Inductive Coupling Research Articles

Heavy metals in human bones from the Roman Imperial Period

Background/Aim: Heavy metals are elements known for their toxic effects even at low concentrations, and human exposure to these elements spans history. This study aimed to investigate trace element levels in the bones of individuals from the Roman Imperial Period. The objectives were to determine the values of specific metals, including heavy metals, make a rough comparison with present-day values, and gain insights into the environmental conditions of that era. Methods: Due to the use of dry bone samples, ethical committee approval was not required for this research. The study analyzed element levels in human bones dated back to the Roman Imperial Period (218-244 AD), unearthed in 2018 during excavations in Turkey-Kayseri. Only bones that archaeologists verified to belong to the specified period were included, while those with uncertain origins were excluded. The samples were taken from os coxae of 15 individuals (eight males and seven females) to analyze Ca, P, Zn, Cu, Pb, and Hg levels. Instrumental techniques such as Wavelength Dispersive X-ray Fluorescence (WDXRF) (X-ray fluorescence) and ICP-MS (Inductive Coupling Plasma-Mass Spectrometer) were used to determine element concentrations. The Ca/P ratio was assessed for diagenesis evaluation, and statistical analysis was performed using Statistical Package for Social Sciences (SPSS) 22.0, with a significance threshold set at P-value <0.05. Results: The Ca/P ratio for the general population was calculated as 2.34 (0.10). The mean concentrations of heavy metals in the bones were as follows: Cu 18.27 (11.04) ppm, Pb 13.30 (5.66) ppm, Zn 27.22 (13.84) ppm, and Hg 2.45 (2.86) ppm. The corresponding P-values for Ca, P, Ca/P, Cu, Zn, Pb, and Hg were 0.109, 0.120, 0.104, 0.063, 0.113, 0.089, and 0.070. No statistically significant difference emerged when comparing elemental accumulations between males and females. Notably, copper and mercury levels were higher in Roman Imperial Period bones than contemporary ones, whereas zinc levels were lower, and lead concentrations aligned with reference values. Conclusion: The study results underscore the historical exposure of Roman Imperial Period individuals to heavy metals. These findings suggest that environmental health concerns related to heavy metal exposure date back millennia, emphasizing the long-standing nature of this issue.

A new high voltage gain DC‐DC converter based on active switched‐inductor technique

SummaryThis article proposes a brand‐new high voltage gain step‐up DC‐DC converter through the amalgamation of active switched‐inductors (A‐SL) and a coupled‐inductor (CL) unit. This topology stands out due to its capacity to achieve noteworthy high voltage amplification employing a lesser amount of components when put in contrast to other comparable topologies. The voltage stress across the switches is low, which enables the utilization of low‐voltage rating switches to elevate efficiency. Moreover, the division of the input current between the switches of the converter enables the power dissipation to be diminished. The CL is utilized in a way that if the turn ratio of its windings is lessened, the voltage boost will be augmented. Furthermore, the leakage energy is recycled through the output diode; therefore, problems such as voltage spikes across the switches do not occur. Moreover, the output diode turns off naturally without reverse recovery problems. The switching pattern of the converter is simple, and both switches are driven simultaneously, and the converter can be controlled using a simple controller in a closed‐loop control method. In addition, the duty cycle range has no limitations. The operation principle and the steady‐state analysis of the proffered converter are discussed in detail for CCM and DCM. The design considerations and efficiency analysis are provided, followed by small‐signal modeling and controller design. Moreover, to evaluate the performance of the proffered converter among other topologies, a comparison study is conducted in terms of voltage gain, total device count, and voltage tension on the power switches and diodes. Finally, a 200–300 W, 28/400 V lab‐based prototype is implemented and tested to validate the analysis.

