Showing papers on "Solenoid published in 2021"

Design and Optimization of an Electric Vehicle Wireless Charging System Using Interleaved Boost Converter and Flat Solenoid Coupler

Abstract: Simple but effective output voltage/current control schemes are essential for electric vehicle wireless charging systems (EVWCSs). This article proposes an EVWCS using interleaved boost converter (IBC) and flat solenoid coupler (FSC). The closed-loop control between the primary and secondary is realized by adjusting the duty cycle of the IBC. The currents and losses in the primary are reduced in the proposed system because the dc bus voltage in the primary is increased by using the IBC. The input current ripple is diminished owing to the interleaved structure. This article also proposes a parameter optimization method to obtain the optimal FSC. Without loss of generality, the total area of the transmitter (Tx) and receiver (Rx) is assumed to be constant, and the Tx is assumed to be larger than the Rx. A scale-down prototype whose output power is 500 W was built in the laboratory to verify the theoretical analysis. The output voltage of the prototype kept constant when the misalignment was 200 mm in the winding direction or 100 mm in the magnetic direction. A highest system efficiency, from dc input to dc output, of 90.1% was achieved when the power transfer distance was 170 mm.

Solenoid-free current drive via ECRH in EXL-50 spherical torus plasmas

Abstract: As a new spherical tokamak (ST) designed to simplify engineering requirements of a possible future fusion power source, the EXL-50 experiment features a low aspect ratio (A) vacuum vessel (VV), encircling a central post assembly containing the toroidal field coil conductors. Multiple electron cyclotron resonance heating (ECRH) resonances are located within the VV to possibly improve current drive effectiveness. The energetic electrons are observed via hard X-ray detectors, carry the bulk of the plasma current ranging from 50kA to 150kA, which is maintained for more than 1s duration. It is observed that over one Ampere current can be maintained per Watt of ECRH power issued from the 28-GHz gyrotrons. The plasma current with high line-density (approaching 1019m-2) has been achieved for plasma currents as high as 76kA. An analysis was carried out combining reconstructed multi-fluid equilibrium, guiding-center orbits, and resonant heating mechanisms. It is verified that in EXL-50 a broadly distributed current of energetic electrons creates smaller closed magnetic-flux surfaces of low aspect ratio that in turn confine the thermal plasma electrons and ions and participate in maintaining the equilibrium force-balance.

High Q -Factor PCB Embedded Flip-Chip Inductors With Multilayer CZTB Magnetic Sheet for Power Supply in Package (PwrSiP)

Abstract: This article investigates a novel approach to the integration of multilayer, thin film magnetics embedded in printed circuit board (PCB) for Power Supply in a Package (PwrSip) applications. A solenoid inductor structure is formed by sandwiching a multilayer CZTB magnetic sheet between two distinct PCBs with copper tracks on each which form the upper and lower windings of the device. A solder reflow process utilizing solder balls mounted on the exposed NiAu pads of one of the PCBs is used to create the electrical connection between the two boards, hence, forming closed current loops for the windings of the inductor. This novel inductor structure enables the use of about 4 oz ( $140~\mu \text{m}$ ) of copper to enclose the multilayer CZTB magnetic sheet, and hence demonstrates very low $R_{\text {dc}}$ . The multilayer CZTB magnetic sheet is characterized by using a Ryowa permeameter. The magnetic sheet exhibited a permeability of 367. The manufactured flip-chip inductor was electrically characterized by using a vector network analyzer (VNA). The device has a footprint of 7.25 mm2 and has an inductance of 52 nH. The fabricated PCB embedded inductor achieved a peak quality factor of 23 at 40 MHz.

