WorldWideScience

Sample records for capacitors

  1. Fractal capacitors

    OpenAIRE

    Samavati, Hirad; Hajimiri, Ali; Shahani, Arvin R.; Nasserbakht, Gitty N.; Lee, Thomas H.

    1998-01-01

    A linear capacitor structure using fractal geometries is described. This capacitor exploits both lateral and vertical electric fields to increase the capacitance per unit area. Compared to standard parallel-plate capacitors, the parasitic bottom-plate capacitance is reduced. Unlike conventional metal-to-metal capacitors, the capacitance density increases with technology scaling. A classic fractal structure is implemented with 0.6-μm metal spacing, and a factor of 2.3 increase in the capacitan...

  2. Rotary capacitor

    CERN Document Server

    1971-01-01

    The rotating wheel of the rotary capacitor representing the most critical part of the new radio-frequency system of the synchro-cyclotron. The three rows of teeth on the circumference of the wheel pass between four rows of stator blades with a minimum clearance of 1 mm at a velocity of 1700 rev/min.

  3. Towards Prognostics of Electrolytic Capacitors

    Data.gov (United States)

    National Aeronautics and Space Administration — A remaining useful life prediction algorithm and degradation model for electrolytic capacitors is presented. Electrolytic capacitors are used in several...

  4. Single Capacitor Paradox

    CERN Document Server

    Pankovic, Vladan

    2009-01-01

    In this work single capacitor paradox (a variation of the remarkable two capacitor paradox) is considered. Simply speaking in an ideal (without any electrical resistance and inductivity) electrical circuit with single charged capacitor and switch, by transition from initial, open state (switch in OFF position) in the final, closed state (switch in ON position), there is a total loss of the initial energy of the electrical field in condenser. Given energy loss can be simply explained without any dissipative effects (Joule heating or electromagnetic waves emission) by work of the electrical field by movement of the charge from one in the other plate of the capacitor. (Two capacitors paradox can be, obviously, explained in the analogous way.)

  5. Capacitor discharge engineering

    CERN Document Server

    Früngel, Frank B A

    1976-01-01

    High Speed Pulse Technology, Volume III: Capacitor Discharge Engineering covers the production and practical application of capacitor dischargers for the generation and utilization of high speed pulsed of energy in different forms. This nine-chapter volume discusses the principles of electric current, voltage, X-rays, gamma rays, heat, beams of electrons, neutrons and ions, magnetic fields, sound, and shock waves in gases and liquids. Considerable chapters consider the applications of capacitor discharges, such as impulse hardening of steel, ultrapulse welding of precision parts, X-ray flash t

  6. High Temperature Capacitor Development

    Energy Technology Data Exchange (ETDEWEB)

    John Kosek

    2009-06-30

    The absence of high-temperature electronics is an obstacle to the development of untapped energy resources (deep oil, gas and geothermal). US natural gas consumption is projected to grow from 22 trillion cubic feet per year (tcf) in 1999 to 34 tcf in 2020. Cumulatively this is 607 tcf of consumption by 2020, while recoverable reserves using current technology are 177 tcf. A significant portion of this shortfall may be met by tapping deep gas reservoirs. Tapping these reservoirs represents a significant technical challenge. At these depths, temperatures and pressures are very high and may require penetrating very hard rock. Logistics of supporting 6.1 km (20,000 ft) drill strings and the drilling processes are complex and expensive. At these depths up to 50% of the total drilling cost may be in the last 10% of the well depth. Thus, as wells go deeper it is increasingly important that drillers are able to monitor conditions down-hole such as temperature, pressure, heading, etc. Commercial off-the-shelf electronics are not specified to meet these operating conditions. This is due to problems associated with all aspects of the electronics including the resistors and capacitors. With respect to capacitors, increasing temperature often significantly changes capacitance because of the strong temperature dependence of the dielectric constant. Higher temperatures also affect the equivalent series resistance (ESR). High-temperature capacitors usually have low capacitance values because of these dielectric effects and because packages are kept small to prevent mechanical breakage caused by thermal stresses. Electrolytic capacitors do not operate at temperatures above 150oC due to dielectric breakdown. The development of high-temperature capacitors to be used in a high-pressure high-temperature (HPHT) drilling environment was investigated. These capacitors were based on a previously developed high-voltage hybridized capacitor developed at Giner, Inc. in conjunction with a

  7. Electrochemical flow capacitors

    Science.gov (United States)

    Gogotsi, Yury; Presser, Volker; Kumbur, Emin Caglan

    2015-10-27

    The present invention generally relates to devices for energy storage technologies, and more particularly to electrochemical flow capacitor systems and applications. In some aspects, these flow capacitors have at least one electrode comprising a non-stationary solid or semi-solid composition comprising supercapacitive particles and an electrolytic solvent in electrical communication with at least one current collector, and energy is stored and/or released by charging and/or discharging the electrode(s).

  8. Fermilab Capacitor Tree

    International Nuclear Information System (INIS)

    The Fermilab Capacitor Tree is a capacitor bank used in series with the feeders carrying 3-phase, 13.8 kV power to the main ring power supply system. Its function is to reduce the voltage droop of the power supplies at high currents, by acting in series resonance with the leakage inductances of the system. A description is given of the electrical system and operational experience since May 1976

  9. Suspended graphene variable capacitor

    OpenAIRE

    AbdelGhany, M.; Mahvash, F.; Mukhopadhyay, M.; Favron, A.; Martel, R; Siaj, M.; Szkopek, T.

    2016-01-01

    The tuning of electrical circuit resonance with a variable capacitor, or varactor, finds wide application with the most important being wireless telecommunication. We demonstrate an electromechanical graphene varactor, a variable capacitor wherein the capacitance is tuned by voltage controlled deflection of a dense array of suspended graphene membranes. The low flexural rigidity of graphene monolayers is exploited to achieve low actuation voltage in an ultra-thin structure. Large arrays compr...

  10. Materials for electrochemical capacitors

    Science.gov (United States)

    Simon, Patrice; Gogotsi, Yury

    2008-11-01

    Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

  11. Capacitor discharge pulse analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Michael Sean; Griffiths, Stewart K.; Tanner, Danelle Mary

    2013-08-01

    Capacitors used in firing sets and other high discharge current applications are discharge tested to verify performance of the capacitor against the application requirements. Parameters such as capacitance, inductance, rise time, pulse width, peak current and current reversal must be verified to ensure that the capacitor will meet the application needs. This report summarizes an analysis performed on the discharge current data to extract these parameters by fitting a second-order system model to the discharge data and using this fit to determine the resulting performance metrics. Details of the theory and implementation are presented. Using the best-fit second-order system model to extract these metrics results in less sensitivity to noise in the measured data and allows for direct extraction of the total series resistance, inductance, and capacitance.

  12. Engineering electrochemical capacitor applications

    Science.gov (United States)

    Miller, John R.

    2016-09-01

    Electrochemical capacitor (EC) applications have broadened tremendously since EC energy storage devices were introduced in 1978. Then typical applications operated below 10 V at power levels below 1 W. Today many EC applications operate at voltages approaching 1000 V at power levels above 100 kW. This paper briefly reviews EC energy storage technology, shows representative applications using EC storage, and describes engineering approaches to design EC storage systems. Comparisons are made among storage systems designed to meet the same application power requirement but using different commercial electrochemical capacitor products.

  13. Protection of large capacitor banks

    International Nuclear Information System (INIS)

    Large capacitor banks, as used in many pulsed plasma experiments, are subject to catastrophic failure in the event of a short in the output or in an individual capacitor. Methods are described for protecting such banks to minimize the damage and down-time caused by such a failure

  14. Electrically tuned super-capacitors

    CERN Document Server

    Chowdhury, Tazima S

    2015-01-01

    Fast charging and discharging of large amounts of electrical energy make super-capacitors ideal for short-term energy storage [1-5]. In its simplest form, the super-capacitor is an electrolytic capacitor made of an anode and a cathode immersed in an electrolyte. As for an ordinary capacitor, minimizing the charge separation distance and increasing the electrode area increase capacitance. In super-capacitors, charge separation is of nano-meter scale at each of the electrode interface (the Helmholtz double layer). Making the electrodes porous increases their effective surface area [6-8]. A separating layer between the anode and the cathode electrodes is used to minimize unintentional electrical discharge (Figure 1). Here we show how to increase the capacitance of super-capacitors by more than 45 percent when modifying the otherwise passive separator layer into an active diode-like structure. Active control of super-capacitors may increase their efficiency during charge and discharge cycles. Controlling ion flow...

  15. Fractal Structures For Mems Variable Capacitors

    KAUST Repository

    Elshurafa, Amro M.

    2014-08-28

    In accordance with the present disclosure, one embodiment of a fractal variable capacitor comprises a capacitor body in a microelectromechanical system (MEMS) structure, wherein the capacitor body has an upper first metal plate with a fractal shape separated by a vertical distance from a lower first metal plate with a complementary fractal shape; and a substrate above which the capacitor body is suspended.

  16. Ferroelectric capacitor with reduced imprint

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Jr., Joseph T. (13609 Verbena Pl., NE., Albuquerque, NM 87112); Warren, William L. (7716 Wm. Moyers Ave., NE., Albuquerque, NM 87122); Tuttle, Bruce A. (12808 Lillian Pl., NE., Albuquerque, NM 87122); Dimos, Duane B. (6105 Innsbrook Ct., NE., Albuquerque, NM 87111); Pike, Gordon E. (1609 Cedar Ridge, NE., Albuquerque, NM 87112)

    1997-01-01

    An improved ferroelectric capacitor exhibiting reduced imprint effects in comparison to prior art capacitors. A capacitor according to the present invention includes top and bottom electrodes and a ferroelectric layer sandwiched between the top and bottom electrodes, the ferroelectric layer comprising a perovskite structure of the chemical composition ABO.sub.3 wherein the B-site comprises first and second elements and a dopant element that has an oxidation state greater than +4. The concentration of the dopant is sufficient to reduce shifts in the coercive voltage of the capacitor with time. In the preferred embodiment of the present invention, the ferroelectric element comprises Pb in the A-site, and the first and second elements are Zr and Ti, respectively. The preferred dopant is chosen from the group consisting of Niobium, Tantalum, and Tungsten. In the preferred embodiment of the present invention, the dopant occupies between 1 and 8% of the B-sites.

  17. High Energy Density Capacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Capacitor size and reliability are often limiting factors in pulse power, high speed switching, and power management and distribution (PMAD) systems. T/J...

  18. Fractal Structures For Fixed Mems Capacitors

    KAUST Repository

    Elshurafa, Amro M.

    2014-08-28

    An embodiment of a fractal fixed capacitor comprises a capacitor body in a microelectromechanical system (MEMS) structure. The capacitor body has a first plate with a fractal shape separated by a horizontal distance from a second plate with a fractal shape. The first plate and the second plate are within the same plane. Such a fractal fixed capacitor further comprises a substrate above which the capacitor body is positioned.

  19. Radiation effects in polycarbonate capacitors

    Directory of Open Access Journals (Sweden)

    Vujisić Miloš

    2009-01-01

    Full Text Available The aim of this paper is to examine the influence of neutron and gamma irradiation on the dissipation factor and capacitance of capacitors with polycarbonate dielectrics. The operation of capacitors subject to extreme conditions, such as the presence of ionizing radiation fields, is of special concern in military industry and space technology. Results obtained show that the exposure to a mixed neutron and gamma radiation field causes a decrease of capacitance, while the loss tangent remains unchanged.

  20. PLZT capacitor on glass substrate

    Energy Technology Data Exchange (ETDEWEB)

    Fairchild, Manuel Ray; Taylor, Ralph S.; Berlin, Carl W.; Wong, Celine Wk; Ma, Beihai; Balachandran, Uthamalingam

    2016-03-29

    A lead-lanthanum-zirconium-titanate (PLZT) capacitor on a substrate formed of glass. The first metallization layer is deposited on a top side of the substrate to form a first electrode. The dielectric layer of PLZT is deposited over the first metallization layer. The second metallization layer deposited over the dielectric layer to form a second electrode. The glass substrate is advantageous as glass is compatible with an annealing process used to form the capacitor.

  1. Microwatt Switched Capacitor Circuit Design

    OpenAIRE

    Vittoz, E.

    1982-01-01

    The micropower CMOS implementation of the three basic components of switched capacitor circuits is discussed. Switches must be carefully designed to allow low voltage operation and compensation of clock feed-through by dummy transistors. Matched capacitors can be implemented in single polysilicon technologies primarily designed for digital micropower circuits. Excellent micropower amplifiers are realized by using simple one-stage circuits which take advantage of the special behaviour of MOS t...

  2. Efficiency Improvement of Capacitor Operation

    Directory of Open Access Journals (Sweden)

    V. P. Kashcheev

    2010-01-01

    Full Text Available A system of modernized capacitor ball-cleaning that prevents formation of depositions on internal capacitor tube surface has been developed in the paper.The system has been introduced at the Minsk TPP-4 (Power Block No.5. The paper presupposes that the economic effect will be nearly 0.43 million US dollars per year at one poer block with turbine Т-250/300-240.

  3. Technology of Pulse Power Capacitors

    Science.gov (United States)

    Qin, Shanshan

    Polymer film of pulse discharge capacitors operated at high repetition rate dissipates substantial power. The thermal conductivity of biaxially oriented polypropylene (BOPP) is measured as a function of metallization resistivity. The thermal conductivity in the plane of the film is about twice that of bulk polypropylene. Thermal design is optimized based on the measurement for large capacitors with multiple windings in a container. High discharge speed results in high current density at the wire arc sprayed end connections which tend to deteriorate gradually, resulting in capacitor failure during operation. To assure the end connection quality before assembly, a test procedure and apparatus for end connection integrity was developed based on monitoring the partial discharge pattern from end connection during discharge. The mechanism of clearing is analyzed which shows arc extinguishes due to the increased arc length and reduced energy so that capacitor can function normally after breakdown. In the case of a clearing discharge, the power dissipation appears to increase with time, although this is not a feature of previous models. Submicrosecond discharge requires minimizing inductance which can be achieved by optimizing the winding structure so that submicrosecond discharge becomes practical. An analysis of the inductance of multisection, very high voltage capacitors is carried out, which identifies low inductance structures for this type of capacitor.

  4. High-Energy-Density Capacitors

    Science.gov (United States)

    Slenes, Kirk

    2003-01-01

    Capacitors capable of storing energy at high densities are being developed for use in pulse-power circuits in such diverse systems as defibrillators, particle- beam accelerators, microwave sources, and weapons. Like typical previously developed energy-storage capacitors, these capacitors are made from pairs of metal/solid-dielectric laminated sheets that are wound and pressed into compact shapes to fit into cans, which are then filled with dielectric fluids. Indeed, these capacitors can be fabricated largely by conventional fabrication techniques. The main features that distinguish these capacitors from previously developed ones are improvements in (1) the selection of laminate materials, (2) the fabrication of the laminated sheets from these materials, and (3) the selection of dielectric fluids. In simplest terms, a high-performance laminated sheet of the type used in these capacitors is made by casting a dielectric polymer onto a sheet of aluminized kraft paper. The dielectric polymer is a siloxane polymer that has been modified with polar pendant groups to increase its permittivity and dielectric strength. Potentially, this polymer is capable of withstanding an energy density of 7.5 J/cm3, which is four times that of the previous state-of-the-art-capacitor dielectric film material. However, the full potential of this polymer cannot be realized at present because (1) at thicknesses needed for optimum performance (.8.0 m), the mechanical strength of a film of this polymer is insufficient for incorporation into a wound capacitor and (2) at greater thickness, the achievable energy density decreases because of a logarithmic decrease in dielectric strength with increasing thickness. The aluminized kraft paper provides the mechanical strength needed for processing of the laminate and fabrication of the capacitor, and the aluminum film serves as an electrode layer. Because part of the thickness of the dielectric is not occupied by the modified siloxane polymer, the

  5. Electromechanical capacitor for energy transfer

    International Nuclear Information System (INIS)

    Inductive energy transfer between two magnets can be achieved with almost 100% efficiency with a transfer capacitor. However, the bulk and cost will be high, and reliability low if conventional capacitors are used. A homopolar machine, used as a capacitor, will be compact and economical. A homopolar machine was designed with counter-rotating copper disks completely immersed in a liquid metal (NaK-78) to work as a pulse capacitor. Absence of solid-brush collectors minimized wear and frictional losses. Wetting of the copper disks throughout the periphery by the liquid metal minimized the resistive losses at the collector interface. A liquid-metal collector would, however, introduce hydrodynamic and magnetohydrodynamic losses. The selected liquid metal, e.g., NaK-78 will produce the lowest of such losses among the available liquid metals. An electromechanical capacitor of this design was tested at various dc magnetic fields. Its measured capacitance was about 100 farads at a dc magnetic field of 1.15 tesla

  6. Tunable circuit for tunable capacitor devices

    Science.gov (United States)

    Rivkina, Tatiana; Ginley, David S.

    2006-09-19

    A tunable circuit (10) for a capacitively tunable capacitor device (12) is provided. The tunable circuit (10) comprises a tunable circuit element (14) and a non-tunable dielectric element (16) coupled to the tunable circuit element (16). A tunable capacitor device (12) and a method for increasing the figure of merit in a tunable capacitor device (12) are also provided.

  7. Electrical characterization of thin film ferroelectric capacitors

    NARCIS (Netherlands)

    Tiggelman, M.P.J.; Reimann, K.; Klee, M.; Beelen, D.; Keur, W.; Schmitz, J.; Hueting, R.J.E.

    2006-01-01

    Tunable capacitors can be used to facilitate the reduction of components in wireless technologies. The tunability of the capacitors is caused by the sensitivity of the relative dielectric constant to a change in polarization with electric field. Thin film ferroelectric MIM capacitors on silicon offe

  8. Heat generation in double layer capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Schiffer, Julia; Linzen, Dirk; Sauer, Dirk Uwe [Electrochemical Energy Conversion and Storage Systems Group, Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University, Jaegerstrasse 17-19, D-52066 Aachen (Germany)

    2006-09-29

    Thermal management is a key issue concerning lifetime and performance of double layer capacitors and battery technologies. Double layer capacitor modules for hybrid vehicles are subject to heavy duty cycling conditions and therefore significant heat generation occurs. High temperature causes accelerated aging of the double layer capacitors and hence reduced lifetime. To investigate the thermal behavior of double layer capacitors, thermal measurements during charge/discharge cycles were performed. These measurements show that heat generation in double layer capacitors is the superposition of an irreversible Joule heat generation and a reversible heat generation caused by a change in entropy. A mathematical representation of both parts is provided. (author)

  9. Capacitor ageing in electronic devices

    OpenAIRE

    Richard B. N. Vital; Tatiane M. Vital

    2015-01-01

    The moment when an electronic component doesn’t work like requirements, previously established is a task that need to be considered since began of a system design. However, the use of different technologies, operating under several environmental conditions, makes a component choice a complex step in system design. This paper analyzes the effects that ageing phenomenon of capacitors may introduce in electronic devices operation. For this reason, reliability concepts, processes and ...