Inductive Compensation of an Open-Loop IPT Circuit: Analysis and Design

The main contribution of this paper is the inductive compensation of a wireless inductive power transmission circuit (IPT) with resonant open-loop inductive coupling. The variations in the coupling coefficient k due to the misalignment of the transmitter and receiver are compensated with only one auxiliary inductance in the primary of the inductive coupling. A low-power prototype was implemented with the following specifications: input voltage Vin = 27.5 V, output power Po = 10 W, switching frequency f = 500 kHz, output voltage Vo = 12 V, transmission distance d = 1.5 mm. Experimental results varying the distance “d” with several values of the compensation inductor demonstrate the feasibility of the proposal. An efficiency of 75.10% under nominal conditions was achieved. This proposal is a simple compensation topology for wireless chargers of cellular phones presenting small distances between the transmitter and receiver.

Biplanar quadrature coil for versatile low-field extremity MRI

Biplanar magnets offer extended flexibility in MRI, particularly appealing due to unmatched accessibility to the patient. At low field strength (<0.2 T), such geometries could be particularly suitable for interventional settings or purpose-built applications such as musculoskeletal imaging. In the proposed work, we present a dual-channel, biplanar coil array for low-field MRI featuring almost fully open access when sited in a biplanar magnet. The proposed detector relies on the assembly of two orthogonal biplanar coils (single transmit channel, two receive channels in quadrature) respectively interfaced with custom inductive couplers. Simulations of the B1 field in each element were performed before the quadrature coil was built and used at ∼ 0.1 T (4.33 MHz). Once assembled, the best performance in our setup was achieved in undermatched conditions in place of conventional 50-Ω matching. Phantom images display the extended coverage of the quadrature coil, with similar SNR from each individual biplanar coil. The combined images show an expected SNR gain of 2 that confirms good decoupling between the two channels (−36 dB). To the best of our knowledge, the proposed coil represents the first implementation of a biplanar geometry at low field and the first quadrature detection for a biplanar design. The open design and overall good sensitivity of our biplanar design enabled fast and quasi-isotropic 3D imaging with (1.6 × 1.6 × 2.2) mm3 resolution in vivo in human extremities.

A new method to improve RF safety of implantable medical devices using inductive coupling at 3.0 T MRI

ObjectiveTo enhance RF safety when implantable medical devices are located within the body coil but outside the imaging region by using a secondary resonator (SR) to reduce electric fields, the corresponding specific absorption rate (SAR), and temperature change during MRI.Materials and methodsThis study was conducted using numerical simulations with an American Society for Testing and Materials (ASTM) phantom and adult human models of Ella and Duke from Virtual Family Models, along with corresponding experimental results of temperature change obtained using the ASTM phantom. The circular SR was designed with an inner diameter of 150 mm and a width of 6 mm. Experimental measurements were carried out using a 3 T Medical Implant Test System (MITS) body coil, electromagnetic (EM) field mapping probes, and an ASTM phantom.ResultsThe magnitudes of B1+ (|B1+|) and SAR1g were reduced by 15.2% and 5.85% within the volume of interest (VoI) of an ASTM phantom, when a SR that generates opposing electromagnetic fields was utilized. Likewise, the Δ|B1+| and ΔSAR1g were reduced by up to 56.7% and 57.5% within the VoI of an Ella model containing a copper rod when an opposing SR was used.ConclusionA novel method employing the designed SR, which generates opposing magnetic fields to partially shield a sample, has been proposed to mitigate the risk of induced-RF heating at the VoI through numerical simulations and corresponding experiments under various conditions at 3.0 T.

TCI Tester: A Chip Tester for Inductive Coupling Wireless Through-Chip Interface

The building block computation system is constructed by stacking various chips three-dimensionally. The stacked chips incorporate the same TCI IP (Through Chip Interface Intellectual Property) but cannot provide identical characteristics, requiring adjustments in power supply and bias voltage. However, providing characteristics measurement hardware for all chips is difficult due to the limitation of chip area or pin numbers. To address this problem, we developed TCI Tester, a small chip to measure electric characteristics by stacking on TCI of every chip. By stacking two TCI Tester chips, it appears that the up-directional data transfer has a stricter condition than down directional one on power supply voltage and operational frequency. Also, the transfer performance is poorer than designed. Similar measurement results are obtained by stacking TCI Tester on other chips with TCI IP. To investigate the reason, we analyzed the power grid resistance of various chips with the TCI IP. Results also showed that the chips with higher resistance have a narrow operational condition and poorer performance. The results suggest that the power grid design is important for keeping the performance through the TCI channel.

