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In a previous paper, we introduced a modified Steinmetz equation to account for dc-bias field effects, which requires only a simple dc permeability measurement to predict total power loss. In this paper, we expanded our investigation to include Finemet nanocrystalline material and found that our modified Steinmetz formalism was effective in predicting dc-bias-related losses for this system as well. In this paper, it was observed that Finemet cores exhibit lower losses than Metglas cores under identical test frequencies and bias fields. In addition, we show that a full characterization of the dc loss component necessitates the consideration of higher order ( $n>1$ ) harmonic components. In order to quantify these higher frequency loss components, a dc–dc converter-based test system was built to intentionally introduce inductor current harmonics by varying the filter capacitance and parasitic inductance of the test system. Both core types were evaluated under fundamental frequencies of 20 to 150 kHz and dc-bias fields of up to 1.3 kA/m, with the inclusion of distorted waveforms obtained by varying filter capacitance. At higher frequencies, the Metglas cores were found to exhibit greater loss fractions associated with the higher order harmonic components. A detailed summary of the measured core loss characteristics for both core types is included and discussed. This paper includes the details of the measurements, the modified Steinmetz relation, and the loss extraction algorithm used for analysis. [ABSTRACT FROM PUBLISHER]

Advanced power systems for electromagnetic propulsion depend on capacitor banks as the first stage of pulsed power. Significant electrical energy is required to support a number of anticipated launch applications. In support of successful integration of these technologies, TPL has developed an improved dielectric material for high energy density capacitors. Recent developments have led to a novel dielectric film that can be fabricated and incorporated into innovative, high-voltage designs using conventional manufacturing processes. Full-scale (100 kJ) capacitors incorporating TPL's established film technology is projected to provide an energy density between 3.5 and 4.0 J/cm3. [ABSTRACT FROM AUTHOR]

This paper presents a multi-coupling wireless power transfer (WPT) system aimed at dealing with various charging requests simultaneously. The proposed WPT system is able to distribute the energy more reasonably based on the top priority principle applying a novel distribution algorithm. Besides, the proposed system has the ability to charge the load in both the constant current mode and constant voltage mode while detecting the state of charging without using the bidirectional wireless communication. Moreover, this paper also puts forward a current injection topology named capacitance buffer rather than the traditional capacitor array in order to alleviate the large demand of the capacitors with different values under different resonant frequencies. Both simulation and experimental results are provided to demonstrate the feasibility and the performance of the proposed system. [ABSTRACT FROM AUTHOR]

Bidirectional inductive power transfer (BIPT) systems enable power transfer between stationary electricity sources and movable consumers in each direction through electromagnetic coupling. Due to its complexity, a mathematical model is required to design and to control these systems. This paper presents the mathematical analysis and the frequency-domain analysis for two different compensated (series–series and parallel–parallel) BIPT systems. This paper contains the modeling procedure of the BIPT system’s coils in the frequency domain. The prediction of its equivalent circuit values, magnetic stray field values, and coil positioning tolerance are determined as well using the JMAG field simulation software. Furthermore, the transmission characteristics and the efficiency of the two compensation topologies are discussed. [ABSTRACT FROM AUTHOR]

In this paper, a pulsed magnetic field system developed for biological applications is presented. The proposed pulsed power setup generates repetitive controlled frequency and width square wave 0–4 kV electrical pulses and supports currents up to 1000 A. As a load, a solenoid-type inductor is used with integrated plastic cuvette for biological cells. Homogeneous repetitive microsecond range pulsed magnetic field up to 15 T inside the effective volume of the cuvette can be generated. The development process, the structure of the pulsed magnetic field setup, and the solutions implemented to achieve biomedical applicability are overviewed in this paper. The presented experimental results showing contactless permeabilization of biological cells in pulsed magnetic field have an excellent potential for the development of a new biomedical treatment technique and applicability of the setup. [ABSTRACT FROM AUTHOR]

This paper describes a novel approach to designing a high-current magnetic field generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. Challenges for robust and practical design are introduced. A few of the main possible solutions for designing versatile and powerful pulses are introduced and discussed. Finally, future improvement in functionality of the HCMFG is proposed. [ABSTRACT FROM AUTHOR]

Vehicle to home (V2H) attracts attention as a way to use electric cars. In V2H, it is necessary to exchange electricity between the electric car and the household. Therefore, bidirectional contactless power feeding technology is effective. In bidirectional non-contact power feeding, it is required that the performance does not deteriorate even if the power transmitting side and the power receiving side are switched. Therefore, it is effective that the capacitor is symmetric as a capacitor connecting method for efficiency compensation and power factor improvement. We adopt the series–series (SS) system connecting the capacitors in series to the coil. However, in the case of the SS method, if the load fluctuates, the current on the primary side increases and the leakage magnetic field increases. Also, an increase in the primary current causes an increase in the output voltage. Therefore, in this paper, in order to suppress the primary current at light load and to stabilize the output voltage, a method of controlling the drive frequency was proposed. As a result, by selecting an appropriate drive frequency, it was possible to suppress increase in the primary side current at light load and realize voltage stabilization. [ABSTRACT FROM AUTHOR]