  10. YANG-MILLS FIELD CAPACITOR

    Directory of Open Access Journals (Sweden)

    Trunev A. P.

    2015-10-01

    Full Text Available The article presents a project of the capacitor in the Yang-Mills theory. Model capacitor represents the equipotential surfaces separated by a space. To describe the mechanism of condensation chromodynamics field used numerical models developed based on an average of the Yang-Mills theory. In the present study, we used eight-scalar component model that in the linear case is divided into two groups containing three or five fields respectively. In contrast to classical electrodynamics, a static model of the Yang-Mills is not divided into independent equations because of the nonlinearity of the model itself. However, in the case of a linear theory separation is possible. It is shown that in this particular case, the Yang-Mills theory is reduced to Poisson theory, which describes the electrostatic and magnetostatic phenomena. In the present work it is shown that in a certain region of the parameters of the capacitor of the Yang-Mills theory on the functional properties of the charge accumulation and retention of the field is similar to the capacitor of the electrostatic field or a magnet in magnetostatics. This means that in nature there are two types of charges, which are sources of macroscopic Yang-Mills field, which are similar to the properties of electric and magnetic charges in the Poisson theory. It is shown that in Yang-Mills only one type of charge may be associated with the distribution density of the substance, while another type of charge depends on the charge distribution of the first type. This allows us to provide an explanation for the lack of symmetry between electric and magnetic charges

  11. Quantum, Photo-Electric Single Capacitor Paradox

    CERN Document Server

    Kapor, Darko

    2009-01-01

    In this work single capacitor paradox (a variation of the remarkable two capacitor paradox) is considered in a new, quantum discrete form. Simply speaking we consider well-known usual, photoelectric effect experimental device, i.e. photo electric cell, where cathode and anode are equivalently charged but non-connected. It, obviously, represents a capacitor that initially, i.e. before action of the photons with individual energy equivalent to work function, holds corresponding energy of the electrical fields between cathode and anode. Further, we direct quantum discretely photons, one by one, toward cathode where according to photo-electrical effect electrons discretely, one by one, will be emitted and directed toward anode. It causes discrete discharge of the cell, i.e. capacitor and discrete decrease of the electrical field. Finally, total discharge of the cell, i.e. capacitor, and total disappearance of the electrical field and its energy will occur. Given, seemingly paradoxical, capacitor total energy loss...

  12. Charging Capacitors According to Maxwell's Equations: Impossible

    CERN Document Server

    Funaro, Daniele

    2014-01-01

    The charge of an ideal parallel capacitor leads to the resolution of the wave equation for the electric field with prescribed initial conditions and boundary constraints. Independently of the capacitor's shape and the applied voltage, none of the corresponding solutions is compatible with the full set of Maxwell's equations. The paradoxical situation persists even by weakening boundary conditions, resulting in the impossibility to describe a trivial phenomenon such as the capacitor's charging process, by means of the standard Maxwellian theory.

  13. Charging Capacitors According to Maxwell's Equations: Impossible

    OpenAIRE

    Funaro, Daniele

    2014-01-01

    The charge of an ideal parallel capacitor leads to the resolution of the wave equation for the electric field with prescribed initial conditions and boundary constraints. Independently of the capacitor's shape and the applied voltage, none of the corresponding solutions is compatible with the full set of Maxwell's equations. The paradoxical situation persists even by weakening boundary conditions, resulting in the impossibility to describe a trivial phenomenon such as the capacitor's charging...

  14. Electrical characterization of thin film ferroelectric capacitors

    OpenAIRE

    Tiggelman, M.P.J.; Reimann, K.; Klee, M.; Beelen, D; Keur, W.; J. Schmitz; Hueting, R.J.E.

    2006-01-01

    Tunable capacitors can be used to facilitate the reduction of components in wireless technologies. The tunability of the capacitors is caused by the sensitivity of the relative dielectric constant to a change in polarization with electric field. Thin film ferroelectric MIM capacitors on silicon offer a re-use of electronic circuitry, low tuning voltages, a high capacitance density, a low cost, a presence of bulk acoustic wave resonance(s) and decoupling functionality. The basic operation and ...

  15. Nanostructured Electrode Materials for Electrochemical Capacitor Applications

    OpenAIRE

    Hojin Choi; Hyeonseok Yoon

    2015-01-01

    The advent of novel organic and inorganic nanomaterials in recent years, particularly nanostructured carbons, conducting polymers, and metal oxides, has enabled the fabrication of various energy devices with enhanced performance. In this paper, we review in detail different nanomaterials used in the fabrication of electrochemical capacitor electrodes and also give a brief overview of electric double-layer capacitors, pseudocapacitors, and hybrid capacitors. From a materials point of view, t...

  16. Capacitors with low equivalent series resistance

    Science.gov (United States)

    Fleig, Patrick Franz (Inventor); Lakeman, Charles D. E. (Inventor); Fuge, Mark (Inventor)

    2011-01-01

    An electric double layer capacitor (EDLC) in a coin or button cell configuration having low equivalent series resistance (ESR). The capacitor comprises mesh or other porous metal that is attached via conducting adhesive to one or both the current collectors. The mesh is embedded into the surface of the adjacent electrode, thereby reducing the interfacial resistance between the electrode and the current collector, thus reducing the ESR of the capacitor.

  17. Capacitor discharges, magnetohydrodynamics, X-rays, ultrasonics

    CERN Document Server

    Früngel, Frank B A

    1965-01-01

    High Speed Pulse Technology, Volume 1: Capacitor Discharges - Magnetohydrodynamics - X-Rays - Ultrasonics deals with the theoretical and engineering problems that arise in the capacitor discharge technique.This book discusses the characteristics of dielectric material, symmetrical switch tubes with mercury filling, and compensation conductor forms. The transformed discharge for highest current peaks, ignition transformer for internal combustion engines, and X-ray irradiation of subjects in mechanical motion are also elaborated. This text likewise covers the transformed capacitor discharge in w

  18. New Niobium Capacitors with Stable Electrical Parameters

    OpenAIRE

    Lohwasser, W.; M. Stenzel; Zillgen, H.

    2002-01-01

    The replacement of the anode material in tantalum capacitors by a new generation of high CV niobium powders offers the possibility to get an economical alternative to tantalum for a wide range of applications. Due to the high CV potential of niobium powder there is also an alternative to low voltage aluminum electrolytic capacitors. We developed a new niobium capacitor which shows stable electrical values. By optimizing the structure of the dielectric and the cathodic layers as well as the pr...

  19. Capacitor ageing in electronic devices

    Directory of Open Access Journals (Sweden)

    Richard B. N. Vital

    2015-10-01

    Full Text Available The moment when an electronic component doesn’t work like requirements, previously established is a task that need to be considered since began of a system design. However, the use of different technologies, operating under several environmental conditions, makes a component choice a complex step in system design. This paper analyzes the effects that ageing phenomenon of capacitors may introduce in electronic devices operation. For this reason, reliability concepts, processes and mechanism of degradation are presented. Additionally, some mathematical models are presented to assist maintenance activities or component replacement. The presented approach compares the operability of intact and aged components.

  20. New Temperature-Insensitive Electronically-Tunable Grounded Capacitor Simulator

    OpenAIRE

    Muhammad Haroon Khan; Muhammad Taher Abuelma'atti

    1996-01-01

    A new circuit for simulating a grounded capacitor is presented. The circuit uses one operationalamplifier (OA), three operational-transconductance amplifiers (OTAs), and one capacitor. The realized capacitor is temperature-insensitive and electronically tunable. Experimental results are included.

  1. Ultra-thin multilayer capacitors.

    Energy Technology Data Exchange (ETDEWEB)

    Renk, Timothy Jerome; Monson, Todd C.

    2009-06-01

    The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric constant, and standoff voltage. For successful device construction, there are a number of challenging requirements including achieving correct stoichiometric and crystallographic composition of the deposited PLZT, as well as the creation of a defect free homogenous film. This report details some success in satisfying these requirements, although 900 C temperatures were necessary for PLZT perovskite phase formation. These temperatures were applied to a previously deposited multi-layer film which was then post-annealed to this temperature. The film exhibited mechanical distress attributable to differences in the coefficient of thermal expansion (CTE) of the various layers. This caused significant defects in the deposited films that led to shorts across devices. A follow-on single layer deposition without post-anneal produced smooth layers with good interface behavior, but without the perovskite phase formation. These issues will need to be addressed in order for ion beam deposited MLCCs to become a viable technology. It is possible that future in-situ heating during deposition may address both the CTE issue, and result in lowered processing temperatures, which in turn could raise the probability of successful MLCC formation.

  2. Pyrrole-Based Conductive Polymers For Capacitors

    Science.gov (United States)

    Nagasubramanian, Ganesan; Di Stefano, Salvador

    1994-01-01

    Polypyrrole films containing various dopant anions exhibit superior capacitance characteristics. Used with nonaqueous electrolytes. Candidate for use in advanced electrochemical double-layer capacitors capable of storing electrical energy at high densities. Capacitors made of these films used in automobiles and pulsed power supplies.

  3. Nanostructured Electrode Materials for Electrochemical Capacitor Applications

    Directory of Open Access Journals (Sweden)

    Hojin Choi

    2015-06-01

    Full Text Available The advent of novel organic and inorganic nanomaterials in recent years, particularly nanostructured carbons, conducting polymers, and metal oxides, has enabled the fabrication of various energy devices with enhanced performance. In this paper, we review in detail different nanomaterials used in the fabrication of electrochemical capacitor electrodes and also give a brief overview of electric double-layer capacitors, pseudocapacitors, and hybrid capacitors. From a materials point of view, the latest trends in electrochemical capacitor research are also discussed through extensive analysis of the literature and by highlighting notable research examples (published mostly since 2013. Finally, a perspective on next-generation capacitor technology is also given, including the challenges that lie ahead.

  4. Switched-capacitor isolated LED driver

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, Seth R.; Kline, Mitchell

    2016-03-22

    A switched-capacitor voltage converter which is particularly well-suited for receiving a line voltage from which to drive current through a series of light emitting diodes (LEDs). Input voltage is rectified in a multi-level rectifier network having switched capacitors in an ascending-bank configuration for passing voltages in uniform steps between zero volts up to full received voltage V.sub.DC. A regulator section, operating on V.sub.DC, comprises switched-capacitor stages of H-bridge switching and flying capacitors. A current controlled oscillator drives the states of the switched-capacitor stages and changes its frequency to maintain a constant current to the load. Embodiments are described for isolating the load from the mains, utilizing an LC tank circuit or a multi-primary-winding transformer.

  5. Modular thyristor controlled series capacitor control system

    Energy Technology Data Exchange (ETDEWEB)

    Clark, K.; Larsen, E.V.; Wegner, C.A.; Piwko, R.J.

    1995-06-13

    A modular thyristor controlled series capacitor (TCSC) system, including a method and apparatus, uses phase controlled firing based on monitored capacitor voltage and line current. For vernier operation, the TCSC system predicts an upcoming firing angle for switching a thyristor controlled commutating circuit to bypass line current around a series capacitor. Each bypass current pulse changes the capacitor voltage proportionally to the integrated value of the current pulse. The TCSC system promptly responds to an offset command from a higher-level controller to control bypass thyristor duty to minimize thyristor damage, and to prevent capacitor voltage drift during line current disturbances. In a multi-module TCSC system, the higher level controller accommodates competing objectives of various system demands, including minimizing losses in scheduling control, stabilizing transients, damping subsynchronous resonance (SSR) oscillations, damping direct current (DC) offset, and damping power-swings. 67 figs.

  6. Bulk Modulus Capacitor Load Cells

    International Nuclear Information System (INIS)

    Measurement of forces present at various locations within the SSC Model Dipole collared coil assembly is of great practical interest to development engineers. Of particular interest are the forces between coils at the parting plane and forces that exist between coils and pole pieces. It is also desired to observe these forces under the various conditions that a magnet will experience such as: during the collaring process, post-collaring, under the influence of cryogens, and during field excitation. A twenty eight thousandths of an inch thick capacitor load cell which utilizes the hydrostatic condition of a stressed plastic dielectric has been designed. These cells are currently being installed on SSC Model Dipoles. The theory, development, and application of these cells will be discussed

  7. Gas evolution in aluminum electrolytic capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Aleixandre, C.; Albella, J.M.; Martinez-Duart, J.M.

    1984-03-01

    Gas evolution in aluminum electrolytic capacitors constitutes one of their main drawbacks in comparison to other types of capacitors lacking a liquid electrolyte. In this respect, one of the most common causes of failure shown by liquid electrolyte capacitors is electrolyte leakage through the seal or even explosions produced by internal pressure buildup. In order to prevent these hazards, some substances, known as depolarizers, are usually added to the capacitor electrolyte with the purpose of absorbing the hydrogen evolved at the cathode (1, 2). Although the gas evolution problem in electrolytic capacitors has been known for a long time, there is a lack of literature on both direct measurements of the gas evolved and assessments of the amount of depolarizer active for the hydrogen absorption process. Aluminum electrolytic capacitors of 100..mu..F and 40V nominal voltage, miniature type (diam 8 mm, height 18.5 mm), were manufactured under standard specifications. The capacitors were filled with about 0.5 ml of an electrolyte consisting essentially of a solution of boric, adipic, and phosphoric acids in ethylene glycol. Picric acid and p-benzoquinone in molar concentrations of 0.01M and 0.05M, respectively, were added as depolarizers, yielding an electrolyte with a resistivity of about 80 ..cap omega..-cm and a pH of 5.1. The pressure inside the capacitors was monitored by a conventional Ushaped manometer made from a capillary glass tube filled with distilled water. The number of mols of gas generated in the capacitor (/eta/ /SUB g/ ) was calculated from the measured pressure (sensitivity 0.1 mm Hg) and the value of the internal volume of the manometercapacitor system.

  8. Alkaline Capacitors Based on Nitride Nanoparticles

    Science.gov (United States)

    Aldissi, Matt

    2003-01-01

    High-energy-density alkaline electrochemical capacitors based on electrodes made of transition-metal nitride nanoparticles are undergoing development. Transition- metal nitrides (in particular, Fe3N and TiN) offer a desirable combination of high electrical conductivity and electrochemical stability in aqueous alkaline electrolytes like KOH. The high energy densities of these capacitors are attributable mainly to their high capacitance densities, which, in turn, are attributable mainly to the large specific surface areas of the electrode nanoparticles. Capacitors of this type could be useful as energy-storage components in such diverse equipment as digital communication systems, implanted medical devices, computers, portable consumer electronic devices, and electric vehicles.

  9. Recent series capacitor applications in North America

    Energy Technology Data Exchange (ETDEWEB)

    Miske, S.A.; Lang, R.J.; Rowe, S.D. [Canadian General Electric Co. Ltd., Toronto, ON (Canada); Bilodeau, P.; Granger, M. [Hydro-Quebec, Montreal, PQ (Canada)

    1995-12-31

    Equipment used in three recent installations of series capacitors were reported on. Each set of equipment was designed to serve markedly different objectives. The first design discussed was that of the twelve series capacitor banks installed on the Hydro-Quebec 735 kV transmission system as part of a program to increase the system reliability of the power flow from James Bay to Montreal. The second was the unique series capacitors installed on the Hydro-Quebec 735 kV and 315 kV transmission systems solely for the purpose of blocking direct current. The third design discussed was the world`s first and only EHV three-phase multi-module thyristor-controlled series capacitor (TCSC) installed at the 500 kV Slatt Substation of the Bonneville Power Administration. This project has demonstrated the impressive power system swing and subsynchronous resonance damping capabilities of this technology. 3 refs., 15 figs.

  10. Development of self-healing capacitors for klystron modulators

    International Nuclear Information System (INIS)

    In order to realize a compact pulse modulator for klystron, a reliable capacitor with a long lifetime is required. We have evaluated lifetime performance of self-healing(SH) capacitor using a PFN-type modulator. From the test results, it was confirmed that the SH capacitor has energy densities more than three times compared with the conventional non-healing(NH) capacitor. This paper describes SH capacitors developed by KEK. (author)

  11. Thermal simulation for geometric optimization of metallized polypropylene film capacitors

    OpenAIRE

    El-Husseini, M.,; VENET, Pascal; Rojat, Gérard; Joubert, Charles

    2002-01-01

    In this paper, we use an analytic model to calculate the losses in the metallized polypropylene film capacitors. The model is validated experimentally for capacitors having the same capacitance but different geometry. For each group of capacitors a temperature distribution in the roll is assumed with the aim of optimizing its thermal performance. It appears that the heating of a long capacitor is higher than that of an equivalent flat capacitor subjected to the same electric stresses.

  12. Definite Solution of the Two Capacitors Paradox

    CERN Document Server

    Pankovic, Vladan

    2009-01-01

    In this work we suggest very simple solution of the two capacitors paradox in the completely ideal (without any electrical resistance or inductivity) electrical circuit. Namely, it is shown that electrical field energy loss corresponds to works done by electrical fields of both capacitors by movement of the electrical charge. It is all and nothing more (some dissipative processes, e.g. Joule heating and electromagnetic wave emission effects) is necessary.

  13. Transmission Line Resonator Segmented with Series Capacitors

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Boer, Vincent; Petersen, Esben Thade

    2016-01-01

    Transmission line resonators are often used as coils in high field MRI. Due to distributed nature of such resonators, coils based on them produce inhomogeneous field. This work investigates application of series capacitors to improve field homogeneity along the resonator. The equations for optimal...... values of evenly distributed capacitors are presented. The performances of the segmented resonator and a regular transmission line resonator are compared....

