International Journal of Applied Electromagnetics and Mechanics - Volume 57, issue S1

Authors: Majer, Krzysztof

Article Type: Research Article

Abstract: This paper presents a method for specifying the magnetizing current of the transformers operating with different submagnetizing of DC flux and for different values of supply voltage (flux density in the core). The theoretical method of calculating of magnetizing currents has been developed. The computation and corresponding measurements were performed for single phase and three phase, three and five legs transformer cores. The influence of magnetization characteristics on the shape of instantaneous current value was investigated. The results obtained were used to determine the peak values of flux density in certain parts of the magnetic circuit. This has a significant …impact on precisely determine vibroacoustic parameters and losses in particular sections of the magnetic circuit of transformers. Show more

Keywords: Transformers, magnetizing current, flux density, submagnetizing

DOI: 10.3233/JAE-182313

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 57, no. S1, pp. 191-200, 2018

Authors: Pietrzak, L. | Wiak, S. | Smolka, K. | Szymanski, L. | Kolacinski, Z. | Raniszewski, G. | Was, L.

Article Type: Research Article

Abstract: Nowadays there are growing need of energy in every aspect of human living. That is the reason of searching for a highly efficient sources of energy. Supercapacitors or ultracapacitors (how supercapacitors are also described) can be used as ones. Main reason is high energy and power density of those devices. The possibility of using supercapacitors grow along with a reduction in their size while maintaining the above mentioned parameters. Accomplishing of that goal imposes the use of modern materials especially nanomaterials during supercapacitors manufacturing. One of materials recently raising scientists’ interest, as material for ultracapacitors electrodes are carbon nanotubes (CNTs). …It is due to the great electrical and mechanical properties and high specific surface. This article presents results of parameters calculation based on finite element method, obtained for supercapacitors models. In the described models used for simulation, electrodes are made of carbon nanotubes, obtained by synthesis using LSCVD method. Show more

Keywords: Supercapacitors, carbon nanotubes, finite element method, energy sources

DOI: 10.3233/JAE-182315

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 57, no. S1, pp. 201-207, 2018

Authors: Psuj, Grzegorz

Article Type: Research Article

Abstract: The use of electromagnetic nondestructive testing methods to assess damage and fatigue changes is a subject of numerous studies. However, the observed signals are influenced by many factors. Thus, making a proper assessment on the basis of single parameters’ behavior is complicated task. Therefore, in this paper, an approach of multiple parameters fusion for evaluation of damage was presented. The range of material changes in steel sample after successive stages of fatigue process was monitored using Magnetic Barkhausen Noise and AC magnetization method in a selected two-dimensional region. The acquired data was then processed for the need of signals parametrization. …The procedures in time, frequency and time-frequency domains were applied. Then the selection of representative features was carried out before the information was combined via multivariate regression. Finally, the obtained function was used to achieve the two-dimensional maps of evaluated damage for successive fatigue periods. Show more

Keywords: Fatigue evaluation, nondestructive evaluation, magnetic Barkhausen noise, AC magnetization method, multi-source data fusion

DOI: 10.3233/JAE-182316

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 57, no. S1, pp. 209-216, 2018

Authors: Wiltuschnig, I.P. | Eckert, P.R. | Flores Filho, A.F. | Dorrell, D.G.

Article Type: Research Article

Abstract: The study in this paper compares three permanent magnet (PM) brushless AC machine topologies with external rotor configuration, which are attractive for in-wheel electric drive applications. All machines use the same stator but have different rotor geometries: a conventional surface PM structure, a surface quasi-Halbach PM array structure, and an interior V-shaped PM structure. For these topologies, the volume of the PM material is the same. A numerical simulation based on finite element analysis was carried out for the three cases to evaluate and compare their behaviour in terms of torque density, magnetic flux density, and torque ripple.

Keywords: Brushless motor, external rotor, interior magnets, permanent magnets, quasi-Halbach array

DOI: 10.3233/JAE-182299

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 57, no. S1, pp. 217-225, 2018

Authors: Yamaguchi, Tadashi | Kawase, Yoshihiro | Asai, Hirofumi | Shibata, Masahide | Toida, Naotaka | Furukawa, Tomoyasu | Kawano, Hiroshi

Article Type: Research Article

Abstract: In this paper, we analyze the interbar current taking into account of the contact resistance between the secondary conductor and the steel sheets of squirrel-cage induction motors using the 3-D parallel finite element method. As a result, the effects of the contact resistance on the interbar current are clarified.

Keywords: 3-D parallel finite element method, squirrel-cage induction motor, interbar current, contact resistance, skew

DOI: 10.3233/JAE-182307

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 57, no. S1, pp. 227-233, 2018

Authors: Zajac, Mieczysław | Sułowicz, Maciej

Article Type: Research Article

Abstract: The subject of this work concerns the problem of signal diagnostics of induction machines carried out in the time-and-frequency domain. It was assumed that the signal carrying the important information about the current state of the machine is the measured signal of the axial flux. The basis for the diagnostic decision making was the analysis of the energy of the detailed wavelet representation, obtained as a result of the use of a specially constructed orthonormal transformation basis. To ensure sufficient resolution of fault detection, the authors constructed orthonormal wavelet basis based on the recursive formulas for generating higher order Legendre polynomials. …The construction of the orthonormal basis was carried out using the scaling function, which was designed using the appropriately scaled Legendre polynomial. The synthesis of the basic wavelet and the orthonormal basis was based on the recurrent dependencies of the multi-resolution analysis using the relationship between the elements of the quadrature mirror filters. Dependencies between elements from two consecutive levels of decomposition were used. By applying the constructed orthonormal basis, the research on the nature of the energy flow of an axial flux signal of an induction motor between adjacent frequency bandwidths in steady-state depending on the machine load was presented. Studies have shown that significant flows of the diagnostic signal energy occur between the adjacent frequency bandwidths periodically at frequency of about 2.5 Hz. This periodic energy flows of the axial flux signal hamper fault detection and diagnostic decision making. The analysis results confirmed that it is possible to ensure a sufficient level of selectivity of a diagnostic system by means of this method. To ensure a sufficient efficiency of diagnostic systems it is required to separate flow effects from fault symptoms. Show more

Keywords: Technical diagnostics, induction motor faults, time-frequency analysis, wavelets, orthogonal polynomials

DOI: 10.3233/JAE-182319

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 57, no. S1, pp. 235-249, 2018