Wound Core Research Articles

New feeding mechanism to enhance the properties of wrapped elastic composite yarn and denim fabrics thereof

In light of the recent technological advancements in composite yarns with multicomponent cores, also known as dual core spun yarns, their utilisation in the textile industry has become widespread. A V-grooved roller is employed to enhance the feeding of multicomponent cores. In this context, diverse composite yarn designs with varying feeding mechanisms can be employed to optimise yarn performance. This study presents an alternative feeding mechanism utilising a W-grooved roller for commercial use in composite yarn production. To achieve this, dual core yarns and wound elastic composite yarns (filament feeding varies with the sheath cotton fibre with elastane in the centre wrapped on the right and left side) were produced using a modified ring spinning system with different parameters. Denim fabrics were then produced using these composite yarns as weft yarns. The results demonstrated that the wrapped elastic composite yarns with left and right filament core positioning exhibited superior yarn properties in terms of strength, elongation at break, evenness and hairiness. Furthermore, denim fabrics made with wrapped elastic composite yarns exhibited superior breaking load and tearing force results on weft basis. These fabrics also exhibited lower growth, defined as the percentage of the fabric returning to its original length after tensile stress removal.

An iteration-based design algorithm for high frequency transformer in SSTs and its validation by finite element analysis

This paper proposes an iteration-based algorithm for the optimum design of a high frequency transformer for solid-state transformer (SST) applications. This algorithm minimizes the total owning cost (TOC) of a distribution type solid-state transformer. The unique features of this algorithm compared with the available algorithms in the literature are as follows: it iterates eight design variables, four constraints are defined for selecting the valid designs, and it works with different core materials and AC test voltages. The algorithm uses various user-defined data inputs to calculate loss capitalization values for TOC calculation. In every iteration, TOC is estimated, and calculated values of design constraints are compared with their threshold limits. A case study is conducted on a high-frequency transformer (HFT) incorporated in 1000-kVA, 11-kV/415-V, Dyn11 three-phase wound core SST. This is to determine the optimum design parameters. In this case study, the algorithm was iterated with 2,100,000 design data inputs, generating 258,272 designs that satisfied all design constraints. The optimum design with minimum TOC is selected from the generated 258,272 designs. The optimum design is validated using finite element analysis in ANSYS software. Comparing the results of both analyses, the deviation is less than 5%. Hence, the algorithm’s reliability is proved.

A two-step stress-annealing with stress-relaxation process for developing low-loss Fe-based nanocrystalline soft magnetic cores

Fe72.5Nb2Mo2Cu1Si15.5B7 at.% nanocrystalline soft magnetic ribbon was stress-annealed at several temperatures around its primary crystallization temperature and magnetic properties were characterized in strips to determine conditions that led to minimal magnetic coercivity, Hc. This optimal stress-annealing (SA) temperature, though yielding minimal Hc in strips, also produced non-linear or rounded BH loops in wound cores. The rounded loops could be changed to linear or flat B-H loops following a secondary static annealing process. Through X-ray diffraction, transmission electron microscopy, and indirect magnetostriction measurements, we determined that the change in loop shape was driven by additional crystallization and stress-relief from the static annealing process. A change in mechanical properties including fracture toughness, loss modulus, and Young’s modulus after SA, were shown to limit the processability of the ribbon. Tape-wound inductors subjected to the optimal 640 °C / 85 MPa / 4 s SA process followed by a static annealing treatment of 500 °C for 1 h resulted in flat loops, an Hc of 0.3 A/m, low magnetostriction of ∼ 2 ppm, and core losses of only 7 W/kg at an induction of 0.4 T when excited at 20 kHz.

Distributed Vibration Monitoring System for 10 kV-400 kVA 3D Wound Core Transformer under Progressive Short-Circuit Impulses.