  14. Recent trend of oil impregnated capacitor (self healing type)

    Energy Technology Data Exchange (ETDEWEB)

    Shioda, Kohei; Wada, Eiichi; Fukai, Masayasu

    1988-09-05

    This paper describes the self healing type high pressure capacitor which is the newest type in oil impregnated capacitors. The self healing type oil impregnated capacitor has a structure holding a sheet of polypropylene film derivative between two sheets of double side metalized paper and this paper supports electrodes. Features of this capacitor are self healing, good impregnation, and built-in pressure sensing type protector. Performance of this capacitor depends on the impregnating agent and electrode. On the other hand, electric characteristic, dielectric characteristic, life, and safety of this capacitor are also examined. As a result, self healing type oil impregnated capacitors are suitable for capacitors of low-loss and high potential gradient. The self healing oil impregnated capacitor is supposed to play an important role for miniaturization, weight reduction, and resource saving. (10 figs, 1 tab)

  15. High-Temperature Capacitor Polymer Films

    Science.gov (United States)

    Tan, Daniel; Zhang, Lili; Chen, Qin; Irwin, Patricia

    2014-12-01

    Film capacitor technology has been under development for over half a century to meet various applications such as direct-current link capacitors for transportation, converters/inverters for power electronics, controls for deep well drilling of oil and gas, direct energy weapons for military use, and high-frequency coupling circuitry. The biaxially oriented polypropylene film capacitor remains the state-of-the-art technology; however, it is not able to meet increasing demand for high-temperature (>125°C) applications. A number of dielectric materials capable of operating at high temperatures (>140°C) have attracted investigation, and their modifications are being pursued to achieve higher volumetric efficiency as well. This paper highlights the status of polymer dielectric film development and its feasibility for capacitor applications. High-temperature polymers such as polyetherimide (PEI), polyimide, and polyetheretherketone were the focus of our studies. PEI film was found to be the preferred choice for high-temperature film capacitor development due to its thermal stability, dielectric properties, and scalability.

  16. BioCapacitor--a novel category of biosensor.

    Science.gov (United States)

    Hanashi, Takuya; Yamazaki, Tomohiko; Tsugawa, Wakako; Ferri, Stefano; Nakayama, Daisuke; Tomiyama, Masamitsu; Ikebukuro, Kazunori; Sode, Koji

    2009-03-15

    This research reports on the development of an innovative biosensor, known as BioCapacitor, in which biological recognition elements are combined with a capacitor functioning as the transducer. The analytical procedure of the BioCapacitor is based on the following principle: a biocatalyst, acting as a biological recognition element, oxidizes or reduces the analyte to generate electric power, which is then charged into a capacitor via a charge pump circuit (switched capacitor regulator) until the capacitors attains full capacity. Since the charging rate of the capacitor depends on the biocatalytic reaction of the analyte, the analyte concentration can be determined by monitoring the time/frequency required for the charge/discharge cycle of the BioCapacitor via a charge pump circuit. As a representative model, we constructed a BioCapacitor composed of FAD-dependent glucose dehydrogenase (FADGDH) as the anodic catalyst, and attempted a glucose measurement. Charge/discharge frequency of the BioCapacitor increased with the increasing glucose concentration, exhibiting good correlation with glucose concentration. We have also constructed a wireless sensing system using the BioCapacitor combined with an infrared light emitting diode (IRLED), an IR phototransistor system. In the presence of glucose, the IRLED signal was observed due to the discharge of the BioCapacitor and detected by an IR phototransistor in a wireless receiver. Therefore, a BioCapacitor employing FADGDH as its anodic catalyst can be operated as a self-powered enzyme sensor. PMID:19013784

  17. Antenna Miniaturization with MEMS Tunable Capacitors

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Morris, Art; Pedersen, Gert Frølund

    2014-01-01

    In today’s mobile device market, there is a strong need for efficient antenna miniaturization. Tunable antennas are a very promising way to reduce antenna volume while enlarging its operating bandwidth. MEMS tunable capacitors are state-ofthe- art in terms of insertion loss and their characterist......In today’s mobile device market, there is a strong need for efficient antenna miniaturization. Tunable antennas are a very promising way to reduce antenna volume while enlarging its operating bandwidth. MEMS tunable capacitors are state-ofthe- art in terms of insertion loss and their...

  18. Printed Barium Strontium Titanate capacitors on silicon

    International Nuclear Information System (INIS)

    In this paper, we show that Barium Strontium Titanate (BST) films can be prepared by inkjet printing of sol–gel precursors on platinized silicon substrate. Moreover, a functional variable capacitor working in the GHz range has been made without any lithography or etching steps. Finally, this technology requires 40 times less precursors than the standard sol–gel spin-coating technique. - Highlights: • Inkjet printing of Barium Strontium Titanate films • Deposition on silicon substrate • Inkjet printed silver top electrode • First ever BST films thinner than 1 μm RF functional variable capacitor that has required no lithography

  19. Printed Barium Strontium Titanate capacitors on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Sette, Daniele [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg); Kovacova, Veronika [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Defay, Emmanuel, E-mail: emmanuel.defay@list.lu [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg)

    2015-08-31

    In this paper, we show that Barium Strontium Titanate (BST) films can be prepared by inkjet printing of sol–gel precursors on platinized silicon substrate. Moreover, a functional variable capacitor working in the GHz range has been made without any lithography or etching steps. Finally, this technology requires 40 times less precursors than the standard sol–gel spin-coating technique. - Highlights: • Inkjet printing of Barium Strontium Titanate films • Deposition on silicon substrate • Inkjet printed silver top electrode • First ever BST films thinner than 1 μm RF functional variable capacitor that has required no lithography.

  20. Clocking Scheme for Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed.......A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed....

  1. Electric field mapping inside metallized film capacitors

    DEFF Research Database (Denmark)

    Nielsen, Dennis Achton; Popok, Vladimir; Pedersen, Kjeld

    2015-01-01

    Failure mode and effect analysis (FMEA) is an important step in the reliability assessment process of electric components. It provides knowledge of the physics of failure of a component that has been subjected to a given stress profile. This knowledge enables improvement of the component robustness...... of the metallization stripes had lost contact to the end-spray. Thus, it is shown that the surface electric potential distributions on micro-sectioned film capacitors can be obtained through KPFM analysis. We have, from KPFM measurements, shown that the degraded capacitors under investigation had suffered from...

  2. Low-Voltage Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Bidari, E.; Keskin, M.; Maloberti, F.; Moon, U.; Steensgaard-Madsen, Jesper; Temes, G.C.

    Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications.......Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications....

  3. Clocking Scheme for Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    1998-01-01

    A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed.......A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed....

  4. Wide Temperature DC Link Capacitors for Aerospace Power Electronics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop advanced DC link capacitors using flexible ultrathin glass dielectric materials. The glass capacitor will be able to be operated in a...

  5. Design and Characterization of Vertical Mesh Capacitors in Standard CMOS

    DEFF Research Database (Denmark)

    Christensen, Kåre Tais

    2001-01-01

    This paper shows how good RF capacitors can be made in a standard digital CMOS process. The capacitors which are also well suited for binary weighted switched capacitor banks show very good RF performance: Q-values of 57 at 4.0 GHz, a density of 0.27 fF/μ2, 2.2 μm wide shielded unit capacitors, 6...

  6. Iodine encapsulation in CNTs and its application for electrochemical capacitor

    Science.gov (United States)

    Taniguchi, Y.; Ishii, Y.; Rashid, M.; Syakirin, A.; Al-zubaidi, A.; Kawasaki, S.

    2016-07-01

    We report the experimental results for new type electrochemical capacitor using iodine redox reaction in single-walled carbon nanotubes (SWCNTs). It was found that the energy density of the present redox capacitor using SWCNTs is almost three times larger than that of the normal electric double layer capacitor.

  7. The mystery of lost energy in ideal capacitors

    OpenAIRE

    James, A. P.

    2009-01-01

    The classical two-capacitor problem shows a mysterious lose of energy even under lossless conditions and questions the basic understanding of energy relation in a capacitor. Here, we present a solution to the classical two-capacitor problem. We find that by reinterpreting the energy calculations we achieve no lose of energy thereby obeying the conservation of energy law.

  8. Equal Plate Charges on Series Capacitors?

    Science.gov (United States)

    Illman, B. L.; Carlson, G. T.

    1994-01-01

    Provides a line of reasoning in support of the contention that the equal charge proposition is at best an approximation. Shows how the assumption of equal plate charge on capacitors in series contradicts the conservative nature of the electric field. (ZWH)

  9. Single Switched Capacitor Battery Balancing System Enhancements

    Directory of Open Access Journals (Sweden)

    Joeri van Mierlo

    2013-04-01

    Full Text Available Battery management systems (BMS are a key element in electric vehicle energy storage systems. The BMS performs several functions concerning to the battery system, its key task being balancing the battery cells. Battery cell unbalancing hampers electric vehicles’ performance, with differing individual cell voltages decreasing the battery pack capacity and cell lifetime, leading to the eventual failure of the total battery system. Quite a lot of cell balancing topologies have been proposed, such as shunt resistor, shuttling capacitor, inductor/transformer based and DC energy converters. The shuttling capacitor balancing systems in particular have not been subject to much research efforts however, due to their perceived low balancing speed and high cost. This paper tries to fill this gap by briefly discussing the shuttling capacitor cell balancing topologies, focusing on the single switched capacitor (SSC cell balancing and proposing a novel procedure to improve the SSC balancing system performance. This leads to a new control strategy for the SSC system that can decrease the balancing system size, cost, balancing time and that can improve the SSC balancing system efficiency.

  10. Capacitors and Resistance-Capacitance Networks.

    Science.gov (United States)

    Balabanian, Norman; Root, Augustin A.

    This programed textbook was developed under a contract with the United States Office of Education as Number 5 in a series of materials for use in an electrical engineering sequence. It is divided into three parts--(1) capacitors, (2) voltage-current relationships, and (3) simple resistance-capacitance networks. (DH)

  11. Electrostatic spray deposition based lithium ion capacitor

    Science.gov (United States)

    Agrawal, Richa; Chen, Chunhui; Wang, Chunlei

    2016-05-01

    Conventional Electrochemical double-layer capacitors (EDLCs) are well suited as power devices that can provide large bursts of energy in short time periods. However, their relatively inferior energy densities as compared to their secondary battery counterparts limit their application in devices that require simultaneous supply of both high energy and high power. In the wake of addressing this shortcoming of EDLCs, the concept of hybridization of lithium-ion batteries (LIBs) and EDLCs has attracted significant scientific interest in recent years. Such a device, generally referred to as the "lithium-ion capacitor" typically utilizes a lithium intercalating electrode along with a fast charging capacitor electrode. Herein we have constructed a lithium hybrid electrochemical capacitor comprising a Li4Ti5O12-TiO2 (LTO-TiO2) anode and a reduced graphene oxide and carbon nanotube (rGO-CNT) composite cathode using electrostatic spray deposition (ESD). The electrodes were characterized using scanning electron microscopy and X-ray diffraction studies. Cyclic voltammetry and galvanostatic charge-discharge measurements were carried out to evaluate the electrochemical performance of the individual electrodes and the full hybrid cells.

  12. Circular plate capacitor with different disks

    CERN Document Server

    Paffuti, Giampiero; Di Lieto, Alberto; Maccarrone, Francesco

    2016-01-01

    In this paper we write a system of integral equations for a capacitor composed by two disks of different radii, generalizing Love's equation for equal disks. We compute the complete asymptotic form of the capacitance matrix both for large and small distances obtaining a generalization of Kirchhoff's formula for the latter case.

  13. Low-Voltage Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Bidari, E.; Keskin, M.; Maloberti, F.;

    1999-01-01

    Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications....

  14. High energy density capacitors using nano-structure multilayer technology

    Energy Technology Data Exchange (ETDEWEB)

    Barbee, T.W. Jr.; Johnson, G.W.; O`Brien, D.W.

    1992-08-01

    Today, many pulse power and industrial applications are limited by capacitor performance. While incremental improvements are anticipated from existing capacitor technologies, significant advances are needed in energy density to enable these applications for both the military and for American economic competitiveness. We propose a program to research and develop a novel technology for making high voltage, high energy density capacitors. Nano-structure multilayer technologies developed at LLNL may well provide a breakthrough in capacitor performance. Our controlled sputtering techniques are capable of laying down extraordinarily smooth sub-micron layers of dielectric and conductor materials. With this technology, high voltage capacitors with an order of magnitude improvement in energy density may be achievable. Well-understood dielectrics and new materials will be investigated for use with this technology. Capacitors developed by nano-structure multilayer technology are inherently solid state, exhibiting extraordinary mechanical and thermal properties. The conceptual design of a Notepad capacitor is discussed to illustrate capacitor and capacitor bank design and performance with this technology. We propose a two phase R&D program to address DNA`s capacitor needs for electro-thermal propulsion and similar pulse power programs. Phase 1 will prove the concept and further our understanding of dielectric materials and design tradeoffs with multilayers. Nano-structure multilayer capacitors will be developed and characterized. As our materials research and modeling prove successful, technology insertion in our capacitor designs will improve the possibility for dramatic performance improvements. In Phase 2, we will make Notepad capacitors, construct a capacitor bank and demonstrate its performance in a meaningful pulse power application. We will work with industrial partners to design full scale manufacturing and move this technology to industry for volume production.

  15. Non-ideal effects of MOS capacitor in a switched capacitor waveform recorder ASIC

    Science.gov (United States)

    Zhang, Hong-Yan; Deng, Zhi; Liu, Yi-Nong

    2016-07-01

    SCAs (Switched Capacitor Arrays) have a wide range of uses, especially in high energy physics, nuclear science and astrophysics experiments. This paper presents a method of using a MOS capacitor as a sampling capacitor to gain larger capacitance with small capacitor area in SCA design. It studies the non-ideal effects of the MOS capacitor and comes up with ways to reduce these adverse effects. A prototype SCA ASIC which uses a MOS capacitor to store the samples has been designed and tested to verify this method. The SCA integrates 32 channels and each has 64 cells and a readout amplifier. The stored voltage is converted to a pair of differential currents (±4 mA max) and multiplexed to the output. All the functionalities have been verified. The power consumption is less than 2 mW/ch. The INL of all the cells in one channel are better than 0.39%. The equivalent input noise of the SCA has been tested to be 2.2 mV with 625 kHz full-scale sine wave as input, sampling at 40 MSPS (Mega-samples per Second) and reading out at 5 MHz. The effective resolution is 8.8 bits considering 1 V dynamic range. The maximum sampling rate reaches up to 50 MSPS and readout rate of 15 MHz to keep noise smaller than 2.5 mV. The test results validate the feasibility of the MOS capacitor. Supported by National Natural Science Foundation of China (11375100), Strategic Pioneer Program on Space Sciences, Chinese Academy of Sciences (XDA04060606-06) and State Key Laboratory of Particle Detection and Electronics

  16. High-Energy-Density Electrolytic Capacitors

    Science.gov (United States)

    Yen, Shiao-Ping S.; Lewis, Carol R.

    1993-01-01

    Reductions in weight and volume make new application possible. Supercapacitors and improved ultracapacitors advanced electrolytic capacitors developed for use as electric-load-leveling devices in such applications as electric vehicle propulsion systems, portable power tools, and low-voltage pulsed power supplies. One primary advantage: offer power densities much higher than storage batteries. Capacitors used in pulse mode, with short charge and discharge times. Derived from commercially available ultracapacitors. Made of lightweight materials; incorporate electrode/electrolyte material systems capable of operation at voltages higher than previous electrode/electrolyte systems. By use of innovative designs and manufacturing processes, made in wide range of rated capacitances and in rated operating potentials ranging from few to several hundred volts.

  17. Hidden Momentum in a moving Capacitor

    CERN Document Server

    Asti, Giovanni

    2015-01-01

    A very simple system like a parallel-plate capacitor reveals striking features when we examine the peculiar phenomena appearing when it is moving at low speed in different directions. Both hidden momentum and hidden energy appear and their addition, with their sign, to the corresponding electromagnetic component results in the expected ordinary kinetic momentum or energy of the electrostatic mass equivalent. What's happening is that passing from one inertial reference frame to another, part of the energy or momentum is transferred from the electromagnetic component to the material part of the system or the other way around. A paradoxical self-accelerating behavior is evidenced if one admits that the capacitor is discharging through an electrical resistance during its motion. It is shown that one must take into account the mass of the produced heat.

  18. Evaluation and Characterization of Magnets and Capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Seiber, L.E.; Cunningham, J.P.; Golik, S.S. (ORISE); Armstrong, G. (Maverick Systems)

    2006-10-15

    Advanced vehicle, fuel cell, hybrid electric vehicle (HEV), and plug in hybrid research and development is conducted by the U.S. Department of Energy (DOE) through its FreedomCAR and Vehicle Technologies (FCVT) program. The mission of this program is to develop more energy efficient and environmentally safe highway transportation technologies. Program activities include research, development, testing, technology validation, and technology transfer. These activities are done at the system and component levels. This report will discuss component level testing of prototype capacitors and magnets. As capacitor and magnet technologies mature, it is important to ascertain the limitations of these new technologies by subjecting the components to standardized tests to evaluate their capabilities. Test results will assist in the determination of their ability to provide improvements in power electronics and motor designs to meet the FCVT goals.

  19. Tunable microstrip resonators with ferroelectric capacitors

    OpenAIRE

    Zakharov, A. V.; Ilchenko, Mikhail Ye.; Karnauh, V. Ya.; Pinchuk, L. S.

    2010-01-01

    The question of increasing the tuning band of microstrip resonators that use ferroelectric capacitors for tuning in the region of increased electric lengths is considered which allows using them in the upper part of the centimeter band (Ku-band, K-band). Band properties of regular and step-irregular resonators operating at the lowest resonant frequency are analyzed.It is determined that step-irregular resonators possess a wider tuning band than regular ones. Their use allows widening the tuni...

  20. The elastic capacitor and its unusual properties

    OpenAIRE

    Partensky, Michael B.

    2002-01-01

    The 'elastic capacitor' (EC) model was first introduced in studies of lipid bilayers (the major components of biological membranes). This electro-elastic model accounted for the compression of a membrane under applied voltage and allowed obtaining information about the membrane's elastic properties from the measurements of its capacitance. Later on, ECs were used to analyze the electrical breakdown of biological membranes. The EC model was also helpful in studies of electric double layers in ...

  1. Materials development for commercial multilayer ceramic capacitors

    OpenAIRE

    Mikkenie, Ronald

    2011-01-01

    Electronic devices like notebooks, smart phones, GPS units, LED TVs and other daily life applications are produced with increased functionality and complexity from year to year. Today’s electronic devices must be equipped with new smart electronic circuitry designs to add more functionality within a single device, while not making them larger in size. As the electronic circuits are made of various components, active semiconducting chips and passive components, like resistors, capacitors and i...

  2. Polarization fatigue of organic ferroelectric capacitors

    OpenAIRE

    Dong Zhao; Ilias Katsouras; Mengyuan Li; Kamal Asadi; Junto Tsurumi; Gunnar Glasser; Jun Takeya; Blom, Paul W. M.; de Leeuw, Dago M.