Demonstrating a magnetic steering of the thrust imparted by the magnetic nozzle radiofrequency plasma thruster

Abstract: Axial and horizontal components of the thrust imparted by a magnetic nozzle radio frequency plasma thruster are measured by attaching the thruster to a pendulum balance, where two horizontal solenoids are additionally mounted near the thruster exit to steer the magnetic nozzle. The thruster is operated at the rf power of 500 W in argon. The two-dimensional profiles of the ion saturation current of a Langmuir probe show the plasma plume deflected along the magnetic field lines. The measured axial thrust is about 1.6 mN for all the horizontal solenoid current, while the horizontal thrust increases from 0 to 0.2 mN when increasing the horizontal solenoid current. These results indicate that the thrust vector can be continuously changed within the angle of several degrees, demonstrating the thrust vector control by the magnetic steering.

Quintuple AISI 1010 carbon steel core coil for highly focused transcranial magnetic stimulation in small animals

Abstract: Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique used to regulate the synaptic activity of neurons in the brain, improving the functionality of connecting regions and bringing effective treatment to different neurological and psychiatric disorders The TMS induced E-field needs to be focal enough to avoid unwanted side effects caused by stimulation of the regions adjacent to the target Attempts at TMS in small animals like rodents are highly constrained, since most of these studies use commercial equipment intended for humans, with power and coil geometries not designed for small animals Using finite element modeling in ANSYS Maxwell, the present work shows the design and evaluation of customized arrays of two and five dual-winding solenoids, including a ferromagnetic core, to restrict the stimulation to areas as small as 1 mm2 Each solenoid is made with 50 turns of a wire with thickness = 1 mm, height = 254 mm and elliptical top-view cross section Ferromagnetic cores with V-shape tip sharpening were included, using AISI 1010 carbon steel of 2 T of saturation flux density (Bsat) at 4×104 A/m, and an initial relative permeability µr=66775 Electric fields and magnetic flux densities were calculated around 400 mm below the coil (vertical distance from the top of the scalp to the cortical layer 5/6 in adult rats) with peak currents of 10kA, in a single non-repetitive pulse at 25kHz The achieved 100V/m in a small area of 1 mm2 suggests the suitability of the coil for in vivo experimentation in rodents Future works will seek to improve the duration of the pulses for repetitive TMS with pulse shaping techniques and validate the novel coil with in vivo experiments in rat models

Optimal Transmit Coil Design for Wirelessly Powered Biomedical Implants Considering Magnetic Field Safety Constraints

Abstract: This article presents an investigation on the optimal design of a transmit coil for a wireless power transfer system (WPTS) for biomedical implants with the goal of maximizing the magnetic flux density (B-field) at the location of the implant while not violating magnetic field exposure limits. Maximizing the B-field correlates to higher transferable electric power for certain WPTSs, such as those that use magnetoelectric receivers. While previous works have optimized the thermal efficiency, or system efficiency, to our knowledge no one yet has developed the procedure to optimize the transmitter to maximize the B-field subject to an imposed safety limit constraint for magnetic field exposure. In addition to this safety constraint, the optimal design of the transmitter is considered when the system geometry or the input current is constrained. Equations for determining the design parameters of an optimal solenoid transmitter are derived subject to constraints on either transmitter size or electric current. If a certain magnetic field strength is required, solutions to the size and current of the transmitter are presented, which allow the desired fields without violating the safety constraint. The mathematical model is experimentally validated, and a case study is described that illustrates the optimal design rules.

Magnetization dynamics of a harmonically confined quantum charged particle in time dependent magnetic fields inside a circular solenoid

Abstract: I consider a quantum spinless charged particle moving in the xy plane under the action of a time-dependent magnetic field described by means of the linear vector potential in the ‘circular’ gauge A = B(t)(−y, x)/2 and in the presence of the confining potential mg2x2+y2/2 . This potential guarantees finite values of all second-order moments in the initial equilibrium (thermal) state. Time-dependent mean values of the energy and magnetic moment are expressed in terms of solutions to the classical equation of motion ε̈+Ω2(t)ε=0 . Simple approximate results are found in the cases of the sudden jump of magnetic field, the parametric resonance, and the adiabatic evolution. They are compared with exact solutions in terms of the hypergeometric function for the specific function B(t) of the Epstein–Eckart type. A great amplification of the magnetic moment is discovered for the initial high-temperature states, both for the fast and slow monotonous variations of the magnetic field. Classical adiabatic invariants do not exist if the magnetic field slowly goes to zero or changes its sign.

