Load Coil Research Articles

Serial Resonant Converter and Load Coil for High Frequency Heating

The paper deals with the design of the voltage source half-bridge resonant inverter with the specific load coil, which is suitable for induction heating applications. To ensure the correct functionality and right frequency range of the self-resonant converter, the parameters as inductance, self-capacitance and resistance of the coil have to be obtained. Parameters of the coil are estimated by utilizing software that uses finite elements method of solution. In order to estimate the accuracy of model, the experimental verifications were taken. For this purpose, the spiral coil made on printed circuit board was created and its parameters were calculated, simulated and compared with measurement results.

A Novel Mat-Based System for Position-Varying Wireless Power Transfer to Biomedical Implants

Wireless power transfer via magnetically resonant coupling is a new technology to deliver power over a relatively long distance. Here, we present a mat-based design to wirelessly power moving targets based on this technology. Our design is specifically applied to transcutaneously power medical implants within free-moving laboratory animals. Our system comprises a driver coil array, a hexagonally packed transmitter mat, a receiver coil, and a load coil, and generates a nearly flat magnetic distribution over a defined area to produce an approximately constant power output independent of the location of the receiver coil. This paper also describes a novel power receiver coil design of the same shape as the exterior of the implant, allowing for maximum magnetic coupling, eliminating the space restrictions due to the coil within the implant, and matching the resonant frequencies of the implant and the transmitter coil. Our new transmitter and receiver designs significantly reduce the size of a biomedical implant and may provide a lifetime power supply to implanted circuits without the need for an internal battery. Our designs are also useful in various other applications involving moving targets, such as part of a robot or a vehicle.

Space-state robust control of a Buck converter with amorphous core coil and variable load

Pulse-width modulation is widely used to control electronic converters. One of the most frequently used topologies for high DC voltage/low DC voltage conversion is the Buck converter. These converters are described by a second order system with an LC filter between the switching subsystem and the load. The use of a coil with an amorphous magnetic material core rather than an air core permits the design of smaller converters. If high switching frequencies are used to obtain high quality voltage output, then the value of the auto inductance L is reduced over time. Robust controllers are thus needed if the accuracy of the converter response must be preserved under auto inductance and payload variations. This paper presents a robust controller for a Buck converter based on a state space feedback control system combined with an additional virtual space variable which minimizes the effects of the inductance and load variations when a switching frequency that is not too high is applied. The system exhibits a null steady-state average error response for the entire range of parameter variations. Simulation results and a comparison with a standard PID controller are also presented.

Effects and Properties of Contactless Power Transfer for HTS Receivers With Four-Separate Resonance Coils

Contactless power transfer (CPT) technology is an available option to realize the possibility of power delivery and storage with connector-free devices across an air gap. The CPT system based on a strong resonance coupling, which consists of four separate coils with the same resonance frequency, can possibly exchange energy within 2 m. We propose a combination CPT technology with HTS receiver coils, and call it the superconducting contactless power transfer (SUCPT) system. The SUCPT technique is expected to be a noble option for transferring electric power from room temperature to a very low temperature vessel without connectors and can improve the portability of the superconducting system. The SUCPT resonance coils consist of source (copper), Tx (copper), Rx (HTS), and load (HTS) coils. The impedance matching for electromagnetically coupled resonators between Tx and Rx coils is sensitive and plays an important role to improve transfer efficiency and distance. In this study, we examined the transmission efficiency and properties of the SUCPT phenomenon with four separate coils from antenna parts of copper coils at 300 K to receiver parts of HTS wire at 77 K as long as the receiver is within 1.1 m distance. Also, we obtained adequate relations between directionality and transmission efficiency for different positions.

Experimental and numerical investigations on stratified air distribution systems with special configuration: Thermal comfort and energy saving

In this paper, using a newly defined cooling coil load calculation method for stratified air distribution (STRAD) systems, the effects of separate location of the return and exhaust grilles on thermal comfort and energy saving are experimentally investigated. The results clearly demonstrated the extra energy saving potentials for STRAD systems with separate locations of return and exhaust grilles. After using the experimental results to validate our CFD method, numerical investigation is carried out for an office setting. Decreasing the height of return grille will increase exhaust air temperature and significantly reduce the cooling coil load. However, the risk of poor thermal comfort caused by too large temperature difference between the head and foot levels also increased, when the return inlet is located close to the floor level. Locating the exhaust grilles at ceiling level and close to external wall while locating the return grilles at the upper boundary of the occupied zone are recommended in practice. It is demonstrated that the purpose to simultaneously achieve satisfied thermal comfort and prominent energy saving can be attained with a STRAD system via deliberate locations of supply outlets and return and exhaust grilles in relation to the heat source locations.