As large-scale, high-proportion, and efficient distribution transformers surge into the grids, anti-short circuit capability testing of transformer windings in efficient distribution seems necessary and prominent. To deeply explore the influence of progressively short-circuit shock impulses on the core winding deformation of efficient power transformers, a finite element theoretical model was built by referring to a three-phase three-winding 3D wound core transformer with a model of S20-MRL-400/10-NX2. The distributions of internal equivalent force and total deformation of the 3D wound core transformer along different paths under progressively short-circuit shock impulses varying from 60% to 120% were investigated. Results show that the equivalent stress and total deformation change rate reach their maximum as the short-circuit current increases from 60% to 80%, and the maximum and average variation rate for the equivalent stress reach 177.75% and 177.43%, while the maximum and average variation rate for the total deformation corresponds to 178.30% and 177.45%, respectively. Meanwhile, the maximum equivalent stress and maximum total deformation reach 29.81 MPa and 38.70 μm, respectively, as the applied short-circuit current increased to 120%. In light of the above observations, the optimization and deployment of wireless sensor nodes was suggested. Therefore, a distributed monitoring system was developed for acquiring the vibration status of the windings in a 3D wound core transformer, which is a beneficial supplement to the traditional short-circuit reactance detection methods for an efficient grid access spot-check of distribution transformers.

Three-Dimensional Numerical Field Analysis in Transformers to Identify Losses in Tape Wound Cores.

To find the total core losses in 1-phase medium-frequency transformers, a 3D numerical field analysis was carried out. The proposed numerical modeling was based on the extended iterative homogenization method (IHM) developed by the authors. The achieved calculation results were validated by the corresponding values obtained experimentally, and a reasonably close agreement was obtained.

Numerical Model for Eddy-Current Loss of Wound Core in Single-Phase Transformer

Taking the wound core transformer widely used in the field of traction energy saving as the research object, considering its unique geometric structure, combined with the magnetic circuit theory and finite element calculation of Ansys Maxwell software, the phenomenon of the magnetic flux distortion of the wound core is revealed, and the influence degree of various factors is analyzed; based on the Maxwell equation system of the magnetic quasi-static field, the calculation model of the magnetic flux distortion considering joints is deduced, and then the numerical calculation model of the eddy-current loss of the wound core considering the magnetic flux distortion is presented, which is verified by no-load tests and can reflect the change of the eddy-current loss caused by the geometry of the core with different frequencies and magnetic flux densities, and it can be applied to large-capacity traction transformer with calculation error less than 3%. The numerical model can quickly calculate the eddy-current loss by core structure parameters and material properties without sample preparation and simulation in design stage, which greatly saves engineering cost and can be used for structural design and optimization of the wound core.

A rapid heat treatment for nanocrystallization of amorphous Fe75.1Cu1Nb1.5Si15.5B6.9 and Fe83Cu1Nb4B12 tape wound cores

A rapid annealing technique for soft magnetic Fe75.1Cu1Nb1.5Si15.5B6.9 and Fe83Cu1Nb4B12 tape wound cores is presented. Its effectiveness for creating a fine-grained nanocrystalline structure is demonstrated by measurements of the magnetic hysteresis loops as well as by structural investigations done by X-ray diffraction. The results show that the technique reduces the average crystallite sizes from about 27 nm to 17 nm for Fe75.1Cu1Nb1.5Si15.5B6.9, and from about 52 nm to 15 nm for Fe83Cu1Nb4B12. The coercivity after the rapid annealing is about three times lower for the Fe75.1Cu1Nb1.5Si15.5B6.9 alloy and up to one order of magnitude lower for the Fe83Cu1Nb4B12 alloy compared to the coercivity after the standardized long-time heat treatment. The improved heat treatment is outstanding in the way that it produces better soft magnetic properties in high-performance alloy cores within much shorter time than the standard core heat treatments.