    2014-01-01

    The polarization of the ferroelectric polymer P(VDF-TrFE) decreases upon prolonged cycling. Understanding of this fatigue behavior is of great technological importance for the implementation of P(VDF-TrFE) in random-access memories. However, the origin of fatigue is still ambiguous. Here we investigate fatigue in thin-film capacitors by systematically varying the frequency and amplitude of the driving waveform. We show that the fatigue is due to delamination of the top electrode. The origin i...

  3. Matching Properties of Femtofarad and Sub-Femtofarad MOM Capacitors

    KAUST Repository

    Omran, Hesham

    2016-04-21

    Small metal-oxide-metal (MOM) capacitors are essential to energy-efficient mixed-signal integrated circuit design. However, only few reports discuss their matching properties based on large sets of measured data. In this paper, we report matching properties of femtofarad and sub-femtofarad MOM vertical-field parallel-plate capacitors and lateral-field fringing capacitors. We study the effect of both the finger-length and finger-spacing on the mismatch of lateral-field capacitors. In addition, we compare the matching properties and the area efficiency of vertical-field and lateral-field capacitors. We use direct mismatch measurement technique, and we illustrate its feasibility using experimental measurements and Monte Carlo simulations. The test-chips are fabricated in a 0.18 \\\\mutext{m} CMOS process. A large number of test structures is characterized (4800 test structures), which improves the statistical reliability of the extracted mismatch information. Despite conventional wisdom, extensive measurements show that vertical-field and lateral-field MOM capacitors have the same matching properties when the actual capacitor area is considered. Measurements show that the mismatch depends on the capacitor area but not on the spacing; thus, for a given mismatch specification, the lateral-field MOM capacitor can have arbitrarily small capacitance by increasing the spacing between the capacitor fingers, at the expense of increased chip area.

  4. Cryogenic Cermic Multilayer Capacitors for Power Electronics

    International Nuclear Information System (INIS)

    Recent advances in the areas of high temperature superconductors and low temperature MOSFET devices have opened the door to the possibility of developing highly efficient low-temperature power electronics. The most commonly used high-efficiency capacitors are based on high dielectric constant (K ∼ 1000-4000) barium titanate doped to yield and X7R temperature dependence (±15% change in capacitance from -55 deg. C to 125 deg. C); however, below their minimum use temperature the capacitance drops-off quickly leading to a low volumetric efficiency and high temperature coefficient of capacitance (TCC) at cryogenic temperatures.A series of low temperature materials with moderate to high dielectric constants have been specifically developed for low temperature operation (below 80K). The capacitors fall into three main categories: low TCC, high volumetric efficiency, and energy storage. In the low TCC category, co-fired multilayer ceramic capacitors (MLCCs) were fabricated with capacitance values up to 62nF at 30K, TCCs from 0.9 to 2% below 80K, and losses on the order of 0.0001. In the high volumetric efficiency category, dielectrics with permittivities ranging from 1,000 to 30,000 were demonstrated

  5. Capacitors can radiate - some consequences of the two-capacitor problem with radiation

    CERN Document Server

    Choy, T C

    2003-01-01

    We fill a gap in the arguments of Boykin et al [American Journal of Physics, Vol 70 No. 4, pp 415-420 (2002)] by not invoking an electric current loop (i.e. magnetic dipole model) to account for the radiation energy loss, since an obvious corollary of their results is that the capacitors should radiate directly even if the connecting wires are shrunk to zero length. That this is so is shown here by a direct derivation of capacitor radiation using an oscillating electric dipole radiator model for the capacitors as well as the alternative less widely known magnetic 'charge' current loop representation for an electric dipole [see for example "Electromagnetic Waves" by S.A.Schlekunoff, van Nostrand (1948)]. Implications for Electromagnetic Compliance (EMC) issues as well as novel antenna designs further motivate the purpose of this paper.

  6. Super capacitor modeling with artificial neural network (ANN)

    Energy Technology Data Exchange (ETDEWEB)

    Marie-Francoise, J.N.; Gualous, H.; Berthon, A. [Universite de Franche-Comte, Lab. en Electronique, Electrotechnique et Systemes (L2ES), UTBM, INRETS (LRE T31) 90 - Belfort (France)

    2004-07-01

    This paper presents super-capacitors modeling using Artificial Neural Network (ANN). The principle consists on a black box nonlinear multiple inputs single output (MISO) model. The system inputs are temperature and current, the output is the super-capacitor voltage. The learning and the validation of the ANN model from experimental charge and discharge of super-capacitor establish the relationship between inputs and output. The learning and the validation of the ANN model use experimental results of 2700 F, 3700 F and a super-capacitor pack. Once the network is trained, the ANN model can predict the super-capacitor behaviour with temperature variations. The update parameters of the ANN model are performed thanks to Levenberg-Marquardt method in order to minimize the error between the output of the system and the predicted output. The obtained results with the ANN model of super-capacitor and experimental ones are in good agreement. (authors)

  7. Capacitor requirements for controlled thermonuclear experiments and reactors

    International Nuclear Information System (INIS)

    Future controlled thermonuclear experiments as well as controlled thermonuclear reactors will require substantial numbers of capacitors. The demands on these units are likely to be quite severe and quite different from the normal demands placed on either present energy storage capacitors or present power factor correction capacitors. It is unlikely that these two types will suffice for all necessary Controlled Thermonuclear Research (CTR) applications. The types of capacitors required for the various CTR operating conditions are enumerated. Factors that influence the life, cost and operating abilities of these types of capacitors are discussed. The problems of capacitors in a radiation environment are considered. Areas are defined where future research is needed. Some directions that this research should take are suggested. (U.S.)

  8. Practical Results of a Five-level Flying Capacitor Inverter

    Directory of Open Access Journals (Sweden)

    O. Sivkov

    2010-01-01

    Full Text Available This paper investigates the realization of a five-level Flying Capacitor Inverter. After a brief description of general Power Electronic Converters and an introduction to the advantages of Multilevel Inverters over conventional two-level Inverters the main focus is on the five-level Flying Capacitor Inverter. The Flying Capacitor Multilevel Inverter (FCMI is a Multilevel Inverter (MI where the capacitor voltage can be balanced using only a control strategy for any number of levels. After a general description of five-level FCMI topology, the simulation and experimental results are presented. The capacitor voltage is stabilized here with various output voltage amplitude values. The simulation and experimental results of five-level FCMI show that the voltage is stabilized on capacitors using the control strategy. A single-phase five-level FCMI model is currently being developed and constructed in the laboratory. Some of the experimental results are available.

  9. Capacitors can radiate - some consequences of the two-capacitor problem with radiation

    OpenAIRE

    Choy, T. C.

    2003-01-01

    We fill a gap in the arguments of Boykin et al [American Journal of Physics, Vol 70 No. 4, pp 415-420 (2002)] by not invoking an electric current loop (i.e. magnetic dipole model) to account for the radiation energy loss, since an obvious corollary of their results is that the capacitors should radiate directly even if the connecting wires are shrunk to zero length. That this is so is shown here by a direct derivation of capacitor radiation using an oscillating electric dipole radiator model ...

  10. Study of electric capacitors using Finite Element Method

    OpenAIRE

    Alina Neamț; Anca Bărcuteanu

    2012-01-01

    A capacitor is made of two armatures and a dielectric between the two armatures. In this paper, we are going to study the plane capacitor , which is made of two equal metal armatures, plane and parallel, having the S surface, situated at a distance d much shorter than the armatures dimensions, between which there is a liniar, homogenous and isotropic dielectric having a constant electrical permittivity.The purpose of studying the plane capacitor, through MEF, presented in this...

  11. Optimization of capacitor banks in the Skagerak networks transmission grid

    OpenAIRE

    Ledesma, Hector Marañon

    2013-01-01

    Capacitor banks have been widely used in electric power networks. This master thesis presents a study of introducing new capacitor banks into a transmission network. The network comprises two areas at Telemark and Vestfold with voltages levels of 55kV, 66kV and 132kV, owned by Skagerak Nett AS. Capacitor banks improve the electric network in five ways: power factor correction, increased capacity, reduction of losses, voltage support and reactive power support. International sta...

  12. MOSFET and MOS capacitor responses to ionizing radiation

    Science.gov (United States)

    Benedetto, J. M.; Boesch, H. E., Jr.

    1984-01-01

    The ionizing radiation responses of metal oxide semiconductor (MOS) field-effect transistors (FETs) and MOS capacitors are compared. It is shown that the radiation-induced threshold voltage shift correlates closely with the shift in the MOS capacitor inversion voltage. The radiation-induced interface-state density of the MOSFETs and MOS capacitors was determined by several techniques. It is shown that the presence of 'slow' states can interfere with the interface-state measurements.

  13. Capacitor performance limitations in high power converter applications

    DEFF Research Database (Denmark)

    El-Khatib, Walid Ziad; Holbøll, Joachim; Rasmussen, Tonny Wederberg

    2013-01-01

    High voltage low inductance capacitors are used in converters as HVDC-links, snubber circuits and sub model (MMC) capacitances. They facilitate the possibility of large peak currents under high frequent or transient voltage applications. On the other hand, using capacitors with larger equivalent...... ratings and capacitances where investigated and compared a) on a component scale, characterizing the capacitors transient performance and b) as part of different converter applications, where the series inductance plays a role. In that way, better insight is achieved on how the capacitor construction can...... affect the total performance of the converter....

  14. Aging Methodologies and Prognostic Health Management for Electrolytic Capacitors

    Data.gov (United States)

    National Aeronautics and Space Administration — Understanding the ageing mechanisms of electronic components critical avionics systems such as the GPS and INAV are of critical importance. Electrolytic capacitors...

  15. Cryogenic Capacitors for Low-Temperature Power Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes to develop low-temperature multilayer ceramic capacitors (MLCCs) capable of operating at cyrogenic temperatures (<77K). These...

  16. Accelerated Aging Experiments for Capacitor Health Monitoring and Prognostics

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper discusses experimental setups for health monitoring and prognostics of electrolytic capacitors under nominal operation and accelerated aging conditions....

  17. Waveform digitization utilizing switched-capacitor arrays

    International Nuclear Information System (INIS)

    Compared with traditional waveform digitization with flash-ADCs, waveform digitization with switched-capacitor arrays (SCAs) is able to achieve the sampling speed above 1 GS/s without degrading the analog to digital conversion precision significantly. In this paper, we present the implementation of a fast waveform digitization system with the use of SCAs, and evaluate its performance of waveform digitization and the waveform timing. At about 5 GS/s, the dynamic input range of the digitizer is about 66 dB, and its timing precision is about 20 ps (RMS). (authors)

  18. Characterization of internal boundary layer capacitors

    International Nuclear Information System (INIS)

    Internal boundary layer capacitors were characterized by scanning transmission electron microscopy and by microscale electrical measurements. Data are given for the chemical and physical characteristics of the individual grains and boundaries, and their associated electric and dielectric properties. Segregated internal boundary layers were identified with resistivities of 1012-1013 Ω-cm. Bulk apparent dielectric constants were 10,000-60,000. A model is proposed to explain the dielectric behavior in terms of an equivalent n-c-i-c-n representation of ceramic microstructure, which is substantiated by capacitance-voltage analysis

  19. Evaluation of high temperature capacitor dielectrics

    Science.gov (United States)

    Hammoud, Ahmad N.; Myers, Ira T.

    Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

  20. Capacitors Would Help Protect Against Hypervelocity Impacts

    Science.gov (United States)

    Edwards, David; Hubbs, Whitney; Hovater, Mary

    2007-01-01

    A proposal investigates alternatives to the present bumper method of protecting spacecraft against impacts of meteoroids and orbital debris. The proposed method is based on a British high-voltage-capacitance technique for protecting armored vehicles against shaped-charge warheads. A shield, according to the proposal, would include a bare metal outer layer separated by a gap from an inner metal layer covered with an electrically insulating material. The metal layers would constitute electrodes of a capacitor. A bias potential would be applied between the metal layers. A particle impinging at hypervelocity on the outer metal layer would break apart into a debris cloud that would penetrate the electrical insulation on the inner metal layer. The cloud would form a path along which electric current could flow between the metal layers, thereby causing the capacitor to discharge. With proper design, the discharge current would be large enough to vaporize the particles in the debris cloud to prevent penetration of the spacecraft. The shield design can be mass optimized to be competitive with existing bumper designs. Parametric studies were proposed to determine optimum correction between bias voltage, impacting particle velocity, gap space, and insulating material required to prevent spacecraft penetration.

  1. Hydrogel membrane electrolyte for electrochemical capacitors

    Indian Academy of Sciences (India)

    S Sampath; N A Choudhury; A K Shukla

    2009-09-01

    Polymer electrolytes are known to possess excellent physicochemical properties that are very useful for electrochemical energy systems. The mobility in polymer electrolytes is understood to be mainly due to the segmental motion of polymer chains and the ion transport is generally restricted to the amorphous phase of the polymer. Gel polymer electrolytes (GPE) that are formed using plastizicers and polymers along with ionic salts are known to exhibit liquid-like ionic conductivity while maintaining the dimensional stability of a solid matrix. In the present study, the preparation and characterization of poly(vinyl alcohol)-based hydrogel membranes (PHMEs) as electrolytes for electrochemical capacitors have been reported. Varying HClO4 dopant concentration leads to different characteristics of the capacitors. The EC comprising PHME doped with 2 M HClO4 and black pearl carbon (BPC) electrodes has been found to exhibit a maximum specific capacitance value of 97 F g-1, a phase angle value of 78°, and a maximum charge-discharge coulombic efficiency of 88%.

  2. SWITCHED-CAPACITOR BASED STEP-DOWN RESONANT CONVERTERS

    Institute of Scientific and Technical Information of China (English)

    Y.P.B.Yeung; K.W.E.Cheng; K.K.Law

    2001-01-01

    A family of switched-capacitor based resonant converters is present.All converters are in step-downmode.By adding different number of switched-capacitor cells,different output voltage conversion ratio can beobtained.All switching devices in the converters operate under zero-current switching.Both high frequencyoperations and high efficiency are possible.

  3. Direct Mismatch Characterization of femto-Farad Capacitors

    KAUST Repository

    Omran, Hesham

    2015-08-17

    Reducing the capacitance of programmable capacitor arrays, commonly used in analog integrated circuits, is necessary for low-energy applications. However, limited mismatch data is available for small capacitors. We report mismatch measurement for a 2fF poly-insulator-poly (PIP) capacitor, which is the smallest reported PIP capacitor to the best of the authors’ knowledge. Instead of using complicated custom onchip circuitry, direct mismatch measurement is demonstrated and verified using Monte Carlo Simulations and experimental measurements. Capacitive test structures composed of 9 bit programmable capacitor arrays (PCAs) are implemented in a low-cost 0:35m CMOS process. Measured data is compared to mismatch of large PIP capacitors, theoretical models, and recently published data. Measurement results indicate an estimated average relative standard deviation of 0.43% for the 2fF unit capacitor, which is better than the reported mismatch of metal-oxide-metal (MOM) fringing capacitors implemented in an advanced 32nm CMOS process.

  4. Metallized Film Capacitor Lifetime Evaluation and Failure Mode Analysis

    CERN Document Server

    Gallay, R

    2015-01-01

    One of the main concerns for power electronic engineers regarding capacitors is to predict their remaining lifetime in order to anticipate costly failures or system unavailability. This may be achieved using a Weibull statistical law combined with acceleration factors for the temperature, the voltage, and the humidity. This paper discusses the different capacitor failure modes and their effects and consequences.

  5. Physics based Degradation Modeling and Prognostics of Electrolytic Capacitors under Electrical Overstress Conditions

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper proposes a physics based degradation modeling and prognostics approach for electrolytic capacitors. Electrolytic capacitors are critical components in...

  6. Prognostics Health Management and Physics based failure Models for Electrolytic Capacitors

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper proposes first principles based modeling and prognostics approach for electrolytic capacitors. Electrolytic capacitors and MOSFETs are the two major...

  7. Design of electric capacitor bank of electrical system

    International Nuclear Information System (INIS)

    Capacitor bank is a electrical equipment which can the function to compensating the line reactive power in that reactive power such reduced and angle between voltage and current is small. Principle of this capacitor bank can compensating the reactive power in which that reduction reactive power and the electric power factor can be improved. With of use the this capacitor bank . can improvement the electric power factor of electrical system in building 70 and 71. In this design, amount of the apparent power 1400 KVAR required two the capacitor capacity 150 KVAR which installed low voltage switchgear A and low voltage switchgear B as figure 4 can to improve the electric power factor of electric system of 0, 82 up to 0,87. With this improve of electric power can increased voltage of 360 volt up to 370 volt. In both capacitor bank such to installed parallel with load which installed on low voltage switchgear A and B. (author)

  8. A capacitor charging power supply using series resonant topology

    International Nuclear Information System (INIS)

    A capacitor charging power supply has to perform under wide range of load variations. Initially the capacitor will act as a short circuit so the topology must be such that it should withstand short circuit condition repetitively. This power supply has been specially developed using series resonant topology for capacitor charging applications. The capacitor charging power supply (CCPS) will charge a 100 uF energy storage capacitor from 0V to 600V in 35 ms exhibiting a charging power of 514.28 J/s at a repetition rate of 25 Hz. Topology selection is based on the fact that the series resonant converter with switching frequency below 50% of the resonant frequency (fs r) act as a current source. (author)

  9. Absorption Voltages and Insulation Resistance in Ceramic Capacitors with Cracks

    Science.gov (United States)

    Teverovsky, Alexander

    2016-01-01

    Time dependence of absorption voltages (Vabs) in different types of low-voltage X5R and X7R ceramic capacitors was monitored for a maximum duration of hundred hours after polarization. To evaluate the effect of mechanical defects on Vabs, cracks in the dielectric were introduced either mechanically or by thermal shock. The maximum absorption voltage, time to roll-off, and the rate of voltage decrease are shown to depend on the crack-related leakage currents and insulation resistance in the parts. A simple model that is based on the Dow equivalent circuit for capacitors with absorption has been developed to assess the insulation resistance of capacitors. Standard measurements of the insulation resistance, contrary to the measurements based on Vabs, are not sensitive to the presence of mechanical defects and fail to reveal capacitors with cracks. Index Terms: Ceramic capacitor, insulation resistance, dielectric absorption, cracking.

  10. Quality inspection on electrolytic capacitors using micro-computed tomography

    Science.gov (United States)

    Pratama, I. B. G. P.; Suparta, Gede B.