A Hybrid Optimal Design Strategy of Wireless Magnetic-Resonant Charger for Deep Brain Stimulation Devices

A hybrid optimal design strategy for wireless magnetic-resonant charger of deep brain stimulation devices is presented. It is proposed that a differential evolution algorithm with discrete variables (turn numbers of coils) and constrains (induced current and voltage in the load loop) is used to design the wireless power transfer system. The variables which normally include the sizes of the load coil, receiver coil, transmitter coil, source coil and capacitances are analyzed in the optimization study. Analytical formulas are embedded in the numerical optimization to speed up the convergence of the searching process. The designed receiver can receive enough power to recharge a 3.7 V circular button-type nickel-metal hydride rechargeable battery which can be implanted into the patients' skull. The performance of the designed system has been verified experimentally.

Inverter Configuration for Simultaneous Dual Frequency Induction Hardening with Independent Control

SummaryInduction hardening is a heat treatment process which selectively heats parts of work-piece with different size and shape. Components like gears require different frequencies with inner core requiring low frequency and outer surface requiring high frequency. Simultaneous application of low and high frequency currents is desirable for proper hardening of gear. This paper proposes a two inverter topology with a load resonant circuit which can provide independent and simultaneous control of low and high frequency currents through the load coil. The load circuit is a combination of two series resonant circuits which operates at the desired low and high frequencies. Power control is achieved with phase modulation of low and high frequency inverters.

On the Design of Efficient Multi-Coil Telemetry System for Biomedical Implants

Two-coil based inductive coupling is a commonly used technique for wireless power and data transfer for biomedical implants. Because the source and load resistances are finite, two-coil systems generally achieve a relatively low power transfer efficiency. A novel multi-coil technique (using more than two coils) for wireless power and data transfer is considered to help overcoming this limitation. The proposed multi-coil system is formulated using both network theory and a two-port model. Using three or four coils for the wireless link allows for the source and load resistances to be decoupled from the Q-factor of the coils, resulting in a higher Q -factor and a corresponding improved power transfer efficiency (PTE). Moreover, due to the strong coupling between the driver and the transmitter coil (and/or between the receiver and the load coil), the multi-coil system achieves higher tunable frequency bandwidth as compared to its same sized two-coil equivalent. Because of the wider range of reflected impedance in the multi-coil system case, it is easier to tune the output power to the load and achieve the maximum power transfer condition for given source voltage than in a configuration with two coils. Experimental results showing a three-coil system achieving twice the efficiency and higher gain-bandwidth product compared to its two-coil counterpart are presented. In addition, a figure of merit for telemetry systems is defined to quantify the overall telemetry system performance.

The effect of the sampling cone position and diameter on the gas flow dynamics in an ICP

An inductively coupled plasma, connected to a sampling cone of a mass spectrometer, is computationally investigated. The effects of the sampler orifice diameter (ranging from 1 to 2 mm) and distance of the sampler cone from the load coil (ranging from 7 to 17 mm) are studied. An increase in sampler orifice diameter leads to a higher central plasma temperature at the place of the sampler, as well as more efficient gas transfer through the sampler, by reducing the interaction of the plasma gas with the sampling cone. However, the flow velocity at the sampler position is found to be independent of the sampler orifice diameter. Moreover, by changing the sampler orifice diameter, we can control whether only the central gas or also the auxiliary gas can exit through the sampler. Finally, with the increasing distance of the sampler from the load coil, the plasma temperature at the place of the sampler decreases slightly, which might also have consequences for the ion generation and transport through the sampling cone.

