Showing papers on "Electromagnetic coil published in 2017"
TL;DR: The developed field modulation theory not only unifies the principle analysis of a large variety of electrical machines, including conventional dc machine, induction machine, and synchronous machine which are just special cases of the general field modulated machines, thus eliminating the problem of the machine theory fragmentation, but also provides a powerful guidance for inventing new machine topologies.
Abstract: This paper proposes a general field modulation theory for electrical machines by introducing magnetomotive force modulation operator to characterize the influence of short-circuited coil, variable reluctance, and flux guide on the primitive magnetizing magnetomotive force distribution established by field winding function multiplied by field current along the airgap peripheral. Magnetically anisotropic stator and rotor behave like modulators to produce a spectrum of field harmonics and the armature winding plays the role of a spatial filter to extract effective field harmonics to contribute the corresponding flux linkage and induce the electromotive force. The developed field modulation theory not only unifies the principle analysis of a large variety of electrical machines, including conventional dc machine, induction machine, and synchronous machine which are just special cases of the general field modulated machines, thus eliminating the problem of the machine theory fragmentation, but also provides a powerful guidance for inventing new machine topologies.
316 citations
TL;DR: In this article, the authors proposed a new method to integrate the compensated coil into the main coil structure, which not only makes the system more compact, but also the extra coupling effects resulting from the integration are either eliminated or minimized to a negligible level.
Abstract: There is a need for charging electric vehicles (EVs) wirelessly since it provides a more convenient, reliable, and safer charging option for EV customers. A wireless charging system using a double-sided LCC compensation topology is proven to be highly efficient; however, the large volume induced by the compensation coils is a drawback. In order to make the system more compact, this paper proposes a new method to integrate the compensated coil into the main coil structure. With the proposed method, not only is the system more compact, but also the extra coupling effects resulting from the integration are either eliminated or minimized to a negligible level. Three-dimensional finite-element analysis tool ANSYS MAXWELL is employed to optimize the integrated coils, and detailed design procedures on improving system efficiency are also given in this paper. The wireless charging system with the proposed integration method is able to transfer 3.0 kW with 95.5% efficiency (overall dc to dc) at an air gap of 150 mm.
245 citations
Patent•
13 Mar 2017
TL;DR: A quantitative measurement system includes an external unit and an internal unit are provided for obtaining quantitative analyte measurements, such as within the body as discussed by the authors, where the internal unit contains optoelectronics circuitry, a component of which may be comprised of a fluorescence sensing device.
Abstract: A quantitative measurement system includes an external unit and an internal unit are provided for obtaining quantitative analyte measurements, such as within the body. In one example of an application of the system, the internal unit would be implanted either subcutaneously or otherwise within the body of a subject. The internal unit contains optoelectronics circuitry, a component of which may be comprised of a fluorescence sensing device. The optoelectronics circuitry obtains quantitative measurement information and modifies a load as a function of the obtained information. The load in turn varies the amount of current through coil, which is coupled to a coil of the external unit. A demodulator detects the current variations induced in the external coil by the internal coil coupled thereto, and applies the detected signal to processing circuitry, such as a pulse counter and computer interface, for processing the signal into computer-readable format for inputting to a computer.
155 citations
TL;DR: In this article, a small 5-turn solenoid was constructed and measured as a function of applied magnetic field, exhibiting an engineering current density of 233 Amm−2 at 4.2 K and 10 T. Critical current measurements were performed on tapes extracted from CORC® wires made using 2 and 3 mm wide tape after bending the wires to various diameters from 10 to 3.5 cm.
Abstract: Conductor on Round Core (CORC®) technology has achieved a long sought-after benchmark by enabling the production of round, multifilament, (RE)Ba2Ca3O7−x coated conductors with practical current densities for use in magnets and power applications. Recent progress, including the demonstration of engineering current density beyond 300 Amm−2 at 4.2 K and 20 T, indicates that CORC® cables are a viable conductor for next generation high field magnets. Tapes with 30 μm substrate thickness and tape widths down to 2 mm have improved the capabilities of CORC® technology by allowing the production of CORC® wires as thin as 3 mm in diameter with the potential to enhance the engineering current density further. An important benefit of the thin CORC® wires is their improved flexibility compared to thicker (7–8 mm diameter) CORC® cables. Critical current measurements were carried out on tapes extracted from CORC® wires made using 2 and 3 mm wide tape after bending the wires to various diameters from 10 to 3.5 cm. These thin wires are highly flexible and retain close to 90% of their original critical current even after bending to a diameter of 3.5 cm. A small 5-turn solenoid was constructed and measured as a function of applied magnetic field, exhibiting an engineering current density of 233 Amm−2 at 4.2 K and 10 T. CORC® wires thus form an attractive solution for applications between 4.2 and 77 K, including high-field magnets that require high current densities with small bending diameters, benefiting from a ready-to-use form (similar to NbTi and contrary to Nb3Sn wires) that does not require additional processing following coil construction.