Cascaded Inverters Increasing the Number of Levels and Effective Switching Frequency in Output Using Coupled Inductors

In this paper, a new coupled-inductor based modular multilevel cascaded inverter using a new phase-shift control is presented. The proposed inverter can generate a high output ac voltage using standard low voltage rating devices. The number of levels in the output pulse width modulation (PWM) voltage and the effective switching frequency of the output filter are increased using coupled inductors and phase-shift control. The switching signals of the cascaded units in the proposed inverter are phase-shifted by 360°/4n, where n is the number of cascaded units. The proposed phase-shift control results in (4n+1) levels in the output PWM voltage of the proposed inverter and increases the effective switching frequency of the output filter by 4n times of the actual switching frequency fsw. As a result, the output waveforms can be generated with better quality and less distortion. In addition, the output filter can be decreased dramatically in size. Besides, fewer coupled inductors are used to reduce the footprints, the number of inductors, and magnetic volume. Moreover, the proposed inverter is exceptionally reliable due to no short-circuit risk in the circuit.

Suggesting a Non-Unity Turn Ratio Two-Winding Coupled Inductor for Filtering CM EMI Noise in an SRC

Switched-mode power supplies (SMPS) are the source of both conducted and radiated electromagnetic interference (EMI) noise. Resonant converters are popular due to the possibility of switching loss reduction using zero voltage switching (ZVS) or zero current switching (ZCS) and also attenuating conducted EMI noise. Conventionally, a common-mode (CM) choke with a single core and two identical windings is used to suppress the CM noise in an EMI filter. This paper introduces an effective and cost-efficient method for mitigating the CM EMI noise in SRCs. The proposed method benefits a two-winding coupled inductor instead of the simple resonant inductor in the SRC. While a unity turn ratio does not meet the desired resonance inductance, the suggested two windings coupled inductor with an unequal number of turns deals with the EMI noise as well as the normal operation of an inductor in the resonant tank. Applying the proposed method significantly achieves up to 20 dB attenuation in the noise amplitude both at the input and output terminals of the converter. Simulations are used for investigating the analysis of the method. Moreover, a series resonant converter is designed and implemented to verify both analysis and simulations.

A Novel Analytical Model for Mutual Inductance Calculations Between Two Nonidentical N-Sided Polygonal Planar Coils Arbitrarily Positioned in 3-D Space for Wireless Power Transfer

Mutual inductance (MI) calculation is of great importance, because there are many systems that operate on the principle of inductive coupling. This paper presents a novel analytical model that calculates the MI between two non-identical n-sided polygonal planar coils located in arbitrary position in 3D space. The model depends upon misalignment of both the primary and the secondary coils of a wireless power transfer (WPT) system operating based on inductive coupling. The polygonal coils used in this model may differ from each other in terms of size, shape and turns number. The misalignment cases considered in the proposed model include lateral, angular, lateral-angular and vertical distance variation between the primary and secondary coils. Based on Stokes Theorem, instead of using the magnetic flux density vector, the magnetic vector potential (MVP) is used to reach the required magnetic flux in the calculation of the MI. A single analytical solution function that can calculate the MI between two planar polygonal coils of any shape in a simple manner and short time duration is obtained by performing difficult mathematical operations through MVP. Results obtained from the developed new model are compared with finite element analysis (FEA), experimental and other studies in the literature. The good agreement of the results of this study with the other results has proved the accuracy and validity of the proposed new analytical model.

Reduction of electromagnetic coupling between parallel high speed interconnects using defected Microstrip structure

In the context of designing printed circuit boards (PCBs) for the upcoming fifth generation double data rate (DDR5) technology, the issue of electromagnetic coupling emerges as a significant challenge. To address this concern, a comprehensive approach to mitigating both forward and backward coupling is proposed in this paper. The presented research introduces an innovative solution by incorporating a Defect Microstrip Structure (DMS) with a meticulously designed mitered meander shape. This unique structure is strategically imposed within the victim microstrip lines, aiming to effectively curtail coupling effects between interconnected microstrip lines. By embedding the mitered meander DMS onto the microstrip line, the electromagnetic (EM) coupling strength is substantially reduced. The reduction in coupling is primarily attributed to the achievement of an optimized ratio between capacitive and inductive coupling among the interconnected microstrip lines. The effectiveness of the proposed method is rigorously evaluated through a series of full-wave electromagnetic simulations. These simulations encompass microstrip lines etched both with and without the integration of the mitered meander-shaped DMS. The analytical framework leverages the ANSYS Structure Simulator (HFSS), a powerful tool for evaluating electromagnetic behaviour.

