Common Coil Research Articles

Design of a Common Coil Magnet Using Existing Racetrack Model Coils (RMC)

Design of a Common Coil Magnet Using Existing Racetrack Model Coils (RMC)

Subscale Stress-Managed Common Coil Design

Subscale Stress-Managed Common Coil Design

Orthogonal-Frequency Simultaneous Wireless Power and Data Transfer for High-Power Wireless EV Charging

In a simultaneous wireless power and data transfer (SWPDT) system using common coils, achieving high-speed communication in high-power wireless charging systems is challenging due to power transfer interference on communication. Based on high-frequency data carrier-based SWPDT (HFDC-SWPDT) technology, this paper proposes an orthogonal-frequency simultaneous wireless power and data transfer (OF-SWPDT) method to minimize interference where the data carrier frequency is orthogonal to the power carrier frequency and its harmonics. In addition, a guard band is inserted between the spectra of power harmonics and data in order to further separate the power and data spectra. Thus, a high-power, high-speed SWPDT system is achieved. Finally, an 11 kW prototype with 64.125 kbps full-duplex communication is developed to validate the proposed method.

Development of superconducting model dipole magnets beyond 12 T with a combined common-coil configuration

The superconducting magnet group at IHEP (the Institute of High Energy Physics, Chinese Academy of Sciences, China) has been engaging in the R&D of high field accelerator magnets since 2014 for the pre-study of the next-generation high energy particle accelerators like CEPC-SPPC (Circular Electron Positron Collider-Super Proton Proton Collider), FCC (Future Circular Collider), etc. A superconducting model dipole magnet named LPF1 was first fabricated with NbTi and Nb3Sn in a combined common-coil configuration in 2017 and tested in 2018, a main field of 10.23 T was reached within two 10 mm apertures. The magnet was reassembled with higher pre-stress in 2019 to investigate the influence of the pre-stress loading level on the performance of common-coil dipole magnets. The main field of this upgraded magnet named LPF1-S was increased to 10.71 T within two 12 mm apertures. By improving the key processing technologies in Rutherford cable fabrication, coil winding, Nb3Sn & NbTi splices soldering and coil impregnation, the recently fabricated model dipole magnet named LPF1-U attained a 12.47 T main field in two 14 mm apertures in 2021. To fully take advantage of Nb3Sn and NbTi superconductors in different field regions, LPF1-U was still designed and developed with a combined coil configuration with Nb3Sn for the inner two coils and NbTi for the outer four coils. Additionally, graded coil topology and different coil LSS (length of straight section) settings were adopted in the optimization of LPF1-U layouts. Bladder and key technology was used for the support structure, and fiber optic sensors based on FBG (fiber Bragg grating) were utilized to monitor the stress distribution and variation in the structures and coils through the whole process from magnet assembly to cool-down and excitation. During the performance test, a relatively large number of trainings were carried out and LPF1-U became more stable after the thermal cycle. A peak field of 12.7 T in the coils (12.47 T main field in apertures) corresponds to an operating current of 6865 A and a load line ratio of 90% was finally attained. It is worth mentioning that LPF1-U is the first hybrid—Nb3Sn, NbTi—common coil dipole magnet that has achieved a main field of more than 12 T in two apertures. The design, fabrication and performance analysis of the LPF series dipole magnets are presented in this paper.

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.

ModMag: A modular magnetic micro-robotic manipulation device

Electromagnetic systems have been used extensively for the control of magnetically actuated objects, such as in microrheology and micro- robotics research. Therefore, optimizing the design of such systems is highly desirable. Some of the features that are lacking in most cur- rent designs are compactness, portability, and versatility. Portability is especially relevant for biomedical applications in which in vivo or in vitro testing may be conducted in locations away from the laboratory microscope. This document describes the design, fabrication, and imple- mentation of a compact, low-cost, versatile, and user-friendly device (the ModMag) capable of controlling multiple electromagnetic setups, includ- ing a two-dimensional 4-coil configuration, a 3-dimensional Helmholtz configuration, a 2-dimensional magnetic tweezer configuration, and a piezoelectric transducer for producing acoustic waves. All electronics for powering the systems are contained in a compact 10″x6”x3” case, which includes a 10″ touchscreen. A graphical user interface provides additional ease of use. The system can also be controlled remotely, allowing for more flexibility and the ability to interface with other software running on the remote computer such as proprietary camera software. Aside from the software and circuitry, we also describe the design of the electromagnetic coil setups and provide examples of the use of the ModMag in experiments.•Low cost and portable magnetic micro-robot manipulation device•Compatible with the 3 most common coil configurations (traditional, Helmholtz, tweezer)