149 citations
TL;DR: In this paper, the authors proposed a resonant reactive shielding coil topology for reducing EMF in a near-field WPT mobile device application, which employs a closed loop and matching capacitors and is demonstrated to dramatically reduce the leakage magnetic field from a WPT system.
Abstract: Demand and interest in wireless power transfer (WPT) have been rapidly increasing lately. However, WPT systems have problems with electromagnetic field (EMF) leakage, which has stimulated interest in methods to suppress EMF leakage levels. In this paper, we propose a compact resonant reactive shielding coil topology for reducing EMF in a near-field WPT mobile device application. The proposed shielding coil employs a closed loop and matching capacitors, and is demonstrated to dramatically reduce the leakage magnetic field from a WPT system. For validation, the proposed shielding was implemented with other shielding topologies and the EMFs were measured and compared. The analytical, simulation, and measurement results were all strongly correlated.
132 citations
TL;DR: A 25 T cryogen-free superconducting magnet (25T-CSM) was developed and installed at the High Field Laboratory for Superconducting Materials (HFLSM), IMR, Tohoku University as mentioned in this paper.
Abstract: A 25 T cryogen-free superconducting magnet (25T-CSM) was developed and installed at the High Field Laboratory for Superconducting Materials (HFLSM), IMR, Tohoku University. The 25T-CSM consists of a high-temperature superconducting (HTS) coil and a low-temperature superconducting (LTS) coil. A high-strength CuNb/Nb3Sn Rutherford cable with a reinforcing stabilizer CuNb composite is adopted for the middle LTS section coil. All the coils were impregnated using an epoxy resin for conduction cooling. Initially, a GdBa2Cu3O y (Gd123) coil was designed as the HTS insert coil, and then a Bi2Sr2Ca2Cu3O y (Bi2223) coil was also developed. The HTS insert and the LTS (CuNb/Nb3Sn and NbTi) outsert coils are cooled by two 4K GM and two GM/JT cryocoolers, respectively. The LTS coils successfully generated a central magnetic field of 14 T at an operating current of 854 A without any training quench. The Gd123 coil generated 10.15 T at an operating current of 132.6 A in the absence of a background field. Subsequently, the operating current of the Gd123 insert was increased in a step-by-step manner under a background field of 14 T. The Gd123 coil could be operated up to 124.0 A stably, which corresponds to 23.55 T, but quenched at around 124.6 A (23.61 T). The Bi2223 insert coil using a Ni-alloy reinforced Bi2223 tape successfully generated 11.48 T at an operation current of 204.7A in a stand-alone test and 24.57 T in a background field of 14 T. The differences between the calculated and the measured values of the central magnetic fields are about 0.4 T for the Gd123 insert and 0.1 T for the Bi2223 insert around 24 T.
128 citations
TL;DR: Phase imaging benefits from strong susceptibility effects at very high field and the high signal‐to‐noise ratio (SNR) afforded by multi‐channel coils, but alternative approaches are required for ultra‐high field systems in which no such coil is available.
Abstract: Phase imaging benefits from strong susceptibility effects at very high field and the high signal-to-noise ratio (SNR) afforded by multi-channel coils. Combining the information from coils is not trivial, however, as the phase that originates in local field effects (the source of interesting contrast) is modified by the inhomogeneous sensitivity of each coil. This has historically been addressed by referencing individual coil sensitivities to that of a volume coil, but alternative approaches are required for ultra-high field systems in which no such coil is available. An additional challenge in phase imaging is that the phase that develops up to the echo time is " wrapped" into a range of 2p radians. Phase wraps need to be removed in order to reveal the underlying phase distribution of interest. Beginning with a coil combination using a homogeneous reference volume coil -the Roemer approach -which can be applied at 3 T and lower field strengths, we review alternative methods for combining single-echo and multi-echo phase images where no such reference coil is available. These are applied to high-resolution data acquired at 7 T and their effectiveness assessed via an index of agreement between phase values over channels and the contrast-to-noise ratio in combined images. The virtual receiver coil and COMPOSER approaches were both found to be computationally efficient and effective. The main features of spatial and temporal phase unwrapping methods are reviewed, placing particular emphasis on recent developments in temporal phase unwrapping and Laplacian approaches. The features and performance of these are illustrated in application to simulated and high-resolution in vivo data. Temporal unwrapping was the fastest of the methods tested and the Laplacian the most robust in images with low SNR. (C) 2016 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.