DESIGN OF WIRELESS EV BATTERY CHARGING SYSTEM USING SQUARECIRCULAR COUPLED COILS WITH DIFFERENT MISALIGNMENTS

Now a days, inductive power transfer (IPT) has gained a lot of attention from researchers as it has ease of use and realiability for electric vehicle (EV) battery charging systems. This paper examines the increasing attention from researchers towards inductive power transfer (IPT) as a means of charging electric vehicle (EV) batteries. This interest originates from the user-friendly characteristics and notable reliability associated with IPT. The evaluation of mutual inductance (MI) holds importance within the domain of Inductive Power Transfer (IPT) systems, as it serves a critical function in enabling effective power transfer. Therefore, it is essential to perform a comprehensive analysis of the mutual inductance between the two coils that are connected through inductive coupling. This study provides an examination of mutual inductance (MI) and efficiency within the context of interoperability conditions of interconnected coils. The transmitter coil is represented as a square structure, denoted as TxS, whereas the receiving coil is represented as a circular structure, denoted as RxC. Furthermore, the application of ferrite cores and steel chassis inclosures, in combination with coils, is utilised for the objective of electric vehicle (EV) battery charging. The magnetic induction (MI) analysis is performed by the utilisation of finite element method (FEM) simulation. The finite element method (FEM) simulation outcomes of the interconnected coils with misalignments, encompassing both non-core and steel chassis configurations, are juxtaposed with the corresponding empirical observations.

Analysis of an Internal Electrical Short in an LHC Orbit-Corrector Magnet

A few beam orbit-corrector circuits of the Large Hadron Collider (LHC) show an unusual behavior during operation. These circuits can be ramped up to their nominal current, however their superconducting magnets quench when they are ramped down using the same ramp-rate. Furthermore, after the quench the measured circuit current increases above its initial value for a few tens of milliseconds. This transient is analyzed with the STEAM-LEDET program, which allows multiphysics transient simulations including electro-magnetic coupling between the turns, 3-dimensional thermal diffusion in the coil windings, ohmic loss, and inter-filament coupling loss. Simulation results show that this atypical magnet behavior can be fully explained by an internal turn-to-turn short. In fact, due to the strong magnetic coupling of the shorted turn to the rest of the coil, whenever the magnet transport current is changed, a current-change with opposite polarity is induced in the shorted turn. During circuit ramp-down, the current through the shorted turn reaches values significantly higher than in the rest of the coil. The simultaneous increase of the superconductor current density due to the induced current and of its temperature due to local ohmic loss in the short can lead to a quench. Subsequently, the current in the shorted turn rapidly reduces, and its energy transfers by inductive coupling to the rest of the coil, causing a temporary increase of its current.

Use of electrical measurements for non-invasive estimation of plasma electron density in the inductively coupled SPIDER ion source

SPIDER (source for the production of ions of deuterium extracted from RF plasma) is the full-scale prototype of the ITER neutral beam injector ion source. The plasma heating takes place inside eight drivers via inductive coupling, through the radiofrequency (RF) coil. To achieve optimum conditions during source operation it is necessary to know the plasma behavior under various operational conditions. One of the essential parameters is the plasma electron density. It is possible to experimentally measure this parameter and, currently, different methods are being explored, such as the estimations coming from a Langmuir probe and optical emission spectroscopy. However, these methods are either available for temporary measurements or require dedicated analyses with large uncertainties. In this regard, alternative, reliable, and fast diagnostic tools will be beneficial for the estimation of the order of magnitude of electron density inside the driver. Two models for the estimation of electron density are recalled, discussed, and further modified in this work: one is based on the classical power balance equation, and the other is recently described in the literature and relies on classical plasma conductivity. Both models use equivalent electrical parameters of the driver derived from available electrical measurements at the output of the RF generator and through the knowledge of the matching network and the transmission line length. This work explicitly focuses on the application of these models to estimate the plasma electron density in a single driver of SPIDER. Furthermore, the estimations are compared with the first experimental results obtained from temporary electrostatic probe measurements and are found to be in good agreement in terms of magnitude and trends.