Area-Efficient Extended 3-D Inductor Based on TSV Technology for RF Applications

Abstract: An extended model of through-silicon via (TSV)-based solenoid inductor is proposed to save on-chip areas for 3-D radio frequency (RF) ICs and package integration. To achieve a high inductance density, the nested topology consists of high-density TSVs in high-resistivity silicon substrate and multilayers of metals in compatible CMOS process. Then, an analytical inductance model, considering the mutual inductance of TSVs and complicated metal traces, is established and verified. The inductance variation in physical dimensions is studied based on the modeled and simulated results of a TSV solenoid inductor in single tier. The proposed TSV solenoid typology gets better performance at inductance density and quality factor around some frequencies through analytical model and full-wave simulations. Further studies are directed toward RF application overview according to broadband and low power consumption.

Compression of a Runaway Electron Flow in an Air Gap with a Nonuniform Magnetic Field

Abstract: The first results of study of the compression of a picosecond runaway electron flow in an air electrode gap by a pulsed guiding magnetic field increasing along the electron trajectory by a factor of 10–20 are reported. The main aim is to increase the density and homogeneity of the current of runaway electrons that are generated near the edge of a tubular cathode and are accelerated in an inhomogeneous electric field to a collector inside a solenoid. Restrictions on the integral current of runaway electrons caused by the reflection of particles with high transverse velocities from a region of concentration of magnetic field lines (magnetic mirror) have been analyzed. Under “optimal” conditions (magnetic field, the diameter of the cathode, and its position with respect to the solenoid are varied), a magnetized tubular runaway electron flow radially compressed by a factor of 3–4 with a current density up to 100 А/cm2 is formed.

Effects of Pulse Voltage Duration on Open–Close Dynamic Characteristics of Solenoid Screw-In Cartridge Valves

Abstract: The hydraulic high-speed on/off valve (HSV)—the critical core component of digital hydraulic technology—has a special structural design and manufacture due to its fast opening and closing, which results in high prices and maintenance costs. The solenoid screw-in cartridge valve (SCV) is widely used in the hydraulic industry because of its merits, such as mature technology, reliable quality, and low cost. The contribution of this study is to replace the high-speed on/off valve with the SCV in some areas of application by introducing positive and negative pulse voltage control for the coil of the SCV, which only modifies the control circuit and needs no change in structure. Based on the analysis of the structure of the SCV, the simulation model was developed in AMESim and validated by experiments to investigate the effects of the pulse voltage duration on the open–close dynamic characteristics and find the optimal pulse voltage duration, so that the SCV can open or close in the shortest time to reduce energy loss as far as possible. The simulation results showed that the positive and negative pulse voltage could quicken the rising or declining speed of the coil current and dramatically decrease the opening and closing delay time. By the experimental comparison with the original control method, the opening time of the SCV decreased from 30 ms to 13 ms, and the closing time was reduced from 139 ms to 14 ms.

Self-excitation pneumatic soft actuator inspired by vocal cords

Abstract: Pneumatic actuators afford advantages such as flexibility, low weight, and explosion-proofness. However, increasing the number of pressure supply tubes and using solenoid valves in a multi-degree-of-freedom system may negate these advantages. Therefore, this study proposes a soft actuator that uses self-excited vibrations realized by using an airflow between two flexible plates to open and close a valve in a manner similar to vocal cords. This valve can be fabricated using simple and flexible materials, unlike those used in conventional self-excited vibration valves and robots, and it can expand the applications of pneumatically driven soft robots. A prototype actuator was constructed, and its operation was verified. Further, a model was developed to analyze the characteristics of the proposed actuator, and the results of simulations based on the analytical model and experiments with the prototype were compared. The simulation successfully predicted that a minimum flow rate is required for producing oscillations and that the plate thickness mainly affects the driving frequency. The results show that the proposed actuator can increase the degree of freedom of a pneumatic soft actuator without requiring the use of a valve.