123 citations
TL;DR: In this article, the three-coil structure is compared with the two-and three-layer structure based on circuit theory to give a more intuitive and comprehensive analysis of the energy efficiency differences between the two structures.
Abstract: With the development of electric vehicles and consumer electronics, wireless power transfer (WPT) is becoming a popular technology. Recently, magnetic resonant coupling has been considered to be the most effective and attractive WPT approach, and the two-coil structure is the most widely used for magnetic resonant coupling. It has been recently reported that the system's energy efficiency can be improved by a three-coil structure. In this paper, the three-coil structure is compared with the two-coil structure based on circuit theory. Simplified circuit models of the two- and three-coil structures are proposed to give a more intuitive and comprehensive analysis of the energy efficiency differences between the two structures. With the simplified model, the condition for a three-coil structure obtaining higher energy efficiency over its two-coil counterpart is derived, and the analysis shows that the WPT system with higher energy efficiency within a wider range of loads can be achieved by properly designed three-coil systems. Additionally, it also shows that the three-coil system has the significant advantage of reducing the current stress and the electromagnetic field emission that is caused by misalignments. The theoretical analysis is confirmed by both simulation and experimental results.
122 citations
TL;DR: A novel sliding mode control based high-precision hydraulic pressure feedback modulation based on an open loop load pressure control based on the linear relationship between the pressure-drop and coil current in valve critical open equilibrium state is proposed and experimentally validated.
Abstract: High precision and fast response are of great significance for hydraulic pressure control in automotive braking systems. In this paper, a novel sliding mode control based high-precision hydraulic pressure feedback modulation is proposed. Dynamical models of the hydraulic brake system including valve dynamics are established. An open loop load pressure control based on the linear relationship between the pressure-drop and coil current in valve critical open equilibrium state is proposed, and also experimentally validated on a hardware-in-the-loop test rig. The control characteristics under different input pressures and varied coil currents are investigated. Moreover, the sensitivity of the proposed modulation on valve's key structure parameters and environmental temperatures are explored with some unexpected drawbacks. In order to achieve better robustness and precision, a sliding mode control based closed loop scheme is developed for the linear pressure-drop modulation. Comparative tests between this method and the existing methods are carried out. The results validate the effectiveness and superior performance of the proposed closed loop modulation method.
121 citations
TL;DR: In this article, an efficient two-dimensional T-A formulation based approach is proposed to calculate the electromagnetic characteristics of tape stacks and coils made of second generation high temperature superconductors.
Abstract: An efficient two dimensional T-A formulation based approach is proposed to calculate the electromagnetic characteristics of tape stacks and coils made of second generation high temperature superconductors. In the approach, a thin strip approximation of the superconductor is used in which the superconducting layer is modeled as a 1-dimensional domain. The formulation is mainly based on the calculation of the current vector potential T in the superconductor layer and the calculation of the magnetic vector potential A in the whole space, which are coupled together in the model. Compared with previous T-based models, the proposed model is innovative in terms of magnetic vector potential A solving, which is achieved by using the differential method, instead of the integral method. To validate the T-A formulation model, it is used to simulate racetrack coils made of second generation high temperature superconducting (2G HTS) tape, and the results are compared with the experimentally obtained data on the AC loss. The results show that the T-A formulation is accurate and efficient in calculating 2G HTS coils, including magnetic field distribution, current density distribution, and AC loss. Finally, the proposed model is used for simulating a 2000 turn coil to demonstrate its effectiveness and efficiency in simulating large-scale 2G HTS coils.
117 citations
TL;DR: Although the dTMS coils offer new tool with potential for both research and clinical applications for psychiatric and neurological disorders associated with dysfunctions of deep brain regions, the selection of the most suitable coil settings for a specific clinical application should be based on a balanced evaluation between stimulation depth and focality.