Coil optimization of ultra-deep azimuthal electromagnetic resistivity logging while drilling tool based on numerical simulation

This paper presents a coil optimization method of the ultra-deep azimuthal electromagnetic (EM) resistivity Logging While Drilling (LWD) to obtain the best parameters of the tool for formation boundary detection by theory. First, a rapid numerical simulation algorithm, i.e. the Fast Hankel Transform (FHT) method, is developed to simulate the logging responses of the layered formation. A system of double inclined coils is selected based on the response characteristics and the depth of detection (DOD) from four common coils. Simulation results demonstrated that the optimal coils are perfectly suitable for anisotropic formation. Then, the crucial parameters of the frequency and spacing of the selected coils with a DOD of 30 m are determined using the Picasso diagram. In addition, the influences of the electrical parameter of the drilling collar and resistivity anisotropy of the formation on the response are investigated. The results show that the conductivity of the drilling collar, the thickness and the resistivity anisotropy of the formation all affect the DOD. Finally, formation models with different layers are created to verify the performance and signal intensity. The results demonstrate that the optimized coils not only have a large DOD but also possess a high signal intensity, further confirming the advantages of the preferred coils. Compared with the conventional physical experiment tests, the method of coil optimization proposed in this paper is more economical and efficient. The findings of this study can help better understand the detection characteristics of the different coils, which can provide theoretical support for designing and developing a tool with the best boundary capability.

Noise Countermeasure Effect of Common Mode Choke Coil on Electromagnetic Radiation Characteristics from Differential Transmission Line

Noise Countermeasure Effect of Common Mode Choke Coil on Electromagnetic Radiation Characteristics from Differential Transmission Line

Designing a circular coil of repetitive transcranial magnetic stimulation at frequencies of 0.5 and 1 Hz using CST studio suite software and comparison of results with theoretical calculations

Context: Since the 1990s, repetitive transcranial magnetic stimulation (rTMS) has been used as a noninvasive method to diagnose and manage the treatment of many neurological disorders. The circular coil is one of the most common coils in rTMS devices. This study presents the design documentation of a circular coil for use in the rTMS device and examines the consistency of the magnetic field intensity (H) and the magnetic flux density (B) obtained from the simulation of its use with the theoretical values. Aims: This study aimed to design a rTMS circular coil at frequencies of 0.5 and 1 Hz using CST Studio Suite software and compare the intensity of the B- and H-fields with theoretical calculations. Materials and Methods: After designing a circular coil, we measured B and H by simulation with CST Studio Suite software and compared the results with theoretical calculations. Results: The magnetic field intensity and the magnetic flux density obtained from the circular coil simulation we designed had an acceptable consistency with the theoretical values. Conclusions: The B- and H-field intensity whether on the body or in the air, or on the antenna, is fairishly consistent with theoretical calculations.

Оценка стягивающих и растягивающих сил в тороидальных и линейных накопителях электроэнергии

Object and purpose of research. Electromagnetic forces in thin-walled coils of toroidal type and common type of different cross-sections (circular, rectangular, disk, spherical) are estimated and compared. Materials and methods. Methods of theoretical electric engineering are used. Main results. It is established that forces for toroidal and common coils have different character. First, there is an effect of centripetal compression, secondly, there is an effect of centripetal tensioning. Conclusions. These effects should be taken into account in the coil design, which have to withstand deformation or damage under compressive or tensioning forces.