Transcranial magnetic stimulation (TMS) is a non-invasive, safe, effective, and food and drug administration approved treatment for major depressive disorder. TMS relies on time-varying magnetic fields to induce an electric field in the brain, resulting in depolarization or hyperpolarization of the neurons. Recently, there has been extensive research to improve the magnetic coil design, effectiveness of TMS treatment, and improvement in the computer modeling of human brains, yet little development is reported on the TMS pulse generators and coil design for small animals. TMS pulse generators, or stimulators, are the circuits which provides pulse current to drive the inductive coils (TMS coils), used to generate time-varying magnetic fields. Commercial TMS stimulators are expensive and have limitations of using standard and non-customizable coils. These stimulators do not support small inductive loads, which require high-current capabilities. Furthermore, the commercial animal coil stimulates the entire body of a mouse, as they are designed for large animals. In this paper, the authors present the design of a small sized TMS stimulator and a focused coil for the application on small animals such as mice. The proposed TMS stimulator will have the potential of handling small inductive loads enabling stimulation of specific regions within the mouse brain. [ABSTRACT FROM AUTHOR]

This paper proposes a common-mode electromagnetic interference (CM-EMI) spectrum calculation method based on double Fourier series for photovoltaic (PV) inverters with chaotic sinusoidal pulsewidth modulation (CSPWM). In this paper, the CM-EMI of a single-phase PV inverter is first analyzed, and the equivalent circuit of the CM-EMI in the single-phase PV inverter is established, then the CSPWM is employed to suppress the CM-EMI in PV inverters. Moreover, the proposed EMI spectrum calculation method based on double Fourier series is applied in evaluating the CM-EMI spectrum of the single-phase PV inverter. Finally, the simulation and experimental results validate the EMI suppression effectiveness of the CSPWM and the correctness of the proposed EMI spectrum calculation method. Therefore, the proposed EMI spectrum calculation method provides a theoretical support for CSPWM to reduce EMI. [ABSTRACT FROM AUTHOR]

A novel flexible three-axial tactile sensor, which is composed of four interdigital capacitors, is presented in this paper. The operation of the sensor is based on the measurement of a load-induced capacitance change. For the configuration of the electrodes, four sensing electrodes and a public electrode are in the same plane, which is based on the fringing effect of the electric field. There are no floating electrodes which are beneficial to flexibility. The dielectric layer consists of air gap and polydimethylsiloxane (PDMS), and the equivalent dielectric constant of the dielectric layer will be changed when the sensor is under external force, which causes the capacitance change. Different from the existing fringing effect tactile sensor, interdigital electrodes are adopted here to enhance the sensitivity and stability of the sensor. Finite element simulation and experimental results show that there is a great enhancement in sensitivity and stability. [ABSTRACT FROM AUTHOR]

Linear oscillating actuators (LOAs) are electric machines that perform linear reciprocating motion. Generally, single-phase short-stroke LOAs that employ rare-earth permanent magnets (PMs) are used. However, they are expensive and are affected by unstable material supply. Therefore, we proposed a ferrite PM LOA to replace rare-earth PM LOAs. In this paper, the structure and operation principle of a conventional rare-earth PM LOA and the ferrite PM LOA are examined. In addition, for the purpose comparison, the models of both LOAs are designed to generate the same back electromotive force and electromagnetic stroke region at equal volumes. Inductance values are analyzed, and load analysis is performed considering a mechanical system. Tuning capacitors are used to compensate for the high inductance of the ferrite PM LOA. In addition, it is confirmed that the performances of the ferrite PM LOA and rare-earth PM LOA are similar. [ABSTRACT FROM AUTHOR]

In this paper, we describe an ultrasensitive differential capacitive dilatometer (ΔL/L ~ 10−9) and novel ratiometric measurement method in the temperature range of 1.9 K < T < 400 K for the investigation of thermal expansion and magnetostriction of single crystal as well as polycrystalline samples. The dilatometer provides a capacitive measurement based on a differential capacitance or the capacitance ratio measured between two parallel plate capacitors of the dilatometer. In this regard, an absolute capacitance bridge is not required, and even more advantageously, the effect of adsorbed gas on the capacitor plates is greatly reduced compared to conventional dilatometers. The differential capacitive dilatometer provides a symmetrical configuration which reduces the effect of temperature gradients. The capabilities of the dilatometer are demonstrated by the measurement of magnetic ordering of a URu2Si2 sample, and of de Haas–van Alphen oscillations in an aluminum sample. [ABSTRACT FROM AUTHOR]

In automotive systems, reliability and cost are paramount for the success of electrical drive systems. Considering the switched reluctance motor (SRM), the power electronics cost dominates the total cost of the electrical drive. In this respect, especially the dc-link capacitor significantly contributes to the total bill of the material. This paper proposes the use of a dc-excited winding in an 8/6 SRM as a means of reducing the capacitor. The energy conversion of the motor is analyzed intensively. The control algorithm of the field winding is investigated and an active control algorithm is proposed to provide and absorb the energy in parallel with the dc-link capacitor. The effectiveness of this control method is confirmed by the cosimulation between the finite-element method and the Simulink. [ABSTRACT FROM PUBLISHER]