Abstract: Stimulation of deeper brain structures by transcranial magnetic stimulation (TMS) plays a role in the study of reward and motivation mechanisms, which may be beneficial in the treatment of several neurological and psychiatric disorders. However, electric field distributions induced in the brain by deep transcranial magnetic stimulation (dTMS) are still unknown. In this paper, the double cone coil, H-coil and Halo-circular assembly (HCA) coil which have been proposed for dTMS have been numerically designed. The distributions of magnetic flux density, induced electric field in an anatomically based realistic head model by applying the dTMS coils were numerically calculated by the impedance method. Results were compared with that of standard figure-of-eight (Fo8) coil. Simulation results show that double cone, H- and HCA coils have significantly deep field penetration compared to the conventional Fo8 coil, at the expense of induced higher and wider spread electrical fields in superficial cortical regions. Double cone and HCA coils have better ability to stimulate deep brain subregions compared to that of the H-coil. In the mean time, both double cone and HCA coils increase risk for optical nerve excitation. Our results suggest although the dTMS coils offer new tool with potential for both research and clinical applications for psychiatric and neurological disorders associated with dysfunctions of deep brain regions, the selection of the most suitable coil settings for a specific clinical application should be based on a balanced evaluation between stimulation depth and focality.
TL;DR: A rail-borne electromagnetic energy harvester with copper-beads spacing is proposed and fabricated, the suitable for harvesting vibration-induced energy of the wheelset/track system and an electromagnetic model is established to predict the induced voltage.
Abstract: Design, modeling, simulation, and vibration testing related to electromagnetic energy harvesters are investigated in this paper. A rail-borne electromagnetic energy harvester with copper-beads spacing is proposed and fabricated, the suitable for harvesting vibration-induced energy of the wheelset/track system. A vehicle-track model considering vehicle traveling load is constructed and numerically solved by fast explicit integration methods. An electromagnetic model is established to predict the induced voltage. The track irregularity power spectrum density is applied as excitation source on the track. Based on the calculation results, both the resonant harvester and the magnetic levitation harvester are designed. The solution utilizes copper beads as radial spacing, which guarantees reliable unidirectional movement of magnets inside a multilayer-multirow coil. Vibration tests are conducted with the proposed track-borne device, and a hydraulic driven system is exploited to generate the realistic wheelset/rail interaction force. The proposed rail-borne energy harvester can be mounted to the track easily and extensively. The magnetic levitation harvester offers an approach for harvesting broadband low-frequency (3–7Hz) wheelset/track interaction with the rail displacement of 0.6 to 1.2 mm. For the resonant harvester, the output power of 119 mW and the output peak-peak voltage of 2.32 V are achieved with the rail displacement of 1.2 mm, the coil height of 48 mm, the load resistance of 45 $\Omega $ , the coil inductance of 105.572 mH, and 3000 numbers of turns. Furthermore, a dc–dc boost converter is proposed, which is capable of converting the alternating voltage of the transducer into 5 V/10-mA dc output at the resonant frequency of 6 Hz, the rail displacement of 2 mm, and the induced voltage of 3.4 V.
TL;DR: A new power transmission coil capable of producing uniform magnetic field is proposed to improve power stability through uniform field that at the same time minimizes the unnecessary peak electromagnetic exposure and improve power transfer efficiency for wireless capsule endoscopy.
Abstract: Magnetic resonance-based wireless power transfer system offers a promising solution to overcome power limitations typically encountered by capsule endoscopy. Despite of much attention in this area, aspects such as power stability and power transfer efficiency remain suboptimal and therefore investigation for further improvement is still required. This paper presents a method to improve power stability as well as power transfer efficiency for wireless capsule endoscopy. A new power transmission coil capable of producing uniform magnetic field is proposed to improve power stability through uniform field that at the same time minimizes the unnecessary peak electromagnetic exposure. To improve power transfer efficiency, a mixed resonance scheme is employed. Our experimental results show improvement over existing methods where the proposed system attained power stability of 94.62% and power transfer efficiency of 4.9% under worst position of the receiving coil. Furthermore, the proposed transmitting coil provides additional advantage, where it minimized the unnecessary peak electromagnetic exposure by 26% as compared to the conventional Helmholtz coil-based system. We believe the proposed system will open new direction for future wireless capsule endoscopy and can also be useful in other industrial applications.
TL;DR: In this article, the authors proposed a dynamic wireless power transfer (WPT) system consisting of several stationary ground-side (primary) coils and a moving vehicle side (secondary) coil.
