Electrical Engineering Applications Research Articles

Recent advances in nonlinear dynamics with selected applications in electrical engineering

Recent advances in nonlinear dynamics with selected applications in electrical engineering

Tribological performance of polymer composites used in electrical engineering applications

Sliding wear performance of 20% mica-filled polyamide 6 (PA6 + 20% mica) and 20% short glass fibre-reinforced polysulphone (PSU + 20 GFR) polymer composites used in electrical applications were investigated using a pin-on-disc wear test apparatus. Two different disc materials were used in this study. These are AISI 316 L stainless steel and 30% glass fibre-reinforced polyphenylenesulphide (PPS + 30%GFR) polymer composite. Wear test was carried out at 10, 20 and 30 N applied load values and 0·5 m/s sliding speed and at ambient temperature and humidity. Different combinations of rubbing surfaces were examined and friction coefficient and specific wear rate values were obtained and compared. For two material combinations used in this investigation, the coefficient of friction shows insignificant sensitivity to applied load values and large sensitivity to material combinations. For specific wear rate, PA6 + 20% mica composite has shown insensitivity to change in load, speed and materials combination while PSU + 20% glass fibre composite has shown high sensitivity to the change in load and material combinations. The friction coefficient of PA6 + 20% mica and PSU + 20 glass fibre rubbing against the AISI 4140 steel disc is between 0·35 and 0·40. In rubbing against PPS + 30% glass fibre their values were between 0·25 and 0·30. Specific wear rate for PA6 + 20% mica and PSU + 20% glass fibre composites are in the order of 10 − 13 to 10 − 14 m2/N. Finally, the wear mechanisms are a combination of adhesive and abrasive wear processes. In terms of application, especially in electrical systems, a substantial contribution was provided to extend switch life. Thus, besides robustness, this also ensured safety for the system and the users against undesirable situations.

Wavelet Multiscale Analysis of a Power System Load Variance

Wavelet transform (WT) represents a very attractive mathematical area for just more than 15 years of its research in applications in electrical engineering. This is mainly due to its advantages over other processing techniques and signal analysis, which is reflected in the time-frequency analysis, and so it has an important application in the processing and analysis of time series. In this paper, for example, the analysis of the hourly load of a real power system over the past few years was performed by applying the continuous WT and using the Morlet wavelet function. The results show that this approach of data analysis can give a better insight into the basic characteristics of the consumption and identify the characteristic periods of the power system load variances over the past years, which can be very interesting for power system planners.

On the FE-analysis of inverse problems: An application in electrical engineering

On the FE-analysis of inverse problems: An application in electrical engineering

Parameter estimation for nonincreasing exponential sums by Prony-like methods

Let zj:=efj with fj∈(-∞,0]+i[-π,π) be distinct nodes for j=1,…,M. With complex coefficients cj≠0, we consider a nonincreasing exponential sum h(x):=c1ef1x+⋯+cMefMx(x⩾0). Many applications in electrical engineering, signal processing, and mathematical physics lead to the following problem: Determine all parameters of h, if 2,N sampled values h(k) (k=0,…,2N-1; N⩾M) are given. This parameter estimation problem is a nonlinear inverse problem. For noiseless sampled data, we describe the close connections between Prony-like methods, namely the classical Prony method, the matrix pencil method, and the ESPRIT method. Further we present a new efficient algorithm of matrix pencil factorization based on QR decomposition of a rectangular Hankel matrix. The algorithms of parameter estimation are also applied to sparse Fourier approximation and nonlinear approximation.

Effect of nitrogen environment on NdFeB thin films grown by radio frequency plasma beam assisted pulsed laser deposition

Abstract NdFeB is a very attractive material for applications in electrical engineering and in electronics, for high-tech devices where high coercive field and high remanence are needed. In this paper we demonstrate that the deposition of nitrogen doped NdFeB thin films by pulsed laser deposition, in the presence of a nitrogen radiofrequency plasma beam, exhibit improved magnetic properties and surface morphology, when compared to vacuum deposited NdFeB layers. A Nd:YAG pulsed laser (3ω and 4ω) was focused on a NdFeB target, in vacuum, or in the presence of a nitrogen plasma beam. Substrate temperature (RT-850 °C), nitrogen gas pressure, and radiofrequency power (75–150 W), were particularly varied. The thin films were investigated by means of X-ray diffraction, atomic force microscopy, scanning electron microscopy, spectroscopic-ellipsometry, and vibrating sample magnetometry.

