Coil Structure Research Articles

A Reconfigurable Rectifier-Based Power Improving Method of Free-Standing Two-Coil Magnetic Field Energy Harvesters Over a Wide Load Range

Free-standing magnetic field energy harvesters (FSMFEHs) have promising potential in charging sensors used in electrical power grids. The output power of the FSMFEH is highly dependent on the load resistance. However, the load resistance of the sensors varies over a wide range during the operation process. Therefore, a crucial challenge for an FSMFEH system is to maintain high output power over a wide load range. In this article, an innovative reconfigurable rectifier-based FSMFEH system with two coils connected in parallel is proposed. First, a new structure of two identical coils in parallel is proposed in magnetic energy harvesting applications. Then, a reconfigurable rectifier with two operation modes is developed to incorporate the new coil structure. By switching between the full-bridge mode and the half-bridge mode according to the actual load demand, the proposed FSMFEH can maintain high output power over a wide load range. In addition, the mode transition can be easily achieved by shorting one of the diodes, leading to a simple and low-loss control. The effectiveness of the proposed FSMFEH system is verified based on a laboratory prototype. It is provided that the experimental result is consistent with the theoretical analysis. The output power can be maintained above 8.19mW within the 50Ω to 1500Ω range when the busbar current is 100A.

An Antioffset Electric Vehicle Wireless Charging System Based on Dual Coupled Antiparallel Coils

Wireless power transfer (WPT) has the advantages of safety, convenience and freedom from the impact of the environment. Misalignment tolerance is a major issue for the electric vehicle wireless charging system. In this letter, a WPT system with anti-offset characteristic is proposed based on dual coupled transmitting coils with antiparallel windings, forming the inductor-capacitor-capacitor-series (LCC-S) topology. The T-shaped equivalent circuit is developed to obtain the decoupling circuit. Based on the misalignment tolerant characteristic of the antiparallel windings, the two transmitting coils are designed to have the same coil structure with antiparallel windings, leading to the same variation trend of the coupling between the two transmitting coils and the receiving coil and the opposite influence on the output. Therefore, the output voltage can be stable within a certain misalignment range. An experimental prototype is built to verify the effectiveness of the proposal. The experimental results show that the output voltage can remain stable within the range of −150 mm to 150 mm in the horizontal direction and 80 mm to 160 mm in the vertical direction.

Design of Wireless Power Transfer System Based on LCC-S

Recently, wireless power transfer (WPT) technology has become a research hot spot due to its benefit of contactless power transfer. Firstly, for the sake of solving the problem of the small coupling coefficient of traditional orbital wireless power transfer systems, a new structure and control strategy of transceiver coil was proposed, and then the optimal parameters of system transmission efficiency were found out by comprehensive analysis of the LCC-S compensation circuit structure and equivalent circuit, and the correctness of the parameters was verified in MATLAB/Simulink simulation. Finally, an experimental prototype was built, and the experimental findings show that the wireless power transfer system based on LCC-S can realize voltage regulation control, the coupling coefficient is increased by 0.4 compared with the traditional orbital structure, and the transmission efficiency of this system is more than 80%.

Study on Driving Characteristics of MEMS Electromagnetic Coil Using in the UAV

The miniaturization and swarm design of unmanned aerial vehicle (UAV) is a research hotspot. For the current electromagnetic drive mode, the electromagnetic drive device is too large to be integrated in the current technology. This paper presents a new micro electromagnetically driven MEMS driving device, in which the electromagnetic coil is small in size, with a large electromagnetic force. We firstly designed and calculated the geometric structure of the electromagnetic coil, and analysed the model using COMSOL multiphysics field simulation software. We then carried out a parametric simulation of the electromagnetic coil. The simulation result shown that the error between theoretical calculation and the simulation of the mechanical and electrical properties of the electromagnetic coil was less than 2% under the same size. It provides an idea for UAV miniaturization design.