The traditional low-frequency electromagnetic field computations do not include stray capacitive effect, while high-frequency solvers do not consider the nonlinear property of materials, and the internal regions of solid conductors as well as external circuit excitations. In this paper, the application of 3-D edge-element finite-element method (FEM) to problems with both inductive and capacitive effects for solid conductors, under external circuit excitations using the formulation with a magnetic vector potential and an electric scalar potential, is presented. The novel field-circuit coupled method that is presented does not need to look for the integration path of electromotive force computation. It has the merit of being convenient in algorithm implementation. Several numerical examples are given to showcase the proposed formulation and the developed computer program using an edge-element FEM. [ABSTRACT FROM AUTHOR]

This paper discusses the implementation of the inverse Jiles–Atherton vector hysteresis model with the 2-D Finite Element Method (FEM) for the analysis of an induction machine operating as self-excited generator. A differential reluctivity tensor couples the hysteresis model with the magnetic vector potential-based finite-element model. Experimental and simulated results (transient and steady state) are presented. [ABSTRACT FROM AUTHOR]

This paper introduces the periodic carrier frequency modulation (PCFM) for permanent magnet synchronous motor (PMSM) drive systems so as to reduce the low-frequency electromagnetic interference (EMI). PMSMs are widely used in many applications and they are usually fed by pulsewidth modulation (PWM) inverters. The EMI of PMSM, which results from the switch of power device, generates undesirable effects on the control system. Therefore, it is of importance to reduce the EMI of PMSM. The common mode (CM) conducted EMI model of the PMSM drive system is constructed to investigate the CM voltage. The simulations and experiments of PMSM fed by the fixed frequency PWM (FFPWM) and PCFM are implemented to analyze the CM conducted EMI. The CM EMI spectra of PMSM fed by the FFPWM and PCFM with different spreading frequency widths are compared to explore the influence of PCFM on the CM conducted EMI. The regular patterns on PCFM in reducing the CM conducted EMI of PMSM drive systems are revealed. [ABSTRACT FROM AUTHOR]

This paper proposes and implements an approach to achieve homogeneous heating in a single-source multiple-coil induction heating system. In a traditional induction heating system, one of the key disadvantages is the inhomogeneous heating effect. In particular, the heating power concentrates on a small ring area of the pan, while the outer part receives much lower power. The proposed induction heating system consists of two concentric coils with its compensated capacitors connecting in series, respectively. Currents in the two coils are controlled by newly employing the magnetic resonant coupling mechanism so that the heating power distribution in the inner and outer parts of the pan can be adjusted accordingly. Therefore, the proposed induction heating can achieve homogeneity and simplicity simultaneously by optimizing the operating frequency of only one inverter. Both the simulation and experimental results are given to validate the feasibility of the proposed homogeneous induction heating. [ABSTRACT FROM AUTHOR]

This paper presents a modified C-dump converter for brushless DC (BLDC) machine used in the flywheel energy storage system. The converter can realize the energy bidirectional flowing and has the capability to recover the energy extracted from the turnoff phase of the BLDC machine. The principle of operation, modeling, and control strategy of the system has been investigated in the paper. Simulation and experimental results of the proposed system are also presented and discussed. [ABSTRACT FROM AUTHOR]

There are many factors which can affect the muzzle velocity of the projectile in the system of the multi-stage synchronous inductive coilgun (SICG), and the discharge position of the armature is important one. If the discharge position of the armature with respect to a drive-coil is changed when a charge capacitor bank is switched into the drive-coil circuit, the muzzle velocity of the projectile launched by the armature will change. In this paper, discharge positions of the armature in a three-stage SICG are investigated. The results indicate that the best discharge position exists in each stage. If the capacitor bank in each stage is switched into the drive-coil circuit when the armature passes through the best discharge position in this stage, the projectile can be accelerated to the maximal muzzle velocity. The best discharge positions in the three-stage SICG are obtained. [ABSTRACT FROM AUTHOR]

High energy density capacitor is a key device in power supply source in Electromagnetic Gun (EMG) system. The increase of energy density of capacitor is beneficial from emerge of metallized technology in electrode and advancement in manufacturing. The paper studies a kind of high energy density capacitormade of polypropylene with metallized electrode. The self-healing ability is improved by optimization of the structural parameter of the metal electrode. First, aimed to be used in EMG, experiments such as lifetime test and voltage withstand test are carried out to study the performance of the capacitor. The metallized film capacitor has an energy density of 1.6 J/cm³ under 10 kV. And the lifetime test finds its lifespan of 2000 shots. Then, the influences of different impregnating materials on the voltage drop are compared in the paper for manufacture improvement purpose. Last, voltage maintaining test are carried out to observe the voltage drop of the capacitor. The output precision of the launch system will be consequently influenced. In order to obtain a stable voltage, a constant current and micropower charge control technique is applied to realize fast and high accuracy charge of capacitor to avoid fluctuation of output energy. Using micropower charge control, the voltage deviation in maintaining stage is less than ±1‰. And the charge system has a repeat accuracy of 0.520‰ with high reliability. [ABSTRACT FROM AUTHOR]