Thermal Analysis of the Pulse Inductor for Electromagnetic Launch Under Continuous Discharge Condition

Abstract: The solenoid pulse inductor is a key component of the electromagnetic launch (EML) system, and effective thermal management is a necessary condition for reliable and stable operation under continuous discharge condition. A 3D transient coupling heat transfer model for the solenoid pulse inductor with liquid cooling mode was established, and the temperature distribution and the characteristics of heat dissipation of the inductor under continuous discharge condition has been analyzed. A temperature measurement system was designed, and the accuracy of the 3D coupling model has been verified. In addition, effects of the flow rate, the inlet temperature and the coolant on the efficiency of liquid cooling were analyzed by using this model. The results show that during continuous discharge, the maximum temperature and maximum temperature difference of the inductor continue to increase, but the rising speed rapidly slows down. Raising the flow rate can effectively improve the efficiency of the liquid cooling and decrease the temperature difference in the inductor during continuous discharge, but the marginal benefit of raising the flow rate is gradually reduced. Dropping the inlet temperature has little effect on the efficiency of the liquid cooling, and ethylene glycol solution can replace deionized water as the liquid cooling coolant for the pulse inductor under low temperature condition. This paper is expected to help to improve the thermal management and optimize the performance of the solenoid pulse inductor.

Optics design of vertical excursion fixed-field alternating gradient accelerators

Abstract: Vertical excursion fixed-field alternating gradient accelerators can be designed with tunes that are invariant with respect to momentum and trajectories that are scaled images of each other displaced only in the vertical direction. This is possible using guiding fields that have a vertical exponential increase, with a skew quadrupole component in the magnet body and a solenoid component at the magnet ends. Numerical analysis was used in optimization due to the coupling effects on orbits and optics. In this paper, idealized magnetic fields are calculated from first principles, taking into account end fields. The parameter dependence of the optics and the dynamic aperture of the ring are calculated for the example of a ring with an approximately 25 m circumference that accelerates proton beams from 3 MeV to 12 MeV. The paper reports for the first time the design of such an accelerator lattice using tools specifically devised to analyze transverse coupled optics without the need for approximations.

An approach to the magnetic field of a finite solenoid with a circular cross-section

Abstract: We present a simple approach, different from approaches in the literature, for calculating the magnetic field of a finite solenoid with a circular cross section, carrying an ideal surface current with an ordinary azimuthal component and a small axial component due to nonideal winding. The results are given as an infinite series whose terms are elementary functions or simple polynomials rather than other infinite series. It is easy to deal with the results because the polynomials involved are partial binomial expansions. These series converge rapidly everywhere, except near the edges of the solenoid. From these results, it is very easy to derive some general properties of the magnetic field, to reduce the field to greatly simplified forms in various special regions, and to address the special cases of infinite and semi-infinite solenoids. The azimuthal field due to nonideal winding is shown to be small everywhere. A solenoid with a small but finite thickness in the radial direction is investigated in detail, and we present simple analytic approximate results for its magnetic field. A comparison with an exact numerical evaluation shows that these are very good approximations.

Analytical Approach for Optimal HTS Solenoid Design

Abstract: High temperature superconducting (HTS) coils have been designed for various applications such as magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR), and superconducting magnetic energy storage (SMES). Typically, the coils are in kilojoule range and have solenoid structure. These are mostly optimized with MATLAB and electromagnetic analysis using finite element method (FEM) software. In this article, an HTS solenoid with maximum energy density is designed with MATLAB optimization toolbox. The design objective is mathematically formulated to prove the feasibility of optimal solution of design problem. This article also presents a mathematical formulation to determine the critical current of the solenoid coil. The critical current so obtained was compared with the literature. The HTS solenoid was designed using this formulation. Its critical current and magnetic fields were compared with those obtained with COMSOL model.

