics of electrical machines. The results then show that the Bayesian approach is able to find models whose predictions match the validation measurement better than conventional methods.
Optimization of Reluctance Motor with Printed Rotor Kaska, Jan; Orosz, Tamas; Karban, Pavel ...
2019 22nd International Conference on the Computation of Electromagnetic Fields (COMPUMAG),
2019-July
Conference Proceeding
A novel way of optimizing a reluctance motor with rotor manufactured by 3D printing technology is presented. The optimization algorithms must take into account the tolerances of its production that ...are generally higher compared with classical processing, which requires a high level of robustness. The paper presents complete 3D mathematical models of the forward and backward tasks together with the ways of their numerical solutions. The methodology is illustrated with a practical example.
The paper presents a comparative analysis of different commercial and academic software. The comparison aims to examine how the integrated adaptive grid refinement methodologies can deal with ...challenging, electromagnetic-field related problems. For this comparison, two benchmark problems were examined in the paper. The first example is a solution of an L-shape domain like test problem, which has a singularity at a certain point in the geometry. The second problem is an induction heated aluminum rod, which accurate solution needs to solve a non-linear, coupled physical fields. The accurate solution of this problem requires applying adaptive mesh generation strategies or applying a very fine mesh in the electromagnetic domain, which can significantly increase the computational complexity. The results show that the fully-hp adaptive meshing strategies, which are integrated into Agros-suite, can significantly reduce the task's computational complexity compared to the automatic h-adaptivity, which is part of the examined, popular commercial solvers.
The diploma thesis contains a proposal and construction solution of a new nursery school in the village of Postřelmov in the stage of project documentation for construction. The kindergarten has a ...rectangular shape and has two above-ground floors and one basement floor. The main entrance to the building is wheelchair accessible and is oriented to the south. In the basement there are 26 parking places for employees of kindergarten and elementary school in Postřelmov and also a technical background. The first floor consists of two classes of kindergarten, on the second floor there is the third class and a large hall, which will be used mainly for cultural events in the kindergarten. The foundation structure is made up of concrete strips and the foundation foots are designed in places of garage parking. The vertical structures in the basement are designed from concrete fittings, the vertical load-bearing structures in the above-ground floors are designed in the Porotherm masonry system, the other non-load-bearing structures are designed in the Ytong system. Due to the large spans, the horizontal structures are designed from prestressed Spiroll ceiling panels. The roofing of the building consists of a flat green extensive roof. The project documentation also includes construction - physical assessment and fire - safety solution of the building.
In current valuation and economics disciplines, it is a commonly held belief that financial crisis is over and a big threat to world economic system is inflation. While many assumptions of these ...claims are of certain significance indeed, this thesis proves a non-trivial chance of outright deflation. Author of this work also shows that attempts of governments and central banks aimed at avoiding deflationary scenarios ultimately cause slower growth and elevated variance in economic activity. Due to existence of such causality, a new variable "tau" entering into CAPM model's risk premium was developed as the original model had previously not captured for impacts of monetary and government policies. In order to quantify a probability and strength of deflationary forces in developed world, three distinct approaches were utilized -- quantitative assessment, historical comparisons, and a pure economic theory based reasoning. Value of variable tau was determined by regressing relationship between implied risk premium and changes in monetary policy while testing for different time lags. Results of the work point to a 10-20% chance of deflation in developed world. Extremely loose monetary policy worldwide than warrants augmenting additional 1-2% risk premium to current implied risk premium of US stock market. Although newly defined models would certainly need more work and refining, author believes that the augmented CAPM version does a good job capturing the "irrational exuberance" mentality attached to policies of major central banks around the world. The three year lead of model-based risk premium compared to the implied one is perceived as one more contribution to current valuation process and understanding of risk.
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