Numerical Analysis of the New Wireless Relay Transmission Model Based on FEM

In this article, a wireless relay transmission system in long-distance wells with new close winding helical coils is proposed. This system can realize more efficient bottom-up superposition transmission of signals in long transmission wells. At the same time, by redesigning the structure of the transmitting and relay antennas, a close winding helical coil structure with metal ring protection is proposed to excite quasi-TEM waves, which improves the efficiency of signal transmission in each channel and the compressive strength of the antenna. The simulation and experimental results demonstrate that under long distance and harsh stratum conditions, the wireless transmission system in long-distance wells has excellent signal transmission performance at extremely low frequencies. Compared with previous antenna structures, the new helical coil has better performance in transmission efficiency. This new wireless relay transmission system can greatly meet the long-distance transmission and conditions of oil and gas wells in the future.

Modeling of Litz-Wire DD Coil With Ferrite Core for Wireless Power Transfer System

DD planar coil with ferrite core is one popular coupling structure in wireless power transfer (WPT), especially for electric vehicle applications. The coil design is critical for improving the performance of WPT system. However, the coupler design purely relying on finite element analysis (FEA) software is time-consuming. And literature on the modeling of DD coil is lacking. Therefore, the model of DD coil with a ferrite core for calculating self-inductance, mutual inductance, and AC resistance is proposed in this paper. The condition when primary and secondary coils have different sizes is also considered. The case that there is misalignment is also analyzed. Meanwhile, a genetic algorithm based on the proposed coil mathematical model is proposed to optimize the coil structure. For verifying the accuracy of the proposed model, the simulation model based on the FEA and a 1.2-kW laboratory prototype are built simultaneously. The calculation values based on the proposed model is highly consistent with the simulation results and experimental values. Error for calculating self-inductance and mutual inductance is within 5% when coils on the primary side and secondary side are in alignment. The error for calculating the AC resistance of the coil is within 10% when the frequency range is 0-200kHz.

Structural optimization design and numerical analysis of in-vessel magnetic compression coils

An FRC (field reversed configuration) device HUST-FRC (HFRC) is under construction at Huazhong University of Science and Technology, and the magnetic compression experiments will be investigated. 22 compression coils installed inside the metal vacuum chamber are designed with a peak current of about 110 kA rising within 50 μs. The coils are subjected to large electromagnetic forces during the compression process, which will challenge the structural stability of the coils. Therefore, it is necessary to estimate the structural stability of the compression coils during the compression progress. The compression process involves complex physical problems such as the coupling of circuit-electromagnetic-thermal-mechanical and non-linear contacts between adjacent coil components. It is also a challenge to calculate the coil current, electromagnetic load, and structure stress. To solve these problems, a joint analysis method is developed based on a two-dimensional (2-D) circuit-electromagnetic-thermal model and a three-dimensional (3-D) electromagnetic-mechanical model. The submodeling method is employed in mechanical simulations to improve the efficiency of coil optimization design. The electromagnetic and mechanical results confirm that the design of the compression coils is valid and feasible.

Comprehensive investigation on misalignment tolerance of inductive power transfer systems

Inductive power transfer (IPT) technology is gaining popularity for wireless charging applications of future electric charging for its contactless power supply. The square and circular planar spiral coils are most widely used in wireless power charge due to its simple structure. This paper gives analyses of comparing these two geometry windings in detail. As for an inductive power transfer system, coupling structures, such as line spacing and magnetic core structure, are of paramount importance, because of their significant impact on power transfer efficiency and voltage stability. By analyzing the characteristics of magnetic field distribution of the coupler, influences of coil shape, size, line spacing and core structures on coupling coefficient and coupling coefficient retaining ratio (CCRR) are firstly investigated. Misalignment tolerance under different coupler structures is then conducted, comprehensive optimization schemes of misalignment tolerance improvement are proposed. Results show that for the coupling coefficient and coupling coefficient retaining ratio, the optimal line spacing and core structures are highly dependent on the coil shape, size and air gap. A 3-kW IPT system was also built and experimental validations on original and optimized structures are performed. And the better misalignment tolerance was achieved with the optimal line spacing, transmitting coil and ferrite core structure.