    2015-03-01

    A set of electrolyte capacitors were inspected using x-ray micro-computed tomography (μ-CT) system developed at the Department of Physics Gadjah Mada University, Indonesia. Testing was done for three electrolyte capacitors. The one is in good condition and the other two are considered broken. Those were broken due to either high voltage operation or leakage of the tube. Under customized μ-CT inspection, 3-D presentations of the objects have been developed. The results showed that the image profiles, radiation attenuation profiles and linear attenuation coefficient distribution on top, middle and bottom area were able to determine the aluminum plate and electrolyte papers. Good electrolyte capacitor has higher radiation attenuation and nearly uniform across the core of the capacitor. This is in contrast with the broken capacitors.

  11. Evaluation of Commercial Automotive-Grade BME Capacitors

    Science.gov (United States)

    Liu, Donhang

    2014-01-01

    Three Ni-BaTiO3 ceramic capacitor lots with the same specification (chip size, capacitance, and rated voltage) and the same reliability level, made by three different manufacturers, were degraded using highly accelerated life stress testing (HALST) with the same temperature and applied voltage conditions. The reliability, as characterized by mean time to failure (MTTF), differed by more than one order of magnitude among the capacitor lots. A theoretical model based on the existence of depletion layers at grain boundaries and the entrapment of oxygen vacancies has been proposed to explain the MTTF difference among these BME capacitors. It is the conclusion of this model that reliability will not be improved simply by increasing the insulation resistance of a BME capacitor. Indeed, Ni-BaTiO3 ceramic capacitors with a smaller degradation rate constant K will always give rise to a longer reliability life.

  12. Advanced Wet Tantalum Capacitors: Design, Specifications and Performance

    Science.gov (United States)

    Teverovsky, Alexander

    2016-01-01

    Insertion of new types of commercial, high volumetric efficiency wet tantalum capacitors in space systems requires reassessment of the existing quality assurance approaches that have been developed for capacitors manufactured to MIL-PRF-39006 requirements. The specifics of wet electrolytic capacitors is that leakage currents flowing through electrolyte can cause gas generation resulting in building up of internal gas pressure and rupture of the case. The risk associated with excessive leakage currents and increased pressure is greater for high value advanced wet tantalum capacitors, but it has not been properly evaluated yet. This presentation gives a review of specifics of the design, performance, and potential reliability risks associated with advanced wet tantalum capacitors. Problems related to setting adequate requirements for DPA, leakage currents, hermeticity, stability at low and high temperatures, ripple currents for parts operating in vacuum, and random vibration testing are discussed. Recommendations for screening and qualification to reduce risks of failures have been suggested.

  13. Capacitor with a composite carbon foam electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1999-04-27

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

  14. Capacitor with a composite carbon foam electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Steven T. (San Leandro, CA); Pekala, Richard W. (Pleasant Hill, CA); Kaschmitter, James L. (Pleasanton, CA)

    1999-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid partides being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy.

  15. The elastic capacitor and its unusual properties

    CERN Document Server

    Partensky, M B

    2002-01-01

    The 'elastic capacitor' (EC) model was first introduced in studies of lipid bilayers (the major components of biological membranes). This electro-elastic model accounted for the compression of a membrane under applied voltage and allowed obtaining information about the membrane's elastic properties from the measurements of its capacitance. Later on, ECs were used to analyze the electrical breakdown of biological membranes. The EC model was also helpful in studies of electric double layers in various electrified interfaces (of which the electrode/ electrolyte interface is the most common example). This comparatively simple model, which analysis requires only high-school physics, has a close relationship to some real-life problems in physics, chemistry and biology. I hope that both teachers and students will find its discussion interesting, challenging and instructive.

  16. Flake tantalum powder for manufacturing electrolytic capacitors

    Institute of Scientific and Technical Information of China (English)

    HE Jilin; YANG Guoqi; PAN Luntao; LIU Hongdong; BAO Xifang

    2008-01-01

    The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage,Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high (20-63 V) voltages.

  17. Breakdown properties of irradiated MOS capacitors

    International Nuclear Information System (INIS)

    The authors have studied the effects of ionizing and non-ionizing radiation on the breakdown properties of different types of MOS capacitors, with thick (200 nm) and thin (down to 8 nm) oxides. In general, no large variations of the average breakdown field, time-to-breakdown at constant voltage, or charge-to-breakdown at constant voltage, or charge-to-breakdown values have been observed after high dose irradiation (20 Mrad(Si) 9 MeV electrons on thin and thick oxides, 17(Si) Mrad Co60 gamma and 1014 neutrons/cm2 only on thick oxides). However, some modifications of the cumulative failure distributions have been observed in few of the oxides tested

  18. Charge fluctuations in nano-scale capacitors

    CERN Document Server

    Limmer, David T; Salanne, Mathieu; Chandler, David; Madden, Paul A; van Roij, René; Rotenberg, Benjamin

    2013-01-01

    The fluctuations of the charge on an electrode contain information on the microscopic correlations within the adjacent fluid and their effect on the electronic properties of the interface. We investigate these fluctuations using molecular dynamics simulations in a constant-potential ensemble with histogram reweighting techniques. This approach offers an efficient and accurate route to the differential capacitance and is broadly applicable. We demonstrate these methods with three different capacitors: pure water between platinum electrodes, and a pure as well as a solvent-based organic electrolyte each between graphite electrodes. The total charge distributions with the pure solvent and solvent-based electrolytes are remarkably Gaussian, while in the pure ionic liquid the total charge distribution displays distinct non-Gaussian features, suggesting significant potential-driven changes in the organization of the interfacial fluid.

  19. Defibrillation thresholds are lower with smaller storage capacitors.

    Science.gov (United States)

    Leonelli, F M; Kroll, M W; Brewer, J E

    1995-09-01

    Present implantable cardioverter defibrillators use a wide range of capacitance values for the storage capacitor. However, the optimal capacitance value is unknown. We hypothesized that a smaller capacitor, by delivering its charge in a time closer to the heart chronaxie, should lower the defibrillation threshold (DFT). We compared the energy required to defibrillate 10 open-chest dogs, after 15 seconds of ventricular fibrillation, with a monophasic, time-truncated waveform delivered from either a 85-microF or a 140-microF capacitor. Shocks were delivered through a pair of 14-cm2 epicardial patch electrodes: The two capacitors were randomly tested twice with each dog using a modified 3-reversal method for each DFT determination. The average stored and delivered DFT energies for the 85-microF capacitor were 6.0 +/- 1.7 joules and 5.2 +/- 1.5 joules, respectively, compared to 6.7 +/- 1.7 joules and 6.0 +/- 1.5 joules for the 140-microF capacitor (P = 0.01 and P = 0.004, respectively). The mean leading edge voltages were higher, the pulse duration shorter, and the mean impedance lower for the 85-microF capacitor. The impedance was inversely related to the pulse duration and the voltage decay suggesting that, at least in part, the mechanism of improved defibrillation could be accounted for by the waveform electrical characteristics. There was an equal number of episodes of postshock bradyarrhythmias and tachyarrhythmias following discharges from each capacitor. Moreover, there was no relationship between the likelihood of these arrhythmias and either the initial voltage or the delivered current nor there was a higher number of episodes of postshock hypotension following the smaller capacitor discharges.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7491309

  20. Development of High Temperature Capacitor Technology and Manufacturing Capability

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2011-05-15

    The goal of the Development of High Temperature Capacitor Technology and Manufacturing Capability program was to mature a production-ready supply chain for reliable 250°C FPE (fluorinated polyester) film capacitors by 2011. These high-temperature film capacitors enable both the down hole drilling and aerospace industries by enabling a variety of benefits including: - Deeper oil exploration in higher temperature and pressure environments - Enabling power electronic and control equipment to operate in higher temperature environments - Enabling reduced cooling requirements of electronics - Increasing reliability and life of capacitors operating below rated temperature - Enabling capacitors to handle higher electrical losses without overheating. The key challenges to bringing the FPE film capacitors to market have been manufacturing challenges including: - FPE Film is difficult to handle and wind, resulting in poor yields - Voltage breakdown strength decreases when the film is wound into capacitors (~70% decrease) - Encapsulation technologies must be improved to enable higher perature operation - Manufacturing and test cycle time is very long As a direct result of this program most of the manufacturing challenges have been met. The FPE film production metalization and winding yield has increased to over 82% from 70%, and the voltage breakdown strength of the wound capacitors has increased 270% to 189 V/μm. The high temperature packaging concepts are showing significant progress including promising results for lead attachments and hermetic packages at 200°C and non-hermetic packages at 250°C. Manufacturing and test cycle time will decrease as the market for FPE capacitors develops.

  1. Floating body cell a novel capacitor-less DRAM cell

    CERN Document Server

    Ohsawa, Takashi

    2011-01-01

    DRAM together with NAND Flash is driving semiconductor technologies with wide spectrum of usage ranging from PC, mobile phone and digital home appliances to solid-state disk (SSD). However, the DRAM cell which consists of a data storage capacitor (1C) and a switching transistor (1T) is facing serious difficulty in shrinking the size of the capacitor whose capacitance needs to be kept almost constant (20~30fF) throughout generations. The availability of a new DRAM cell which does not rely on an explicit capacitor for storing its data is more than ever awaited for further increasing the bit dens

  2. Comb-Line Filter with Coupling Capacitor in Ground Plane

    Directory of Open Access Journals (Sweden)

    Toshiaki Kitamura

    2011-01-01

    Full Text Available A comb-line filter with a coupling capacitor in the ground plane is proposed. The filter consists of two quarter-wavelength microstrip resonators. A coupling capacitor is inserted into the ground plane in order to build strong coupling locally along the resonators. The filtering characteristics are investigated through numerical simulations as well as experiments. Filtering characteristics that have attenuation poles at both sides of the passband are obtained. The input susceptances of even and odd modes and coupling coefficients are discussed. The filters using stepped impedance resonators (SIRs are also discussed, and the effects of the coupling capacitor for an SIR structure are shown.

  3. Fission fragment detector by thin film capacitors. Pt. 2

    International Nuclear Information System (INIS)

    Fission fragments produce current pulses in thin film capacitors at applied electric fields lower than those required for the induction of breakdowns by such charged particles. This paper describes the use of silicon dioxide capacitors for the detection of fission fragments by these current pulses. With capacitor areas of 2 x 10-2 cm2, the pulses are not detectable when the oxide is relatively thin, but with 3,800 A thick oxide, fission fragments produce pulses of about 10-15C. The mechanisms producing the current pulses by fission fragments are finally discussed. (orig.)

  4. Destructive tests on low voltage metallized polypropylene capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Cesari, S.

    1988-08-01

    This paper gives the results of destructive tests conducted on low voltage capacitors with metallized polypropylene dielectrics of the dry and impregnated types. The purpose of the tests was to check the behaviour of capacitors of the self-healing type in the event of a dielectric failure. A failure in the self-healing process of metallized polypropylene capacitors is usually accompanied by an increase in inside pressure which can cause the explosion in the casing if the capacitor is not equipped with a proper safety device. The tests were performed in accordance with ENEL (Italian Electricity Board) specifications. The effects of different test parameters, such as dielectric temperature and short-circuit current, were investigated and the results of the experiments were compared with those obtained in service and during service life tests.

  5. Electric Double-layer Capacitor Based on Activated Carbon Material

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this study electric double-layer capacitors (EDLCs) based on activated carbon material and organic electrolyte (tetraethyl ammonium tetrafluoroborate) were explored. The fabrication method for EDLC is presented and the performance of EDLC was examined by using the cyclic voltammetry, constant-current charging and discharging technique, electrochemical impedance spectroscopy measurements. Influence of various components and design parameters on the performance of the capacitors were preliminarily investigated. Up to now, EDLC based on carbon materials can deliver 20.7 W/kg at the discharge rate ofI=0.3 mA, together with the energy density of 8.5 Wh/kg. Equivalent series resistance (ESR) is 0.716 Ω.cm2. The specific power of the capacitor is low and further attempts to raise the power capability of the capacitors are necessary. Some considerations are put forward to further improve the performance of EDLC.

  6. MOVING CAPACITOR DISCHARGE ON THE LONG TRANSMISSION LINE

    OpenAIRE

    Patsiuk V.I.

    2008-01-01

    The class of nonstationary problems about the moving electric capacitor discharge on the long-distance transmission line is solved by means of characteristics method. The different velocities of the capacitor’s motion are considered.

  7. Improvement program for polycarbonate capacitors. [hermetically sealed, and ac wound

    Science.gov (United States)

    Bailey, R. R.; Waterman, K. D.

    1973-01-01

    Hermetically sealed, wound, AC, polycarbonate capacitors incorporating design improvements recommended in a previous study were designed and built. A 5000 hour, 400 Hz ac life test was conducted using 384 of these capacitors to verify the adequacy of the design improvements. The improvements incorporated in the capacitors designed for this program eliminated the major cause of failure found in the preceding work, termination failure. A failure cause not present in the previous test became significant in this test with capacitors built from one lot of polycarbonate film. The samples from this lot accounted for 25 percent of the total test complement. Analyses of failed samples showed that the film had an excessive solvent content. This solvent problem was found in 37 of the total 46 failures which occurred in this test. The other nine were random failures resulting from causes such as seal leaks, foreign particles, and possibly wrinkles.

  8. Fringe Capacitance of a Parallel-Plate Capacitor.

    Science.gov (United States)

    Hale, D. P.

    1978-01-01

    Describes an experiment designed to measure the forces between charged parallel plates, and determines the relationship among the effective electrode area, the measured capacitance values, and the electrode spacing of a parallel plate capacitor. (GA)

  9. Barium titanate nanocomposite capacitor FY09 year end report.

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Tyler E.; DiAntonio, Christopher Brian; Yang, Pin; Chavez, Tom P.; Winter, Michael R.; Monson, Todd C.; Roesler, Alexander William; Fellows, Benjamin D.

    2009-11-01

    This late start RTBF project started the development of barium titanate (BTO)/glass nanocomposite capacitors for future and emerging energy storage applications. The long term goal of this work is to decrease the size, weight, and cost of ceramic capacitors while increasing their reliability. Ceramic-based nanocomposites have the potential to yield materials with enhanced permittivity, breakdown strength (BDS), and reduced strain, which can increase the energy density of capacitors and increase their shot life. Composites of BTO in glass will limit grain growth during device fabrication (preserving nanoparticle grain size and enhanced properties), resulting in devices with improved density, permittivity, BDS, and shot life. BTO will eliminate the issues associated with Pb toxicity and volatility as well as the variation in energy storage vs. temperature of PZT based devices. During the last six months of FY09 this work focused on developing syntheses for BTO nanoparticles and firing profiles for sintering BTO/glass composite capacitors.

  10. Fission fragment detector by thin film capacitors. Pt. 1

    International Nuclear Information System (INIS)

    Heavy ion detection by solid dielectrics has been so far obtained by chemical etching. In this paper the detection of fission fragments is based on the counting of breakdowns in thin films of solid dielectries. These films are used as dielectric materials in capacitors with one electrode usually less than 1000 A thick. Breakdowns in such capacitors are non-shorting and can be sometimes repeated up to millions of times per cm2 of the capacitor area. The property that makes these capacitors suited for detection is that fission fragments induce breakdowns at fields distinctly lower than those due to the application of field only. The characteristics of these new detecting systems are described and compared with those of the damage track detectors. (orig.)

  11. Prognostic Techniques for Capacitor Degradation and Health Monitoring

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper discusses our initial efforts in constructing physics of failure models for electrolytic capacitors subjected to electrical stressors in DC-DC power...

  12. Nanocurrent oscillator indefinitely powered by a capacitor battery

    CERN Document Server

    Ragni, Luigi

    2012-01-01

    Some electrolytic capacitors show dielectric behaviour that can not be entirely explained by the well known long lasting relaxation. Extra charges able to generate a useful conduction current can be detected for an indefinite time. A squarewave oscillator based on MOSFET CMOS technology and requiring less than 2 nW was powered for 80 days at 25 {\\deg}C by a 58.2 mF capacitor battery, without voltage decrease during the last 53 days of observation. The battery consisted of three series of 16 parallel, 15 years aged, capacitors with DC capacitance of 10.9 mF. Capacitors so old, stored without voltage application, were affected by degradation and thinning of the alumina layer that could promote tunnelling of the charge. The main purpose of the present study is to stimulate further investigations aimed at confirming or disputing the observed phenomenon and, if necessary, at shedding light on its physical mechanisms.

  13. Highly-Durable Carbon Electrode for Electrochemical Capacitors

    OpenAIRE

    Soshi Shiraishi

    2013-01-01

    [EN] The electric double layer capacitor (EDLC) is an electrochemical capacitor storing electric energy by charging the electric double layer on the micropores of a nanoporous carbon electrode such as activated carbon. The EDLC has a fast charge-discharge property and excellent cycle life, but its energy density is lower than other electrochemical energy storage devices such as the rechargeable battery. The energy density of the EDLC can be improved by increasing the double layer capacitance ...

  14. The possibility of giant dielectric materials for multilayer ceramic capacitors

    OpenAIRE

    Ishii, Tatsuya; Endo, Makoto; Masuda, Kenichiro; Ishida, Keisuke

    2013-01-01

    There have been numerous reports on discovery of giant dielectric permittivity materials called internal barrier layer capacitor in the recent years. We took particular note of one of such materials, i.e., BaTiO3 with SiO2 coating. It shows expressions of giant electric permittivity when processed by spark plasma sintering. So we evaluated various electrical characteristics of this material to find out whether it is applicable to multilayer ceramic capacitors. Our evaluation revealed that the...

  15. CAPMIX - Deploying Capacitors for Salt Gradient Power Extraction

    OpenAIRE

    Bijmans, M.F.M.; Burheim, O.S.; Bryjak, M.; Delgado, A; Hack, P.; Mantegazza, F.; Tenisson, S.; Hamelers, H.V.M.

    2012-01-01

    The process of mixing sea and river water can be utilised as a power source. At present, three groups of technology are established for doing so; i) mechanical; Pressure Retarded Osmosis PRO, ii) electrochemical reactions; Reverse ElectroDialysis (RED) and Nano Battery Electrodes (NBE) and iii) ultra capacitors; Capacitive Double Layer Expansion (CDLE) and Capacitors charge by the Donnan Potentials (CDP). The chemical potential for salt gradient power systems is only limited by th...

  16. Capacitor bonding techniques and reliability. [thermal cycling tests

    Science.gov (United States)

    Kinser, D. L.; Graff, S. M.; Allen, R. V.; Caruso, S. V.

    1974-01-01

    The effect of thermal cycling on the mechanical failure of bonded ceramic chip capacitors mounted on alumina substrates is studied. It is shown that differential thermal expansion is responsible for the cumulative effects which lead to delayed failure of the capacitors. Harder or higher melting solders are found to be less susceptible to thermal cycling effects, although they are more likely to fail during initial processing operations.