From Mathematical Analysis to Experimental Calculation: Teaching Three-Phase Short-Circuits of a Synchronous Generator

Besides highlighting the physical model in electrical engineering curricula, the mathematical model should also be emphasised. Mathematical derivation can clearly show students how to obtain the conclusions from the original equations, and how to simplify the complex theories to the experimental equations. This paper uses the three-phase short-circuit calculations of a synchronous generator to demonstrate the evolution from mathematical theory to practical application. From various expressions in a typical example, the students can learn to analyse the same problem in different situations. This will help them to master the analytical method from mathematical theory to electrical engineering application.

An Approach to Conformal Transformation Using Symbolic Language Facilities: Application in Electrical Engineering

Several studies have been published on this subject concerning especially the calculation of the transformation integral and the plotting of the field spectrum. The method presented in this paper covers larger topics including field strength, circulation, and flux and offers solutions either in closed form or, if not possible, resorting to numerical integration and avoiding, for the considered cases, the utilization of any numerical method like the finite element method. In the present work, the usage of a symbolic language is presented and certain new results have been obtained. The method permits applying the conformal transformation avoiding the hand calculation of integrals for cases in which this calculation is very difficult by traditional procedures because it involves finding some changes of variable suitable for the considered case. For this purpose, the Maple 12 software has been used. An application for electrical engineering which has been considered led the author to find a new solution superior to the known ones.

Impedance spectroscopy of composites based on waste polymeric materials for electrical engineering purposes

We have developed a high-sensitivity capacitance transducer and a method for measuring the complex of elec- trical indices of composites based on waste polymeric materials in the frequency range from 100 Hz to 1 MHz. The electrical properties of composites depending on the electric field frequency and the content and type of the filler have been investigated. Introduction. The development of effective methods for controlling and diagnosing the electrical properties of electrical-engineering composites based on waste polymeric materials is dictated by the necessity of their testing for the compliance of the complex of their electrical indices (relative permittivity, bulk electrical resistivity, dielectric loss tangent) with the norms regulated by the corresponding standards (1-3). The urgency of the problem is due to the fact that composites based on waste polymeric materials can find various applications in electrical engineering. For exam- ple, composites containing finely dispersed quartz sand or lignin as fillers can be used as electrical insulating materials, and composites based on powdery carbon fibers, powdery electrolytic copper, or rubber crumbs obtained from used tires can be used as current-conducting materials for a wide range of technical and household objects. In this connection, the purpose of the present work is to develop effective methods for controlling and diag- nosing composites based on waste polymeric materials with the aim of investigating their electrical properties depend- ing on the content and type of the filler in the electric field frequency range from 100 Hz to 1 MHz. Materials and Methods of Investigation. The technology of obtaining composites based on waste polymeric materials containing powdery carbon fiber (PCF), sand (S), PGRS powder, or powdery electrolytic copper (PEC) is as follows. Waste polyethylene film was ground with the help of a knife grinder. A certain quantity of fractured particles was placed on microrollers heated to a temperature of 115-120 o C, and the necessary quantity of powdery carbon fiber predried at a temperature of 150-200 o C was added to it portionwise; then the mixture was stirred for 5-7 min until a homogeneous mass was obtained. From the rolled sheet, composite plates with given sizes were formed by the method of hot pressing for 15-20 min at a temperature of 160-170 o C. To investigate the electrical properties of composites based on waste polymeric materials, we created a meas- uring facility incorporating a high-sensitivity capacitive transducer (sensor) and a small-sized digital immitance meter in which there is an interface for current control data output to the monitor of the personal computer screen. The de- sign of the high-sensitivity capacitive transducer is shown in Fig. 1. The capacitive transducer designed by us has the following advantages over the existing analogs: a) it permits obtaining information on the complex of electrical indices of composites based on waste poly- meric materials in the electric field frequency range between 100 Hz and 1 MHz; b) it permits determining the thickness of the composite plate by means of a micrometric device in the 0.1-6 mm range with an accuracy of 0.005 mm;

New routes to flame retard polyamide 6,6 for electrical applications

Polyamide 6,6 is used in many industrial fields such as housing materials, transport or electrical engineering applications. Due to its chemical composition, this polymer is easily flammable. As far as the main applications concern electrical and electronic equipments, its flame-retardant properties become an important requirement. The most discriminating tests are the limiting oxygen index, UL94 and glow wire flammability index. The aim is to obtain high limiting oxygen index values, V0 rating at UL94 test for 1.6- or 0.8-mm-thick samples and a validation at 960°C of the glow wire flammability index. The usual way to fire retard polyamide 6,6 consists of incorporating an important loading of fire-retardant additives, which often reduce the intrinsic properties of the polymer. It is also difficult to combine a thin polymer thickness (e.g. 0.8 mm) and a high amount of additives because of processing issues. In this article, we first carried out a rapid screening to determine the best fire retardant for polyamide 6,6 and its optimized amount to achieve the previously defined fire retardant properties. It was shown that an amount of 23% of aluminium diethylphosphinate Exolit OP1230 allows reaching the requirements. Then, carrying out two different surface treatments (coating of polysiloxanes by plasma-enhanced chemical vapour deposition and use of an intumescent waterborne varnish), we have tried to reach the same results. It was shown that the use of surface treatment alone does not allow reaching the objectives. As a consequence, the combination of the bulk approach at low loadings with the surface treatment was investigated. This new route allows the combination of the condensed phase mechanism of the intumescent barrier with the gas phase mechanism of the OP1230 and leads to very good results: the use of 5% of the flame-retardant additives combined with a 100-µm-thick waterborne intumescent varnish leads to better results than a 23% of additive loading.