Stray-Capacitance As a Simple Tool for Monitoring and Locating Heat Generation Demonstrated in Three Superconducting Magnets

Real-time monitoring of heat loads in cryogenic systems is critical for many applications, particularly high field magnets. We demonstrated that by monitoring changes in the capacitance of local probes consisting of thin metal strips with a porous glass fiber dielectric, boiling helium from as little as 0.1 J of deposited heat can be located by an analysis of the response speed and amplitude in nearby probes. We further implemented stray-capacitance monitoring of a magnet's metal support structures, a more global probe of the magnet volumes, in three high temperature superconducting Bi-2212 magnet types. Global structural stray-capacitance monitoring was evaluated for a single racetrack coil, a common coil dipole, and a canted cosine theta winding, showing a quench response comparable to voltage signals without inductive effects. The response of the local and global probes was compared in the single racetrack coil with well-known quench properties. Monitoring the cool-down of the common coil dipole demonstrated the added benefit of the global stray-capacitance as a liquid level monitor. This simple method of monitoring the capacitance has proven to be a versatile and robust technique for monitoring and locating heat.

Wireless power transfer system for angled concave conditions utilizing quasi-bowl-shaped couplers

Wireless power transfer (WPT) is favored by consumers due to its convenience, safety, and flexible layout. Circular and rectangular coils are the most common coil structures in WPT systems. However, they are not suitable for installation conditions with angled groove areas such as railways, conveyors, and so on. To fully utilize installation space and to improve transfer efficiency, this paper has proposed a quasi-bowl-shaped (QBS) magnetic coupler, which can suitably fit on angled grooves. First, a QBS coupler model was presented. Second, formulas of its spatial magnetic field density were derived. Third, the influences of the bending distance and bending angle on the coupler coefficient were analyzed. Fourth, five magnetic core types were presented and analyzed for coupler optimization. Finally, QBS WPT performances were tested on a newly built experiment platform. Experimental results show that the QBS coupler can realize a constant transfer efficiency of 92.36% at an axial distance of 6 cm, and it can realize a constant transfer efficiency of 84.17% at an axial distance of 10 cm.

Development and optimization of a receive-only surface array with purely geometrical decoupling for rat brain MRI at 2 T

Magnetic resonance imaging (MRI) experiments on small animals, as well as in humans, require specific radiofrequency (RF) coil designs in order to maximize field homogeneity during excitation and signal-to-noise ratio (SNR) during reception. Therefore, the use of dedicated transmit-only and receive-only coil geometries has been preferred as standard technology configuration. Among the receive coil geometries, the surface coil has been widely used to increase the SNR in localized regions of interest. With the advent of MRI-phased arrays, the high sensitivity of surface coils can be achieved in extended regions, further allowing parallel imaging acquisition methodologies to accelerate acquisition time. This work describes the development and characterization of a two-channel receive-only RF coil set specifically designed for MRI acquisition of rat brain in a 2 T system for neuroscience studies. We have developed and compared the performance of one common surface coil with a two-channel phased array with purely geometric decoupling between coil elements (i.e., without using low input impedance preamplifiers), both actively detuned during reception and having exactly the same dimensions. The results have shown that the single-channel surface coil achieved up to 5 times higher SNR at 5 mm depth compared to a volume coil commonly used for rat brain MRI in our laboratory, while the two-channel array achieved 4 times higher SNR at the same depth, with the additional advantage of producing an extended area with higher sensitivity. In vivo brain images of anesthetized rats confirmed the SNR gain for both receive-only single-channel surface coil and two-channel array in comparison with a volume coil. We have verified that only using the partial overlapping technique does not provide sufficient isolation to eliminate mutual coupling interaction between elements, since residual coupling can still affect the coil performance.