After setting up a mathematical model for rectangular-shaped Mn-Zn ferrite capacitors, this paper investigates dimensional effects on the intrinsic complex permittivity and the measured apparent complex permittivity of Mn-Zn ferrite blocks. The simple block structure of the samples guarantees their easy and precise preparation. Above a few hundred kilohertz, dimensional effects make the measured apparent complex permittivity deviate from its intrinsic value. This paper uses a Newton-Raphson based method to trace the intrinsic complex permittivity and permeability from the measured impedances of two rectangular-shaped Mn-Zn ferrite capacitors in the frequency range from a few hundred kilohertz to 40 MHz. From the traced intrinsic complex permittivity and permeability, the apparent complex permittivity of a third sample with different dimensions is then calculated theoretically. The papers also presents results of experiments carried out to measure the apparent complex permittivity of the third sample; agreement between the measured and the calculated values is very good. This justifies the validity of the method presented in this paper, when used to determine the dimension-independent intrinsic complex permittivity and permeability of Mn-Zn ferrites. [ABSTRACT FROM AUTHOR]

High energy density capacitor is a very important component to supply energy in pulse power source. Owing to its high dielectric constant (up to 105 or more), ceramic material is regarded as a sound dielectric for producing high energy density capacitors. With the energy density under the same order of several hundred J/L, ceramic capacitors can endure hirer inverse voltage (>70%) and have longer life (shot times > 106) compared with metallized film. Multilayer ceramic capacitors (MLC) of low rated voltage have been used for power decoupling and bypass in telecommunication equipments for many years. In this paper, MCL samples of high voltage have been produced, and their electrical characteristics tested in a pulse energy discharge circuit. From the result, the relations between the changes of capacitance, dielectric loss, the charge frequency, and the lifetime have been deduced. The features in discharge wave are also presented. Some failure mechanisms for these capacitors are put forward in this paper. In conclusion, MLC is suitable for making high energy density capacitor, which can endure high reverse voltage, high current, and possesses long lifetime. [ABSTRACT FROM AUTHOR]

This paper presents a field-circuit-coupled method to investigate differences between intrinsic and measured permittiveties for a Mn-Zn ferrite. Electric and magnetic fields in a flat cylindrical ferrite, which is used here to construct a ferrite capacitor, are solved analytically. Then, complex power supplied to the capacitor is calculated. On the basis of the complex power, parametears in an equivalent circuit for the ferrite capacitor are extracted. The paper examines the validity of the developed mathematical model. Numerical results show that for a ferrite with high permeabilities, measured permittivities follow intrinsic values well at low frequency but fail to embody the intrinsic values when the frequency runs above several hundred kilohertz. Numerical results also demonstrate that the dimensions of the sample under investigation play a role in measurement errors. The larger the radius of the cylindrical ferrite is, the higher the errors are. Correction curves are generated, from which the measured permittivities can be corrected to reflect the intrinsic values. [ABSTRACT FROM AUTHOR]

A wireless charging system contains a high-frequency power source, a wireless transformer/coupler, a rectifier, and the load. The wireless transformer/coupler is the key element of the wireless charging system, and the power source and the rectifier design are all dependent on its design. For a two coil type wireless transformer, the maximum efficiency is limited by the coupling coefficient, which rapidly decreases with increasing distance between the primary and secondary coils. The four coil system is widely used in low-power applications, where the maximum power transfer operating point is away from the maximum efficiency point. This paper proposes an inductive charging coupler with small assistive coils, where the high power and maximum efficiency regions overlap. [ABSTRACT FROM PUBLISHER]

The finite-element formulation proposed in this paper is for the frequency domain and covers the entire range from static/stationary fields to wave propagation. It does not involve any frequency-dependent thresholds, leads to complex symmetric system matrices and unique solutions, and applies to the most general structures, comprising both lossy and lossless regions. Compared with non-stabilized methods, e.g., the electric field formulation, the price to be paid is one extra scalar potential in the lossy region. Numerical examples demonstrate that the proposed method is well-suited for direct and iterative solvers, and remains stable in the static case. [ABSTRACT FROM PUBLISHER]

In this paper, an integrated motor-drive and battery-charging (IMB) system with a doubly salient electromagnetic machine (DSEM) is proposed to be implemented for electric vehicles. In the driving mode, the front-end dc/dc converter is employed to boost the battery voltage to improve the speed range and acceleration ability of the DSEM. The field windings distribution of a 12/10-pole DSEM is arranged for the constant self-inductance, and adopted as the inductance of the front-end dc/dc converter to eliminate the traditional filter inductance and excitation loss of the machine. In the charging mode, the windings of DSEM could be exploited as the filter inductances to obtain the unity power factor operation and constant current charging ability. The simulations and experiments have been accomplished to verify the feasibility of the independent field current control method for the proposed IMB system. [ABSTRACT FROM AUTHOR]