A modified PSO technique for electrical engineering applications

A modified PSO technique for electrical engineering applications

Oscillation Properties for Second-Order Half-Linear Dynamic Equations on Time Scales

Since Hilger (1990) introduced the theory of time scales, many authors have expounded on various aspects of this new theory; see the books (Bohner & Peterson, 2001, 2003) and the papers (Agarwal et al., 2007; Bohner & Saker, 2004; Chen, 2010; Chen & Liu, 2008; Doslý & Hilger 2002; Erbe et al., 2008; Hassan, 2008; Hassan, 2009; Karpuz, 2009; Medico & Kong, 2004; Saker, 2005; Zhang, 2011). A time scale T is an arbitrary nonempty closed subset of the reals R (see Hilger, 1990; Bohner & Peterson, 2001, 2003), and the cases when this time scale is equal to the reals or to the integers represent the classical theories of differential equations and of difference equations. Many results concerning differential equations carry over quite easily to corresponding results for difference equations, while other results seem to be completely different from their continuous counterparts. The study of dynamic equations on time scales reveals such discrepancies, and helps avoid proving results twice–once for differential equations and once again for difference equations. The general idea is to prove a result for a dynamic equation where the domain of the unknown function is a time scale. In this way results not only related to the set of real numbers or set of integers but those pertaining to more general time scales are obtained. Therefore, not only can the theory of dynamic equations unify the theories of differential equations and difference equations, but it is also able to extend these classical cases to cases “in between,” e.g., to the so-called q-difference equations. Dynamic equations on time scales have a lot of applications in population dynamics, quantum mechanics, electrical engineering, neural networks, heat transfer, and combinatorics. Bohner and Peterson (2001) summarizes and organizes much of time scale calculus. For advances of dynamic equations on time scales, we refer the reader to (Bohner & Peterson, 2003).

Extended frequency analysis of magnetic losses under rotating induction in soft magnetic composites

We present novel results on magnetic losses in soft magnetic composites (SMCs) excited with rotating field. Soft composites are very promising in electrical engineering applications, where new topologies of electrical machines with two- and three-dimensional induction loci are increasingly found. An experimental characterization of industrial SMC products has, therefore, been carried out, up to the kilohertz range, under alternating and circular flux loci, making use of a specifically designed and optimized loss measuring setup. The obtained results have been analyzed for all kinds of excitation, according to the loss separation concept, with the emphasis being placed on the relationship between the rotational and the alternating loss components. In particular, it is found that the ratio between the rotational and the alternating losses is, for any given peak induction, independent of frequency.

A Finite Element Model of Magnetization of Superconducting Bulks Using a Solid-State Flux Pump

Superconductors have a bright future; they are able to carry very high current densities, switch rapidly in electronic circuits, detect extremely small perturbations in magnetic fields, and sustain very high magnetic fields. Of most interest to large-scale electrical engineering applications are the ability to carry large currents and to provide large magnetic fields. There are many projects that use the first property, and these have concentrated on power generation, transmission, and utilization; however, there are relatively few, which are currently exploiting the ability to sustain high magnetic fields. The main reason for this is that high field wound magnets can and have been made from both BSCCO and YBCO, but currently, their cost is much higher than the alternative provided by low-Tc materials such as Nb3Sn and NbTi. An alternative form of the material is the bulk form, which can be magnetized to high fields. This paper explains the mechanism, which allows superconductors to be magnetized without the need for high field magnets to perform magnetization. A finite-element model is presented, which is based on the E-J current law. Results from this model show how magnetization of the superconductor builds up cycle upon cycle when a traveling magnetic wave is induced above the superconductor.

