Coil Turns Research Articles

Research on the coupling relationship between metal particles in lubricating oil and inductive coils based on self-excitation single coil

Characterizing the operational wear status of mechanical equipment based on online monitoring of metal particles in lubricating oil plays a significant role in the effect of equipment fault diagnosis technology. According to the theoretical analysis of the electromagnetic induction principle and Biot–Savart’s law, combined with the finite element simulation analysis, systematic study and analysis were conducted on the distribution of magnetic field inside a single inductance coil, the coupling relationship between metal particles in lubricating oil, and the inductance coil. This paper analyzed the effects of four important design parameters that were the excitation frequency, the inside diameter of the coil, the turns number of the coil, and the length of the coil. On magnetic field uniformity and monitoring sensitivity, experiments demonstrated that: the correlation between the uniformity of the magnetic field on the testing surface of the sensor inductance coil and the coil radius and length is the highest, followed by the correlation with the number of coil turns. The correlation with the excitation frequency can be ignored in a negligible manner. In addition, experimental results indicated that if the ratio between the inside diameter of the inductance coil and the length of the coil (R/L) was less than 0.41, the magnetic field uniformity would reach over 91%. Meanwhile, results showed that the sensitivity of the sensor to ferromagnetic and non-ferromagnetic particles increased with the decrease in the coil inner diameter and inductance and increased with the increase in the excitation frequency. There is a specific length that can make the sensor coil monitoring, which is the most sensitive.

A Magnetic Flux Collection Enhanced Arc-Shaped Core and Its Optimal Coil Turn Design Method of Free-Standing Magnetic Field Energy Harvester

A Magnetic Flux Collection Enhanced Arc-Shaped Core and Its Optimal Coil Turn Design Method of Free-Standing Magnetic Field Energy Harvester

Bioinformatics analysis of the RNA binding protein DDX39 of Toxoplasma gondii

To analyze the RNA binding protein of Toxoplasma gondii (TgDDX39) using bioinformatics technology, and to evaluate the immunogenicity of TgDDX39, so as to provide insights into development of toxoplasmosis vaccines. The amino acid sequences of TgDDX39 were retrieved from the ToxoDB database, and the physicochemical properties, transmembrane structure domain, signal peptide sites, post-translational modification sites, coils, secondary and tertiary structures, hydrophobicity, and antigenic epitopes of the TgDDX39 protein were predicted using online bioinformatics tools, incluiding ProtParam, TMHMM 2.0, SignalP 5.0, NetPhos 3.1, COILS, SOPMA, Phyre2, ProtScale, ABCpred, SYFPEITHI and DNA-STAR. TgDDX39 protein was predicted to be an unstable hydrophilic protein with the molecular formula of C2173H3458N598O661S18, which contained 434 amino acids and had an estimated molecular weight of 49.1 kDa and a theoretical isoelectric point of 5.55. The protein was predicted to have an extremely low possibility of signal peptides, without transmembrane regions, and contain 27 phosphorylation sites. The β turn and random coils accounted for 39.63% of the secondary structure of the TgDDX39 protein, and a coiled helix tended to produce in one site. In addition, the TgDDX39 protein contained multiple B and T cell antigenic epitopes. Bioinformatics analyses predict that TgDDX39 protein has high immunogenicity and contains multiple antigenic epitopes. TgDDX39 protein is a potential candidate antigen for vaccine development.