Study on molecular mechanisms of destabilizing Aβ(1–42) protofibrils by licochalcone A and licochalcone B using molecular dynamics simulations

Amyloid-beta (Aβ) protofibrils are closely related to Alzheimer's disease. Their behaviors with or without the presence of Aβ fibrillization inhibitors have been intensively studied by molecular dynamics simulations. In this work, the molecular mechanisms of licochalcone A and licochalcone B on destabilizing Aβ(1–42) protofibrils are explored. It is found that both two licochalcones can disorder the configuration of the Aβ(1–42) protofibril. The stable interactions between the Aβ(1–42) protofibril and licochalcone A or licochalcone B are able to be formed. A reduction of the β-sheet structure contents and an increment of the random coil structures of Aβ(1–42) protofibril are observed in the presence of either licochalcone A or licochalcone B. The hydrogen bonds inside the Aβ(1–42) protofibril could be partially collapsed to varying degrees by two licochalcones. Furthermore, the van der Waals interactions between Aβ(1–42) protofibril and licochalcone A make an important contribution to the binding free energy, while the contribution of the electrostatic interactions between Aβ(1–42) protofibril and licochalcone B is more prominent in the binding affinity. Our work may help in the development of new drug candidates for disrupting the Aβ protofibril.

Multi-Objective Optimization Design and Performance Comparison of Magnetorheological Torsional Vibration Absorbers of Different Configurations.

The purpose of this study is to provide a convenient optimization design method for magnetorheological torsional vibration absorbers (MR-TVA) suitable for automotive engines, which is a damper matching design method that takes into account the needs of the engine operating conditions. In this study, three kinds of MR-TVA with certain characteristics and applicability are proposed: axial single-coil configuration, axial multi-coil configuration and circumferential configuration. The magnetic circuit model, damping torque model and response time model of MR-TVA are established. Then, under the constraints of weight, size and inertia ratio, according to different torsional vibration conditions, the MR-TVA mass, damping torque and response time are multi-objective optimized in two directions. The optimal configurations of the three configurations are obtained from the intersection of the two optimal solutions, and the performance of the optimized MR-TVA is compared and analyzed. The results show that the axial multi-coil structure has large damping torque and the shortest response time (140 ms), which is suitable for complex working conditions. The damping torque of the axial single coil structure is generally large (207.05 N.m), which is suitable for heavy load conditions. The circumferential structure has a minimum mass (11.03 kg) and is suitable for light load conditions.

In silico analysis of the possible crosstalk between O-linked β-GlcNAcylation and phosphorylation sites of Disabled 1 adaptor protein in vertebrates.

Disabled 1 (Dab1) is an adaptor protein with essential functions regulated by reelin signaling and affects many biological processes in the nervous system, including cell motility, adhesion, cortical development, maturation, and synaptic plasticity. Posttranslational modifications directly guide the fates of cytoplasmic proteins to complete their functions correctly. Reciprocal crosstalk between O-GlcNAcylation and phosphorylation is a dynamic modification in cytoplasmic proteins. It modulates the functions of the proteins by regulating their interactions with other molecules in response to the continuously changeable cell microenvironment. Although Dab1 contains conserved recognition sites for phosphorylation in their N-terminal protein interaction domain, the O-β-GlcNAcylation and phosphorylation sites of human Dab1 sequence, their reciprocal crosstalk, and potential kinases catalyzing the phosphorylation remain unknown. In this study, we determined potential thirty-seven O-β-GlcNAcylation and sixty-seven phosphorylation sites. Conserved twenty-one residues of these glycosylated sites were also phosphorylated with various kinases, including ATM, CKI, DNAPK, GSK3, PKC, PKG, RSK, cdc2, cdk5, and p38MAPK. In addition, we analyzed these conserved sites at our constructed two- and three-dimensional structures of human Dab1 protein. Dab1 protein models were frequently composed of coil structures as well as α-helix and β-strands. Many of these conserved crosstalk sites between O-β-GlcNAcylation and phosphorylation were localized at the coil region of the protein model. These findings may guide biochemical, genetic, and glyco-biology based on further experiments about the Dab1 signaling process. Understanding these modifications might change the point of view of the Dab1 signaling process and treatment for pathological conditions in neurodegenerative diseases such as Alzheimer's disease.