A Multi-Receiver MHz WPT System with Hybrid Coupler

Abstract: The megahertz (MHz) operating frequency increases the spatial freedom, making it more suitable for multi-receiver wireless power transfer (WPT) scenarios. Generally, in a single-receiver WPT system, similar shapes (e.g. spiral) of the transmitting coil and the receiving coil help to improve the cross coupling. However, in multi-receiver cases, traditional spiral receiving coils limit the maximum number of receivers, and the coil coupling varies obviously as position changes. This paper proposes a hybrid coupler of a spiral transmitting (Tx) coil and solenoid receiving (Rx) coils, which can effectively increase the upper limit of the number of receivers, and is also suitable for some receivers with special shapes (e.g. tubular). In addition, a new design method for the impedance matching network (IMN) of MHz WPT systems, which improves the robustness of the systems when the number of receivers varies, is also proposed.

Can classical electrodynamics predict nonlocal effects

Abstract: Classical electrodynamics is a local theory describing local interactions between charges and electromagnetic fields and therefore one would not expect that this theory could predict nonlocal effects. But this perception implicitly assumes that the electromagnetic configurations lie in simply connected regions. In this paper, we consider an electromagnetic configuration lying in a non-simply connected region, which consists of a charged particle encircling an infinitely long solenoid enclosing a uniform magnetic flux, and show that the electromagnetic angular momentum of this configuration describes a nonlocal interaction between the encircling charge outside the solenoid and the magnetic flux confined inside the solenoid. We argue that the nonlocality of this interaction is of topological nature by showing that the electromagnetic angular momentum of the configuration is proportional to a winding number. The magnitude of this electromagnetic angular momentum may be interpreted as the classical counterpart of the Aharonov–Bohm phase.

Development of Coax Compacted Joint Assembly Process for the ITER Central Solenoid

Abstract: The Central Solenoid (CS) is the core element of the ITER magnet system, contributed as in-kind procurement by the US Domestic Agency. Made up of six modular inter-exchangeable module coils, vertically stacked, forming a 15 m high and 4 m outer diameter solenoid, to be inserted inside the central tokamak core, after assembly of the 18 D-shaped Toroidal Field (TF) coils. Each module uses a Nb3Sn conductor internally cooled by circulation of supercritical helium at 4.5 K and supplied, for each module, with a 45 kA current by the way of two vertical leads exiting from the module outer radius. The available space between the CS and TF magnets being very limited, the US DA has developed a compact - so called Coax Joint (CJ) - devoted to connect the respective twelve module leads to the feeders located at top and bottom of the CS via dedicated busbar extensions. The CS coax joint assembly procedure as developed by US DA would make use of CS assembly onsite soldering process, to be executed under supervision of the ITER Organization (IO) in the tokamak assembly hall. In order to mitigate risks related to these soldering activities needed at assembly stage, IO has proposed an alternative assembly process based on indium wires compaction - so called Coax Compacted Joint (CCJ)- and initiated its prototype development and qualification in time. The hereby presented CCJ design solution is based on four copper quadrants, each including an embedded straight Rutherford-type superconductor cable-strip to transport the current. The current is transferred from the lead to the quadrants by the way of compacted indium wires. A steel jacket welded around the joint ensures the mechanical support as well as the needed leak tightness. The paper describes developments made by CEA under IO supervision from the conceptual design to the testing of joints in relevant cryogenic and operative conditions.