Parameter Optimization of Electric Pulse Deicer for Overhead Ground Wire Based on Finite Element Method

Because it is difficult to implement short-circuit deicing, overhead ground wire deicing has always been a difficult problem in power grid ice prevention and disaster reduction. In this paper, the working principle of the overhead ground wire electric pulse deicing device is introduced. Then the electric pulse force calculation model of the overhead ground wire is established. The validity of the model is verified by comparing the model-calculated values of coil inductance and resistance with the experimentally measured values. The effect of coil turns, multiplier thickness, and the side length of the multiplier on the pulse force peak and impulse are analyzed. Finally, the electric pulse deicing test of the short-size ground wire is carried out in the artificial climate chamber. The results show that with the increase in the number of turns of the coil, the peak value of the pulse force decreases gradually, the impulse increases gradually, but the growth rate slows down. With the increase of the thickness of the multiplier, the peak value and impulse of the pulse force increase almost unchanged near the skin depth. With the increase of the side length of the multiplier, the peak value and impulse of the pulse force gradually increase until the area of the multiplier is close to the area of the coil. The electric pulse deicing test shows that the deicing length increases with the increase of the number of coil turns, and the deicing efficiency of the 60-turn coil deicing device is 90%.

An Accurate Power Model and High Power Density Design Method of Free-Standing Magnetic Field Energy Harvesters With H-Shaped Core

To achieve more output power of the free-standing magnetic field energy harvester (FSMFEH) with a smaller core volume, designing the core and coil parameters of FSMFEH is critical. However, the lack of an FSMFEH power model leads to the absence of a detailed design method. To address this issue, building an accurate FSMFEH output power model is required. In this work, by quantifying coil mutual inductance and internal resistance as core and coil parameters, an accurate power model of FSMFEH with all parameters is established based on the H-type core. As a result, based on the proposed model, the optimal values of the core column size, the core lamination size, the coil turns, and the wire diameter are designed. Experiment results show that the proposed model can maintain high accuracy, and the power density deviation is within 5% compared with the theoretical value. Besides, the optimized parameters designed according to the model analysis are effective for improving the power density. When the current of the busbar is 100A, the maximum power density can reach 4.182mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , and the corresponding maximum output power is 13.25mW with the optimized parameters.

Sudden-Discharging Quench Dynamics in a No-Insulation Superconducting Coil.

It is generally agreed that no-insulation (NI) high-temperature superconducting (HTS) magnets do not quench because of the turn-to-turn energy-releasing bypass unique to NI. However, these magnets, especially with high operating current and low ambient thermal capacity, still occur unexpected quenches when the current through the magnets suddenly drops to zero (i.e., the sudden-discharging quench). Here, we report this kind of quench, which is different from that widely-reported quench happening during charging (i.e., the energizing quench). Here, a demonstrative coil with 655-turns, 350 A operating current, and 4 K conduction cooling, is used to prove this sudden-discharging quench, and a simulation model is built to reveal the quench dynamics. Results show the turn-to-turn heat triggers the initial partial quench in the inner coil turns and then the induced overcurrent spreads out the quench like an avalanche to the outer coil turns.

Eddy Current and Loss of Graded-Resistance No-Insulation Coils in HTS Synchronous Machines of Electrical Aircraft

The No-insulation (NI) high temperature superconductor (HTS) machine is a promising propulsion technique for future large-scale electrical aircraft because of its high power density and enhanced thermal stability. However, in the machine environment, the ripple magnetic fields can induce significant eddy currents and losses on the NI coil. A grading turn-to-turn resistivity technique has been proposed to solve this problem, in which higher turn-to-turn resistivity is applied on the outermost turns of the NI coil, and lower turn-to-turn resistivity is kept on middle turns. The purpose of this research is to study the effects of grading turn-to-turn resistivity technique on the eddy current and loss of both single and multiple NI HTS coils exposed to ripple fields. To investigate the electromagnetic behavior and loss mechanism of NI HTS coils, a simulation model is proposed that couples the equivalent circuit model and finite element model. Results show that the grading turn-to-turn resistivity can effectively reduce the induced eddy current and lead to a uniform distribution of eddy current among turns of both single and multiple windings. It reduces magnetization loss in superconducting layers but increases the turn-to-turn loss on the radial contacts. These results are useful for the development of NI HTS machines with high thermal stability.