Stratified air distribution systems in a large lecture theatre: A numerical method to optimize thermal comfort and maximize energy saving

Complaints on thermal comfort and confusions on cooling load calculation are still two main issues for the design of stratified air distribution (STRAD) system. This paper investigated these two issues for STRAD systems applied in a large space lecture theatre. The simulation results revealed that best satisfied thermal environment was obtained when supplied air from floor level, terrace and desk-edge mounted grilles simultaneously. A new method for the calculation of the occupied zone cooling load, which is based on CFD (computational fluid dynamics) simulation was proposed and tried. The effective cooling load factor concept was further clarified, which can be conveniently used to calculate the occupied zone cooling load and then determine the supply airflow rate. The concepts of occupied zone cooling load reduction and the associated but different cooling coil load reduction were differentiated, and it was illustrated that cooling coil load reduction up to 16.5% of the space cooling load can be achieved with split location of return and exhaust grilles. These simulation works provide a good basis for full-scale experimental validation of the key energy saving features of a well-designed stratified air distribution system.

공진 코일의 크기와 부하 저항이 자계 공명 무선 전력 전송 장치의 전달 효율에 주는 영향에 관한 연구

In this paper, the wireless power transfer system using the magnetic resonance was designed and the effect of resonant coil radius and load resistance to this system was analyzed by the circuit analysis method. As a result, the calculated transmitted-power is similar to measured one, and the coil size has a small effect to the coupling coefficients in the resonant frequency band. In addition, the fact that the calculated transmitted-power according to the source frequency is similar to measured one confirms that the circuit analysis methode in this paper is valid. The input side transmission efficiency including only the loss in the power transfer circuit is almost 90[%] with the large coil in the 10[cm] transfer distance, and 65[%] with the small coil in 1[cm]. The source side transmission efficiency is 30~40[%] at both coil when load resistance below 4.7[] has been connected. Considering that the maximum is 50[%], this is valid in the practical applications.

Effect of single aerosol droplets on plasma impedance in the inductively coupled plasma

The impedance of an inductively coupled plasma was indirectly monitored by two different means—through a RF-probe coil placed inside the torch housing and from tapping the phase-detector signal of the impedance-matching network. During single-droplet introduction, temporal spikes in both the RF-probe coil and the phase-detector signals were readily observed, indicating a momentary change in plasma impedance. The changes in plasma impedance were found to be due solely to plasma perturbation by droplet introduction, and not to an artifact caused by imperfect automatic impedance matching. The temporal changes in plasma impedance were found to be directly proportional to the temporally integrated atomic emission of hydrogen, which is assumed in turn to be directly proportional to the volume of the introduced droplet. A small satellite droplet, with an estimated diameter of 27μm (i.e., ~10pL in volume), caused a readily measurable change in plasma impedance. By assuming that the change in RF-probe voltage is directly proportional to the variation in RF power delivered by the load coil, the instantaneous power change coupled to the plasma during single-droplet introduction was estimated. Typical increases in peak RF power and total energy coupled to the plasma, for a single 50-μm droplet introduction, were thereby estimated to be around 8 to 11W and 0.03 to 0.04J, respectively.This impedance change was also exploited as a trigger to signal the droplet-introduction event into the plasma. This trigger signal was obtained through a combination of the RF-probe and the phase-detector signals and offered typical jitter from 1 to 2ms. With the proper choice of a trigger threshold, no trigger misfire resulted and the achievable efficiencies of the trigger signal were 99.95, 97.18 and 74.33% for plasma forward power levels of 900, 1200, and 1500W, respectively. The baseline noise on the RF-probe coil and the phase-detector signals, which increase with plasma forward power, contribute to both the jitter and the reduced trigger efficiency. The noise components that increase sharply with plasma forward power are at audio-frequencies between 150 and 300Hz, and are attributed to gas dynamics in the plasma.

Operating parameters and observation modes for individual droplet analysis by inductively coupled plasma‐atomic emission spectrometry