Abstract: Solving a short mileage and a long charging time is indispensable in putting electrical vehicles (EVs) on the full-scale market. A dynamic wireless power transfer (WPT) system is one of the effective solutions, because it can feed electric power to moving EVs. This paper proposes a dynamic WPT system consisting of several stationary ground-side (primary) coils and a moving vehicle-side (secondary) coil. This system is characterized by the use of the common vehicle-side coil to both dynamic and stationary WPT situations. Theoretical analysis concludes that the dynamic WPT system resulting from a stationary WPT system is the same in equivalent circuit as the stationary system. The dynamic WPT system employs solenoid coils that are superior to circular coils in terms of misalignment and flux-distribution performance. A downscaled dynamic WPT system rated at 3 kW is designed, constructed, and tested to verify the principles of operation, and the capability of continuous power transfer.
TL;DR: The MRC mechanism is utilizes to effectuate flexible induction heating; thus, handling the requirements of varying vertical displacement and horizontal misalignment for various cooking styles.
Abstract: This paper proposes and implements the concept of flexible induction heating based on the magnetic resonant coupling (MRC) mechanism. In conventional induction heating systems, the variation of the relative position between the heater and workpiece significantly deteriorates the heating performance. In particular, the heating effect dramatically reduces with the increase of vertical displacement or horizontal misalignment. This paper utilizes the MRC mechanism to effectuate flexible induction heating; thus, handling the requirements of varying vertical displacement and horizontal misalignment for various cooking styles. Differing from a conventional induction heating, the proposed induction heating adopts one resonant coil in the heater and one resonant coil in the workpiece, which can significantly strengthen the coupling effect, and, hence, the heating effect. Both the simulation and experimental results are given to validate the feasibility and flexibility of the proposed induction heating.
TL;DR: In this paper, a flexible neutral grounding method based on electromagnetic hybrid Petersen coil (EHPC), which consists of a magnetically controlled reactor and an active power compensator (APC), is proposed.
Abstract: This paper proposes a flexible neutral grounding method based on electromagnetic hybrid Petersen coil (EHPC), which consists of a magnetically controlled reactor and an active power compensator (APC). Under normal conditions, the system's neutral point grounds through a reactor of high reactance. When a single line-to-earth fault occurs, the EHPC can be controlled flexibly to suppress the recovery voltage of faulty phase and to reduce the ground-fault current to almost zero. This paper expounds the two operating modes and corresponding characteristics, the measuring method of insulation parameters of the system (mainly including capacitance to earth and leakage resistance), and the full compensation principle for arc suppression based on the equivalent negative impedance of EHPC. This paper also proposes a compound control method of neutral-to-earth impedance based on neutral-point displacement voltage and a compensating method for the harmonic component of the ground-fault current. Compared to traditional grounding methods, this method can be fast and reliably make the residual current approach almost zero without arc reignition while greatly reducing the output capacity of APC and, thus, decreasing the cost of this device. Simulations and experiments verify the correctness of this measuring method and feasibility of this flexible grounding control strategy.
TL;DR: In this article, the authors developed a ReBCO coil for 3 T MRI superconducting magnets and evaluated the magnetic field using the magnetic resonance imaging (MRI) to evaluate the uniformity and stability of magnetic field.
Abstract: The superconducting magnet is effective to get a high stable and high magnetic field for magnetic resonance imaging (MRI). The current MRI superconducting magnet needed cooling in the liquid helium (4.2 K) to use NbTi superconducting wire. In the past few years, price increase and low availability of liquid helium has become a serious problem. Under such circumstances, the development of a high-temperature superconducting (HTS) coil dispensing with liquid helium cooling is greatly desired. The research and development project of the high stable magnetic field ReBCO coil system fundamental technology that started from the latter half of 2013 develops a ReBCO coil for 3 T MRI superconducting magnets. It gets a prospect of the practical use as the final aim. In this project, we will produce an HTS test coil of 300 mm bore experimentally and evaluate the magnetic field. This coil is cooled in less than 20 K by a GM refrigerator. We are going to make MRI used by the ReBCO coil field to evaluate the uniformity and stability of the magnetic field.
TL;DR: In this paper, a Tikhonov regularization approach called REGCOIL was proposed to improve the free-boundary reconstruction of the target plasma shape while increasing the minimum distances between coils, preventing collisions between coils while improving access for ports and maintenance.