In the linear induction launcher (LIL), the barrel is divided into sections, and either a discharging capacitor bank or a flywheel motor/generator set energizes the sections sequentially with polyphase currents. Within the sections, the drive coils of the LIL can be connected either in series or in parallel. In previous publications, two different parallel-connected configurations of the drive coils `were described. One has a single flywheel generator per section supplying all the phases, and all the drive coils per-phase are parallel connected. However, the generators get larger and larger the nearer one gets to the muzzle. The second configuration has one pair of shaft-coupled flywheel generators for each N-S pole-pair, but has all of the generator-pairs (in a given section) shaft-coupled together to form a cascaded array. This arrangement permits one to supply the increasingly larger energy needs by dividing the energy among many generators of nearly equal output. Since all the generators in one section are shaft-coupled together, forming a cascade array, they produce the same voltages and frequencies. This paper deals with the effect of running the generators/section at incrementally increasing frequency and voltage, rather than at a constant level. In effect, it means that each section of the whole launcher would be operated as an individual sub-launcher. By doing this, the acceleration of the projectile becomes smoother. Moreover, it would be possible to disconnect generators in a section from their drive coils once the projectile has passed them by; this would help to improve the system efficiency. This paper describes the new pulse-generator configuration, explains the improvement on the system efficiency, and provides graphs to compare the new results with those obtained previously with the cascade array configuration. [ABSTRACT FROM AUTHOR]

This paper proposes an algorithm to analyze the magnetizing process of a new anisotropic bonded NdFeB permanent magnet (PM) which is magnetized by a capacitor discharge impulse magnetizing fixture. In the algorithm, the magnetic field analysis and the prediction of the residual magnetic flux density are achieved by using the transient finite element method (FEM) incorporating the scalar Jiles-Atherton (J-A) hysteresis model. The validity of the suggested method is demonstrated by applying to a 4-pole ring-type anisotropic bonded NdFeB PM and comparing the numerical results with the experiment ones. [ABSTRACT FROM AUTHOR]

Integration of passive magnetic devices is essential in the design of highly efficient power converters. This is due to the necessity to conserve as much space as possible for modern devices such as thin LED TVs and small bright LED illumination. This paper focuses on this multiphysics issue and presents a novel integrated magnetic system (IMS), investigated by the finite element method (FEM). Two different FEM approaches are applied to prove the accuracy of the analyzed data. Both magnetic systems have been developed with a novel capacitor layer design. This provides the system with the required resonance tank integrated in the conductor arrangement, without any interference to the transformer section or vice versa. [ABSTRACT FROM PUBLISHER]

This paper discusses the Joule losses in a thin film noise suppressor based on 3-D equivalent circuit network analysis and 3-D full wave electromagnetic field simulation. The thin film and transmission line is divided into number of elements in a plane perpendicular to surface of thin film. Each element is represented by four resistances in length and width direction and capacitors between conductors. Joule loss is quantitatively calculated as a function of sheet resistance using equivalent circuit network analysis. From this result it is successful by shown the Joule loss in thin film is a function of sheet resistance, not the intrinsic resistivity of the thin film or thickness as previous analyses. It is also shown that the Joule loss in the thin film is determined by the two major factors; the eddy current and conduction current deviated from the signal line in the form of displacement current. This result shows that the proposed equivalent circuits well explain the mechanism of the Joule losses in thin film. [ABSTRACT FROM AUTHOR]

Advances in high-power-density batteries have rekindled interest in using inductive store as a pulse compression system. Although these batteries are considered very power dense, they lack over an order of magnitude of power density to drive a deployable electric gun. However, one can add an inductive circuit to a battery bank to make a hybrid system that has a much higher power density than batteries alone. A battery-inductor hybrid pulsed-power supply boasts several advantages over pulsed alternators, as inductors are static and relatively easy to cool. Inductors are potentially more energy dense than capacitors, making a battery-inductor hybrid pulsed-power supply an attractive alternative to capacitor-based pulsed-power supplies. The opening switch has been a major obstacle in previous inductive store projects, but in simulation, a new circuit topology—the Slow Transfer of Energy Through Capacitive Hybrid (STRETCH) meat grinder—greatly attenuates the problem. This paper discusses the design, construction, and testing of a small-scale STRETCH meat grinder system, which was successfully used to power a miniature railgun. [ABSTRACT FROM AUTHOR]

We present a wide-band experimental, characterization of an on-chip shunt inductor and capacitor (LC) interconnect. (A previous paper by the authors considered the series LC case). In order to capture the effects of patasitic parameters on the wide-band transmission and reflection characteristics of shunt LC interconnects, we propose a generalized frequency-independent circuit model for fast-running simulations. The model is accurate to above its second resonant frequency, with low average simulation errors for both reflection and transmission coefficients compared to the measured two-port S parameters over the frequency range of 1 to 14 GHz. [ABSTRACT FROM AUTHOR]

Presents information on a study which discussed pulse power capability of high energy density capacitors based on a dielectric material. Development of dielectric materials; Description of capacitor design; Details on capacitor testing