Magnetostrictive Vibration Characteristics of Amorphous Alloy Transformer With Three-Dimensional Wound Core

Magnetostrictive Vibration Characteristics of Amorphous Alloy Transformer With Three-Dimensional Wound Core

Structure optimization design and magneto-mechanical characteristics analysis of amorphous alloy with oriented silicon steel composite wound core

Three-dimensional wound cores are widely used in three-phase distribution transformer due to the symmetrical magnetic circuit structure. Amorphous alloy and oriented silicon steel are two kinds of ferromagnetic materials commonly used to make distribution transformer cores, each has own advantages and disadvantages in magnetic and mechanical characteristics. The amorphous alloy and oriented silicon steel composite core can synthesize the advantages of both. In this paper, a double-layer composite wound core (DCWC) structure is proposed and the corresponding dual nonlinear electric circuit and magnetic circuit coupling model is established. A structure optimization design method for the DCWC based on the free parameter scanning method is proposed by taking the percentage of oriented silicon steel in the composite core and the structure parameters as free variables. Based on the proposed optimization design method, a DCWC is designed and the experimental prototypes are manufactured. Further, the flux density distribution, core loss and mechanical vibration displacement of the DCWC are analyzed, and the effectiveness of the proposed method is verified by comparing with the measured results.

Electromagnetic anisotropic homogeneous model for eddy‐current field in single‐phase wound core

AbstractThe analysis of the eddy‐current field in the wound core widely used in the field of transformer energy conservation is taken as the theme. Adopting the homogenisation idea to consider the unique geometry of the wound core and features of its equivalent multi‐stage circular cross‐section magnetic boundary, a homogeneous model consisting of a columnar material with continuous homogeneous electromagnetic anisotropy is established by deriving the Maxwell equations of the magnetic quasi‐static field in the columnar coordinate system. Finally, a homogeneous fine element model for the eddy‐current field in the wound core is established and the accuracy of the model has been verified by the test platform. The result shows that the homogeneous model can be effectively used for the analysis of the eddy‐current field in the wound core, and the error of calculating the eddy‐current loss under different excitation conditions is less than 6% under the premise of extremely saving the engineering calculation cost, which will help improve the operational performance of the wound core and contribute to the energy‐saving goal of the high‐voltage equipment.

Solid-State Transformers of Smart High-Power Battery Charger for Electric Vehicles

There is no doubt that society will not turn back: most thermal vehicles will switch to electric ones, not only for cars but also for bigger vehicles. Fast chargers will become more and more essential parts of the global system, they will provide a charge control of batteries and galvanic insulation from the grid. At the present times, compact realizations are based on Solid-State Transformers (SSTs) operating at high frequencies with their well-known advantages and disadvantages, including power limits and reasonably high costs. The authors propose a medium-frequency transformer (MFT) structure using Grain Oriented Electrical Steel (GOES) wound cores and aluminum foil windings. Thanks to this solution, the cost of the device can be reduced. GOES has losses that increase with frequency but decrease with temperature; therefore, the authors propose a transformer structure allowing a hot core inside coils at usual temperatures. This idea is applied to a 400-kW compact battery charger connected to a DC smart grid.

Research on Magnetic Characteristics and Short-Circuit Force of 3D Wound Core Transformer

The problem of eddy current loss in power transformers directly affects the technical economy of the transformer, which is a problem that cannot be ignored in the design and calculation of power transformers. Studying how to reduce the eddy current losses caused by leakage magnetic fields is a difficult point in transformer design. The load loss of low-voltage foil copper windings in a 10 kV/400 kVA 3D wound core transformer is calculated, and the three-dimensional finite element models of the transformer are established by Using Magnet software and COMSOL Multiphysics software, and the calculation results are compared. At the same time, the short-circuit force of foil windings is shown in the simulation. The results show that the three-dimensional finite element models are correct.

Analysis of magnetic field characteristics and no-load losses of three-dimensional wound core transformer

Three-dimensionally wound core transformers (TWCTs) are widely used because of their low iron loss. This paper investigates the triangularly arranged TWCT core structure and a conventional planar laminated core transformer’s flat “E” core structure (PLCT). First, the magnetic field structures of the two transformers are analyzed using the equivalent magnetic circuit method to study the symmetry of the three-phase reluctance. Then, using the finite element method, a three-dimensional simulation model was built to analyze the no-load performance of TWCT and PLCT with the same dimensional parameters and the same core material. The no-load flux of each coil, the induced voltage on the secondary side, and the no-load iron loss of the core are analyzed. The analysis results show that TWCT has a 7.48% lower no-load loss than PLCT, which verifies the superiority of TWCT in terms of no-load loss.