Quench protection of the BabyIAXO magnet

BabyIAXO, a 20 m-long twin-bore helioscope aiming for search of axion like particles, is currently in the engineering design phase and its construction is to be completed within the next 4 years. In addition to X-ray detectors and focusing optics, the system is equipped with a 50 MJ magnet with a common coil layout, containing two 10 m-long NbTi flat racetrack coils cooled by a group of cryocoolers. It has to operate at 10 kA, preferably in persistent mode with disconnected power supply, allowing to simplify the sun-tracking rotation system of BabyIAXO. A direct current mode is possible as well. Hence, quench protection is a high priority. Here, we present the electrical circuit of the BabyIAXO magnet and its protection layout when operated in persistent mode. The quench process is calculated using a 3-D thermo-electrical model of the coil windings, also accounting for the presence of the coil casing and the quench-back effect. Impact of the operating current, conductor properties, voltage detection threshold and location of hot-spot on the peak temperature is discussed. Quench protection aspects of the HTS busbars and persistent mode switch are also addressed.

Mechanical Design and Analysis of the Baby-IAXO Magnet Cold Mass, Cryostat and Support System

According to the so-called Primakoff effect, axions and axion-like particles can transform into photons in the presence of a strong magnetic field. To continue the search for these hypothetical particles, a new helioscope called the International Axion Observatory IAXO, and its subscale but fully functional demonstrator Baby-IAXO, are being designed. To increase the detector's sensitivity by a factor of 10 compared to the present CAST helioscope, the experiment needs a stronger magnetic field and in a much larger volume. The superconducting magnet of Baby-IAXO features two 10 m long flat racetrack coils spaced by 0.8 m, arranged in a common coil configuration and generating an average magnetic field of 2.1 T in the two 700 mm detection bores positioned in between the coils. The cold mass structure based on using mainly Al6061-T651, is designed to guarantee pre-stress of the coils during curing and sustain the magnetic loads by the Lorentz force. At ultimate current of 12 kA, the repelling force between the two coils is 33 MN. Furthermore, the supporting structure has to keep the coils in position as they are in an unstable equilibrium in the plane parallel to the racetracks. To support the cold mass in the cryostat, an arrangement of rods was chosen in order to minimize the cryogenic load. The system is composed of 16 titanium rods, which in addition to supporting the expected force loads also keeps the magnet centered. The total mass of the magnet is 35 t comprising an 18 t cold mass and a 15 t cryostat. The magnet is installed on an elevated 360° rotating platform further constraining the cryostat design. Here the mechanical design of cold mass, cold mass supporting system and cryostat of the Baby-IAXO magnet are presented.

Method for the calculation of coupling coefficient between two arbitrary‐shaped coils

A new analytic method to calculate the coupling coefficient including self-inductances and mutual inductance between two arbitrary-shaped coils is proposed. The proposed method is applicable for all common coil geometries such as rectangular, square, polygonal, circular coils etc. In the formula, the coil function, which is a completely a new type of function, is defined. The differences in shape and position of the coils are only on the choice of the coil function and its complex conjugate. The layouts of the two coils including separation change and lateral misalignment are discussed. An experimental setup has been built to validate the analytic calculations. Theoretical and experimental results are then compared to be in good agreement, which verify the effectiveness of the proposed method.

Sistema de carga inalámbrica para vehículos eléctricos en reposo

El lento crecimiento del uso de vehículos eléctricos se debe a múltiples problemas, uno de ellos es la carga del auto utilizando cable, método conocido como plug-in. Una alternativa tecnológica que puede sustituir a los cables es el sistema de transferencia de energía mediante inducción electromagnética; por el momento esta transferencia de energía es de baja potencia comparada con el sistema por cable. El objetivo de este proyecto de investigación es demostrar que el sistema de carga por inducción es totalmente factible para un vehículo estacionado. Para ello se usa una bobina fuente ubicada en el piso del parqueadero, y una bobina captadora localizada en el bastidor del auto. En este trabajo se demuestra experimentalmente cómo varía la potencia de transferencia al variar las distancias entre las dos bobinas; se consideran tres alternativas: bobinas con núcleos de aire, bobinas con núcleo de hierro común y bobinas con núcleos de hierro separados. Las mediciones se realizan en un prototipo formado por dos bobinas separadas una distancia d y provisto de una escala de medida en milímetros. Finalmente, se evalúa el comportamiento de la energía transferida en función de la distancia entre bobinas y las tres alternativas de núcleo magnético

Impedance calculation of arbitrary-shaped thin-walled coils for eddy-current testing of planar media