  17. Carbon-Based Fibrous EDLC Capacitors and Supercapacitors

    OpenAIRE

    Lekakou, C.; O. Moudam; Markoulidis, F; Andrews, T.; J. F. Watts; Reed, G.T.

    2011-01-01

    This paper investigates electrochemical double-layer capacitors (EDLCs) including two alternative types of carbon-based fibrous electrodes, a carbon fibre woven fabric (CWF) and a multiwall carbon nanotube (CNT) electrode, as well as hybrid CWF-CNT electrodes. Two types of separator membranes were also considered. An organic gel electrolyte PEO-LiCIO4-EC-THF was used to maintain a high working voltage. The capacitor cells were tested in cyclic voltammetry, charge-discharge, and impedance test...

  18. Enhancement of dielectric breakdown strengths in polymer film capacitors

    International Nuclear Information System (INIS)

    This paper reports that breakdown voltages of wound, polymer film/metal foil capacitors have been dramatically increased by briefly exposing them (after they had been spirally wound) to a low pressure, low temperature gas plasma. Exposure of wound, polycarbonate-based capacitors to a 96%CF4/4%O2 gas plasma for 4 minutes, for example, produced a 200% increase in breakdown voltage

  19. Partial Discharge in Capacitor Model at Low Temperature

    OpenAIRE

    Rain, P.; M. Kachi; M. Remadnia; L. Herous; M. Nemamcha; Gosse, J.P.

    2009-01-01

    The partial discharge plays an important role in the ageing and the rupture process of solid or mixed insulation systems. Ithas been recognized that the failure of this insulation can be joined to the presence of partial discharge often in inclusionssparkling. Liquid filled cavities can be considered as the most likely defects that can exist in capacitors. In this paper wedescribe the partial discharge evolution at low temperatures in all-PP film capacitors according to the time and the appli...

  20. Anisotropic magneto-capacitance in ferromagnetic-plate capacitors

    OpenAIRE

    Haigh, J. A.; Ciccarelli, C; Betz, A. C.; Irvine, A; Novák, V.; Jungwirth, T.; Wunderlich, J.

    2015-01-01

    The capacitance of a parallel plate capacitor can depend on applied magnetic field. Previous studies have identified capacitance changes induced via classical Lorentz force or spin-dependent Zeeman effects. Here we measure a magnetization direction dependent capacitance in parallel-plate capacitors where one plate is a ferromagnetic semiconductor, gallium manganese arsenide. This anisotropic magneto-capacitance is due to the anisotropy in the density of states dependent on the magnetization t...

  1. Ruthenium Oxide Electrochemical Super Capacitor Optimization for Pulse Power Applications

    Science.gov (United States)

    Merryman, Stephen A.; Chen, Zheng

    2000-01-01

    Electrical actuator systems are being pursued as alternatives to hydraulic systems to reduce maintenance time, weight and costs while increasing reliability. Additionally, safety and environmental hazards associated with the hydraulic fluids can be eliminated. For most actuation systems, the actuation process is typically pulsed with high peak power requirements but with relatively modest average power levels. The power-time requirements for electrical actuators are characteristic of pulsed power technologies where the source can be sized for the average power levels while providing the capability to achieve the peak requirements. Among the options for the power source are battery systems, capacitor systems or battery-capacitor hybrid systems. Battery technologies are energy dense but deficient in power density; capacitor technologies are power dense but limited by energy density. The battery-capacitor hybrid system uses the battery to supply the average power and the capacitor to meet the peak demands. It has been demonstrated in previous work that the hybrid electrical power source can potentially provide a weight savings of approximately 59% over a battery-only source. Electrochemical capacitors have many properties that make them well-suited for electrical actuator applications. They have the highest demonstrated energy density for capacitive storage (up to 100 J/g), have power densities much greater than most battery technologies (greater than 30kW/kg), are capable of greater than one million charge-discharge cycles, can be charged at extremely high rates, and have non-explosive failure modes. Thus, electrochemical capacitors exhibit a combination of desirable battery and capacitor characteristics.

  2. Improvement of Routine Test Process of High Voltage Power Capacitors

    OpenAIRE

    Vennerberg, Patrik

    2009-01-01

    The capacitor test process at ABB Capacitors in Ludvika must be improved to meet future demands for high voltage products. To find a solution to how to improve the test process, an investigation was performed to establish which parts of the process are used and how they operate. Several parts which can improves the process were identified. One of them was selected to be improved in correlation with the subject, mechanical engineering. Four concepts were generated and decision matrixes were us...

  3. Definite solution of the two (many) capacitors paradox

    OpenAIRE

    Pankovic, Vladan

    2009-01-01

    In this work we suggest very simple solution of the two capacitors paradox in the completely ideal (without any electrical resistance or inductive) electrical circuit. Namely, it is shown that electrical field energy loss corresponds to works done by electrical fields of both capacitors by movement of the electrical charge. It is all and nothing more (some dissipative processes, e.g. Joule heating and electromagnetic wave emission effects) is necessary. Additionally, we shortly demonstrate th...

  4. Space Vehicle Power System Comprised of Battery/Capacitor Combinations

    Science.gov (United States)

    Camarotte, C.; Lancaster, G. S.; Eichenberg, D.; Butler, S. M.; Miller, J. R.

    2002-01-01

    Recent improvements in energy densities of batteries open the possibility of using electric rather that hydraulic actuators in space vehicle systems. However, the systems usually require short-duration, high-power pulses. This power profile requires the battery system to be sized to meet the power requirements rather than stored energy requirements, often resulting in a large and inefficient energy storage system. Similar transient power applications have used a combination of two or more disparate energy storage technologies. For instance, placing a capacitor and a battery side-by-side combines the high energy density of a battery with the high power performance of a capacitor and thus can create a lighter and more compact system. A parametric study was performed to identify favorable scenarios for using capacitors. System designs were then carried out using equivalent circuit models developed for five commercial electrochemical capacitor products. Capacitors were sized to satisfy peak power levels and consequently "leveled" the power requirement of the battery, which can then be sized to meet system energy requirements. Simulation results clearly differentiate the performance offered by available capacitor products for the space vehicle applications.

  5. Capacitor discharge ignition system having a charging control means

    Energy Technology Data Exchange (ETDEWEB)

    Fitzner, A.O.

    1984-02-28

    The invention provides charging control circuitry for a capacitor descharge ignition system having power capacitors connected to be discharged by main electronic switches such as SCR's into ignition transformers to sequentially fire the engine's spark plugs. The charging control circuits each include a charging SCR to limit charging current flow to the main capacitor, unless a discharge pulse into the ignition transformer has occurred in the recent past. Thus if a short circuit in either the main capacitor or main SCR in one of the ignition circuits prevents that ignition circuit form properly functioning, the charging SCR will limit the flow of charging current to the defective circuit and allow the other ignition circuit to receive charging current. The gate of the charging SCR is controlled by an amplified signal from a memory capacitor which is charged by the discharge pulse from the corresponding ignition circuit. The same memory capacitor also provides power to drive an indicator such as a light emitting diode.

  6. Physics Based Modeling and Prognostics of Electrolytic Capacitors

    Science.gov (United States)

    Kulkarni, Chetan; Ceyla, Jose R.; Biswas, Gautam; Goebel, Kai

    2012-01-01

    This paper proposes first principles based modeling and prognostics approach for electrolytic capacitors. Electrolytic capacitors have become critical components in electronics systems in aeronautics and other domains. Degradations and faults in DC-DC converter unit propagates to the GPS and navigation subsystems and affects the overall solution. Capacitors and MOSFETs are the two major components, which cause degradations and failures in DC-DC converters. This type of capacitors are known for its low reliability and frequent breakdown on critical systems like power supplies of avionics equipment and electrical drivers of electromechanical actuators of control surfaces. Some of the more prevalent fault effects, such as a ripple voltage surge at the power supply output can cause glitches in the GPS position and velocity output, and this, in turn, if not corrected will propagate and distort the navigation solution. In this work, we study the effects of accelerated aging due to thermal stress on different sets of capacitors under different conditions. Our focus is on deriving first principles degradation models for thermal stress conditions. Data collected from simultaneous experiments are used to validate the desired models. Our overall goal is to derive accurate models of capacitor degradation, and use them to predict performance changes in DC-DC converters.

  7. Cryogenic Heat Engines Made Using Electrocaloric Capacitors

    Science.gov (United States)

    Franz, Justin; Ordonez, Carlos A.

    2001-10-01

    It is possible to operate a heat engine using a cold substance, such as liquid nitrogen, as a heat sink and the atmosphere as a heat source.(C. A. Ordonez, American Journal of Physics 64), (1996) 479-481. With sufficient work produced per unit mass of liquid nitrogen, such a cryogenic heat engine may be suitable for powering short range, non-polluting automobiles.(C. A. Ordonez, Energy Conversion and Management 41) (2000) 331-341. Using existing liquid nitrogen plants to produce liquid nitrogen at about 50% of Carnot efficiency, and using renewable energy to power the liquid nitrogen plants, the cost to use liquid nitrogen to power an automobile per mile driven would be a few times the cost of using gasoline in the U.S. The increased ``fuel" cost may be acceptable for short range vehicles provided such vehicles have an acceptable price. We report on thermal-to-electrical energy conversion systems being studied for use as cryogenic heat engines. Specifically, capacitors made using paraelectric materials can provide energy conversion based on the electrocaloric effect. The electrocaloric effect is a change in electric field across a material that results from a change in temperature of the material.

  8. Capattery double layer capacitor life performance

    Science.gov (United States)

    Evans, David A.; Clark, Nancy H.; Baca, W. E.; Miller, John R.; Barker, Thomas B.

    Double layer capacitors (DLCs) have received increased use in computer memory backup applications for consumer products during the past ten years. Their extraordinarily high capacitance density along with their maintenance-free operation makes them particularly suited for these products. These same features also make DLCs very attractive in military type applications. Unfortunately, lifetime performance data has not been reported in the literature for any DLC component. Our objective in this study was to investigate the effects that voltage and temperature have on the properties and performance of single and series-connected DLCs as a function of time. Evans model RE110474, 0.47-farad, 11.0-volt Capatteries were evaluated. These components have a tantalum package, use welded construction, and contain a glass-to-metal seal, all incorporated to circumvent the typical DLC failure modes of electrolyte loss and container corrosion. A five-level, two-factor Central Composite Design was used in the study. Single and series-connected Capatteries rated at 85 C, 11.0-volts operation were subjected to test temperatures between 25 and 95 C, and voltages between 0 and 12.9 volts (9 test conditions). Measured responses included capacitance, equivalent series resistance, and discharge time. Data were analyzed using a regression analysis to obtain response functions relating DLC properties to their voltage, temperature, and test time history. These results are described and should aid system and component engineers in using DLCs in critical applications.

  9. BioCapacitor: A novel principle for biosensors.

    Science.gov (United States)

    Sode, Koji; Yamazaki, Tomohiko; Lee, Inyoung; Hanashi, Takuya; Tsugawa, Wakako

    2016-02-15

    Studies regarding biofuel cells utilizing biocatalysts such as enzymes and microorganisms as electrocatalysts have been vigorously conducted over the last two decades. Because of their environmental safety and sustainability, biofuel cells are expected to be used as clean power generators. Among several principles of biofuel cells, enzyme fuel cells have attracted significant attention for their use as alternative energy sources for future implantable devices, such as implantable insulin pumps and glucose sensors in artificial pancreas and pacemakers. However, the inherent issue of the biofuel cell principle is the low power of a single biofuel cell. The theoretical voltage of biofuel cells is limited by the redox potential of cofactors and/or mediators employed in the anode and cathode, which are inadequate for operating any devices used for biomedical application. These limitations inspired us to develop a novel biodevice based on an enzyme fuel cell that generates sufficient stable power to operate electric devices, designated "BioCapacitor." To increase voltage, the enzyme fuel cell is connected to a charge pump. To obtain a sufficient power and voltage to operate an electric device, a capacitor is used to store the potential generated by the charge pump. Using the combination of a charge pump and capacitor with an enzyme fuel cell, high voltages with sufficient temporary currents to operate an electric device were generated without changing the design and construction of the enzyme fuel cell. In this review, the BioCapacitor principle is described. The three different representative categories of biodevices employing the BioCapacitor principle are introduced. Further, the recent challenges in the developments of self-powered stand-alone biodevices employing enzyme fuel cells combined with charge pumps and capacitors are introduced. Finally, the future prospects of biodevices employing the BioCapacitor principle are addressed. PMID:26278505

  10. Instantaneous thermal modeling of the DC-link capacitor in PhotoVoltaic systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Ma, Ke; Wang, Huai;

    2015-01-01

    Capacitors have been witnessed as one of the weak points in grid-connected PhotoVoltaic (PV) applications, and thus efforts have been devoted to the design of reliable DC-link capacitors in PV applications. Since the hot-spot temperature of the capacitor is one of the failure inducers, instantane......Capacitors have been witnessed as one of the weak points in grid-connected PhotoVoltaic (PV) applications, and thus efforts have been devoted to the design of reliable DC-link capacitors in PV applications. Since the hot-spot temperature of the capacitor is one of the failure inducers...

  11. Graphene-Based Flexible and Transparent Tunable Capacitors.

    Science.gov (United States)

    Man, Baoyuan; Xu, Shicai; Jiang, Shouzheng; Liu, Aihua; Gao, Shoubao; Zhang, Chao; Qiu, Hengwei; Li, Zhen

    2015-12-01

    We report a kind of electric field tunable transparent and flexible capacitor with the structure of graphene-Bi1.5MgNb1.5O7 (BMN)-graphene. The graphene films with low sheet resistance were grown by chemical vapor deposition. The BMN thin films were fabricated on graphene by using laser molecular beam epitaxy technology. Compared to BMN films grown on Au, the samples on graphene substrates show better quality in terms of crystallinity, surface morphology, leakage current, and loss tangent. By transferring another graphene layer, we fabricated flexible and transparent capacitors with the structure of graphene-BMN-graphene. The capacitors show a large dielectric constant of 113 with high dielectric tunability of ~40.7 % at a bias field of 1.0 MV/cm. Also, the capacitor can work stably in the high bending condition with curvature radii as low as 10 mm. This flexible film capacitor has a high optical transparency of ~90 % in the visible light region, demonstrating their potential application for a wide range of flexible electronic devices. PMID:26138450

  12. Study of electric capacitors using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Alina Neamț

    2012-12-01

    Full Text Available A capacitor is made of two armatures and a dielectric between the two armatures. In this paper, we are going to study the plane capacitor , which is made of two equal metal armatures, plane and parallel, having the S surface, situated at a distance d much shorter than the armatures dimensions, between which there is a liniar, homogenous and isotropic dielectric having a constant electrical permittivity.The purpose of studying the plane capacitor, through MEF, presented in this paper,is to establish the stress to which the dielectrics may be subject to, in daily practice, and the influence that their superposition in an electric field has, on each of them. The study of the plane capacitor , finalised with observations on the raise of the dependence of the electric field intensity in air on the size of the air layer and having as parameter the type of dielectric material introduced between the armatures, is an example of confirmation or invalidation of the possibility and utility of using layers of dielectrics between the armatures of the capacitors.

  13. MIS capacitor studies on silicon carbide single crystals

    Science.gov (United States)

    Kopanski, J. J.

    1990-01-01

    Cubic SIC metal-insulator-semiconductor (MIS) capacitors with thermally grown or chemical-vapor-deposited (CVD) insulators were characterized by capacitance-voltage (C-V), conductance-voltage (G-V), and current-voltage (I-V) measurements. The purpose of these measurements was to determine the four charge densities commonly present in an MIS capacitor (oxide fixed charge, N(f); interface trap level density, D(it); oxide trapped charge, N(ot); and mobile ionic charge, N(m)) and to determine the stability of the device properties with electric-field stress and temperature. The section headings in the report include the following: Capacitance-voltage and conductance-voltage measurements; Current-voltage measurements; Deep-level transient spectroscopy; and Conclusions (Electrical characteristics of SiC MIS capacitors).

  14. On the exploitability of thermo-charged capacitors

    CERN Document Server

    D'Abramo, Germano

    2009-01-01

    Recently (arXiv:0904.3188) the concept of vacuum capacitors spontaneously charged thanks to the heat absorbed from single thermal source at room temperature has been introduced, along with a detailed mathematical description of the functioning and a discussion on its main paradoxical feature that seems to violate the Second Law of Thermodynamics. In the present paper we investigate the theoretical and practical possibility of exploiting such thermo-charged capacitors as voltage/current generators: we show that if very weak provisos on the physical characteristics of the capacitors are fulfilled, then a measurable current should flow across the device, allowing the generation of potentially usable voltage, current and electric power out of a single thermal source at room temperature.

  15. Limiting factors for carbon based chemical double layer capacitors

    Science.gov (United States)

    Rose, M. Frank; Johnson, C.; Owens, T.; Stevens, B.

    1993-01-01

    The Chemical Double Layer (CDL) capacitor improves energy storage density dramatically when compared with conventional electrolytic capacitors. When compared to batteries, the CDL Capacitor is much less energy dense; however, the power density is orders of magnitude better. As a result, CDL-battery combinations present an interesting pulse power system with many potential applications. Due to the nature of the CDL it is inherently a low voltage device. The applications of the CDL can be tailored to auxiliary energy and burst mode storages which require fast charge/discharge cycles. Typical of the applications envisioned are power system backup, directed energy weapons concepts, electric automobiles, and electric actuators. In this paper, we will discuss some of the general characteristics of carbon-based CDL technology describing the structure, performance parameters, and methods of construction. Further, analytical and experimental results which define the state of the art are presented and described in terms of impact on applications.

  16. High-speed FSK Modulator Using Switched-capacitor Resonators

    CERN Document Server

    Salehi, Mohsen

    2015-01-01

    In this paper, an ultra-fast frequency shift-keying (FSK) modulation technique based on switched capacitor resonators is presented. It is demonstrated that switching a reactive component such as a capacitor, in a high-Q resonator with proper switching signal can preserve the stored energy and shift it to a different frequency. Switching boundaries are found by continuity of electric charge and magnetic flux. It is shown that if switching time is synchronous with zero crossing of the voltage signal across the switched capacitor, impulsive components can be avoided and continuity of electric charge is satisfied without energy dissipation. We use this property to realize a fast binary frequency-shift keying (FSK) modulator with only a single RF source. In this technique, the modulation rate is independent of the resonator bandwidth and can be as high as the lower carrier frequency. Experimental results are presented to validate the simulations.