Automatically controlled frequency-tunable rf plasma thruster: Ion beam and thrust measurements

Abstract: An automatically controlled frequency-tunable radiofrequency (rf) system is installed in an rf plasma thruster consisting of a stepped-diameter insulator source tube wound by a single-turn loop antenna and a solenoid providing a magnetic nozzle, and immersed in vacuum. The frequency and the output power are controlled so as to minimize the reflection coefficient and to maintain the net power corresponding to the forward minus reflected powers at a constant level. The reproducibility of the impedance matching and the stability of the net rf power are assessed, providing a stable operation of the thruster. When increasing the rf power up to 500 W, discontinuous changes in the source plasma density, the imparted thrust, and the signal intensity of the ion beam downstream of the thruster are observed, indicating effects of the discharge mode on the thruster performance and the ion energy distribution.

Design of a vehicle height and body posture adjustment hybrid automaton of electronically controlled air suspension

Abstract: Summary The vehicle height and body posture adjustment of electronically controlled air suspension (ECAS) poses great challenges to hybrid control, since it involves discrete events of solenoid val...

Monitoring of solenoid parameters based on neural networks and optical fiber squeezer for solenoid valves diagnosis

Abstract: As crucial parts of various engineering systems, solenoid valves (SVs) operated by electromagnetic solenoid (EMS) are of great importance and their failure may lead to cause unexpected casualties. This failure, characterized by a degradation of the performances of the SVs, could be due to a fluctuations in the EMS parameters. These fluctuations are essentially attributed to the changes in the spring constant, coefficient of friction, inductance, and the resistance of the coil. Preventive maintenance by controlling and monitoring these parameters is necessary to avoid eventual failure of these actuators. The authors propose a new methodology for the functional diagnosis of electromagnetic solenoids (EMS) used in hydraulic systems. The proposed method monitors online the electrical and mechanical parameters varying over time by using artificial neural networks algorithm coupled with an optical fiber polarization squeezer based on EMS for polarization scrambling. First, the MATLAB/Simulink model is proposed to analyze the effect of the parameters on the dynamic EMS model. The result of this simulation is used for training the neural network, then a simulation is proposed using the neural net fitting toolbox to determine the solenoid parameters (Resistance of the coil R, stiffness K and coefficient of friction B of the spring) from the coefficients of the transfer function, established from the model step response. Future work will include not only diagnosing failure modes, but also predicting the remaining life based on the results of monitoring.

Using solenoid as multipurpose tool for measuring beam parameters.

Abstract: Solenoids are frequently used for focusing low-energy beams. In this paper, we show how they can serve as multipurpose diagnostics tools to measure various beam parameters, including energy, emittance, the second moments of the transverse distribution, and the beam position and angle with respect to the solenoid’s axis. The energy measurement is based on rotation of the plane of the transverse motion, as opposed to generating dispersion with a dipole. Measurement of the beam trajectory with respect to the solenoid axis is done by analyzing the beam orbit downstream of the solenoid while varying its current. The second moments are calculated by analyzing the beam image on a profile monitor while accounting for the beam rotation caused by the solenoid. We describe in detail the corresponding procedures and the experimental results of these measurements.

Design of a compact, cryogen-free superconducting solenoid for the electron lens of the Fermilab Integrable Optics Test Accelerator (IOTA)

Abstract: The proposed electron lens for Fermilab's Integrable Optics Test Accelerator (IOTA) will broaden its capabilities by enabling new research in nonlinear integrable optics, space-charge compensation, proton beam cooling, and more The electron lens is based on a 5–10 keV, 1–2 A electron beam, shaped using a 07 m long, 08 T solenoidal magnetic field A cryogen-free superconducting solenoid has been designed to provide this solenoidal field, taking into consideration the constraints on space, utilities, and infrastructure in the IOTA experimental hall The solenoid is made of copper stabilized niobium-titanium conductor, conduction-cooled using 4 K closed-cycle cryocoolers This paper describes the overall design of the solenoid encompassing its mechanical construction, current leads optimization, cryogenic thermal modeling that provides estimates of cooldown time and static/dynamic heat loads, and quench analysis