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The purpose of this study is to find out the influence degree of harmonic current on the generator operating parameters. In practical operation of the salient-pole synchronous generator, the heat generated by eddy current loss may lead to the breaking of damper winding, and the damper winding is a key component for ensuring the reliable operation of generators. Therefore, it is important to study the distribution characteristics and the influence factors of eddy current loss. Taking a 24-MW bulb tubular turbine generator as a reference, the influence factors that affect the eddy current loss of damper winding are analyzed.

A two-dimensional (2-D) electromagnetic field model of the generator is established, and the correctness of the model is verified by comparing simulation results and experiment data. The eddy current losses of damper winding in various conditions are calculated by using the finite element method.

It is identified that the cogging effect, pole shoe magnetic saturation degree, pole arc coefficient and armature reaction are the main factors that affect the eddy current loss of the generator rotor. When the generator is installed with magnetic slot wedges, the distribution characteristic of eddy current loss is obtained through the study of the eddy current density distributions in the damper bars. The variations of eddy current losses with time are gained when the generator has different permeability slot wedges, pole arc coefficients and pole shoe magnetic saturation degrees.

The study of this paper provides a theoretical reference for the design and optimization of bulb tubular turbine generator structure.

The research can help enhance the understanding of eddy current distribution characteristics and influence factors of eddy current loss in bulb tubular turbine generator.

The purpose of this paper is to reduce eddy current loss in a wire that is affected by an alternating field passing through it. This allows the efficiency of transformers to be upgraded and the quality factor in coils to be increased.

The use of a magnetoplated wire (MPW) is proposed to reduce eddy current loss in a wire. An MPW is a copper wire (COW) whose circumference is plated with a magnetic thin film. In additional, the theoretical equation for eddy current loss in an MPW is derived for ease of analysis.

The eddy current loss in an MPW is calculated as a function of the relative permeability and resistivity of its magnetic thin film to reduce the resistance due to the proximity effect of a coil. The eddy current loss in an MPW whose magnetic thin film has a relative permeability of 500 and a resistivity of 0.12 μΩm can be reduced to 4 percent that of COW at a frequency of 1 MHz.

The use of MPW can be expected to upgrade the efficiency of transformers and to increase the quality factor in coils.

In this paper, we consider the fundamental characteristics of motion in the universe in terms of the whole and local evolutionary forms of fluids, based on the theory of blown‐ups and the experiment of spinning disc of currents. It is pointed out that the practical meaning of “the invisible Tao”, see Lao Tsu for more details, is that of currents, and the central theory of fluid dynamics is the vortex flow dynamics, and the practicability of the nonlinear evolutions of mathematical models is getting away from the assumption of continuity.

Aims to investigate the eddy current loss in permanent magnets of IPM motors.

Uses the 3D finite element method (3D FEM).

Finds that the effect of the current phase on the eddy current loss is very different according to the number of slots.

Investigates the eddy current loss in a permanent magnet of an IPM motor.

The purpose of this paper is to present the method which relatively easily allows to approximate the hysteresis loop of the dynamo or transformer steel sheets. The paper also looks into the formulation of an equation allowing determination of distribution of the flux density and eddy currents in cross-section of these sheets.

An exponential function was applied in the presented method relating to the approximation of the hysteresis loop. When the field strength changes its value, then, the flux density are the sum or difference of a function, describing the lower or upper hysteresis curve and some “ransient” component. On the basis of Maxwell’s equations and Amper’s law, one non-linear differential equation was formulated which allows to calculate the flux density and eddy currents in a cross-section of a transformer sheet.

The method which relatively easily allows approximation of the hysteresis loop of ferromagnetic material is presented in the paper. The paper presents the derivation of one non-linear differential equation, allowing calculation of the flux density and eddy currents in the cross-section of the transformer sheets, taking into account the hysteresis phenomenon.

The paper presents the method that can be used in modeling of the hysteresis loops of dynamo or transformer sheets, and the final non-linear differential equation can be applied in calculations of the magnetic field and eddy currents in cross-section of the transformer sheets.

The paper refers to important issues of modeling and calculations of the magnetic and eddy current field distribution in transformer steel sheets.

The paper seeks to propose a specific approach based on Dynamic Analysis and Chaos Theory aiming to emphasize the differences into the eddy current signals obtained by related non‐destructive tests, when the inspected specimens have flaws with different shapes.

Non‐linear eddy current analysis is very useful for flaw detection in many in‐service inspections. State‐of‐the‐art technologies allow one to define position and depth of defects, but the shape identification is still an open problem. In this paper, experimental data have been subjected to a dynamical analysis in order to relate the trend of eddy current signals to the shape of analyzed defect.