Abstract: Several fast methods for computing stellarator coil shapes are compared, including the classical NESCOIL procedure [Merkel, Nucl. Fusion 27, 867 (1987)], its generalization using truncated singular value decomposition, and a Tikhonov regularization approach we call REGCOIL in which the squared current density is included in the objective function. Considering W7-X and NCSX geometries, and for any desired level of regularization, we find the REGCOIL approach simultaneously achieves lower surface-averaged and maximum values of both current density (on the coil winding surface) and normal magnetic field (on the desired plasma surface). This approach therefore can simultaneously improve the free-boundary reconstruction of the target plasma shape while substantially increasing the minimum distances between coils, preventing collisions between coils while improving access for ports and maintenance. The REGCOIL method also allows finer control over the level of regularization, it preserves convexity to ensure the local optimum found is the global optimum, and it eliminates two pathologies of NESCOIL: the resulting coil shapes become independent of the arbitrary choice of angles used to parameterize the coil surface, and the resulting coil shapes converge rather than diverge as Fourier resolution is increased. We therefore contend that REGCOIL should be used instead of NESCOIL for applications in which a fast and robust method for coil calculation is needed, such as when targeting coil complexity in fixed-boundary plasma optimization, or for scoping new stellarator geometries.
TL;DR: In this paper, a semi-analytical approach for the analysis of the skin and proximity effects in multi-turn coils is proposed, where the complex permeability of a round conducting wire immersed in uniform time-harmonic magnetic fields is represented in a closed form.
Abstract: Native application of finite-element method (FEM) to the analysis of skin and proximity effects in multi-turn coils results in large equation systems, whose solution needs long computational time. This paper proposes a semi-analytical approach to overcome this problem. For the analysis of the proximity effect, the complex permeability of a round conducting wire immersed in uniform time-harmonic magnetic fields is represented in a closed form. Then, the homogenized complex permeability over the cross section of the multi-turn coil is analytically evaluated using the Ollendorff formula. The magnetoquasistatic problem is thus replaced by the magnetostatic one, in which the multi-turn coil is treated as a uniform material with the homogenized complex permeability. The skin effect is taken into consideration by introducing the corresponding impedance in the circuit equation. The proposed method is shown to give the impedance of multi-turn coils, which is in good agreement with that obtained by the conventional FEM as well as experiments.
TL;DR: This paper describes the adoption of multi-objective hybrid particle swarm optimization (MOHPSO) and multi- objective real-numbered particle Swarm optimization (MORpsO) algorithms for a circular coupler design to increase performances and automate the design process.
Abstract: Recent expansion of emerging wireless power transfer technology has not been followed by an adequate systematic approach to the magnetic couplers design. The relation between design parameters (mutual inductance, coupling coefficient, leakage field flux density, coil quality factor, and so on) and structural parameters (coils and ferrite shape, size, thickness, and so on) has not been thoroughly explored, and practical designs often depend on trial-and-error methods supported by the finite-element modeling simulation to verify a final design. In order to fill that gap, this paper describes the adoption of multi-objective hybrid particle swarm optimization (MOHPSO) and multi-objective real-numbered particle swarm optimization (MORPSO) algorithms for a circular coupler design to increase performances and automate the design process. Objectives of this paper are threefold: 1) apply MOHPSO and investigate if there are some unconventional structures of circular couplers capable of outperforming traditional designs; 2) identify a minimum set of key optimization parameters for a circular magnetic coupler; and 3) demonstrate the operation of an MORPSO algorithm to optimize a circular magnetic coupler. The Pareto front concept is applied to provide multi-objective optimization. Two different multi-objective function pairs are considered, the first pair being the coil coupling coefficient ( $ {k}$ ) and maximum leakage field magnetic flux density ( $ {B_{\max }}$ ); for the second pair, the product between quality factor ( $ {Q}$ ) and $ {k}$ is combined with ( $ {B_{\max }}$ ). To validate the optimization algorithm effectiveness and accuracy, a selected magnetic coupler is fabricated and tested. Due to superior execution time, and satisfactory optimization capabilities, the MORPSO algorithm is employed to generate a final optimum design. Collected measurements demonstrate a very good agreement between the experimental and simulation results.
TL;DR: In this paper, a numerical investigation is carried out to study the laminar liquid flow and coupled heat transfer performance in rectangular microchannel heat sink (MCHS) equipped with wire coil inserts.
TL;DR: In this article, a closed-loop wireless power transfer (WPT) system for deep brain stimulation-implanted biomedical applications was demonstrated, where an inner dual-layer printed spiral coil (PSC) and outer helical coil (helical coil) coordinated with a T-type impedance-matching network.