Coil Design Method Considering Power, Efficiency, and Magnetic Field Strength of Coreless Coils Using Numerical Analysis in Wireless Power Transfer

Wireless power transfer to electric vehicles while driving is a technology that is currently attracting attention as it has the potential to solve the problems faced by EVs that will become popular worldwide in the future. In the case of dynamic wireless power transfer (DWPT) to electric vehicles, it is necessary to transmit the required power with high efficiency and ensure safety. While there are multiple safety requirements, there are also regulatory values for the magnetic field strength emitted from the coil, which must be satisfied before it can be implemented in society. This research aims to speed up the design of coils by using only numerical analysis, in contrast to conventional coil design using electromagnetic field analysis. In the future construction of wireless power transfer systems, it is of great significance to discuss the design using only numerical analysis, as there are many design parameters. Experiments were carried out and compared with the numerical analysis and found to be in agreement. A power transmission of 20 kW converted value was carried out to verify the effect of the size, pitch, and number of turns of the transmission coils on the efficiency and magnetic field strength. The effect of input voltage was also discussed by simulation, and the optimum coil was derived. As a result, when the coil size was 800 × 600 mm, the number of turns was 46, the pitch was 6.1 mm and the input voltage was 1400 V, the analysis showed that a power transmission of 20 kW with an efficiency of 99.3% and a far magnetic field leakage strength of 81.6 dBμA/m could be achieved. Even with a coreless coil, the magnetic field strength could be below the regulation value. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

PERFORMANCE EVALUATION OF A SMALL-SCALE MAGNETORHEOLOGICAL DAMPER FOR CIVIL ENGINEERING APPLICATIONS

Magnetorheological dampers (MRDs) are devices that adjust their damping properties in response to an external magnetic field. Large-scale MRDs have been successfully used as vibration control devices in structures. This study focuses on modelling and optimizing an MRD using COMSOL Multiphysics. Various parameters, such as coil turns and current, are optimized to achieve the maximum flux value in the MRD. The simulation yielded a maximum magnetic flux of 0,44 T with 500 coil turns. Based on the optimized MRD parameters, a numerical equation is then used to calculate the total damping force. The maximum numerical and experimental damping forces corresponding to a 2,0 A current were 989,39 and 1004,63 N, respectively. The numerical damping force is then compared to the experimental results to validate the accuracy of the model. The MRD is integrated into a scaled-down reinforced concrete frame and subjected to a cyclic loading test for performance evaluation. The results show that the MR dampers improve the performance of the frame structure, increasing its load-carrying capacity and energy dissipation by 19,45 % and 20,43 %, respectively. The findings of the study provide valuable insights into the behaviour of MRDs and their optimization using numerical simulations, as well as highlight the importance of experimental validation for accurate prediction of the performance of MRDs in practical civil engineering applications.

Genome-wide identification and characterization of glutathione S-transferase gene family in quinoa (Chenopodium quinoa Willd.).

The present investigation was envisaged for large scale in-silico genome wide identification and characterization of glutathione S-transferases (GSTs) in Chenopodium quinoa. In this study, a total of 120 GST genes (CqGSTs) were identified and divided into 11 classes of which tau and phi were highest in numbers. The average protein length of protein was found to be 279.06 with their corresponding average molecular weight of 31,819.4kDa. The subcellular localization analysis results showed that proteins were centrally localized in the cytoplasm followed by chloroplast, mitochondria and plastids. Structural analysis revealed the presence of 2 -14 exons in CqGST genes. Most of the proteins possessed two exon one intron organization. MEME analysis identified 15 significantly conserved motifs with a width of 6-50 amino acids. Motifs 1, 3, 2, 5, 6, 8, 9 and 13 were found specifically in tau class family; motifs 3, 4, 5, 6, 7 and 9 were found in phi class gene family, while motifs 3, 4, 13 and 14 were found in metaxin class. Multiple sequence alignment revealed highly conserved N-terminus with active site serine (Ser; S) or cysteine (Cys; C) residue for the activation of GSH binding and GST catalytic activity. The gene loci were found to be unevenly distributed across 18 different chromosomes with a maximum of 17 genes located on chromosome number 7. Dominance of alpha helix was followed by coil, extended strand and beta turns. Gene duplication analysis revealed that segmental duplication and purifying type selection were highest in number and found to be main source of expansion of GST gene family. Cis acting regulatory elements analysis showed the presence of 21 different elements involved in stress, hormone and light response and cellular development. The evolutionary relationship of CqGST proteins carried out using maximum likelihood method revealed that all the tau and phi class GSTs were closely associated with those of G. max, O. sativa and A. thaliana. Molecular docking of GST molecules with the fungicide metalaxyl showed that the CqGSTF1 had the lowest binding energy. The comprehensive study of CqGST gene family in quinoa provides groundwork for further functional analysis of CqGST genes in the species at molecular level and has potential applications in plant breeding.

