Coil Structure Research Articles

Designing Ultrahigh Frequency Motor Rotor Position Search Coils for Electric Propulsion in Drones

As the core of electric propulsion in drones, the motor has higher requirements for its reliability and fault tolerance. Accurate acquisition of rotor position information is a prerequisite for a motor-driven drone’s system to operate stably. Traditional search coils can provide fault tolerance for position detection, but they cannot detect rotor position in the full speed range (stationary to rated speed). In order to make the search coils provide rotor position in the full speed range, this study proposes to inject an ultrahigh frequency (UHF) signal (50–100 kHz) into the search coils. By optimizing the self-inductance of the search coil, the mutual inductance between the search coil and the armature winding, the back electromotive force (BEMF) of the search coil, and the mutual inductance between the search coils, the structure of the UHF search coil designed in this paper is helpful to extract the UHF feedback signal. Finally, based on the mapping relationship between the self-inductance of the search coil and the rotor position, the rotor position of the motor can be detected in the full speed range. The novelty of the proposed work lies in the UHF search coil with zero mutual inductance coupling to the armature winding, small BEMF, and low interphase mutual inductance that can detect the rotor position in the full speed domain. Maxwell software is used to optimize the structure of the UHF search coil, and the feasibility of the design results is verified by co-simulation.

Theoretical and simulation analysis on the spatial resolution of magnetic metal debris sensors

Inductive debris sensor is becoming increasingly important in online oil debris detection. This work proposes a new criterion for evaluating the performance of an inductive oil debris sensor: spatial resolution. When multiple metal particles in lubricating oil simultaneously pass through the sensor, it is vital that clear signals responding to each particle are produced. The spatial resolution is referred to the allowable distance between two particles when the sensor can accurately distinguish the particle signals. Theoretical analysis shows that spatial resolution has a relationship with the output signal of a single particle. A COMSOL model is established to simulate a coil output when two adjacent particles pass, and the output signals change with the distance between two particles, the particle size and the coil structures. Results show that the relevant factors affecting the spatial resolution, and a small coil radius can help improve the sensor’s accuracy of debris identification.

High hydrostatic pressure (HHP) as a green technology opens up a new possibility for the fabrication of electrospun nanofibers: Part I- improvement of soy protein isolate properties by HHP

A common problem of electrospinning of plant proteins is that these kinds of proteins, including soy protein isolate (SPI), should be highly soluble and preferably in a random coil structure rather than the globular conformation. The current solution is to apply thermal treatment; however, it results in extensive organoleptic consequences (e.g. color degradation and off-flavor) and loss of nutrients. Thus, if a non-thermal technology such as high hydrostatic pressure (HHP) increases the disordered structure of the protein, it could facilitate the electrospinning of the protein and eliminate the barriers of thermal treatment, forming our hypothesis in this research. To this end, initially, extensive experiments including protein solubility, sulfhydryl content, turbidity, surface hydrophobicity, circular dichroism, and viscosity tests were carried out on HHP (200, 400 and 600 MPa) and thermally treated SPI samples (3.5% and 7% w/w). The results of sulfhydryl content revealed that disulfide bonds decreased at 400 MPa more intensely than other pressures while surface hydrophobic forces were promoted at this pressure. The circular dichroism test results showed that HHP treatment resulted in higher disordered structures and lower ordered ones, which is particularly helpful for the electrospinning process; besides, lower β-sheet content achieved by HHP treatment is especially useful for attaining defect-free fibers. For the first time, in this research, ideal electrospun fibers with average diameters of 300–400 nm were achieved through HHP processing, without using any thermal energy.

An Acentric Archimedes Spiral Coil For Inspection of an Aluminium Plate with an Inhomogeneous Thickness

ABSTRACT Electromagnetic acoustic resonance (EMAR) technology has potential to improve signal-to-noise ratio (SNR) and reduce noise effects in metal plate thickness measurement. However, using traditional EMAR to detect inhomogeneous-thickness specimens can result in difficulties accurately determining thickness and identifying interfaces due to multiple resonant frequencies. This paper proposes a signal processing method called frequency-frequency energy density separation (FFEDS) to obtain the energy density ratio (EDR) for different thicknesses using EMAR. A new coil structure, the Acentric Archimedes Spiral Coil (A-AS-Coil), and two scanning schemes (transverse and rotational) are designed. Experimentally, transverse scanning with the A-AS-Coil shows a nonlinear change in EDR, improving sensitivity in identifying interfaces. Rotational scanning with the A-AS-Coil increases the change in EDR by 106.2%, different from the conventional spiral coil.