Modeling and Optimal Design of Inductor-Integrated Three-Phase 3-D Wound Core Transformer Under SPWM Excitation

Compared with the laminated core transformer (LCT), the 3D wound core transformer(3D-WCT) has the characteristics of symmetrical magnetic circuit and low vibration. This article focuses on the modeling and optimal design of the 3D-WCT for isolated DC/AC application. Firstly, based on the Jiles-Aterton model, a nonlinear magnetic circuit model of the 3D-WCT is established to calculate the flux density and core loss accurately under SPWM excitation. A thermal network model is presented for the steady-state temperature-rise calculation of the forced-air cooled 3D-WCT. Secondly, the optimal design method is carried out on the basis of the magnetic circuit and thermal network models. Based on the optimized design results, a regression analysis is performed to establish the relationship between the design variables and the performance objectives. Finally, a 75kVA 3D-WCT prototype is manufactured and tested in the actual inverter power supply to verify the established magnetic circuit and thermal network models. The 3D-WCT prototype is applied to the 150kVA inverter power supply, which contributes to achieving high power density and high efficiency of the power supply.

Abstract Number ‐ 123: Retained microvascular wire during acute stroke thrombectomy and stenting.

Introduction There is limited information on retained wires during neuro interventional ischemic cases, although there is a wealth of information on cardiac cases. Retained wires can present with thrombosis, perforation, or may be followed for longer period of time, with no complications. Changes in outcome vary on the ability of the wire to migrate, the size of the vessel adjacent to the wire, and the difficulty in retrieving the retained item. Methods We present a case report on a 56‐year‐old man who presented in 2018 with a left internal carotid occlusion horizontal petrous level, with no early signs of stroke on CT, and 106 mL penumbra on CT perfusion (CTP), with dense expressive and receptive aphasia. Results Patient developed hemiparesis while sitting sitting up, and drops in blood pressure, below the presenting blood pressure of 200 over 100 mmHg. The patient was taken for emergent thrombectomy. Patient underwent petrous thrombectomy with a residual high grade stenosis. This was followed by cavernous angioplasty, and Wingspan stenting. We attempted to cross the stenosis with a Gateway balloon and Synchro2 microwire. The wire tip was trapped and separated after extensive rotation, with a retained 5 mm tip. After inspecting the wire, there is no clear evidence of any a retained product. The tip was secured with a Wingspan stent. After thrombectomy and stenting aphasia improved. Four days later the patient developed worsening aphasia, and was found to have stent reocclusion. During CT angiography (CTA) it became apparent that a small wire extended from the left internal carotid petrous segment at the level of the wingspan stent down to the descending aorta. CT angiography of the chest and abdomen after reperfusion found that the wire was anchored in the left internal carotid, and extended down to the renal artery. Thrombus was aspirated, and ICA reconstructed with coronary stents in the petrous, and self‐expanding stents in the cervical segments, with TICI 3 reperfusion. Follow‐up imaging with CT chest and abdomen at six months, one year, and four years found the wire to be still anchored to the left internal carotid stent, and stable in the superior mesenteric artery. There is no evidence of thrombus formation, or distal embolization. We examined a Synchro2 microwire ex vivo were able to detach the tip, and have the inner core unravel up to a meter in length. Given that the wire shaft did not appear to be altered, the retained product was likely an unraveled inner core. Conclusions Retained neurovascular products can predispose to reocclusion, and should be secured. Once secured the course can be benign. When a wire with a wound core is fractured, unwound core can remain behind with the wire appearing as if it has been fully retrieved.

Study of the Effect of Magnetic Abrasive Finishing on the Material Removal of AA1100 Aluminum Alloy

This study evaluates the performance of magnetic abrasive finishing (MAF) of aluminum alloy in terms of achieving materials removal (MR). A vertical milling machine is used to perform the finishing process using a developed MAF unit that consists of an inductor made out of a 150 mm long and 20 mm diameter iron core wound with 1500 turns and 0.5 mm copper wire. The commutator and magnetic pole are attached at the top and bottom of the inductor, respectively. The required current is supplied using a DC power supply. The South Pole workpiece is a 100×50×3 mm3 plate of AA 1100 aluminum alloy, whereas the magnetic pole represented the North Pole. Pole rotational speed, applied current, and abrasive finishing time was selected as input parameters of the MAF with three-level of (270, 600. 930 rpm; 0.5, 1, 1.5 Amp; 6,9,12 min). The L9 orthogonal array of the Taguchi method was utilized to examine the impact of each independent input. The obtained results clarify that applied current was the most effective factor in terms of its contribution (63.16%) in the produced MR, followed by time finishing and rotational speed.