Mitochondrial Dysfunction: A Cellular and Molecular Hub in Pathology of Metabolic Diseases and Infection.

Mitochondria are semiautonomous doubly membraned intracellular components of cells. The organelle comprises of an external membrane, followed by coiled structures within the membrane called cristae, which are further surrounded by the matrix spaces followed by the space between the external and internal membrane of the organelle. A typical eukaryotic cell contains thousands of mitochondria within it, which make up 25% of the cytoplasm present in the cell. The organelle acts as a common point for the metabolism of glucose, lipids, and glutamine. Mitochondria chiefly regulate oxidative phosphorylation-mediated aerobic respiration and the TCA cycle and generate energy in the form of ATP to fulfil the cellular energy needs. The organelle possesses a unique supercoiled doubly stranded mitochondrial DNA (mtDNA) which encodes several proteins, including rRNA and tRNA crucial for the transport of electrons, oxidative phosphorylation, and initiating genetic repair processors. Defects in the components of mitochondria act as the principal factor for several chronic cellular diseases. The dysfunction of mitochondria can cause a malfunction in the TCA cycle and cause the leakage of the electron respiratory chain, leading to an increase in reactive oxygen species and the signaling of aberrant oncogenic and tumor suppressor proteins, which further alter the pathways involved in metabolism, disrupt redox balance, and induce endurance towards apoptosis and several treatments which play a major role in developing several chronic metabolic conditions. The current review presents the knowledge on the aspects of mitochondrial dysfunction and its role in cancer, diabetes mellitus, infections, and obesity.

A New Design to Rayleigh Wave EMAT Based on Spatial Pulse Compression.

The main disadvantage of the electromagnetic acoustic transducer (EMAT) is low energy-conversion efficiency and low signal-to-noise ratio (SNR). This problem can be improved by pulse compression technology in the time domain. In this paper, a new coil structure with unequal spacing was proposed for a Rayleigh wave EMAT (RW-EMAT) to replace the conventional meander line coil with equal spacing, which allows the signal to be compressed in the spatial domain. Linear and nonlinear wavelength modulations were analyzed to design the unequal spacing coil. Based on this, the performance of the new coil structure was analyzed by the autocorrelation function. Finite element simulation and experiments proved the feasibility of the spatial pulse compression coil. The experimental results show that the received signal amplitude is increased by 2.3~2.6 times, the signal with a width of 20 μs could be compressed into a δ-like pulse of less than 0.25 μs and the SNR is increased by 7.1-10.1 dB. These indicate that the proposed new RW-EMAT can effectively enhance the strength, time resolution and SNR of the received signal.

Hofmeister anion effects synergize with microbial transglutaminase to enhance the techno-functional properties of pea protein

Pea protein are emerging as the most potential alternative for meat products, but its application was hindered by their weaker gelling properties. Here, the feasibility of combining the Hofmeister anion (CO32–, Citrate3-, and SO42-) effect with microbial transglutaminase (MTG) cross-linking strategy to improve the techno-functional properties of pea protein was studied. Hofmeister anions or/and MTG treatment of pea protein caused a clear shift in far-UV CD spectra towards β-turn and random coil structures. Furthermore, Hofmeister anion and MTG-induced crosslinking caused a reduction of surface hydrophobicity in contrast with anions-treated. Compared to CO32– and SO42-, Citrate3- treatment can better improve the efficiency of MTG-crosslinking, as demonstrated by a reduction in free amino group contents and an increase in mean diameter size. Using MTG in combination with Hofmeister anions showed significantly improved foam property and gel hardness as well as decrease gelation temperature of pea protein, specifically Citrate3- treatment. Thus, this research provides a novel and effective method to improve the effect of MTG-cross-linked pea protein, which will play an essential role in future food production.