This paper presents a constant frequency tertiary side resonant dc/dc converter topology. The proposed converter topology gives the opportunity to integrate all the resonant inductors with the output transformer and provides greater flexibility in selecting the resonant capacitors. The harmonic equivalent circuit model and frequency domain analysis, which incorporates the effect of the leakage inductance of the high frequency transformer are presented. Steady state characteristics curves are presented to describe the effect of the leakage inductance and resonant circuit parameters on the performance of the converter. It is shown that with a tuned parallel resonant circuit on the tertiary winding the converter can be operated at higher frequencies. Finally, the experimental results show a higher than 80% efficiency for a 500 W, 48 V to 5 V dc/dc converter operating at 128 kHz. [ABSTRACT FROM PUBLISHER]

The influence of pulsed magnetization history in pulsed electromagnetic actuator on system output mechanical parameters has been discussed. Hysteresis behavior of pulsed linear electromagnetic actuators considerably degrades the precision and stability of impact energy system’s performance. In this paper, a method is developed to provide stability for the dosed impact energy in pulsed linear electromagnetic actuators. Theoretical conclusions and experimental results have been provided. [ABSTRACT FROM AUTHOR]

In this paper, the authors have designed a light condenser device based on the integrated gradient-index (GRIN) lens for the light delivery in a heat-assisted magnetic recording head. The function of the GRIN light condenser is to solve the mode size mismatch and to realize a smooth and efficient light condensation between an external laser diode and a nano-waveguide. Two realizable approaches based on the alloying and two-material film stack to actualize the equivalent index profile have been discussed. From the numerical examples, optimized coupling efficiencies of 93.2% and 86.0% can be achieved for the case of transverse electric and transverse magnetic polarized light, respectively. [ABSTRACT FROM PUBLISHER]

A new method of contactless energy transmission to such moving loads as electric vehicles (EVs) is proposed in this paper. By employing rectangular and spiral coils for primary and secondary windings in our cordless power station (CLPS), we could transmit over 200 W of energy to our fabricated EV motor set-up and confirmed the actual operation of it. The rectangular coil is for stable transmission against coil misalignment and the spiral coil is for efficient receiving of flux from the primary coil. By placing many rectangular coils with their longer sides along in line with the EV's moving direction, the transmitted energy was more or less stable against the EV's displacement. Furthermore, a switched excitation system on the primary coils enhanced the total transmission efficiency. A switched excitation system is our new structure and it allows only one coil excited which is the nearest to the load among other coils for the sake of the overall efficiency improvement. Using the rectangular spiral-coils and the switched excitation system, we could actually drive our fabricated EV motor set-up of the nominal output 200 W. [ABSTRACT FROM PUBLISHER]

In this paper, integrated air-suspended inductors were newly developed on silicon substrate for on-chip radio frequency (RF) circuit and system applications. For the improvement of Q-factors and self-resonant frequencies of the integrated inductors, they were designed and fabricated by using air-suspended spiral conductor lines, photoresist sacrificial layer, and electroplating technique. For forming the air-suspended conductor lines without selectively etching the substrate and using any metal or insulating posts, the conductor lines were designed to have a shape of ‘U’ at the center of each conductor line. In comparison of the fabricated conventional planar and air-suspended inductors, an increase of 25% in the Q-factor was achieved for the air-suspended inductors. The self-resonant frequency was also increased about 10 to 15% compared with the planar ones. The proposed inductor geometry and fabrication processes were developed for integrating with metal-insulator-metal (MIM) RF capacitors. [ABSTRACT FROM PUBLISHER]

High frequency planar transformer (HFPT) is an up-and-coming technology which can be used for designing a contact-less battery charging platform. In this paper, fractal-based high frequency planar transformers are presented with two different structures: 4-to-1 and 16-to-4 turn ratio. Because they are PCB-based transformers, two cases of 0.8 mm and 1.6 mm thickness were investigated. A finite-element method has been used to calculate the magnetic field. LLC resonant converter has been designed to improve the conversion efficiency. The voltage ratio has been measured with and without a capacitor at the primary side. The winding with a capacitor can increase the efficiency without any distortion and harmonics. [ABSTRACT FROM AUTHOR]