Analysis and design of a novel cubic WPT system in a metal environment for an enclosed sensor scenario

AbstractThis paper proposes a novel cubic WPT system for an enclosed sensor scenario, and its transmission characteristics in a metal environment have been analyzed. In addition, stable and high transmission efficiency can be normally achieved in all positions. The proposed quasi‐double D coil structure is composed of two pairs of transmitting coils; each transmitting coil pair is placed face to face and connected serially. Through current amplitude modulation, magnetic flux can flow towards the centre of the receiving coil and keep the system high efficiency when the rotation angle of the receiving coil changes. However, the installation position of the receiving coil is not fixed in the switch cabinet application, and an irregular iron wall and the metal shell of sensors could also lead to inconsistent iron loss of multiple transmitters. To overcome the resulting disturbances in efficiency, the improved current amplitude control method and the optimal load have been theoretically deduced in the case of the position variation of the receiving coil in a metal environment. Finally, experimental results in two‐dimensional space verify the omnidirectional transmission capability of the proposed quasi‐double D coil, and efficiency disturbances are effectively alleviated.

Simulation and experimental study on planar remote field eddy current detection of hidden defects in aircraft multilayer structure

ABSTRACT Multi-layer metal flat structure is an important load-bearing component of the aircraft, with the characteristics of large thickness and complex structure. The structure is prone to produce various defects in the process of its use. The remote field eddy current detection technology is not limited by the skin effect and can penetrate the measured component with large thickness. In view of the large volume of traditional remote field eddy current sensor, which is difficult to apply to complex detection environment, a small-volume remote field eddy current sensor with coaxial placement and the differential structure of the detection coil is designed and developed. The simulation and experimental results show that the magnetic circuit structure and composite shield damping are beneficial to improve the detection capability of the sensor. Setting the balance coil greatly reduces the effect of the direct-coupled magnetic field on the detection coil and improves the sensitivity of the sensor. The detection signal of the remote field eddy current sensor is directly proportional to the defect equivalent volume, and within a certain defect size range, if the defect equivalent volume is similar, the remote field eddy current sensor is more sensitive to the defect depth.

Effects of helical condenser coil designs on the heating process of the domestic refrigerator for hot water production: A numerical study

Enhancement of heat transfer characteristics in helical condenser coils by modifying the coil shape has been reported by many researchers. While the influence of different types of condenser coil designs on the operating performance of refrigeration machines for hot water production unit is available in the literature, there exists no published numerical or experimental analysis of the impact of geometric parameter of immersed helical condenser coil on heat transfer characteristics and water velocity distribution during water heating process, which is the subject of our article. With using CFD methodology, a numerical study was carried out to present the water velocity distribution with varying coil parameters such as pipe diameter, tube pitch, and turns number. After validating the numerical model by the experimental ones, the effect of coil parameters on water velocity distribution was examined. The results confirm that by reducing the coil pitch and increasing the tube diameter, an increase of the water velocity and a higher natural convection is obtained. On the other hand, the results indicate that with reducing the turns number, the water velocity and the heat transfer coefficient is also increasing. Indeed, the average water velocity of condenser coil with N = 11 turns is higher than the other two condenser coil structures, which presents 21.34% and 63.56% higher than that of N = 13 turns and N = 15 turns, respectively. Thus, this investigation could provide some guidance to obtain the optimum condenser coil structure for water heating process.

Influence of coil structure and position on the performance of miniature radio frequency ion thrusters

In this article, the influence of coil structure and position on the energy coupling efficiency of the miniature radio frequency (RF) ion thruster (μRIT) HRIT-4 with a diameter of 4 cm was studied. The experimental results show that the performance of the thruster can be improved by increasing the number of coil turns or decreasing the turn spacing, but if the distance between the coil and the screen grid is too small, the performance of the thruster will be significantly reduced. It is found that increasing the number of coil turns or decreasing the turn spacing will increase the resistance of the coil itself, but it will also obviously increase the inductance. Increasing the number of coil turns will also increase the resistance of the plasma source, and finally improve the performance of the thruster. On the other hand, due to the mutual inductance between the coil and the screen grid, the mutual inductance will be enhanced when the distance between the coil and the screen grid is reduced, and the mutual inductance will reduce the inductance of the thruster and increase the resistance of the thruster, eventually leading to the performance degradation of the thruster.

