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Article
Publication date: 15 November 2018

Maria Dems, Krzysztof Komeza, Jacek Szulakowski and Witold Kubiak

The purpose of this paper is to present the application of the loss approximation method for non-oriented electrical steel developed by the authors. A new model of a…

Abstract

Purpose

The purpose of this paper is to present the application of the loss approximation method for non-oriented electrical steel developed by the authors. A new model of a toroidal sample with dimensions ensuring high uniformity of the field was presented.

Design/methodology/approach

A critical analysis of the methods used was carried out. Based on these considerations, the authors proposed their own loss approximation method, which allows obtaining high accuracy in a wide range of induction and frequency. The proposed method is based on the assumption that for a certain frequency range losses can be describe by two terms formula. For a fixed value of the peak flux density Bm, the graph of specific loss divided by the frequency should have the form of a straight line. Then, the obtained coefficients for different Bm are the basis for approximation with the power function.

Findings

The comparison of measurement and approximation results shows that the method allows to obtain very good accuracy in a wide range of induction and frequency.

Research limitations/implications

More detailed studies on the impact of cutting on a larger number of samples with different geometrical dimensions are needed.

Practical implications

Application of the new method provides a better approximation of the curve of the loss and thus a more accurate calculation of the core loss in the electrical machines.

Originality/value

The paper presents the application of the loss approximation method for non-oriented electrical steel developed by the authors. A new model of a toroidal sample with dimensions ensuring high uniformity of the field was presented. It is shown that the approximation introduced allows for high accuracy in a wide range of frequency and magnetic flux density.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 18 January 2019

Marcin Lefik, Krzysztof Komeza, Ewa Napieralska-Juszczak, Daniel Roger and Piotr Andrzej Napieralski

The purpose of this paper is to present a comparison between reluctance synchronous machine-enabling work at high internal temperature (HT° machine) with laminated and solid rotor.

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Abstract

Purpose

The purpose of this paper is to present a comparison between reluctance synchronous machine-enabling work at high internal temperature (HT° machine) with laminated and solid rotor.

Design/methodology/approach

To obtain heat sources for the thermal model, calculations of the electromagnetic field were made using the Opera 3D program including effect of rotation and the resulting eddy current losses. To analyse the thermal phenomenon, the 3D coupled thermal-fluid (CFD) model is used.

Findings

The presented results show clearly that laminated construction is much better from a point of view of efficiency and temperature. However, solid construction can be interesting for high speed machines due to their mechanical robustness.

Research limitations/implications

The main problem, despite the use of parallel calculations, is the long calculation time.

Practical implications

The obtained simulation and experimental results show the possibility of building a machine operating at a much higher ambient temperature than it was previously produced for example in the vicinity of the aircraft turbines.

Originality/value

The paper presents the application of fully three-dimensional coupled electromagnetic and thermal analysis of new machine constructions designed for elevated temperature.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 27 September 2019

Racha Aydoun, Guillaume Parent, Mounaim Tounzi, Jean-Philippe Lecointe and Krzysztof Komeza

This paper aims to deal with a performance comparison of an 8/6 radial-flux switched reluctance machine (RFSRM) and an axial-flux switched reluctance machine (AFSRM)…

Abstract

Purpose

This paper aims to deal with a performance comparison of an 8/6 radial-flux switched reluctance machine (RFSRM) and an axial-flux switched reluctance machine (AFSRM), presenting equivalent active surfaces.

Design/methodology/approach

An axial machine was designed based on the equivalent active surfaces of a radial one. After estimating the machine inductances with a reluctance network, finite elements numerical models have been implemented for a more precise inductance determination and to estimate the electromagnetic torque for both machines. Finally, the AFSRM was thoroughly examined by analyzing the impact of some geometric parameters on its performance.

Findings

The comparison of the RFSRM and AFSRM at equivalent active surfaces showed that the obtained axial machine is more compact along with an improvement in the electromagnetic torque.

Practical implications

The equivalent AFSRM is more compact, therefore more interesting for transport and on-board applications.

Originality/value

The RFSRM and AFSRM performance comparison using the same active surfaces has not been done. Moreover, the AFSRM presented has a rare design with no rotor yoke and where the rotor teeth are encapsulated in a nonmagnetic structure, allowing a more compact design.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 38 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 November 2016

Ewa Napieralska-Juszczak, Piotr Napieralski, Krzysztof Komeza and Youcef Zeroukhi

The purpose of this paper is to determine the physical design parameters that influence the total resistance of a twisted conductor (cable). One of the physical parameters…

Abstract

Purpose

The purpose of this paper is to determine the physical design parameters that influence the total resistance of a twisted conductor (cable). One of the physical parameters characterizing this type of structures is the uneven distribution of resistivity due to hardening, which is the result of stress exerted on the wires during the manufacturing process.