  17. Highly-Durable Carbon Electrode for Electrochemical Capacitors

    Directory of Open Access Journals (Sweden)

    Soshi Shiraishi

    2013-01-01

    Full Text Available The electric double layer capacitor (EDLC is anelectrochemical capacitor storing electric energy bycharging the electric double layer on the microporesof a nanoporous carbon electrode such as activatedcarbon. The EDLC has a fast charge-dischargeproperty and excellent cycle life, but its energydensity is lower than other electrochemical energystorage devices such as the rechargeable battery.The energy density of the EDLC can be improvedby increasing the double layer capacitance and themaximum charging voltage. In this review, the authordescribes the activated carbon electrodes for use ina durable EDLC for high voltage charging.

  18. Candidate organic electrolytes for electric double-layer capacitor application

    Institute of Scientific and Technical Information of China (English)

    B.Fang; Y.Wei; K.Suzuki; M.Kumagai

    2004-01-01

    Electrolytic conductivity,viscosity and electrochemical behavior were investigated for organic electrolytes based on PC(Propylene carbonate),MAN(Methoxy acetonitrile) and GBL(γ-Butyrolactone) solvents.It was found that 1 mol/L Et4NBF4-MAN had the highest conductivity,lowest viscosity and acceptable potential window.The specific capacitance and energy density obtained from the capacitor using 1 mol/L Et4NBF4-MAN as electrolyte were the highest among all the tested electrolytes.1 mol/L Et4NBF4-GBL also seemed promising to be used in electric double-layer capacitor (EDLCs).

  19. A fully woven touchpad sensor based on soft capacitor fibers

    CERN Document Server

    Gu, Jian Feng; Skorobogatiy, Maksim

    2011-01-01

    A novel, highly flexible capacitor fiber (with 100 nF m-1 typical capacitance per length) having a multilayer periodic structure of dielectric and conductive polymer composite films is fabricated by drawing technique. The fiber is used to build a woven touchpad sensor. Then, we study the influence of the fiber length, capacitance and volume resistivity on the touch sensing performance. A theoretical ladder network model of a fiber network is developed. A fully woven textile sample incorporating one-dimension array of the capacitor fibers is fabricated. Finally we show that such an array functions as a two-dimensional touch sensor.

  20. A Silicon-Based Ferroelectric Capacitor for Memory Devices

    Institute of Scientific and Technical Information of China (English)

    任天令; 张林涛; 刘理天; 李志坚

    2002-01-01

    We study a silicon-based Pb TiO3/Pb(Zro.53 Tio.47)O3/Pb TiO3 capacitor, prepared by an improved sol-gel method.The ferroelectric capacitor has a high remanent polarization of 15 pC/crm2 at a coercive field of about 30 k V/cm,an ultra-low leakage current density of 0.1 hA/crm2, and almost fatigue free properties. It can be used as a promising candidate for ferroelectric memory devices.

  1. Online MOS Capacitor Characterization in LabVIEW Environment

    Directory of Open Access Journals (Sweden)

    Chinmay K Maiti

    2009-08-01

    Full Text Available We present an automated evaluation procedure to characterize MOS capacitors involving high-k gate dielectrics. Suitability of LabVIEW environment for online web-based semiconductor device characterization is demonstrated. Developed algorithms have been successfully applied to automate the MOS capacitor measurements for Capacitance-Voltage, Conductance-Voltage and Current-Voltage characteristics. Implementation of the algorithm for use as a remote internet-based characterization tool where the client and server communicate with each other via web services is also shown.

  2. Smart and flexible capacitor charger for warm environments

    OpenAIRE

    Rydberg, Tobias

    2016-01-01

    A studio camera flash system being developed by Eascal AB needs a capacitor charging power supply (CCPS) that can work in a hot environment without problems and also not emit too much heat itself. The CCPS needs to be able to operate from battery power as well as net power, so called off-line, and to charge a capacitor to between 0-400 V. Most power supplies do not act upon a rise in temperature until it overheats and shuts down or goes into fail-safe mode where they stop delivering power. T...

  3. Pulse Capacitors for Next Generation Linear Colliders. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Hooker, M.W.

    2000-03-03

    During this Phase I SBIR research program, Nanomaterials Research Corporation (NRC) successfully demonstrated high-voltage multilayer capacitors produced from sub-100 nm ceramic powders. The devices produced by NRC exhibited properties that make them particularly useful for pulse power applications. These properties include (1) high capacitance (2) low loss (3) high breakdown voltage (4) high insulation resistance and (5) rapid discharge characteristics. Furthermore, the properties of the nanostructured capacitors were consistently found to exceed those of components that represent the state of the art within the industry. Encouraged by these results, NRC is planning to submit a Phase II proposal with the objective of securing seed capital to continue this development effort.

  4. RF MEMS Fractal Capacitors With High Self-Resonant Frequencies

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-23

    This letter demonstrates RF microelectromechanical systems (MEMS) fractal capacitors possessing the highest reported self-resonant frequencies (SRFs) in PolyMUMPS to date. Explicitly, measurement results show SRFs beyond 20 GHz. Furthermore, quality factors higher than 4 throughout a band of 1-15 GHz and reaching as high as 28 were achieved. Additional benefits that are readily attainable from implementing fractal capacitors in MEMS are discussed, including suppressing residual stress warping, eliminating the need for etching holes, and reducing parasitics. The latter benefits were acquired without any fabrication intervention. © 2011 IEEE.

  5. Differential RF MEMS interwoven capacitor immune to residual stress warping

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-27

    A RF MEMS capacitor with an interwoven structure is designed, fabricated in the PolyMUMPS process and tested in an effort to address fabrication challenges usually faced in MEMS processes. The interwoven structure was found to offer several advantages over the typical MEMS parallel-plate design including eliminating the warping caused by residual stress, eliminating the need for etching holes, suppressing stiction, reducing parasitics and providing differential capability. The quality factor of the proposed capacitor was higher than five throughout a 2–10 GHz range and the resonant frequency was in excess of 20 GHz.

  6. Reliability Modeling Development and Its Applications for Ceramic Capacitors with Base-Metal Electrodes (BMEs)

    Science.gov (United States)

    Liu, Donhang

    2014-01-01

    This presentation includes a summary of NEPP-funded deliverables for the Base-Metal Electrodes (BMEs) capacitor task, development of a general reliability model for BME capacitors, and a summary and future work.

  7. Integrated Diagnostic/Prognostic Experimental Setup for Capacitor Degradation and Health Monitoring

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper proposes the experiments and setups for studying diagnosis and prognosis of electrolytic capacitors in DC-DC power converters. Electrolytic capacitors...

  8. Infant-mortality testing of high-energy-density capacitors used on Nova

    International Nuclear Information System (INIS)

    Nova is a solid-state large laser for inertial-confinement fusion research. Its flashlamps are driven by a 60-MJ capacitor bank. Part of this bank is being built with high-energy-density capacitors, 52-μF, 22 kV, 12.5 kJ. A total of 2645 of these capacitors have been purchased from two manufacturers. Each capacitor was infant-mortality tested. The first test consisted of a high-potential test, bushing-to-case, since these capacitors have dual bushings. Then the capacitors were discharged 500 times with circuit conditions approximating the capacitors normal flashlamp load. Failure of either of these tests or if the capacitor was leaking was cause for rejection

  9. Reliability Evaluation of Base-Metal-Electrode Multilayer Ceramic Capacitors for Potential Space Applications

    Science.gov (United States)

    Liu, David (Donhang); Sampson, Michael J.

    2011-01-01

    Base-metal-electrode (BME) ceramic capacitors are being investigated for possible use in high-reliability spacelevel applications. This paper focuses on how BME capacitors construction and microstructure affects their lifetime and reliability. Examination of the construction and microstructure of commercial off-the-shelf (COTS) BME capacitors reveals great variance in dielectric layer thickness, even among BME capacitors with the same rated voltage. Compared to PME (precious-metal-electrode) capacitors, BME capacitors exhibit a denser and more uniform microstructure, with an average grain size between 0.3 and 0.5 m, which is much less than that of most PME capacitors. BME capacitors can be fabricated with more internal electrode layers and thinner dielectric layers than PME capacitors because they have a fine-grained microstructure and do not shrink much during ceramic sintering. This makes it possible for BME capacitors to achieve a very high capacitance volumetric efficiency. The reliability of BME and PME capacitors was investigated using highly accelerated life testing (HALT). Most BME capacitors were found to fail with an early avalanche breakdown, followed by a regular dielectric wearout failure during the HALT test. When most of the early failures, characterized with avalanche breakdown, were removed, BME capacitors exhibited a minimum mean time-to-failure (MTTF) of more than 105 years at room temperature and rated voltage. Dielectric thickness was found to be a critical parameter for the reliability of BME capacitors. The number of stacked grains in a dielectric layer appears to play a significant role in determining BME capacitor reliability. Although dielectric layer thickness varies for a given rated voltage in BME capacitors, the number of stacked grains is relatively consistent, typically around 12 for a number of BME capacitors with a rated voltage of 25V. This may suggest that the number of grains per dielectric layer is more critical than the

  10. SOGI-based capacitor voltage feedback active damping in LCL-filtered grid converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang;

    2015-01-01

    The capacitor voltage feedback active damping control is an attractive way to suppress LCL-filter resonance especially for the systems where the capacitor voltage is used for grid synchronization, since no extra sensors are added. The derivative is the core of the capacitor voltage feedback active...... derivative is more suited for capacitor voltage feedback active damping control. Experimental results validate the effectiveness of the proposed method....

  11. How to get mechanical work from a capacitor and two batteries

    CERN Document Server

    Miranda, E N

    2012-01-01

    The work done by a parallel plate capacitor is evaluated when the plate separation is changed. Two cases are considered: 1) the capacitor has a constant charge; 2) the capacitor is at constant voltage. The net work is calculated when the device follows a closed cycle in the charge-voltage space. For certain conditions a net mechanical work can be obtained from the cycling capacitor. The analysis is simple enough to be explained in a general physics course.

  12. Does a coupling capacitor enhance the charge balance during neural stimulation? An empirical study

    NARCIS (Netherlands)

    Van Dongen, M.N.; Serdijn, W.A.

    2015-01-01

    Due to their DC-blocking characteristic, coupling capacitors are widely used to prevent potentially harmful charge buildup at the electrode–tissue interface. Although the capacitors can be an effective safety measure, it often seems overlooked that coupling capacitors actually introduce an offset vo

  13. Accelerated lifetime testing of energy storage capacitors used in particle accelerators power converters

    CERN Document Server

    AUTHOR|(SzGeCERN)679542; Genton, Charles-Mathieu

    2015-01-01

    Energy storage capacitors are used in large quantities in high power converters for particle accelerators. In this application capacitors see neither a DC nor an AC voltage but a combination of the two. The paper presents a new power converter explicitly designed to perform accelerated testing on these capacitors and the results of the tests.

  14. BORON NITRIDE CAPACITORS FOR ADVANCED POWER ELECTRONIC DEVICES

    Energy Technology Data Exchange (ETDEWEB)

    N. Badi; D. Starikov; C. Boney; A. Bensaoula; D. Johnstone

    2010-11-01

    This project fabricates long-life boron nitride/boron oxynitride thin film -based capacitors for advanced SiC power electronics with a broad operating temperature range using a physical vapor deposition (PVD) technique. The use of vapor deposition provides for precise control and quality material formation.

  15. Test demonstration of magnet power supply with the flying capacitor

    International Nuclear Information System (INIS)

    Japan Proton Accelerator Research Complex (J-PARC) aims at achieving a MW-class proton accelerator facility. One of the promising solutions for increasing the beam power is to fasten the repetition rate of Main Ring (MR) from current rating of 2.5 sec to 1 sec in the future. However, in this scheme, the increase of output voltage and the power variation on the electric system are serious concerns for main magnets. We have considered that the energy recovery scheme based on capacitive energy storage is one of the best solution to compensate the power variation induced by a magnet power supply. In order to achieve the idea, we have decided to innovate the flying capacitor method to produce the high output voltage and return the capacitor energy with magnetic energy. However driving power supply with the flying capacitor method needs to establish the charging method of them in each pattern. In this article, we report the test result of magnetic power supply with the mini model of the power supply using the flying capacitor method. (author)

  16. Carbons, ionic liquids and quinones for electrochemical capacitors

    Directory of Open Access Journals (Sweden)

    Raul eDiaz

    2016-04-01

    Full Text Available Carbons are the main electrode materials used in electrochemical capacitors, which are electrochemical energy storage devices with high power densities and long cycling lifetimes. However, increasing their energy density will improve their potential for commercial implementation. In this regard, the use of high surface area carbons and high voltage electrolytes are well known strategies to increase the attainable energy density, and lately ionic liquids have been explored as promising alternatives to current state of the art acetonitrile-based electrolytes. Also, in terms of safety and sustainability ionic liquids are attractive electrolyte materials for electrochemical capacitors. In addition, it has been shown that the matching of the carbon pore size with the electrolyte ion size further increases the attainable electric double layer (EDL capacitance and energy density.The use of pseudocapacitive reactions can significantly increase the attainable energy density, and quinonic-based materials offer a potentially sustainable and cost effective research avenue for both the electrode and the electrolyte. This perspective will provide an overview of the current state of the art research on electrochemical capacitors based on combinations of carbons, ionic liquids and quinonic compounds, highlighting performances and challenges and discussing possible future research avenues. In this regard, current interest is mainly focused on strategies which may ultimately lead to commercially competitive sustainable high performance electrochemical capacitors for different applications including those requiring mechanical flexibility and biocompatibility.

  17. Accelerated Aging Experiments for Capacitor Health Monitoring and Prognostics

    Science.gov (United States)

    Kulkarni, Chetan S.; Celaya, Jose Ramon; Biswas, Gautam; Goebel, Kai

    2012-01-01

    This paper discusses experimental setups for health monitoring and prognostics of electrolytic capacitors under nominal operation and accelerated aging conditions. Electrolytic capacitors have higher failure rates than other components in electronic systems like power drives, power converters etc. Our current work focuses on developing first-principles-based degradation models for electrolytic capacitors under varying electrical and thermal stress conditions. Prognostics and health management for electronic systems aims to predict the onset of faults, study causes for system degradation, and accurately compute remaining useful life. Accelerated life test methods are often used in prognostics research as a way to model multiple causes and assess the effects of the degradation process through time. It also allows for the identification and study of different failure mechanisms and their relationships under different operating conditions. Experiments are designed for aging of the capacitors such that the degradation pattern induced by the aging can be monitored and analyzed. Experimental setups and data collection methods are presented to demonstrate this approach.

  18. Current Control of Grid Converters Connected with Series AC Capacitor

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang;

    2015-01-01

    The series ac capacitor has recently been used with the transformerless grid-connected converters in the distribution power grids. The capacitive characteristic of the resulting series LC filter restricts the use of conventional synchronous integral or stationary resonant current controllers. Thus...

  19. Capacitor placement for transmission systems using ordinal optimization approach

    Energy Technology Data Exchange (ETDEWEB)

    Lin, S.-Y. [National Chiao Tung Univ., Hsinchu, Taiwan (China); Lin, C.-H. [Kao-Yuan Univ. Technology, Kaohsiung, Taiwan (China)

    2007-07-01

    Capacitor placement poses a challenge in power system design because it involves integer variables for determining the placement locations and discrete variables for deciding the number of capacitor banks to be installed. It is also a large-dimension constrained optimization problem for considering the system constraints and, investment constraint. This paper proposed an ordinal optimization (OO) approach for solving this problem. The approach consisted of five OO iterations. The size and solution quality of the resulting candidate solution set was reduced and improved, iteration by iteration. A reasonable capacitor placement pattern was obtained in the final iteration. In addition, in order to demonstrate the computational efficiency of the approach and the quality of the obtained solutions, the genetic algorithm was compared with the TABU search method. The paper defined the problem statement and discussed the OO approach and explained the five iterations and theory. The test results demonstrated that the proposed approach is suitable for the capacitor placement problem. 16 refs., 2 tabs.

  20. Mismatch-shaping switching for two-capacitor DAC

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper; Moon, U.; Temes, G.C.

    1998-01-01

    A mismatch-shaping scheme is proposed for a two-capacitor digital-to-analogue converter (DAC). It uses a delta-sigma loop for finding the optimal switching sequence for each input word. Simulations indicate that the scheme can be used for the realisation of DACs with 16 bit linearity and SNR perf...

  1. Mismatch-Shaped Pseudo-Passive Two-Capacitor DAC

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper; Moon, Un-Ku; Temes, Gabor C.

    1999-01-01

    A simple mismatch-shaping scheme is proposed for a two-capacitor DAC. Unlike in other mismatch-shaping systems, the shaped error is generated by direct filtering of a well-defined bounded signal, which can be generated as white noise. The operation is closely related to a specific digital interpo...

  2. A simple capacitor model for radio emission associated with earthquakes

    Institute of Scientific and Technical Information of China (English)

    Ares de Parga Gonzalo; Ram(I)rez-Rojas Alejandro

    2004-01-01

    In this brief report we propose a simple model based on the properties of an electric capacitor under short-circuit conditions as a possible mechanism of radio emissions associated with earthquakes. This model can be considered as complementary to other models concerning the same problem.

  3. A novel MEMS inertial sensor with enhanced sensing capacitors

    Institute of Scientific and Technical Information of China (English)

    Dong Linxi; Yan Haixia; Huo Weihong; Xu Li; Li Yongjie; Sun Lingling

    2009-01-01

    A novel MEMS inertial sensor with enhanced sensing capacitors is developed. The designed fabricated process of the sensor is a deep RIE process, which can increase the mass of the seismic to reduce the mechanical noise, and the designed capacitance sensing method is changing the capacitance area, which can reduce the air damping between the sensing capacitor plates and reduce the requirement for the DRIE process precision, and reduce the electronic noise by increasing the sensing voltage to improve the resolution. The design and simulation are also verified by using the FEM tool ANSYS. The simulated results show that the transverse sensitivity of the sensor is approximately equal to zero. Finally, the fabricated process based on silicon-glass bonding and the preliminary test results of the device for testing grid capacitors and the novel inertial sensor are presented. The testing quality factor of the testing device based on the slide-film damping effect is 514, which shows that the enhanced capacitors can reduce mechanical noise. The preliminary testing result of the sensitivity is 0.492 pf/g.