Optimization and Analysis of High-frequency Data Receiver Coil for Artificial Retina

High-frequency coils are vital parts of the wireless data transfer system of implantable electronics for achieving higher data rates. Coil structure and its geometrical parameters are the deciding factors of the optimized coil design. In this paper, the physical parameters of the coil are optimized to resonate at a high frequency. A simple parametric approach is used to extract the physical parameters of the coil for optimizing the coil features at high frequency using MATLAB. The key challenges associated with the disparity in coil characteristics after implantation in the eye are being investigated. Tissue layers that mimic the human eyeball are modelled using HFSS software. The coil is simulated in the tissue environment to evaluate the electrical characteristics of the coil in the biological medium. To validate the simulation model, the implant coil is characterized in the porcine eye to analyse the electrical behaviour of the coil in tissue media. The measured Q factor of the coil in the air is 19.69 and in the tissue is 3.3. Experimental results of the coil implanted in the porcine eye show that the resonant frequency of the coil is reduced by 20%, which limits the operation of the coil at higher frequencies when implanted. This exploratory study on the interaction of biological medium with the electrical behaviour of the coil can be used to predict energy losses in tissues and hence aid in devising compensation techniques for improving the data transmission efficiency of the artificial retinal system.

Design of PCB Rogowski Coil Current Sensor With Low Droop Distortion

Wide bandgap devices (SiC and GaN) bring the potential for a great increase in power density of power electronics, but also pose a challenge to the bandwidth of the current sensor because of the high operating frequency. Rogowski coil is suitable for high-frequency current measurement due to its characteristic of differential output, but the existing design is difficult to take into account the sensitivity and mutual inductance at the same time, and faces the inherent defect of droop distortion. This article proposes an optimal printed circuit board (PCB) Rogowski coil structure design method for SiC MOSFET power module and a novel sample-filter-hold (SFH) method to minimize droop distortion in integrators. First, the optimal parameters with multiobjective constrained optimization of the Rogowski coil current sensor for the SiC-MOSFET power module are obtained. Then, the influence factors of droop distortion of the sensor in buck converters and inverters are quantitatively analyzed for the first time and an SFH suppression method is proposed, which can eliminate the offset caused by droop distortion reliably and accurately. Finally, the experimental results demonstrate that the proposed Rogowski coil design method and the SFH method for lower droop distortion achieve better low-frequency performance compared to the commercial Rogowski coil.

Perylene derivative and persulfate as highly efficient electrochemical system for constructing sensitive amperometric aptasensor

To design highly efficient electrochemistry system was important for construct simple and sensitive biosensors, which was crucial in clinical diagnosis and therapy. In this work, a novel electrochemistry probe N,N′-di (1-hydroxyethyl dimethylaminoethyl) perylene diimide (HDPDI) with positive charges was reported to show two-electron redox behavior in neutral phosphate buffer solution between 0 and -1.0 V. And K2S2O8 in solution could significantly increase the reduction current of HDPDI at −0.29 V, which was interpreted with cyclic catalysis mechanism of K2S2O8. Moreover, HDPDI as electrochemical probe and K2S2O8 as signal enhancer was used to design aptasensors for protein detection. Thrombin was used as target model protein. Thiolate ssDNA with thrombin-binding sequence was immobilized on gold electrode to selectively capture thrombin and adsorb HDPDI. The thiolate ssDNA without binding with thrombin was with random coil structure and could adsorb HDPDI through electrostatic attraction interaction. However, the thiolate ssDNA binding with thrombin became G-quadruplex structure and hardly adsorbed HDPDI. Thus, with increasing the concentration of thrombin, the current signal stepwisely decreased and was taken as detection signal. Compared with other aptasensors based on electrochemistry molecules without signal enhancer, the proposed aptasensors exhibited wider linear response for thrombin between 1 pg mL−1 and 100 ng mL−1 with lower detection limit 0.13 pg mL−1. In addition, the proposed aptasensor showed good feasibility in human serum samples.