Eddy-current testing is used in a variety of fields, so it is important to analyze the coil impedance. Previous studies on impedance calculation have mainly focused on circular and rectangular coils. This paper presents a general method to evaluate the impedance of an arbitrary-shaped thin-walled coil facing with a planar media. The impedance formulas are deduced by using second order vector potential (SOVP) method. In the formulas, the coil function, which is in double-integral form, is defined. The impedance calculation for arbitrary-shaped coils can be represented by the corresponding coil function. The coil functions for common coils such as circular, triangular, rectangular and trapezoidal coils are also derived in this paper. Finally, the impedance and impedance change of various shaped coils above an aluminum plate are measured, and compared with calculated values. The results indicated that they have a good agreement.

S151. Assessing lower limb cortical function with threshold tracking transcranial magnetic stimulation

Introduction Transcranial magnetic stimulation (TMS) is a useful, non-invasive tool that can explore the functional integrity of the primary motor cortex and corticomotor pathways. Although the application of TMS has rapidly increased in the last decade using upper limb muscle targets, there remains a relative paucity of lower limb studies. Additionally, the paired-pulse TMS paradigms that have been applied to explore lower limb cortical parameters have shown significant variability in motor evoked potential (MEP) amplitudes, questioning the reliability and clinical utility of this technique. Threshold tracking TMS (TT-TMS) was recently developed to overcome such methodological problems, but this protocol has been limited to upper limb studies. Importantly, the inherent differences in upper and lower limb normal cortical function and the differing pattern of disease in lower limb predominant neurological disorders highlights the need for a more robust understanding of lower limb corticomotoneuronal function. Thus, the aim of the present study was to employ TT-TMS to establish lower limb cortical parameters and to investigate side-to-side differences to determine laterality of normal cortical function. Methods Studies were performed in 40 healthy participants recording from the tibialis anterior muscle bilaterally. Three common coil choices (90 mm circular coil, 70 mm figure-8 coil, 110 mm double cone coil) were explored. Single-pulse TMS, paired-pulse TT-TMS and nerve conduction studies were performed. Results The double cone coil had the greatest efficacy, generating a significantly lower resting motor threshold than the circular (p = 0.04) or figure-8 (p = 0.01) coils. Paired-pulse TT-TMS generated an averaged short interval intracortical inhibition of 11.3 ± 1.2%, with an averaged intracortical facilitation of −8.5 ± 1.1%. Central motor conduction time (CMCT) was 8.9 ± 0. 6 ms.There were no differences between dominant and non-dominant sides for all single (RMT, MEP latency, MEP amplitude, MEP/CMAP ratio, CSP and CMCT) and paired-pulse TT-TMS parameters (peak SICI 1 ms, peak SICI 3 ms, averaged SICI and ICF). Similarly, peripheral measures of nerve function were not significantly different between the dominant and non-dominant hemispheres for all measures tested. Conclusion This study successfully assessed cortical excitability and corticospinal pathways from the lower limbs using TT-TMS, establishing normative data, symmetry of normal cortical function, and validating the double cone coil for future studies. These findings can now be applied to explore further aspects of lower limb physiology and used for the clinical interpretation of motor cortical dysfunction across a range of neurological diseases. Together with previously established upper limb TT-TMS, this study will now inevitably allow for a more comprehensive evaluation of normal neuronal processes and patterns of disease across a larger area of cortical representation.

Magnetic and Mechanical Design of a 16 T Common Coil Dipole for an FCC

A EuroCirCol is a conceptual design study for a post-LHC research infrastructure based on an energy-frontier 100 TeV circular hadron collider. In the frame of the high-field accelerator magnet design work package of this study, the feasibility of a 16 T dipole in a common coil configuration is being studied. This paper shows the electromagnetic design optimization performed to achieve the required field quality while minimizing the superconductor volume and taking into account the input parameters and assumptions of the EuroCirCol study. The finite element models have been used to analyze the stress distribution and deformations under the large Lorentz forces due to the very high magnetic field. Several iterations have been necessary to obtain a feasible magnet design. The 3-D electromagnetic calculations are also included in this paper.