Design/methodology/approach

The authors have developed a method to take into account the effect of localized hardening on the inhomogeneous distribution of electrical conductivity in the distorted structures of the conductor. To achieve this goal, the authors have implemented a mechanical-electrical simulation method. The resistance characteristics have been measured as a function of mechanical stress.

Findings

As demonstrated by the results of measurements conducted on various samples and with various cable design parameters, the resistance of a given material (copper or aluminum), expressed as a function of stress, does not depend on the type of force applied. Therefore, the same characteristics may be applied to various cable designs.

Practical implications

The method presented in this paper enables more detailed investigation of the influence of particular design parameters on the total resistance of a cable. It also provides the ability to determine optimal settings of design parameters.

Originality/value

The approach is distinct from similar studies because it takes into account the deformed geometry of the conductor and the uneven distribution of the resistivity within a filament. In the literature, it is sometimes stated that the distribution of resistivity in a compacted cable is uneven, but its measurement is deemed impossible. This paper provides a method for determining such a distribution.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 35 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 2 March 2015

Maria Dems, Krzysztof Komeza, Slawomir Wiak and Sara Fernández Coya

– The purpose of this paper is to present the distribution of the magnetic field and additional losses analysis of the induction motors (IM) with opened and closed rotor slots.

Abstract

Purpose

The purpose of this paper is to present the distribution of the magnetic field and additional losses analysis of the induction motors (IM) with opened and closed rotor slots.

Design/methodology/approach

In the field-circuit approach the distribution and changes of magnetic flux density in the motor are computed using a time-stepping finite element method. The additional losses in each element are evaluated at different frequencies.

Findings

An approximate analytical formulation is derived for rapid losses computation confirmed by the results of field-circuit method. For high-voltage motors due to the size ratios of the core and relatively deep stator and rotor slots major role in causing loss of higher harmonics play a fundamental slot harmonics. Higher harmonics order bigger than 100 cause only small part of total higher harmonics core losses. Closed rotor slots construction influenced significantly on no-load losses mainly due to reduction of losses at slot upper part. For nominal load condition that influence is not so strong according to the saturation of slot tips by rotor leakage flux. Nevertheless, core losses at load are several times higher as at no-load.

Research limitations/implications

In future research authors will take into account motors feed from PWM inverter, working in the frequency range up to 400 Hz.

Practical implications

The results of investigation will be used in more detailed design of IMs especially for motors with closed rotor slots.

Originality/value

The methods presented in the paper was not used before. Also results of additional losses in the motor core calculation, especially according motors with closed slots at no load and load conditions are new.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 13 July 2010

Krzysztof Komęza, Xosé M. López‐Fernández and Marcin Lefik

The purpose of this paper is to present the plan to develop the known algorithm for thermal and electromagnetic coupled problem calculation. This is used for three‐phase…

Abstract

Purpose

The purpose of this paper is to present the plan to develop the known algorithm for thermal and electromagnetic coupled problem calculation. This is used for three‐phase induction motor (IM) on nominal load. An additional purpose is verification empiric expressions of the heat transfer and equivalent thermal conductivity coefficients for external faces and air zones in analysed motor taken from literature.

Design/methodology/approach

The numerical investigations proposed in this paper are based on 3D finite element models for thermal and electromagnetic fields analysis. Electromagnetic analysis includes iron core losses. It gives additional heat sources to thermal analysis. Heat transfer and equivalent thermal conductivity coefficients are assessed applying empiric expressions. Thermal model is experimentally validated.

Findings

The results of calculations and experimental test shows that heat transfer coefficient for external zones taken from literature does not guarantee the equal accuracy of the distribution of the temperature in all volume of the machine.

Research limitations/implications

Taken from literature, empirical equations do not give correct values of heat transfer coefficient. It states ways to go further in the evaluation of heat transfer coefficients.

Originality/value

This paper presents modelling methodology of 3D transient thermal field coupled with electromagnetic field applied in three‐phase IM at rated load conditions.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 13 July 2010

Nabil Hihat, Krzysztof Komęza, Ewa Napieralska‐Juszczak, Jean‐Philippe Lecointe and Tadeusz Niewierowicz

The purpose of this paper is to present a comparative analysis concerning the influence of eddy currents on the distribution of the magnetic flux density in the laminated…

Abstract

Purpose

The purpose of this paper is to present a comparative analysis concerning the influence of eddy currents on the distribution of the magnetic flux density in the laminated anisotropic structures.