Design of Two Orthogonal Transmitters With Double L-Type Ferrite for the Wireless Charging System in Unmanned Aerial Vehicles

This article proposes a wireless charging system based on a novel magnetic coupler with high coupling capacity for recharging the unmanned aerial vehicles (UAVs). The novel magnetic coupler includes two transmitters and one receiver, in which the transmitters consist of double orthogonal rectangular coils and double orthogonal L-type cores and the receiver is an air-cored receiving coil perpendicular to one coil of the transmitter and parallel to the other coil of the transmitter. The magnetic flux is concentrated in the receiving coil as much as possible while guaranteeing the magnetic flux operation space away from a UAV body by coil structure itself. A prototype of the UAV wireless charging system based on the novel magnetic coupler is built and tested. The experimental wireless charging system designed for Phantom 4 RTK can deliver 102 W at a dc-to-battery efficiency of 91.02% at the maximum output power point, which is adapted to the wireless charging in UAVs.

A Simultaneous Power and Data Transmission Technology Based on Coil Multiplexing in Domino-Resonator WPT Systems

To achieve parallel power and data transmission in domino-resonator wireless power transfer (WPT) systems, a novel simultaneous power, and data transfer (SPDT) technology based on coil multiplexing is proposed in this letter. Benefiting from the magnetic field characteristics of the bipolar coil structure, the power and data can be injected into multiplexed coils with different flow directions, leading to opposite induced voltage polarities in each coupling coil. Subsequently, a corresponding resonator circuit is developed to form independent power and data resonance loops. In addition, an injected data transmission scheme is developed for domino-resonator WPT systems. Compared with traditional SPDT methods, additional wave trappers and coupling structures are avoided by this proposed technology, and the interference between power and data transfer is significantly eliminated. A 23.6 W laboratory prototype with five domino resonators is built to validate the feasibility of this proposed technology. The experimental results show that the power transfer efficiency reaches 70% at 50 kb/s data transfer rate.

Mutual Inductance Calculation of Circular Coils for an Arbitrary Position With a Finite Magnetic Core in Wireless Power Transfer Systems

Mutual inductance can be increased, and magnetic leakage can be reduced by adding finite magnetic core materials to the coil structure. However, the problem of the calculation of the mutual inductance between two arbitrarily positioned circular coils with a finite magnetic core has not been resolved. In this article, an analytical formula for calculating the mutual inductance between two circular coaxial coils on a finite magnetic core is obtained based on regional hierarchical expansion analysis (RHEA), the Maxwell equation, the Bessel function, and the boundary conditions for electromagnetic fields. The mutual inductance between two arbitrarily positioned coils is obtained by using the analytical geometry method. A series of experiments are carried out to verify the analytic calculations. The experimental results for each misalignment case are compared with the calculated results and simulated results. The theoretical results and simulated results are in good agreement with the experimental data, which verifies the validity of the proposed method.

Evaluation of effects of temperature and humidity on the secondary structure of Ganirelix in an injectable formulation and comparison with Orgalutran® using circular dichroism spectroscopy.

Ganirelix, a drug used in in vitro fertilization (IVF), prevents ovulation in women who are not ready to have children by inhibiting a gene that produces gonadotropin. Peptides are macromolecules that are able to preserve a predetermined shape while carrying out the structural and regulatory roles for which they were originally intended. Peptide structures can be altered in the production and storage processes. Therapeutic peptides' biological activity can be drastically altered by even small modifications in their primary and secondary structures. The molecules' secondary structures can be monitored by subjecting them to different processing or storage conditions. In our investigation, we used circular dichroism (CD) spectroscopy with two different software programs for secondary structure evaluation to look at how environmental factors like temperature and humidity affected the secondary structure of Ganirelix in an injectable formulation. The CD results revealed that the alpha-helical (regular and distorted), beta-sheet, beta-strands (regular and distorted), beta-turn, and random coil structures of temperature and humidity stressed generic drug products are comparable to reference-listed drug.