Factors influencing the induced primary emission and induced secondary emission in the frequency range of 2 to 150 kHz

The induced primary emission leads to changes in the primary emission of a device and the induced secondary emission leads to changes in the propagation of supraharmonics in the adjacent phase due to the connection of single-phase loads spread over three phases in an installation. The induced primary emission and induced secondary emission are shown to give a significant contribution to the total emission measured at a given point in an installation. The induction of the emission is caused by the inductive and capacitive coupling among the conductors within the cables. This paper presents an analysis of four parameters that impact the magnitude of the induced emissions. Simulations carried out in COMSOL, show that the type of cable used impacts the induced emission and studies show that shielded cable with a stranded conductor with the shield grounded will lead to a reduction in the induced emissions. Among the other parameters, i.e., the load and transformer impedance and the length of the cable, the length of the cable is dominating in deciding the magnitude of the induced emissions. Analysis is carried out using Monte Carlo simulation and varying parameters stochastically. For all investigated parameters there is a strong frequency dependency. The stochastic variation of the load impedance in one phase causes a variation of 5% whereas the change in length of the cable leads to a maximum 40% variation in the considered frequency range for induced primary emission. Measurement results are presented to validate the results.

Low-field MRI's Spark on Implant Safety: A Closer Look at Radiofrequency Heating.

Advances in low-field magnetic resonance imaging (MRI) are making imaging more accessible without significant losses in image quality. In addition to being more cost-effective and easier to place without as much needed infrastructure, it has been publicized that the lower field strengths make MRI safer for patients with implants. To test this claim, we conducted a total of 368 simulations with wires of various lengths and geometries in a gel phantom during radiofrequency (RF) exposure at 23 MHz and 63.6 MHz (corresponding to MRI at 0.55 T and 1.5 T). Our results showed that heating in the gel around wire tips could be higher in certain cases at 0.55 T. To examine the impact on real patients, we simulated two models of patients with deep brain stimulation (DBS) implants of different lengths. These simulations provide quantitative evidence that low-field MRI is not always safer, and this paper serves to illustrate some of the basic principles involved in RF heating of elongated implants in MRI environments.Clinical Relevance- This paper illustrates the physical concepts of resonance and inductive coupling in RF heating during MRI scanning with implants through systematic simulations and discusses the impact of these principles in practice.

Geometric decoupling using clip-path conductors for whole-brain transceiver array at 7 T

In magnetic resonance imaging (MRI), a radiofrequency (RF) coil array with a large number of elements is commonly employed for transmission and reception to improve the uniformity of the RF transmitting magnetic field and increase the signal-to-noise ratio. Additionally, multi-element RF arrays can reduce the acquisition time using the parallel imaging technique. However, mutual inductance coupling is unavoidable in multi-element RF coil arrays. Therefore, many researchers have studied geometric and artificial decoupling techniques to minimize mutual inductance coupling. This study proposes a decoupling method using clip-path conductors (CPCs). The CPC geometry locates the top-right and bottom-left positions in the loop coil to reduce the mutual inductance coupling between adjacent elements. The decoupling performance of the CPC coil was verified via electromagnetic simulations and bench measurements. An eight-element transceiver CPC array was manufactured, and phantom and healthy volunteer images were acquired using a 7-T MRI system.