Electric charge trapping, residual stresses and properties of ceramics after metal/ceramics bonding

Abstract The use of ceramic components in electrical engineering and mechanical applications is rapidly increasing. Most of these applications require the use of ceramics bonded with metal. In this paper, we have studied the role of residual stresses occurring after joining between an industrial alumina ceramic (Al 2 O 3 ) and Ni-based super-alloy, on the dielectric behaviour of ceramics. The electric charging phenomenon i.e. trapping–detrapping or diffusion of electric charges is studied by Scanning Electron Microscope Mirror Effect (SEMME) coupled with the Induced Current Method (ICM). Knowing that localized trapped charges in ceramics is a source of damage, the correlation between residual stress intensity, apparent-toughness of ceramics and ability to trap charges near the interface was demonstrated: the SEMME and ICM measurements of the quantities of trapped charges near the interface, highlighted the changes in the ceramic properties related to residual stresses due to both thermo-mechanical effect and diffusion of metallic species in the ceramics, during the bonding process.

A new artificial bee swarm algorithm for optimization of proton exchange membrane fuel cell model parameters

An appropriate mathematical model can help researchers to simulate, evaluate, and control a proton exchange membrane fuel cell (PEMFC) stack system. Because a PEMFC is a nonlinear and strongly coupled system, many assumptions and approximations are considered during modeling. Therefore, some differences are found between model results and the real performance of PEMFCs. To increase the precision of the models so that they can describe better the actual performance, optimization of PEMFC model parameters is essential. In this paper, an artificial bee swarm optimization algorithm, called ABSO, is proposed for optimizing the parameters of a steady-state PEMFC stack model suitable for electrical engineering applications. For studying the usefulness of the proposed algorithm, ABSO-based results are compared with the results from a genetic algorithm (GA) and particle swarm optimization (PSO). The results show that the ABSO algorithm outperforms the other algorithms.

Research of Digital Measurement and Control Technology for the Inverter of Power Supply

In this paper, basic content and development of power presented; and the present condition of inverter power supply is discussed; then practical significance and developmental prospect to the technology based on digitalization about power converter are described in detail; and new direction of study is explored for the development about electrical engineering discipline and application of the technology about solar energy.

Electrical properties analysis of micro and nano composite epoxy resin materials

This work deals with the study of micro and nanosilica filled epoxy resin samples carried out in the framework of CIGRE WG D1.24 cooperative test program. This program focused on chemical, electrical and electrostatic properties of epoxy based nanodielectrics for electrical engineering applications. Epoxy based samples filled with micro and/or nanoparticles of silica were characterized by transmission electron microscopy, dielectric spectroscopy, conduction current and space charge measurements. These mutually complementary techniques were used to examine the effect of the size and quantity of silica particles on the electrical properties of the analyzed materials. The analysis of charge injection, polarization, trapping and conduction phenomena has allowed the modeling of dielectric behavior of the studied materials under multiple stresses. The Schottky Injection and Space Charge Limited Current models were studied to explain conduction phenomena. A composition of micro and nano-sized silica particles accumulating the smallest amount of space charge is also proposed.

Innovative Calorimetric AC Loss Measurement of HTSC for Power Applications

The applications of high-temperature superconductors (HTS) in electric power components have been widely reported and various studies have been made to define their alternating current (AC) losses-a key design parameter for many practical high power electrical engineering applications. However, very few studies over the range 25 to 45 K have been conducted even though this is one of the favored temperature ranges for cost-effective applications of HTS. Methods and techniques used to characterize and measure these losses have been so far grouped into `electrical' and `calorimetric' approaches with external conditions set to resemble the application conditions. In this paper, we present an approach using the calorimetric method to accurately determine losses in the superimposed AC and DC fields likely to be experienced in practical devices such as Fault Current Limiters. This technique provides great simplification compared to pick-up coil and lock-in amplifier methods and is applied to a lower temperature range. The preliminary loss data at 40 K will be presented in applied AC magnetic fields with DC fields up to 1T. The data of losses obtained on this sample will allow the estimation and minimization of losses in practical high power HTS coils and will be used in the verification of numerical coil models.

Comparison of two methods for magnetic field synthesis on a solenoid’s axis

Magnetic field synthesis problems have been discussed at length in scientific literature but they still remain as a topic of research in electrical engineering, physics and medical applications. In these disciplines, there is often a need to design an electromagnetic arrangement which can generate a magnetic field of required distribution. Such an arrangement can also work as an active shield. The aim of an active shield is to generate a specified magnetic field which counteracts the external magnetic fields in a protected region. The idea of active shielding is to construct a suitable arrangement of coils, excited with currents that generate an opposite magnetic field sufficient to cancel out the unwanted external fields. The opposite field must have the same frequency and amplitude as the external field. If the incident field presents a wide bandwidth, the final aim is to generate an opposite field in the same frequency range or at least in a range as large as possible. Two independent methods of magnetic fields synthesis, i.e. iteratively regularized Gauss–Newton method and Genetic Algorithm coupled with Bezier curves-based method, are discussed and compared in this paper.