Several operating parameters for single-droplet analysis by inductively coupled plasma‐atomic emission spectrometry were investigated and optimized. Two plasma observation modes, both of which measure the plasma side-on, were compared. In the “whole-vertical” mode, the entire vertical emission pattern of the center portion of the central channel was spatially integrated, whereas in the “lateral” mode emission from a thin horizontal slice of the vertical plasma image was measured. The limits of detection (LOD) as well as measurement precision attainable by these two observation modes were found to be practically identical. However, the lateral mode is preferred because emission is then more insensitive to a small drift in carrier-gas flow than in the vertical mode. Precision was found to degrade at carrier-gas flows that yield maximum sensitivities in both observation modes. As a result, the best precision and lowest LODs cannot be achieved under the same plasma operating conditions and a compromise is needed. In this study, precision was given a higher priority than LOD because each individual droplet is regarded as a new sample in single-droplet analysis and each such sample can be measured only once. For best precision, the observation region should be 3mm downstream of the atomization site to avoid the adverse local plasma cooling effect of the vaporizing particle. Under optimized conditions, the best precision is about 3–4% and the absolute detection limits for eleven elements (Ag, B, Ca, Cd, Cu, Fe, Mg, Ni, Pb, Sr, and Zn) range from sub-single to hundreds of femtograms, which corresponds to 106 to 109 atoms for single-droplet analysis. In addition, a new synchronization trigger method for droplet analysis was developed. This method is based on Hα emission collected between the first and second lowest turns of the load coil. This trigger signal fires while the droplet is still intact, resides inside the lowest portion of the load coil, and is typically around 1 to 2ms ahead of the atomization event. Jitter between this trigger signal and analyte emission is typically less than 100μs, and is precise enough for correct timing for signal acquisition and integration.

Mechanical Design, Assembly and Testing of a Support Structure for LARP ${\rm Nb}_{3}{\rm Sn}$ Quadrupole Magnets for LHC

A support structure for the 120 mm Nb3Sn quadrupole magnet is presently under development for use in the upgrade for LHC at CERN. The design aims to build on existing technology developed in LARP with the LQ and HQ mag- nets and to further optimize the features required for operation in the accelerator. The structure and the proposed assembly methods include features for maintaining mechanical alignment of the coils to achieve the required field quality. It also includes a helium containment vessel and provisions for cooling with 1.9 K helium. The development effort includes the assembly of a 15 cm model to verify required coil load is achieved. Status of the R&D effort and an update on the magnet design, including its incorporation into the design of a complete one meter long cold mass is presented.

The Characteristic Analysis of Weak Current Sensor

The electrical equipment loss caused by the lightning and power’s increasing demand is reduced by monitoring the extent of the surge protector failure through measuring its leakage current on-line. Proposed a method of monitoring the surge protector’s failure degree online based on mutual inductance current sensor, established its mathematical model, analyzed the influence of coil turns, load resistance and stray capacitance on the amplitude-frequency and phase-frequency characteristic. And used impact and sinusoidal signal to composite a motivic signal to test the optimized current sensor’s time-domain response feature by simulation. Experiments show: while the range of measured current is 0.2~9 mA, the mutual inductance current sensor designed can resist the impact of 50 kA high current, the current measurement error can be less than 0.11 mA, meet requirement of the leakage current on-line monitoring.

Full-Wave Analysis of Double Positive/Double Negative Loaded Dipole Antennas

The influence of material inclusions on the input impedance of loaded dipoles is analytically investigated. Novel and accurate analytical expressions for the input impedance of the loaded dipoles are proposed based on the mode-matching technique. Boundary conditions are also enforced to obtain several simultaneous equations for the discrete modal coefficients inside the radiating region. A study of the input impedance of the whole multi-layered structure is accomplished by the cascade connection of mediums as characterized by their constitutive parameters. Computation is performed to illustrate impedance behavior in terms of geometries and frequency. Derived analytical formulas are successfully validated through a proper comparison with the results obtained with the commercial software CST Microwave Studio (www.cst.com).

The effect of matrix composition on radially resolved argon metastable atom populations in an emission ICP

We report radially resolved relative number densities for argon metastable atoms recorded by bleaching absorbers in a short segment of the absorption path of a continuous wave diode laser with a pulsed dye laser. The densities were measured in the presence and in the absence of high concentrations of metallic species. Mg, Ca, Sr, Ba, Y, Cu, La, Nd, Sm, and Gd were introduced into the plasma to model a variety of matrix species. At a height of 12 mm above the load coil, all of the introduced matrix species with the exception of copper caused significant increases in the steady-state argon metastable atom density. To examine the relationship between the argon metastable atoms and analyte or matrix ions, we recorded transient changes in argon metastable density in response to pulsed laser radiation tuned to a resonance ionic line of a selected metal in the plasma. Saturation of the ionic resonance lines caused transient decreases in the argon metastable atom density on a nanosecond time scale. The response of the argon metastable atoms to excitation of metal species is too fast to be due to collisions between excited metal ions and argon metastable atoms. We attribute the observed responses to heating of the electrons by suprathermal inelastic collisions between electrons and excited metal ions, followed by enhanced collisional excitation by electrons of argon atoms in the 4s levels.