Loss Modeling and Reluctance Quantifying of C-Type Amorphous Core for High-Frequency Inductors

The wound core with ultrathin magnetic strip is expected to improve the high-frequency performance of the electronic devices in efficiency and scale. However, the analysis of magnetic properties and calculation of the magnetic loss, including core loss and air-gap loss for cutting double C-type core, are complex and have not been entirely solved. In this article, the magnetic properties of a C-type amorphous core (AMCC0025) at different air-gap lengths are measured through a newly constructed tester. The measurement results are analyzed in detail, and the mechanism of magnetic loss influenced by the air gap is revealed by quantifying the reluctance of the C-type core. An accurate core loss model considering a fringing effect is derived, together with another additional loss model is realized by regression analysis. The evaluation results show that the average error for the partial total loss is less than 10%, and the average error for additional loss and core loss is within 5%. All errors meet the requirements of engineering calculation.

Measurement of magnetic properties of grain-oriented electrical steel under bending stress in a wide frequency range

To clarify the mechanism of the magnetic properties deterioration and the increasing loss of the Grain-Oriented (GO) electrical steel wound cores under serving conditions, the effect of the bending stress in a wide frequency range should be thoroughly investigated. In this paper, a magnetic properties measuring system for GO electrical steel under different bending stress from 50 Hz to 1000 Hz is proposed. To ensure the accuracy and reproductivity of the measurements, the waveform of magnetic flux densities should be controlled to be sinusoidal. However, the bending stress aggravates the material’s nonlinear properties, making waveform control very difficult. To solve this problem, a frequency-domain adaptive dual-loop feedback control algorithm is developed. Obtained results show that the proposed method has a good effect on waveform control under bending stress, and the loss of the material under different magnetizing conditions is then analyzed.

Equivalent circuit of an inductor on a nanocrystalline core with a high magnetic permeability

Based on the measured impedance of the inductors based on a toroidal core wound from a thin (18 m) nanocrystalline tape, with a different number of winding turns, an equivalent high frequency (0 Hz - 500 MHz) circuit model was built. The equivalent circuit model was built taking into account the physical processes occurring in the inductor: effect of wire resistance, effect of core material, mutual effect of wire and core material. The attempt explaining why the frequency characteristics (modulus and phase) of the inductor complex impedance have such a character in a wide frequency band (up to 500 MHz) was made. It was shown that for constructing an equivalent circuit model (structure and parameters), measuring only the inductors resistance modulus is not enough. It is also necessary to measure the phase of the inductor complex resistance, which is ignored in many works on the synthesis of an e inductor equivalent circuit. The fundamental difference between the operation of a nanocrystalline core and a ferrite core as applied to high-frequency filters is shown.

Industrial stress annealed wound cores compared to other solutions

Stress annealed nanocrystalline wound FeCuNbSiB cores, now available on the market, provide NO localized air gap, a range of low permeability (µr = 200 to 3000), low magnetic losses (386 W/kg at 0,8T-50 kHz), a high B-H linearity and a constant temperature drift of the magnetic properties (uncoated core) that makes it easy to correct. This paper aims to support engineers in passive magnetic component design by comparing this new industrial product with competing solutions at µr ∼ 1000, the nanocrystalline cut core and the iron-based amorphous wound core. On the one hand, the amorphous solution appears to be more dissipative than nanocrystalline solutions. On the other hand, the latter have a high frequency stability (cut off frequency: 5–7 MHz) and better temperature stability of losses (−90 mW/kg.°C) compared to the amorphous solution (−135 mW/kg.°C). The magnetic losses of the cut core are equal or slightly superior to the stress annealed product they are compared at high induction and medium frequency.