Electromagnetic investigation of neuron growth by using pulsed electromagnetic field stimulation

Electromagnetic field (EMF) applications for humans have been widely used for medical therapy for a long time. Various nerve diseases such as complex regional pain syndrome, cerebral palsy and spinal cord injuries may occur as a result of damage on the nerve cells. In addition, EMF applications are taken into consideration in terms of tissue regeneration. The use of electricity for nerve regeneration is applied internally or externally. The use of direct current (DC) electric fields to stimulate axon elongation and nerve regeneration in nerve cells has been applied in various studies. In our study, electromagnetic field was used for the controlled and directional growth of Dorsal Root Ganglia (DRG) nerve cells. An amplifier circuit, which can produce amplified signals to generate proposed pulsed electromagnetic fields (PEMF) is designed. The electromagnetic field is produced on FR-4 copper plate, which highlights electrical field unlike previous studies, since there is no circular coil structure preferred. The elongation of nerve cells is planned to be in one direction, hence the signal to be applied is produced as a novel asymmetrical waveform (sawtooth) in addition to triangular and square waveforms which were previously preferred in recent studies. By the aid of proposed novel construction and produced signal waveform, PEMF system can be applied for nerve diseases effectively. The morphological nerve cell elongation results and PEMF results have been investigated and the effectiveness of the proposed system is verified.

PCB Rogowski Coils for Capacitors Current Measurement in System Stability Enhancement

In terms of high-current measurement of capacitors, PCB Rogowski coils have attracted much attention because of their small size and easy installation. However, they are vulnerable to electromagnetic interference. In order to improve the immunity of the coil, this paper studies the influence of the structure and parameter changes of the double-layer PCB coil on the measurement accuracy of mutual inductance. By testing the frequency response of four common coil structures, a differential winding coil structure is proposed. Based on the measurement of large capacitance current, the influence of non-electrical parameters of coils on the measurement accuracy of mutual inductance is experimentally verified.

Application of transglutaminase modifications for improving protein fibrous structures from different sources by high-moisture extruding

Plant proteins can be extruded under high moisture content (above 40 %) to form meat-like fibrous structures, which is the basis for meat-like substitute products. However, the proteins’ extrudability from various sources remain challenging in terms of generating fibrous structures under combinations of high-moisture extrusion with transglutaminase (TGase) modifications. In this study, proteins from soy (soy protein isolate, SPI, and soy protein concentrate, SPC), pea (pea protein isolate, PPI), peanut (peanut protein powder, PPP), wheat (wheat gluten, WG), and rice (rice protein isolate, RPI) were texturized using high-moisture extrusion combined with transglutaminase (TGase) modifications to enact changes in protein structure and extrusion capabilities. The results showed that soy proteins (SPI or SPC) responsed to torque, die pressure and temperature during extrusion, and this phenomenon was more pronounced at a higher protein content (SPI). In contrast, rice protein exhibited poor extrudability, leading to large losses of thermomechanical energy. TGase significantly affects the orientation of protein fibrous structures along the extrusion direction by impacting the rate of protein gelation during the high-moisture extrusion process, with the impact mainly occurring in the cooling die. Globulins (mainly 11S) played a major role in forming fibrous structures and the aggregation of globulins or reduction of gliadins under TGase modification impacted the orientation of the fibrous structure along the extrusion direction. Some thermomechanical treatment during high-moisture extrusion results in protein conversion from compact structure into more extended or stretched state, and the increase of random coil structures for proteins derived from wheat and rice would lead to these looser structures in the extrudates. Thus, TGase can be combined with high-moisture extrusion to regulate the formation of plant protein fibrous structures, dependent on the specific protein source and content.

Highly Elastically Deformable Coiled CNT/Polymer Fibers for Wearable Strain Sensors and Stretchable Supercapacitors.

Stretchable yarn/fiber electronics with conductive features are optimal components for different wearable devices. This paper presents the construction of coil structure-based carbon nanotube (CNT)/polymer fibers with adjustable piezoresistivity. The composite unit fiber is prepared by wrapping a conductive carbon CNT sheath onto an elastic spandex core. Owing to the helical coil structure, the resultant CNT/polymer composite fibers are highly stretchable (up to approximately 300%) without a noticeable electrical breakdown. More specifically, based on the difference in the coil index (which is the ratio of the coil diameter to the diameter of the fiber within the coil) according to the polymeric core fiber (spandex or nylon), the composite fiber can be used for two different applications (i.e., as strain sensors or supercapacitors), which are presented in this paper. The coiled CNT/spandex composite fiber sensor responds sensitively to tensile strain. The coiled CNT/nylon composite fiber can be employed as an elastic supercapacitor with excellent capacitance retention at 300% strain.