Design/methodology/approach

The influence of the magnetic flux normal to the lamination surface is particularly analysed. Several models containing internal air gaps and overlapping are tested. For every structure, the eddy currents are first taken into account and then, they are neglected. At last, the 3D simulation of the anisotropic conductivity permits to analyse separately the longitudinal and normal flux in the structure and the eddy currents induced by those fluxes.

Findings

The study leads to a more realistic numerical model with conducting laminations. The results show that the normal flux does not turn at once on lamination. The normal and longitudinal fluxes induce eddy currents which modify the flux distribution in the laminated structure.

Practical implications

The results of the presented simulations make it possible to elaborate a more realistic numerical model of homogenized characteristics taking into account eddy currents.

Originality/value

The eddy currents induced by the fluxes modifies the field distribution in the structure and should be taken into account. The internal air‐gaps higher than 0.1 mm have an influence on the field distribution; the isolation between the laminations of 0.01 mm has a smaller but not negligible effect on the magnetic flux. The direction of the normal flux from one sheet to another one does not change immediately after the entrance of the lamination, the transition is progressive.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 July 2006

Sławomir Wiak, Krzysztof Smółka, Maria Dems and Krzysztof Komęza

This paper aims to focus on the numerical modelling of 3D structure of surface micromachined (MEMS) accelerometers.

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Abstract

Purpose

This paper aims to focus on the numerical modelling of 3D structure of surface micromachined (MEMS) accelerometers.

Design/methodology/approach

The paper focuses on the methods of mechanical design and analysis of electrostatic accelerometers (comb drive structure) and uses computer simulation procedure leading to final structure design, then to be defined as a basic structure for stress analysis.

Findings

The strategy in computer modeling of accelerometer MEMS is satisfactory in order to simulate the electromechanical characteristics of different accelerometer structures (IMEMS).

Originality/value

A novel complex strategy in computer modeling of accelerometer MEMS, based on solid modeling is proposed.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 25 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 5 July 2013

Youcef Zeroukhi, Ewa Napieralska Juszczak, Krzysztof Komeza, Fabrice Morganti and Guillaume Vega

In the majority of devices for measuring the resistance of wires or cables, the supplying voltage is applied via some clamping arrangement. Thus, current enters the bundle…

Abstract

Purpose

In the majority of devices for measuring the resistance of wires or cables, the supplying voltage is applied via some clamping arrangement. Thus, current enters the bundle of conductors through the side surface of the outside wire. The purpose of this project was to establish the distance from the supplying point after which the current may be considered to be uniform and normal to the cable cross‐section.

Design/methodology/approach

When current passes from one wire to another, the crucial parameter is the resistance of the contact region. The paper presents a method by which this region can be identified and relevant resistance measured. A comprehensive simulation was conducted for different types of wires and cables to assess the influence of design parameters on the current distribution and uniformity.

Findings

The distance from the current entry point (the clamps) to the position where current density may be considered uniform has been established. This has facilitated estimating recommended positions of voltage taps with reference to current taps.

Practical implications

The look‐up tables and graphs allow adjustments to the position of the taps and/or correction of the measured results.

Originality/value

The original contribution of this paper is in the way the contact region is identified where current passes from one wire to another. Original relationships have been proposed showing the relationship between contact resistance and the design parameters of the cable and mechanical stress.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 September 2012

Jakub Andrzejewski, Krzysztof Komęza and Raphaël Romary

The large size of models and long computing time prevent the creation of full‐scale, three‐dimensional models of end region of turbogenerators. Only exact…

Abstract

Purpose

The large size of models and long computing time prevent the creation of full‐scale, three‐dimensional models of end region of turbogenerators. Only exact three‐dimensional model can illustrate complex phenomena of end region losses. Also some methods of decreasing such losses cannot be simulated in two‐dimensional models. The purpose of this paper is to focus on a method of creating three‐dimensional models of turbogenerators' end regions for calculations of eddy current losses.

Design/methodology/approach

Time‐stepping is the most expensive part of computation. A harmonic model would be free from that disadvantage and it can provide a tool to make an accurate, fully three‐dimensional model of a steady state for different loads and provide results in a reasonable time.

Findings

The research focuses on the method of creating three‐dimensional models of turbogenerators end region for calculations of eddy current losses. By using two‐dimensional, time‐stepping models and empirical loss functions for a main flux and three‐dimensional models for eddy current losses from a perpendicular flux of an end connections, it is found that fast analysis of that complex part of a machine can be achieved.

Originality/value

The approach proposed in the paper is a universal and novel method of calculation losses of turbogenerators' end regions. Combining two‐dimensional and three‐dimensional models provides advantages of both known methods: fast computation time from simplified models and good representation of complex geometry of a machine.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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