In particular, a dynamical reconstruction by means of recurrence plots (RPs) has been carried out in order to detect analogies and differentiations between different eddy current signals. Moreover, cross‐correlation between RPs of a reference benchmark and testing eddy current signals has been applied in order to emphasize a different dynamical behaviour and to detect a particular flaw's shape. In this way, a real‐time algorithm for defect shape classification has been performed.

Proposed approach is very interesting, and it is an innovation in non‐destructive testing procedures. In fact, the shape identification of a flaw is still an open challenge. The proposed approach, based on dynamic analysis, gives the key to solve this particular ill‐posed problem, by introducing a relation between the eddy current measurements and the shape of defect existing in the inspected specimen. Very interesting preliminary results have been obtained.

Research effort to integrate an analysis module of inductive field into an eddy current NDT system to realise a hybrid technique, which is capable of automatically analysing the inductive field so as to set up the optimum parameters for the system, has not been well addressed. This paper describes the work that leads to the realization of such a hybrid technique. First, two finite element models are described. Next, an analytical algorithm based on these models is proposed. By integrating the algorithm into an eddy current NDT system, a smart hybrid technique can be realized. This is beneficial in setting up relevant parameters such as the working frequencies and the detection distance. Thus, the test precision can be improved. Taking a cylindrical inductive sensor as an example, some calculation results are provided to illustrate the analysis of the inductive field produced in an eddy current NDT system.

In the laminated core of transformer, motor, etc. each electrical steel sheet is usually insulated in order to reduce the eddy current loss. Raw steel sheets without insulation are sometimes used in a small core of electrical machines and electronic equipments, because the cost of iron core can be reduced if cheap steel sheets without insulation are used in the core. The purpose of the paper is to show how the contact resistance between sheets of laminated core affects the interlaminar eddy current and to show the criterion for judgment of the necessity of insulation.

The eddy current losses of core made of SPCC (cold rolled steel sheets) of different widths with and without insulation under various conditions are analyzed by using the finite element method (FEM) considering the contact resistance. The equivalent circuit for such a laminated core without insulation is shown. The experimental investigation is also carried out.

A criterion for the judgment of insulation is examined. It is shown that the increase of eddy current is affected by the ratio (this corresponds to the criterion) of the resistance of steel and the contact resistance.

The paper clarifies a criterion for the necessity of insulation between sheets of laminated core. It is shown that a similar tendency to the measured value of eddy current loss can be obtained by utilizing the modeling method of laminated core.

The purpose of this paper is to investigate the process of rapid prototyping eddy current sensors using 3D printing technology. Making full use of the advantages of 3D printing, the authors study on a new method for fabrication of an eddy current sensor.

In this paper, the authors establish a 3D model using SolidWorks. And the eddy current sensor is printed by the fused deposition modeling method.

Measurement results show that the 3D printing eddy current sensor has a wider linear measurement range and better linearity than the traditional manufacturing sensor. Compared to traditional eddy current sensor fabrication method, this 3D printed sensor can be fabricated at a lower cost, and the fabrication process is more convenient and faster.

This demonstrated 3D printing process can be applied to the 3D printing of sensors of more sophisticated structures that are difficult to fabricate using conventional techniques.

In this work, the process of rapid prototyping eddy current sensors using 3D printing is presented. Sensors fabricated with the 3D printing possess lots of merits than traditional manufactures. 3D printed sensors can be customized according to the configuration of the overall system, thus reducing the demand of sensor's rigid mounting interfaces. The 3D printing also reduce design costs as well as shortens the development cycle. This allows for quick translation of a design from concept to a useful device.

The purpose of this paper is to supply a numerical analysis tool to solve eddy currents induced in nonlinear materials such as steel by boundary element method (BEM), and then apply it to design and analysis of power devices.

Utilizing integral formulas derived on the basis of rapid attenuation of the electromagnetic fields, the paper formulates eddy currents in steel. In the formulation, nonlinear terms are regarded as virtual sources, which are improved iteratively with the electromagnetic fields on the surface. The periodic electromagnetic fields are expanded in Fourier series and each harmonic is analyzed by BEM. The surface and internal electromagnetic fields are obtained numerically one after the other until convergence by the Newton‐Raphson method.

It is confirmed that this approach gives accurate solutions with meshes much larger than the skin depth and therefore is adequate to apply to a large‐scale application.

The eddy current is formulated by utilizing the impedance boundary condition in order to meet a large‐scale application, and so solutions near the edge are poor. In the case of better solutions being required, some modifications are necessary.

To lessen computer memory consumption, the parallel component of the currents to the steel surface is analyzed as a 2D problem and the normal component is obtained from the parallel component. One 2D equation for one analyzing region is discretized by dividing the region into layers adaptively and then solved. Next, another is solved sequentially. This method gives a compatible numerical analysis tool with finite element method.