Abstract: This paper demonstrates a closed-loop wireless power transfer (WPT) system for deep brain stimulation-implanted biomedical applications. A novel two-layer PCB FR4 coil design is proposed as a second coil for enlarging the WPT efficiency. High-efficiency implantable WPT technology was achieved by applying an inner dual-layer printed spiral coil (PSC) and outer helical coil and this coordinated with a T-type impedance-matching network. To reduce the loading effect, which lowers Q factor in implanted devices, four-coil WPT systems are recommended compared with two- or three-coil WPT systems. A practical four-coil system was implemented for verification, for which a dual-layer printed circuit board composed of a PSC, with a load loop on the other side of FR4, was designed and implemented around the system on a chip. PSCs for biomedical implants can be optimized by designing the geometric parameters. The implant coil occupies an area measuring $5 \times 5$ mm, and is implemented on both an FR4 board and an implantable flexible substrate with the optimized geometric parameters. Finally, the transmission efficiencies of using FR4 and flexible printed circuit boards, at a distance of 10 mm, were 19.1% and 14.8% through the air and 11.7% and 7.7% through the tissue, respectively, thus enabling the supply of milliwatts of power to the stimulation circuits, and successfully demonstrating the stimulation tissue model with a V/I output current of up to 180 $\mu \text{A}$ .
20 May 2017
TL;DR: In this article, the authors present an overview of coil designs for wireless charging of EVs, which addresses their basic structures, operating principles, and distinct features, including the basic topologies including the circular rectangular pad (CRP), circular pad (CP), homogeneous pad (HP), double-D pad (DDP), double D quadrature pad(DdQp), and bipolar pad (BP), and discuss the corresponding advantages and limitations of each topology.
Abstract: With the electric vehicle (EV) market growing fast, the emerging wireless EV charging technology has attracted more and more attention in recent years. As a key part of wireless charging system for EVs, the coil design is indispensable for improving the system performance. This paper presents an overview of coil designs for wireless charging of EVs, which addresses their basic structures, operating principles, and distinct features. The basic topologies including the circular rectangular pad (CRP), circular pad (CP), homogeneous pad (HP), double-D pad (DDP), double-D quadrature pad (DdQp), and bipolar pad (BP), are introduced and discussed. Also, the corresponding advantages and limitations of each topology are analyzed and discussed. Besides, some key issues of practical design problems are compared in the coil topologies. Finally, the human exposure issues are revealed.
TL;DR: The Globus-M spherical tokamak has demonstrated practically all of the project objectives during the 15-year period of operation as mentioned in this paper, and the increase of the magnetic field up to 1.0 T together with the plasma current up to 0.5 T will result in significant enhancement of the operating parameters in the upgraded GlobusM2 machine.
Abstract: The Globus-M spherical tokamak has demonstrated practically all of the project objectives during the 15-year period of operation. The main factor limiting further progress in plasma performance is a relatively low toroidal magnetic field. The maximum toroidal magnetic field achieved on Globus-M was 0.4 T with the exception of a limited number of shots with 0.55 T, which led to damage of the toroidal field coil in 2002. The increase of the magnetic field up to 1.0 T together with the plasma current up to 0.5 MA will result in the significant enhancement of the operating parameters in the upgraded Globus-M2 machine. The experimental program will be focused on plasma heating and non-inductive current drive and will contribute to the creation of a physical and technological base for the compact fusion neutron source development. In the article a brief overview of the physical background for the machine upgrade is outlined. The current status of the project implementation is described. First experimental results on moderate magnetic field increase from 0.4 T up to 0.5 T in the existing Globus-M machine are discussed. The improvement of plasma confinement as well as enhancement of efficiency of the beam driven current is observed.
TL;DR: In this paper, a discharge system with two sets of power supplies and a timing control system for the production of a dual-frequency discharge current in a single coil was presented, which can be employed to generate an attractive force between the coil and the workpiece in the forming process.
Abstract: The ability to generate an attractive force for electromagnetic forming is an interesting and challenging issue, compared with conventional electromagnetic repulsion processes. This work presents a discharge system with two sets of power supplies and a timing control system for the production of a dual-frequency discharge current in a single coil. The discharge current can be employed to generate an attractive force between the coil and the workpiece in the forming process. The effectiveness of the system was verified both by numerical simulations and by a series of experiments of sheet metal forming. Our results show that an AA 1060 aluminum alloy sheet with a thickness of 1 mm, at a distance of 9 mm from the coil bottom, can be attracted towards the coil with a maximum deformation of about 4.7 mm. We also demonstrate that there is an optimum value for deformation depth, which is related to the initial discharge voltage of the fast discharge system. The presented method and results can be helpful in designing electromagnetic forming systems and widening their applications.
TL;DR: An analytical modeling approach is established to accurately predict the Lorentz force generated by the square coil with the 1-D Halbach PM array by considering the corner region, and the proposed modeling approach can be extended easily to apply on other coil designs such as the circular coil.