Multi-parameters study on underwater coil launch

The projectile launched by electromagnetic weapon has strong kinetic energy. In order to study the laws and characteristics of electromagnetic induction coilgun launching underwater, a multi-stage coilgun model was established in this paper. Based on the control variates method, the effects of trigger position, coil turns, capacitance value and other parameters on the launching process were studied, then the effects of above factors on the launching efficiency and exit speed were analyzed. The results show that the optimal trigger position offsets to the direction of the breech with the increase of the projectile speed; the optimal coil turns for a certain projectile and launching occurs when the trigger position is determined; the increase of the capacitance value can increase the exit speed of projectile, and the capacitance value should be selected according to the efficiency-speed curve when the launch efficiency is considered; the seawater resistance has little influence on the acceleration of the projectile, and comparatively large influence when there is no driving force. The research results of this paper can provide theoretical support for the manufacture of underwater coilgun prototype.

高周波励磁下における低透磁率トロイダルコアの測定精度に及ぼす巻線の影響

High frequency magnetic measurements for low permeability toroidal cores are demonstrated using various primary and secondary coils on low permeability magnetic toroidal cores, and effects of coils on their precision is discussed. As the number of turns in primary and secondary coils are reduced, measured permeability shows higher dispersion. This fact relates to the deviation of the strength of magnetizing field due to the small number of primary windings. It is also demonstrated several winding methods of primary coil to reduce the dispersion.

In situ detection of delamination and critical current degradation caused by the thermal stress in epoxy impregnated REBa2Cu3O7−δ coils

Epoxy impregnated superconducting coils have better structural integrity and thermal stability. However, for REBa2Cu3O7−δ (REBCO, RE=Rare earth) coils, the mismatch of thermal expansion coefficients between epoxy and REBCO tapes is a serious problem. In this work, the temperature distribution, stress evolution during the cooling process, critical current distribution, and delamination sites inside REBCO coils impregnated using Stycast 2850FT have been studied. We measured the temperature distribution and the hoop strain in the penultimate turn of impregnated coils during the cooling process and analyzed the thermal stress evolution. No damage was observed for coils with the ratio between outer and inner diameter Ro/Ri&amp;lt;1.93. The delamination behavior occurred in coils with Ro/Ri&amp;gt;2.37, where the coils even exhibited a two-stage delamination. The delamination mechanism of REBCO coils was proposed from three aspects: the mechanical analysis, the critical current degradation, and the microscopic analysis. In this work, we found that the actual delamination behavior may appear earlier than the steady-state temperature, and temperature distribution will push the radial stress peak toward the inner radius of the coil, making the inner turn more susceptible to delamination. Multiple delamination locations were accurately predicted and confirmed. The measured compressive hoop strain first increased from −4212 με to −4684 με with the increase in Ro/Ri and then decreased to −3835 με obviously due to delamination. This work reveals in detail the delamination mechanism in impregnated REBCO coils, which is of great significance for the development of damage-free coils.