A mutually decoupled coil system to improve sensitivity of inductively coupled communication

AbstractThis paper proposes a mutually decoupled transmission and receiver coil (MDC) system to improve the sensitivity of inductively coupled communication. The proposed communication system is intended to be mounted on the frame of a spectacle and used to transfer a detectable voltage signal through weak inductive coupling with an implant measuring intraocular pressure (IOP). The implant consists of a coil that resonates with a capacitor. The capacitance of this capacitor is designed to change with the IOP, thus leading to a change in the self‐resonant frequency of the implant. The transmission coils excite the implant, while the decoupled receiver coils continuously monitor the self‐resonant frequency of the implant. The induced voltage across the receiver coil is used to determine the IOP. Simulation results show that a 1.43% change in the sensor capacitance leads to a 1 mV change in the voltage induced across the receiver coils. The experimental results reveal that raising the self‐inductance of the MDC on the transmission side results in a 0.5%/mV increase in sensitivity.

An AC-DC LED Integrated Streetlight Driver with Power Factor Correction and Soft-Switching Functions

The use of light-emitting diodes (LEDs) in street lighting applications has been greatly welcomed with the current trends of energy saving, environmental protection, carbon reduction, and sustainable development. This paper presents a novel AC-DC LED integrated streetlight driver that combines an interleaved buck converter with a coupled inductor and a half-bridge series resonant converter with a full-bridge rectifier into a single-stage power conversion topology with power factor correction (PFC) and soft switching capabilities. The PFC is achieved by designing the coupling inductor in the interleaved buck converter sub-circuit in discontinuous conduction mode. In addition, the resonant tank in the half-bridge series resonant converter sub-circuit is designed to be similar to an inductive load, thus giving the power switch a zero-voltage switching (ZVS) function, decreasing switching losses and increasing the overall efficiency of the proposed circuit. A prototype circuit of the proposed LED integrated streetlight driver with a power rating of 165 W (235 V/0.7 A) and 110 V input utility voltage has been developed and tested. According to the measurement results, a power factor greater than 0.98, a total harmonic distortion coefficient of the input current less than 3%, and an efficiency greater than 89% were obtained in the AC-DC LED integrated streetlight driver. Therefore, the experimental results are satisfactory and demonstrate the functionality of the proposed AC-DC LED integrated streetlight driver.

Dual Coupled Inductors With Controllable Integrated Leakage Inductance and CM Noise Suppression for CF-DAB Converter

A dual coupled inductors (DCI) structure is proposed, which integrates the two dc inductances, a high frequency transformer and a leakage inductance into two standard EE cores. And the dc inductance and leakage inductance can be accurately controlled by designing the number of PCB windings and the air gap length. Consequently, a DCI DAB converter is derived by the derivation process of the DCI structure. Furthermore, to suppress the CM noise, an improved PCB winding coupled inductor structure is proposed to reduce the parasitic capacitance. The proposed improved coupled inductor structure is obtained by the exchanged PCB layers and misaligned PCB windings. Finally, the validity of the proposed topology and design is verified by experimental results from a 1-kW laboratory prototype.

An E-Core Based Integrated Coupled Inductor for Interleaved Boost Converter

Interleaving in a boost converter is beneficial for lowering input and output current ripples through ripple cancellation due to phase-shift between channel currents. However, interleaving does not affect the channel current ripple. The channel current comprises circulating Differential Mode (DM) current and Common Mode (CM) boost current, whose ripples constitute the total channel current ripple. Inverse coupling between channel inductors effectively lowers channel current ripple while maintaining the same input and output current ripples. However, with a single inverse coupled inductor, its leakage inductance, which serves as a boost inductor, depends on the winding arrangement and is challenging to balance in both channels. To overcome this, the inverse coupled inductor can be implemented as a cascade of inverse (DM inductance) and direct (CM inductance) coupled inductors. The DM and CM currents and their ripples then depend on CM and DM inductances, respectively. Nonetheless, this approach results in increased size and count of magnetic cores. In this paper, an Integrated Magnetic Structure (IMS), based on a gapped EE-core, is proposed that combines both CM and DM inductances in a single core. The CM and DM inductances are independent and depend on separate winding turns. A reluctance model is derived, and a design procedure is developed where core parameters are expressed in terms of converter parameters. Finally, the proposed IMS concept is validated through a 300 W, 100 V to 168 V prototype, switching at 70 kHz.