Visualization, velocimetry, and mass spectrometric analysis of engineered and laser-produced particles passing through inductively coupled plasma sources

Velocities of particles passing through the load coil region of an inductively coupled plasma (ICP) attached to a quadrupole mass spectrometer (MS) were measured by particle image velocimetry (PIV). Particles were produced either by laser ablation (LA) of solid targets or from drying analyte-spiked microdroplets ejected by a piezoelectrically actuated quartz capillary. For instance, velocities determined under conditions typically applied to LA-ICP-MS analyses were found to range between 10 and 20 m s−1, depending on the axial position. Our data, furthermore, evidence significant changes of the gas velocity upon modifications of the ICP operating conditions such as plasma power, gas flow rate, and torch injector diameter if helium is admixed in excess of >50% of the total gas flow passing through the injector. For instance, an increase of the ICP RF power from 800 to 1600 W resulted in particle velocity gradients up to 15 m s−1 kW−1 measured after the third turn of the RF-coil. Temporal changes in velocity, i.e. particle accelerations over the axis of the load coil region were specified to 300–1000 m s−2. In addition, ICP-MS analyses of laser-produced aerosols carried out at constant volumetric flow rates but reduced injector diameters made signal intensities of elements such as Y, Ce, or U drop by up to two orders of magnitude suggesting incomplete particle evaporation as well as notably different aerosol penetration depths. Sensitivities measured in this case turned out to correlate with boiling points of the respective oxides rather than the element-specific ionization potentials commonly observed. The mechanisms controlling gas velocity and sensitivity variations are discussed and consequences on LA-ICP-MS analyses are drawn.

An isotopic perspective on mass bias and matrix effects in multi-collector inductively-coupled-plasma mass spectrometry

Lead and Tl isotope intensities and ratios were measured in radial and axial plasma profiles using multi-collector inductively-coupled-plasma mass spectrometry (MC-ICP-MS). Signal profiles for 204Pb, 206Pb, 207Pb and 208Pb display mass dependent radial and axial distributions in the plasma. In radial profiles lighter isotopes exhibit greater dispersal from the plasma axis than heavier isotopes, in agreement with ICP-MS elemental observations. However, signal maxima (Imax) for heavier Pb isotopes occur closer to the load coil than Imax for lighter Pb isotopes, the reverse of ICP-MS elemental observations. These mass dependent distributions predict that the radial dispersion and axial Imax locations for 203Tl and 205Tl isotopes should occur interspersed with the values for simultaneously measured Pb isotopes. Instead however, their values are appropriate for masses greater that 208Pb, indicating that the observed profiles are not the product of a single stage mass dependent process and that other element properties also effect the distributions. Isotope ratio (and thus mass bias) variation with sampling depth reflects both the mass dependent separation of the numerator and denominator isotope Imax along the axis of the plasma and the distance along the axis of the plasma over which the isotope signals are distributed. Addition of matrix to the plasma significantly reduces the variability of these two characteristics suggesting that more accurate correction of instrumental mass bias and more accurate normalization of sample ratios to standard values could be achieved by addition of a common matrix to samples and standards.

RF 유도형 플라즈마 프로세스에 대한 분광학적 연구

This paper is tried to analysis the optical emission spectroscopy related to the position of inductive load coil and flow rates of methane and oxygen in the RF inductive plasma process. According to the position of load coil, peak of H_α, H_β, and CH were appeared strongly at the middle position of the coil and it decreased both direction. The electron temperature was approximately 0.9[eV] at that position. Emission intensities of H_α, H_β, and CH increased linearly by increasing input power. In addition, intensities of H_α and H_β increased by increasing the flow rate of oxygen. It might be ascribed that the oxygen species were bonded with C_n H_mby suppressing the combination with hydrogen atoms. Consequently, the optimal position of the inductive coil is decided to the intermediate position between 4th and 5th turns, the wanted carbon thin-film is possible to deposit by controlling flow rates of methane and oxygen.