Detailed design of machines incorporating permanent magnets requires precise knowledge of materials' magnetization characteristics. Nd-Fe-B magnets are known for their “hard” properties and thorough characterization of these magnets in easy and hard directions requires very strong magnetic fields (in the range of MA/m). Application of such high fields results in high voltages induced in the pick-up coils—in presented case the induced voltage reaches up to 50–60 V. Signal is acquired using precise NI ADC accepting input voltage in range of \pm5 V max. This means that direct connection between pick-up and ADC is not possible. Obvious solution to this problem is to decrease number of turns in pick-up coils, however for high quality results the number of turns should be large and ideally an integer. The ADC could be exchanged but fast, precise and high-input-voltage ADC is not cost-effective. Additionally, especially in case of slow ADCs, transitions present in magnetization signal can exceed available bandwidths distorting the results. Perfect solution to highlighted problems is the attenuation of the signals and their further digital reconstruction. Attenuation might be performed using active integrators—reported error are in the level of 1% in \sim3 MA/m field. It might be also based on passive devices—preferred approach eliminating input voltage limits and power considerations for the pick-up system. Reconstruction might be done on the basis of the model of an attenuator or reconstructive filtering (equalization). Two types of attenuators are presented in this paper. RC attenuator which provided reversible spectrum and amplitude adjustment and R attenuator affecting only the amplitude of the signal. Reconstruction error from RC attenuator was on the level of \pm0.1% in the most important part of the signal. R attenuator provided comparable error with added merit of very easy de-attenuation procedure which makes it an attractive solution for high field measurements. Some results from Nd-Fe-B magnet characterization in \sim11 MA/m (\sim14 T) field using similar R attenuator device are presented. Proposed passive attenuators made this high field characterization possible. [ABSTRACT FROM AUTHOR]

A design method and load evaluation system for a single-phase linear permanent magnet generator (SPLPMG) for Stirling engines are proposed. The generator was designed considering the short stroke of the system and the characteristics of high-speed reciprocating motion. The accuracy of the 2-D finite-element method (FEM) was improved by considering the outer core and inner core split lamination characteristics. A test rig for evaluating the SPLPMG was fabricated. The evaluation system consisted of a crankshaft that converted the rotational motion into reciprocating motion, so that the linear generator could be evaluated as a rotational power source. The load test was carried out according to the operational frequency of the generator. An SPLPMG output of 3 kW was obtained, and the FEM analysis results and evaluation results were similar. [ABSTRACT FROM AUTHOR]

This paper presents the results of an investigation into numerical simulation tools for high-impedance surfaces (HIS), with the primary aim of assisting in the design and optimization of these structures in electromagnetic compatibility (EMC) applications. The mathematically simple stub technique was used for capacitors and inductances to model lumped L and C in transmission line configurations. The basic principles of the transmission line modeling (TLM) method, such as the equivalences between the field quantities and circuit parameters, are briefly discussed and are applied on a uniform and a high-impedance transmission lines. [ABSTRACT FROM AUTHOR]

The impulsive acceleration of active protection elements such as armor plates or other terminal ballistics interception devices can preferably be realized by single-stage electromagnetic launcher systems using pancake coils. The technology with controlled multipartite coil assemblies represents a new supplementary topic in the entire field of ballistics. However, the essential condition is the availability of modular high-energy-density pulsed-power supply units with low volume and weight. During the last years, modular structured energy packs have been built up at ISL as a basic installation for various applications in the field of pulsed-power electronics; in particular, they are developed to feed active protection launcher systems. Each power supply module comprises one energy storage capacitor, a thyristor stack, a corresponding number of crowbar diodes, and a well-designed coaxial power line serving as a pulse-forming network and current-limiting reactor. To provide high flexibility, these modules can be triggered separately and independently by fiber-optic transmitters with an overall jitter lower than 50 ns. This paper describes the basic design of a 50-kJ energy pack and the further developed setup with a strongly reduced overall height obtained by using a novel multichip thyristor. Additionally, a 2-D steerable launcher system supplied by these modules will be presented. [ABSTRACT FROM AUTHOR]

Super capacitor has the advantage of quick charge, large power density, and long cycle life. The shortage is the lower energy density compared with electrochemistry batteries. These features make it suitable for a short-distance electric bus used in the city. Because of the capacitance difference between the capacitor cells, after a number of deep discharging/charging cycles, the voltage difference between cells will be enlarged. This will accelerate the aging of the weak super capacitors and affect the output power. So, a management system with an equalization function is essential. In this paper, a practical super-capacitor stacks management system with dynamic equalization techniques is proposed. The function of the management system includes: monitoring the current, voltage, and temperature of the stacks, control of charge, and discharge with equalization online. A switched-capacitor equalization approach is adopted showing a low-cost way to meet the accuracy requirements. The dynamic equalized charging and discharging circuit is described. The algorithm to increase the operation speed and the precision is analyzed. By dynamically redistributing the current, the equalization procedure can be quicker and more efficient. This approach has been verified by experiments. [ABSTRACT FROM AUTHOR]

This paper describes miniaturized inertia generators for converting mechanical energy into electrical energy for military applications, especially as power supplies for electrical fuzes. In order to minimize the volume of the generators, our design adopted a ring-shaped magnet enclosing a coil assembly. The inertia generators are intended not to ignite an electrical detonator hut to charge a capacitor that drives the electric circuit of fuze. A mechanical safety system, a shear plate, is used as a release mechanism for the inertia generators to prevent them from operating accidentally. We designed the inertia generators by using the simulation results of an electromagnetic analysis tool. in an experimental study, we performed safety tests on the shear plate and firing tests of the fabricated inertia generators. The present inertia generators show that a voltage of 14.2 V was charged on a capacitor of 30 μF within the charging time of 0.68 ms and the critical acceleration for safety was 5000 G, verifying that the inertia generators can be used as power supplies for small-caliber electrical fuzes. [ABSTRACT FROM AUTHOR]