Abstract: This paper presents a novel design of six-degree-of-freedom (6-DOF) magnetically levitated (maglev) positioner, where its translator and stator are implemented by four groups of 1-D Halbach permanent-magnet (PM) arrays and a set of square coils, respectively. By controlling the eight-phase square coil array underneath the Halbach PM arrays, the translator can achieve 6-DOF motion. The merits of the proposed design are mainly threefold. First, this design is potential to deliver unlimited-stroke planar motion with high power efficiency if additional coil switching system is equipped. Second, multiple translators are allowed to operate simultaneously above the same square coil stator. Third, the proposed maglev system is less complex in regard to the commutation law and the phase number of coils. Furthermore, in this paper, an analytical modeling approach is established to accurately predict the Lorentz force generated by the square coil with the 1-D Halbach PM array by considering the corner region, and the proposed modeling approach can be extended easily to apply on other coil designs such as the circular coil, etc. The proposed force model is evaluated experimentally, and the results show that the approach is accurate in both single- and multiple-coil cases. Finally, a prototype of the proposed maglev positioner is fabricated to demonstrate its 6-DOF motion ability. Experimental results show that the root-mean-square error of the implemented maglev prototype is around 50 nm in planar motion, and its velocity can achieve up to 100 mm/s.
TL;DR: In this paper, the authors report on the convective heat transfer, friction factor, effectiveness and number of transfer units (NTU) of Fe 3 O 4 /water nanofluids flow in a double pipe U-bend heat exchanger with and without wire coil inserts under turbulent flow conditions.
TL;DR: It is observed that a flux sensing simple internal observer coil (OC) is more succinct than external flux sensors for stator fault detection using a novel radial flux sensing technique.
Abstract: This paper presents the distinct advantages of stator fault detection using a novel radial flux sensing technique. Intensive research efforts in the past have been focused on the flux signature analysis as they have been more efficient compared to classical motor current signature analysis. In this paper, it is observed that a flux sensing simple internal observer coil (OC) is more succinct than external flux sensors. The proposed simplified, inexpensive technique has yet not been reported in the literature. The new results of root mean square (RMS), fundamental, third harmonic, and total harmonic distortion analysis of the voltage spectra of the OCs are found to exhibit variations in relation to the severity of interturn faults as compared to the healthy condition. The mathematical theory of the technique is provided and supported by an experimental validation. An experiment for confirming the performance of the proposed method was done on a 2.2-kW three-phase four-poles, 440-V squirrel-cage induction motor, increasing the fault level in steps from 1% to 15% combined with variations in load from no load to full load.
TL;DR: A novel coil design and adaptive hardware is proposed to improve PTE in magnetic resonant coupling WPT and mitigate coil misalignment, a crucial roadblock in the acceptance of WPT for EVs.
Abstract: Wireless power transfer (WPT) could revolutionize global transportation and accelerate growth in the electric vehicle (EV) market, offering an attractive alternative to cabled charging. Coil misalignment is inevitable due to driver parking behavior and has a detrimental effect on power transfer efficiency (PTE). This paper proposes a novel coil design and adaptive hardware to improve PTE in magnetic resonant coupling WPT and mitigate coil misalignment, a crucial roadblock in the acceptance of WPT for EVs. The new design was verified using ADS, providing a good match to theoretical analysis. Custom designed receiver and transmitter circuitry was used to simulate vehicle and parking bay conditions and obtain PTE data in a small-scale setup. Experimental results showed that PTE can be improved by 30% at the array's center, and an impressive 90% when misaligned by three-fourths of the array's radius. The proposed novel coil array achieves overall higher PTE compared to the benchmark single coil design.
Patent•
21 Feb 2017
TL;DR: In this article, a floating electromagnetic field generator (FLG) is used to generate electricity from a surgical bed, which is attached to a brace component, and the second arm is attached parallel to the first arm.
Abstract: Floating electromagnetic field generator systems and methods are provided. The system comprises a surgical bed portion. The system also comprises a brace component disposed within the surgical bed portion. Additionally, the system comprises a first arm that is attached to the brace component. The first arm is positioned adjacent to the surgical bed portion. Additionally, the first arm has at least one field generator coil embedded therein. The system also comprises a second arm that is attached to the brace component. The second arm is positioned adjacent to the surgical bed portion. Additionally, the second arm has at least one field generator coil embedded therein. The second arm is positioned parallel to the first arm.