Wireless Power Transfer in Electric Vehicles: A Review on Compensation Topologies, Coil Structures, and Safety Aspects

The scarce availability of non-renewable sources and the staggering amount of pollution have inevitably provoked many countries to opt for renewable sources. Thence, invariably, more renewable energy-based applications are hoarded by market stakeholders. Compared to all spheres of renewable energy applications, a considerable part of the energy is pulled into transportation. Wireless power transfer techniques play a significant role in charging infrastructure, considering the current development and advancement in the automotive industry. It will promise to overcome the widely known drawbacks of wired charging in electric vehicles. The effectiveness of wireless charging depends on coil design, compensation techniques, and the airgap between the coils. However, coil misalignment, improper compensation topologies, and magnetic materials reduce the efficacy. We can improve efficacy by overcoming the problems mentioned above and optimizing charging distance, time, and battery size. This paper comprehensively discussed the various electric vehicle charging technologies in conjunction with common charging standards, a list of factors affecting the charging environment, and the significance of misalignment problems. Furthermore, this review paper has explored the suitable coil design structure and different compensation techniques for an efficient wireless charging network.

Structural characterization of soy protein hydrolysates and their transglutaminase-induced gelation properties

Soy protein hydrolates (SPHs) were produced by hydrolyzing soy protein isolate (SPI) for different times (5–180 min) using Alcalase, followed by cross-linking with transglutaminase (TGase) and their gelation capacity were then evaluated. The hydrolysis degree (DH) of SPHs increased from 1.37% to 6.61% as the increasing hydrolysis time from 5 min to 180 min. Compared to SPI, enzymatic hydrolysis enhanced the surface hydrophobicity and random coil structure, but decreased the free sulfydryl content, α-helix and β-turn structures of SPHs. Notably, the low hydrolysis (DH: 1.37–2.17%) improved the protein solubility, disulfide bond content and β-sheet structure, decreased the turbidity of SPHs solutions in comparison with those hydrolyzed highly (DH: 3.12–6.61%). In addition, the TGase-pretreated SPHs displayed typical weak gel-forming capacities upon acyl transfer and protein cross-linking. In contrast, low-hydrolyzed SPHs (DH: 2.17%) exhibited superior gelation behaviors, as confirmed by uniform networks with small cavities, larger relaxation time distribution, higher viscoelasticity and water-holding capacity of 54%. In general, TGase indeed promoted the gelation capacity of SPHs subjected to limited hydrolysis, which facilitates the application of SPHs in food formulation.

Novel coil design and analysis for high-power wireless power transfer with enhanced Q-factor

The power transfer efficiency (PTE) is a crucial aspect for effective wireless power transfer (WPT) applications. The quality factor (Q) of the WPT coil plays a critical role in ensuring higher PTE. In this paper, a novel method of improving the Q of a WPT coil is proposed. Resistance reduction techniques are presented which involves variation of the trace pitch, width, and thickness. This approach targets the high AC losses centered in the inner turns, which subsequently results in an increased Q. Numerical analysis with respect to the inductance and resistance models are presented, analyzed, and compared to that of the EM simulation results. To verify the efficacy of the proposed coil structure, a prototype is fabricated where good agreement is achieved between the measured and simulated results. The proposed coil attained a quality factor increment of about 19.24% at 85 kHz in comparison to the conventional one. The proposed technique can be used to optimize planar spiral coils to attain higher Q.