Structure design and separation test of a conical AC magnetic separator for recovering magnetite powder

ABSTRACT In the dense-medium coal preparation process magnetite powder is used, however, due to poor recovery of the magnetite, the consumption of magnetite increases which ultimately reflects in the economics. In order to continuously and efficiently recover the magnetite, a novel three-phase conical magnetic separator based on the principle of an alternating magnetic field generated by a three-phase linear motor, was developed. The distribution law of the magnetic field in the separation chamber was studied, and the magnetic separator’s basic structure and parameters were determined. By varying the feed rate, coil current, coil turns, and particle size, magnetic separation experiments were conducted and compared with traditional magnetic separators. The results confirmed the excellent sorting performance of the conical AC magnetic separator.

Simulation and Optimization Design of Inductive Wear Particle Sensor.

In order to monitor the diagnosis of mechanical equipment by monitoring the metal wear particles carried in large aperture lubricating oil tubes, the simulation optimization structure design was carried out based on the traditional three-coil inductance wear particle sensor. The numerical model of electromotive force induced by the wear particle sensor was established, and the coil distance and coil turns were simulated by finite element analysis software. When permalloy is covered on the surface of the excitation coil and induction coil, the background magnetic field at the air gap increases, and the induced electromotive force amplitude generated by wear particles is increased. The effect of alloy thickness on the induced voltage and magnetic field was analyzed to determine the optimum thickness, and increase the induction voltage of the alloy chamfer detection at the air gap. The optimal parameter structure was determined to improve the detection ability of the sensor. Ultimately, by comparing the extreme values of the induced voltage of various types of sensors, the simulation determined that the minimum allowable detection of the optimal sensor was 27.5 µm ferromagnetic particles.

A dual coil induction heating machine for jewelry factories developed by electromagnetic analysis

An induction heating machine (IHM) generates magnetic flux density (B) and high temperature for combining precious metals as products in a jewelry factory. Since factories require new generation IHMs for increased productivity and cost savings, a dual coil IHM development approach is presented here to replace conventional, single-coil IHM using electromagnetic analysis (EMA). First, the experiments and the EMA investigated B generated by a conventional one using the factory operating condition. Both agreed, confirming the methodology and reliability of the EMA, which was analyzed to determine Bp. The Bp represents a B property for the new dual coil IHM to be expected to generate a comparable signal to the single coil. Then, in development, two novel designs of dual coil IHM (series and parallel) were investigated based on current flow circuits. For these designs, Bp was investigated using the EMA. As expected, the EMA results showed that both coils generated a different Bp, which was unfortunately incompatible with the conventional IHM and thus was inappropriate in actual use. However, the series dual coil showed better applicability since it generated B higher than the parallel coil under the same operating conditions. Next, the EMA was applied to determine the Bp of the series dual coil by varying the applied current (I), frequency (f), number of coil turns (N), and distance between coils (d). Finally, the EMA results revealed two options of the series dual coil with the optimum I, f, N, and d generating Bp comparable to the conventional IHM, as intended, achieving the factory's need with two times the productivity.

Resonant Mechanism for a Long-Distance Wireless Power Transfer Using Class E PA and GaN HEMT

This paper presents a study on long-distance wireless power transfer (WPT), which formulates the voltage gain in terms of the coupling coefficient between the power transmitting unit (PTU) and the power receiving unit (PRU) coils. It is proposed that maximum power transfer efficiency (PTE) can be reached when maximum voltage gain is achieved under a matching condition between the coil quality factor and the coupling coefficient. In order to achieve maximum power delivered to load (PDL), we need to elevate the input voltage as high as the high breakdown-voltage of gallium nitride (GaN) high-electron mobility transistors (HEMT) along with class E amplifier circuit topology. In order to promote voltage gain, knowledge of the coupling coefficient between two coils including the factors of the coil diameter, wire diameter, coil turns, and the coil resistance are derived. It was observed that a lower coil resistance leads to a reduced parallel quality, which facilitates long-distance wireless power transfer. Experimental results support the findings that the maximum PTE occurred at the maximum voltage gain existing at a specific distance matches the coupling coefficient between coils. A maximum power point tracking (MPPT) method is also developed to achieve maximum PDL. At a distance of 35 cm, experiments with more than 100 W successfully receive a PTE of 57% at the PRU when the received voltage reached 1.4 kV. This is used to verify the concepts and analysis that are proposed in this paper.