Analysis and Optimal Design of Magnet Coil for Magnetic Field Test Facility in ITER

The power electronic devices of ITER will bear a magnetic field strength of more than 5 mT, which may affect the operation of the devices and cause different degrees of damage to the devices. Therefore, these power electronic devices need a magnetic field anti-interference test. The core of the test facility is a magnetic field coil. First, the mathematical models of two-coil and multicoil systems considering the cross section are established. The general formula, optimization design objective, and optimization design process of the coil parameters are obtained, and the optimization scheme of the optimal solution is determined. Then, the multicoil systems are analyzed according to the actual design requirements and the actual site conditions. Some parameters that play a major role are used in the magnetic field distribution as variables to analyze and select the appropriate coil structure. Finally, the four-coil-group system with equal side lengths is applied as the coil structure based on the design requirements, power loss, weight, and manufacturing difficulty. Finite element software simulation results and experimental results prove the feasibility and correctness of the theoretical analysis.

Purification, structure and characterization of the novel antimicrobial lipopeptides produced by Paenibacillus ehimensis HD

Considerable challenges remain in the development and application of natural antimicrobial substances for food preservation to meet food safety needs. In this paper, ehimensins F4, F5, and F6, three antimicrobial peptides produced by Paenibacillus ehimensis HD, were purified by using macroporous adsorption resin and RP-HPLC. The molecular mass of ehimensins F4 and F5 was 1101 Da and that of ehimensin F6 was 1115 Da. LC–MS/MS demonstrated that each ehimensin consisted of fatty acids, 2,4-diaminobutyric acid, and amino acids. Meanwhile, circular dichroism revealed that each ehimensin was mainly composed of random coil and β-sheet structures. The three ehimensins maintained high activities under different conditions because they were stable over a wide range of temperatures and pH and in the presence of protease. Moreover, they exhibited low hemolysis activities and obvious antimicrobial activities against various food pathogenic bacteria and fungi. Soaking the strawberries in 1.0 mg/mL ehimensins for 1 min at room temperature could significantly inhibit fungal growth. And the shelf life of the strawberries was extended from 1 day to 4 days. These results suggested that ehimensins from P. ehimensis HD have great potential for use as biopreservatives to improve food safety.

Identification and Characterization of Three New Antimicrobial Peptides from the Marine Mollusk Nerita versicolor (Gmelin, 1791)

Mollusks have been widely investigated for antimicrobial peptides because their humoral defense against pathogens is mainly based on these small biomolecules. In this report, we describe the identification of three novel antimicrobial peptides from the marine mollusk Nerita versicolor. A pool of N. versicolor peptides was analyzed with nanoLC-ESI-MS-MS technology, and three potential antimicrobial peptides (Nv-p1, Nv-p2 and Nv-p3) were identified with bioinformatical predictions and selected for chemical synthesis and evaluation of their biological activity. Database searches showed that two of them show partial identity to histone H4 peptide fragments from other invertebrate species. Structural predictions revealed that they all adopt a random coil structure even when placed near a lipid bilayer patch. Nv-p1, Nv-p2 and Nv-p3 exhibited activity against Pseudomonas aeruginosa. The most active peptide was Nv-p3 with an inhibitory activity starting at 1.5 µg/mL in the radial diffusion assays. The peptides were ineffective against Klebsiella pneumoniae, Listeria monocytogenes and Mycobacterium tuberculosis. On the other hand, these peptides demonstrated effective antibiofilm action against Candida albicans, Candida parapsilosis and Candida auris but not against the planktonic cells. None of the peptides had significant toxicity on primary human macrophages and fetal lung fibroblasts at effective antimicrobial concentrations. Our results indicate that N. versicolor-derived peptides represent new AMP sequences and have the potential to be optimized and developed into antibiotic alternatives against bacterial and fungal infections.

In-situ molding of micro three-dimensional columnar structure by electric-field-focused electrospinning

An electric-field-focused electrospinning method was proposed to realize the in-situ molding of micro three-dimensional (3D) columnar structure. A grounded guide tip was utilized to generate a focused electric field to accelerate the charge transferring. The charged jet could be guided to deposited layer by layer into coil structure under the action of inner elastic stress. The dynamic evolution behavior of 3D columnar structures was performed. The distance between nozzle and collector was increased synchronously to establish the mechanical equilibrium between the electrical field force and the inner elastic stress. The mechanical equilibrium occurred when the jet stretching rate was equal to the fiber stacking rate. Lower stretching rate relaxed the jet and increased the diameter of 3D columnar structures. Larger stretching rate increased the inner stress and decreased the diameter of 3D columnar structures. Then, micro 3D columnar structures with diameter and height of 20 µm∼80 µm and 10 µm∼1.68 mm in different shapes including cylindrical, bowl, conical and porcelain bottle shape were realized.