An invention scheme of pulsed magnetohydrodynamic generator (PMHDG) in milliseconds order of magnitude that can be used directly in electric launchers is presented for the first time. It is either different from ordinary small power dc MHD generators for power plants, or different from explosive MHD generators where its pulsed current width is in the microseconds order of magnitude. Operating principle of the PMHDG is as follows: fuels or oxidizing agents within two storage vessels are injected into a combustion chamber to combust by a pump and a valve, after waiting for the pressure (or density) of generated conductive electric MHD ascends some threshold value, a self-controlled valve in combustion chamber throat is opened automatically. As a result, conductive electric MHD passes into a generating channel in pulse to generate electric current. Obviously, by controlling the amount of the working substance entering into the combustion chamber with the injector valve, and adapting the spring pressure of the self-controlled valve, we can control the pulsewidth. and obtain different values of high power to be used directly by the electric launcher. Besides, this paper gives a theory-mathematical model in which some characteristics of the generator were expressed. This helps us to understand the relationship between various physical quantifies about the generator, and provides a basis to research their mutual influences. In addition, in physical design of the circuit, we adopted a proper high energy density capacitor as auxiliary energy storage. On one hand, the generator can realize the self-excited generation by using the capacitor; on the other hand, the high energy capacitor is charged directly by the generator and energy stored within the capacitor is realized, so as to form a generator-capacitor combined high power pulsed power supply that can be used by high energy electric launchers. [ABSTRACT FROM AUTHOR]

This paper describes a series of experiments and their numerical simulations in which cracks were created in conductors by using high-transient magnetic fields. The tests were conducted on small samples of 7075 aluminum alloy in a test fixture that placed the samples in series with a high-voltage capacitor bank and constrained the samples from moving. Notches were machined in the samples at various depths for the purpose of creating an initiation site for the cracks. After each pulse, the samples were unmounted and examined under an optical microscope. The peak current was varied to examine its effect on crack tip behavior. It was found that the crack tip extended linearly, was blunted by cavitation (blowholes formed due to intense heating), or bifurcated-depending on the level of the peak current. Multiple pulses were also applied to one sample to study the effects of repeated pulsing on crack extension. Finite-element computations were performed using the three-dimensional finite-element analysis program EMAP3D in conjunction with the stress code DYNA3D. The computational results confirm most of the features observed in the experiments. [ABSTRACT FROM AUTHOR]

High-voltage transformers can be built with coaxial transmission lines. This paper describes a transformer design that uses the coaxial screen as primary winding and the inner conductor as secondary. An advantage of transmission line transformers is that the insulation problem is solved and the construction can be kept simple; the coupling between the primary and secondary coils is high even though the transformer uses an air core. The air core brings another advantage: the capacity to store large quantities of magnetic energy. The combination of a high coupling factor and large energy storage capacity makes this transformer ideal for charging high-voltage capacitors fast. The winding type for the transformer is alternating Archimedean spirals. Here, we present a magnetic field analysis of the transformer's primary, secondary, and mutual inductance using a finite-element solver. We compare the measured magnetic flux density versus the calculated value. The step-up winding ratio of the transformer influences the coupling factor marginally if the construction has an even number of spiral layers for each set of windings. However, the result from the finite-element solver predicts a drop in coupling factor if the step-up transformer construction has an odd number of spiral layers. The copper conductors used in the transformer resemble isotropic copper pipes. [ABSTRACT FROM AUTHOR]

The Army's Pulse Power For Future Combat System (FCS) Army Technology Objective (ATO) program is developing the high-voltage pulse power components required to allow for the integration of revolutionary survivability and lethality in ground combat vehicles. This paper will describe recent advances in high energy density (HED) biaxially-oriented poly-propylene (BOPP) capacitors. Intermediate energy storage for many pulse power loads is achieved through the use of high energy-density thin-film capacitors, currently utilizing BOPP as the dielectric film of choice. Recent advances in HED BOPP capacitors over the last decade have resulted in the energy density more than doubling from ~0.5 J/cc in the early 1990s to ~1.2 J/cc in the 2003-2004 timeframe while still possessing reasonable direct current (dc) life and shot life. Further research has resulted in RED capacitors with energy densities of 2.0 J/cc at reduced shot and dc life levels which are candidates for applications in which the number of shots are not critical to the application. Current research and development efforts through SAIC and Advance Capacitor Inc/ICAR (ACI/ICAR) are being pursued with the goal of developing >1.8 J/cc while maintaining reasonable dc and shot life. In addition, efforts are also ongoing to develop exceptionally long dc-life HED capacitors. [ABSTRACT FROM AUTHOR]

The paper presents a new electronic starter for single phase induction motors. It replaces the well known starting capacitor as a phase shifting component in the auxiliary winding circuit. Moreover, the auxiliary winding is disconnected automatically, without any additional switch, when the motor gets close to its rated speed. The operation principle of the starter is theoretically explained, and illustrated with experimental results. [ABSTRACT FROM PUBLISHER]