Measurements of natural convection heat transfer of a helical coil varying the pitch and the turn

A helical coil is gaining interest as the part of a compact heat exchanger since it allows large heat transfer area. Many small modular reactor designs adopt the helical coil steam generator. We measured the local and total heat transfers of the helical coil using ring bundles to confirm the influences of pitches and turns. The pitch to coil diameter ratio was varied from 1.08 to 3.97 and the turns from 2 to 12, with the Ra of 3.63 × 107. Based on the analogy between heat and mass transfers, mass transfer experiments were performed replacing heat transfer ones. For a small pitch, the heated plume from the lower ring provides preheated plume to the upper ring, resulting in an impaired heat transfer. However, for a large pitch, initial velocity is provided, enhancing the heat transfer. The comprehensive heat transfer influences also depend on the coil turns. The measurements of total heat transfer showed the peak at around the pitch to coil diameter ratio range from 1.50 to 2.02 regardless of the number of coil turns.

Research on Detection Performance of Four-Coil Inductive Debris Sensor

The online monitoring of debris in oil can timely and accurately reflect the wear status of mechanical equipment. The inductive debris sensor based on the electromagnetic induction can effectively detect various parameters of debris. The four-coil structure-based of the sensor is theoretically introduced. The optimal coil length, the turns of the excitation coil and the turn ratio are obtained through simulation in order to improve the sensitivity of the inductive debris sensor. The effects of the excitation frequency and the movement velocity, size, position and material of the debris on the sensor output are investigated. The sensing signal recovered by coherent demodulation confirms the sensor’s effectiveness in identifying metal debris. The experiment realized the identification of iron debris with a diameter of 93.5 μm and copper debris with a diameter of 447.3 μm under the 3 mm pipe radius, providing a reference for the design of four-coil inductive debris sensor.

Investigating the Manufacturing Process of Heat-Treated Nb3Sn-CICC Conductor for CFETR CSMC Modules

The center solenoid model coil (CSMC) of the China fusion engineering test reactor (CFETR) requires a high heat treatment temperature of 650 °C, which would destroy the insulation layer by carbonization and cause coil failure. To avoid this, using the manufacturing technology and routine process of the ITER center solenoid coil as a reference, in this article, a solution is introduced that is applied for manufacturing the CFETR CSMC module. The coil is heat treated before insulation and after winding. A single turn of the heat-treated coil is separated and the wrapping turn insulation is applied, and then the separated layers are reversed back into the integrated coil. To manufacture the integrated coils, the heat-treated coils are molded. After heat treatment, the interlayer separation distance of the Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn cable-in-conduit conductor in the coil should satisfy the allowable strain range of the superconductor, which is crucial for designing the rotational support structure of the interlayer separation. In addition, to achieve the accurate final shape of the coil and meet the design requirements, as well as to ensure coil contour accuracy after layer by layer separation, the antideformation ability of the coil mold is a key research topic. Herein, mechanical properties of the key components were optimized and numerical calculations and ANSYS simulations were used for statistical analyses. Results from the analyses indicated that the equivalent stress on the device is less than the maximum permissible stress of the raw material. The device was manufactured and compared with a design mold. The overall deformation error was <5%, movement error of the electric frame was <2%, rotation error of rotating was less than ±1° per 360°, levelness between the upper and lower platform was <1 mm, and motion error was less than ±1 mm per 100 mm. These results demonstrated the optimized structure design of the device. In the as-obtained device, the coil could separate a single turn and wrapping turn insulation could be applied. Parameters of the manufactured coil satisfied all the CSMC design requirements; these results indicate that the proposed device is suitable for manufacturing the CFETR CSMC module coil.