  4. Pulsed current signals in capacitor type particle detectors

    International Nuclear Information System (INIS)

    The problem of pulsed current signals in capacitor type sensors, due to drifting surface charge domain is considered for the analysis of the operational characteristics in photo- and particle-detectors. In this article, the models of the formation of the pulsed currents have been analyzed in vacuum and dielectric filled capacitor-like detectors. Injected charge drift regimes such as Shockley-Ramo's-type (large charge drift) and free flight within Coulomb's force field (small charge drift) are discussed. It has been shown that solutions of the injected charge drift in the vacuum gap capacitor can be employed to emulate charge drift over free path in dynamic solution of the problem with scattering. Pulsed current signals and charge drift in the detectors of the capacitor filled with dielectric type have been analyzed, where the bipolar charge injection and various drift regimes appear. The bipolar carrier drift transformation to a monopolar one is considered, after either electrons or holes, injected within the material, reach the external electrode. The impact of the dynamic capacitance and load resistance in the formation of drift current transients is highlighted. It has been illustrated that the synchronous action of carrier drift, trapping, generation and diffusion can lead to a vast variety of possible current pulse waveforms

  5. Carbons, ionic liquids and quinones for electrochemical capacitors

    Science.gov (United States)

    Diaz, Raul; Doherty, Andrew

    2016-04-01

    Carbons are the main electrode materials used in electrochemical capacitors, which are electrochemical energy storage devices with high power densities and long cycling lifetimes. However, increasing their energy density will improve their potential for commercial implementation. In this regard, the use of high surface area carbons and high voltage electrolytes are well known strategies to increase the attainable energy density, and lately ionic liquids have been explored as promising alternatives to current state of the art acetonitrile-based electrolytes. Also, in terms of safety and sustainability ionic liquids are attractive electrolyte materials for electrochemical capacitors. In addition, it has been shown that the matching of the carbon pore size with the electrolyte ion size further increases the attainable electric double layer (EDL) capacitance and energy density. The use of pseudocapacitive reactions can significantly increase the attainable energy density, and quinonic-based materials offer a potentially sustainable and cost effective research avenue for both the electrode and the electrolyte. This perspective will provide an overview of the current state of the art research on electrochemical capacitors based on combinations of carbons, ionic liquids and quinonic compounds, highlighting performances and challenges and discussing possible future research avenues. In this regard, current interest is mainly focused on strategies which may ultimately lead to commercially competitive sustainable high performance electrochemical capacitors for different applications including those requiring mechanical flexibility and biocompatibility.

  6. New Materials and New Configurations for Advanced Electrochemical Capacitors

    OpenAIRE

    Naoi, Katsuhiko; Simon, Patrice

    2008-01-01

    Today, electrochemical capacitors (ECs) have the potential to emerge as a promising energy storage technology. The weakness of EC systems is certainly the limited energy density, which restricts applications to power delivery over only few seconds. As a consequence, many research efforts are focused on designing new materials to improve energy and power densities. These are reviewed below.

  7. Thermodynamic model for bouncing charged particles inside a capacitor

    Science.gov (United States)

    Rezaeizadeh, Amin; Mameghani, Pooya

    2013-08-01

    We introduce an equation of state for a conducting particle inside a charged parallel-plate capacitor and show that it is similar to the equation of state for an ideal gas undergoing an adiabatic process. We describe a simple experiment that shows reasonable agreement with the theoretical model.

  8. Highly Accurate Derivatives for LCL-Filtered Grid Converter with Capacitor Voltage Active Damping

    DEFF Research Database (Denmark)

    Xin, Zhen; Loh, Poh Chiang; Wang, Xiongfei;

    2016-01-01

    The middle capacitor voltage of an LCL-filter, if fed back for synchronization, can be used for active damping. An extra sensor for measuring the capacitor current is then avoided. Relating the capacitor voltage to existing popular damping techniques designed with capacitor current feedback would...... then proposed, based on either second-order or non-ideal generalized integrator. Performances of these derivatives have been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately. Experimental results presented have...

  9. Pattern recognition of typical defects in high-voltage storage capacitors based on DC partial discharge

    Institute of Scientific and Technical Information of China (English)

    WU GuangNing; BIAN ShanShan; ZHOU LiRen; ZHANG XueQin; RAN HanZheng; YU ChengLong

    2009-01-01

    High-voltage storage capacitors(hereinafter call capacitors for short)have been widely used in pulsed power technology.In accordance with the actual work conditions of capacitors,direct current partial discharge(DCPD)detection was put forward.The whole test system was based on the impedance balance circuit characterized by good configuration and anti-interference ability.Through DCPD detection on capacitors which contained four typical defects respectively,test results revealed that DCPD signals could well reflect the state of capacitor insulation.DCPD distribution spectra of capacitors containing four typical defects were obviously different.Defects in capacitors could be exactly judged by computer-aided pattern recognition based on support vector machine(SVM).

  10. Simulation Research of Transient Over-voltage on High-voltage Shunt Capacitor Banks

    Institute of Scientific and Technical Information of China (English)

    HU Quan-wei; ZHOU Xing-xing; SI Wen-rong; ZHANG Yang; LI Jur-hao; LI Yan-ming

    2011-01-01

    With the development of power systems,a large number of shunt capacitors are used to improve power quality in the distribution network.The shunt capacitor banks are operated much frequently,as a result,the capacitor banks will bear large numbers of over-voltage inevitably.If the over-voltage exceeds certain amplitude,the capacitor will be damaged.This paper aims at the capacitor banks in the 35 kV side of Shanghai Xu-xing 500 kV substation,and applies ATP-EMTP to simulate the over-voltages generated by operating the switches under different angles of the source.Finally,according to the results of simulation and theoretical analysis,a best choice (i.e.angles of the source) to switch on capacitor banks is proposed.In this case the over-voltage on the capacitor will be limited to lowest.

  11. Graphene oxide-based flexible metal–insulator–metal capacitors

    International Nuclear Information System (INIS)

    This work explores the fabrication of graphene oxide (GO)-based metal–insulator–metal (MIM) capacitors on flexible polyethylene terephthalate (PET) substrates. Electrical properties are studied in detail. A high capacitance density of ∼4 fF µm−2 measured at 1 MHz and permittivity of ∼6 have been obtained. A low voltage coefficient of capacitance, VCC-α, and a low dielectric loss tangent indicate the potential of GO-based MIM capacitors for RF applications. The constant voltage stressing study has shown a high reliability against degradation up to a projected period of 10 years. Degradation in capacitance of the devices on flexible substrates has been studied by bending radius down to 1 cm even up to 6000 times of repeated bending. (paper)

  12. Graphene oxide-based flexible metal-insulator-metal capacitors

    Science.gov (United States)

    Bag, A.; Hota, M. K.; Mallik, S.; Maiti, C. K.

    2013-05-01

    This work explores the fabrication of graphene oxide (GO)-based metal-insulator-metal (MIM) capacitors on flexible polyethylene terephthalate (PET) substrates. Electrical properties are studied in detail. A high capacitance density of ˜4 fF µm-2 measured at 1 MHz and permittivity of ˜6 have been obtained. A low voltage coefficient of capacitance, VCC-α, and a low dielectric loss tangent indicate the potential of GO-based MIM capacitors for RF applications. The constant voltage stressing study has shown a high reliability against degradation up to a projected period of 10 years. Degradation in capacitance of the devices on flexible substrates has been studied by bending radius down to 1 cm even up to 6000 times of repeated bending.

  13. On the Anomalous Weight Losses of High Voltage Symmetrical Capacitors

    CERN Document Server

    Porcelli, Elio B

    2015-01-01

    In this work, we analyzed an anomalous effect verified from symmetrical capacitor devices, working in very high electric potentials. The mastery of that effect could mean in the future the possible substitution of propulsion technology based on fuels by single electrical propulsion systems. From experimental measurements, we detected small variations of the device inertia that cannot be associated with known interactions, so that the raised force apparently has not been completely elucidated by current theories. We measured such variations within an accurate range and we proposed that the experimental results can be explained by relations like Clausius-Mossotti one, in order to quantify the dipole forces that appear in the devices. The values of the weight losses in the capacitors were calculated by means of the theoretical proposal and indicated good agreement with our experimental measurements for 7kV and with many other experimental works.

  14. Carbon-Based Fibrous EDLC Capacitors and Supercapacitors

    Directory of Open Access Journals (Sweden)

    C. Lekakou

    2011-01-01

    Full Text Available This paper investigates electrochemical double-layer capacitors (EDLCs including two alternative types of carbon-based fibrous electrodes, a carbon fibre woven fabric (CWF and a multiwall carbon nanotube (CNT electrode, as well as hybrid CWF-CNT electrodes. Two types of separator membranes were also considered. An organic gel electrolyte PEO-LiCIO4-EC-THF was used to maintain a high working voltage. The capacitor cells were tested in cyclic voltammetry, charge-discharge, and impedance tests. The best separator was a glass fibre-fine pore filter. The carbon woven fabric electrode and the corresponding supercapacitor exhibited superior performance per unit area, whereas the multiwall carbon nanotube electrode and corresponding supercapacitor demonstrated excellent specific properties. The hybrid CWF-CNT electrodes did not show a combined improved performance due to the lack of carbon nanotube penetration into the carbon fibre fabric.

  15. Gravitational and electric energies in collapse of spherically thin capacitor

    CERN Document Server

    Ruffini, Remo

    2013-01-01

    In our previous article (PHYSICAL REVIEW D 86, 084004 (2012)), we present a study of strong oscillating electric fields and electron-positron pair-production in gravitational collapse of a neutral stellar core at or over nuclear densities. In order to understand the back-reaction of such electric energy building and radiating on collapse, we adopt a simplified model describing the collapse of a spherically thin capacitor to give an analytical description how gravitational energy is converted to both kinetic and electric energies in collapse. It is shown that (i) averaged kinetic and electric energies are the same order, about an half of gravitational energy of spherically thin capacitor in collapse; (ii) caused by radiating and rebuilding electric energy, gravitational collapse undergoes a sequence of "on and off" hopping steps in the microscopic Compton scale. Although such a collapse process is still continuous in terms of macroscopic scales, it is slowed down as kinetic energy is reduced and collapsing tim...

  16. Carbon activation process for increased surface accessibility in electrochemical capacitors

    Science.gov (United States)

    Doughty, Daniel H.; Eisenmann, Erhard T.

    2001-01-01

    A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm.sup.3 is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350.degree. C. for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

  17. High energy storage capacitor by embedding tunneling nano-structures

    Energy Technology Data Exchange (ETDEWEB)

    Holme, Timothy P; Prinz, Friedrich B; Van Stockum, Philip B

    2014-11-04

    In an All-Electron Battery (AEB), inclusions embedded in an active region between two electrodes of a capacitor provide enhanced energy storage. Electrons can tunnel to/from and/or between the inclusions, thereby increasing the charge storage density relative to a conventional capacitor. One or more barrier layers is present in an AEB to block DC current flow through the device. The AEB effect can be enhanced by using multi-layer active regions having inclusion layers with the inclusions separated by spacer layers that don't have the inclusions. The use of cylindrical geometry or wrap around electrodes and/or barrier layers in a planar geometry can enhance the basic AEB effect. Other physical effects that can be employed in connection with the AEB effect are excited state energy storage, and formation of a Bose-Einstein condensate (BEC).

  18. Vibrating capacitor method in the development of semiconductor gas sensors

    International Nuclear Information System (INIS)

    Adsorption usually results in work function shifts on catalytically active surfaces such as semiconductor gas sensors. The purpose of the present article is to summarise the capabilities of the vibrating capacitor from the simplest adsorption-induced work function tests to the scanning, vibrating, capacitor-yielded olfactory pictures and other chemical pictures. After a brief history and review of theoretical bases, the latest results will be discussed in detail. Olfactory pictures from semiconductor surfaces give a new chance to improve the selectivity of gas analysis. Chemical pictures from thin SnO2 layers produced by atomic layer epitaxy reveal the inhomogeneities of the technology. CPD maps taken from Pd nanolayer (activator)-covered surfaces help to find the best layer-depositing parameters for the activation process of the thin semiconductor gas sensor films

  19. Neutron induced degradation in nitrided pyrogenic field oxide MOS capacitors

    CERN Document Server

    Vaidya, S J; Shaikh, A M; Chandorkar, A N

    2002-01-01

    Neutron induced oxide charge trapping and generation of interface states in MOS capacitors with pyrogenic and nitrided pyrogenic field oxides have been studied. In order to assess the damage due to neutrons alone, it is necessary to account for the damage produced by the accompanying gamma rays from neutron radiation. This is done by measuring the intensity of gamma radiation accompanying neutrons at different neutron fluences at the irradiation position. MOS capacitor structures were subjected to neutron radiation in a swimming pool type of reactor. Other samples from the same batch were then subjected to an equivalent dose of gamma radiation from a Co sup 6 sup 0 source. The difference in the damage observed was used to characterize the damage caused by neutrons. It is observed that neutrons, though uncharged, are capable of causing ionization damage. This damage is found to be significant when the radiation is performed under biased conditions. Nitridation in different ambients is found to improve the radi...

  20. Failure Modes in Capacitors When Tested Under a Time-Varying Stress

    Science.gov (United States)

    Liu, David (Donhang)

    2011-01-01

    Power-on failure has been the prevalent failure mechanism for solid tantalum capacitors in decoupling applications. A surge step stress test (SSST) has been previously applied to identify the critical stress level of a capacitor batch to give some predictability to the power-on failure mechanism [1]. But SSST can also be viewed as an electrically destructive test under a time-varying stress (voltage). It consists of rapidly charging the capacitor with incremental voltage increases, through a low resistance in series, until the capacitor under test is electrically shorted. When the reliability of capacitors is evaluated, a highly accelerated life test (HALT) is usually adopted since it is a time-efficient method of determining the failure mechanism; however, a destructive test under a time-varying stress such as SSST is even more time efficient. It usually takes days or weeks to complete a HALT test, but it only takes minutes for a time-varying stress test to produce failures. The advantage of incorporating a specific time-varying stress profile into a statistical model is significant in providing an alternative life test method for quickly revealing the failure mechanism in capacitors. In this paper, a time-varying stress that mimics a typical SSST has been incorporated into the Weibull model to characterize the failure mechanism in different types of capacitors. The SSST circuit and transient conditions for correctly surge testing capacitors are discussed. Finally, the SSST was applied for testing Ta capacitors, polymer aluminum capacitors (PA capacitors), and multi-layer ceramic (MLC) capacitors with both precious metal electrodes (PME) and base metal electrodes (BME). The test results are found to be directly associated with the dielectric layer breakdown in Ta and PA capacitors and are independent of the capacitor values, the way the capacitors were built, and the capacitors manufacturers. The test results also show that MLC capacitors exhibit surge breakdown

  1. A review of molecular modelling of electric double layer capacitors.

    Science.gov (United States)

    Burt, Ryan; Birkett, Greg; Zhao, X S

    2014-04-14

    Electric double-layer capacitors are a family of electrochemical energy storage devices that offer a number of advantages, such as high power density and long cyclability. In recent years, research and development of electric double-layer capacitor technology has been growing rapidly, in response to the increasing demand for energy storage devices from emerging industries, such as hybrid and electric vehicles, renewable energy, and smart grid management. The past few years have witnessed a number of significant research breakthroughs in terms of novel electrodes, new electrolytes, and fabrication of devices, thanks to the discovery of innovative materials (e.g. graphene, carbide-derived carbon, and templated carbon) and the availability of advanced experimental and computational tools. However, some experimental observations could not be clearly understood and interpreted due to limitations of traditional theories, some of which were developed more than one hundred years ago. This has led to significant research efforts in computational simulation and modelling, aimed at developing new theories, or improving the existing ones to help interpret experimental results. This review article provides a summary of research progress in molecular modelling of the physical phenomena taking place in electric double-layer capacitors. An introduction to electric double-layer capacitors and their applications, alongside a brief description of electric double layer theories, is presented first. Second, molecular modelling of ion behaviours of various electrolytes interacting with electrodes under different conditions is reviewed. Finally, key conclusions and outlooks are given. Simulations on comparing electric double-layer structure at planar and porous electrode surfaces under equilibrium conditions have revealed significant structural differences between the two electrode types, and porous electrodes have been shown to store charge more efficiently. Accurate electrolyte and

  2. Optimization of Capacitor for Sub Sea Motor Drive Application

    OpenAIRE

    Thapa, Umesh

    2010-01-01

    Optimization of Capacitor for Sub Sea Motor Drive ApplicationStudent: Umesh ThapaSupervisor: Prof. Lars NorumContact: Espen HauganProblem DescriptionSubsea drives are very large and expensive equipments. Normally subsea drives are encapsulated in thick walled tanks holding 1 atmosphere. As new gas fields are being discovered continually at deeper waters, this type of solution is becoming more costly. So interest in investigating the possibility of minimizing the size of electric motor drives ...

  3. Anti-Ferroelectric Ceramics for High Energy Density Capacitors

    OpenAIRE

    Aditya Chauhan; Satyanarayan Patel; Rahul Vaish; Bowen, Chris R.

    2015-01-01

    With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE) display evidence of being a stro...

  4. Microstructured organic ferroelectric thin film capacitors by solution micromolding

    OpenAIRE

    Lenz, Thomas; Zhao, Dong; Richardson, George; Katsouras, Ilias; Asadi, Kamal; Glasser, Gunnar; Zimmermann, Samuel T.; Stingelin, Natalie; Christian Roelofs, W. S.; Kemerink, Martijn; Blom, Paul W. M.; De Leeuw, Dago M.

    2015-01-01

    Ferroelectric nanostructures offer a promising route for novel integrated electronic devices such as non-volatile memories. Here we present a facile fabrication route for ferroelectric capacitors comprising a linear array of the ferroelectric random copolymer of vinylidenefluoride and trifluoroethylene (P(VDF-TrFE)) interdigitated with the electrically insulating polymer polyvinyl alcohol (PVA). Micrometer size line gratings of both polymers were fabricated over large area by solution micromo...

  5. Carbons, ionic liquids and quinones for electrochemical capacitors

    OpenAIRE

    Raul eDiaz; Doherty, Andrew P.

    2016-01-01

    Carbons are the main electrode materials used in electrochemical capacitors, which are electrochemical energy storage devices with high power densities and long cycling lifetimes. However, increasing their energy density will improve their potential for commercial implementation. In this regard, the use of high surface area carbons and high voltage electrolytes are well known strategies to increase the attainable energy density, and lately ionic liquids have been explored as promising alterna...

  6. Dynamic thermoelectric and heat transport in mesoscopic capacitors

    OpenAIRE

    Lim, Jong-Soo; López, Rosa; Sánchez, David

    2013-01-01

    We discuss the low-frequency response of charge and heat transport to oscillatory voltage and temperature shifts in mesoscopic capacitors. We obtain, within scattering theory, generic expressions for the quantum admittances up to second order in the ac frequencies in terms of electric, thermoelectric, and heat capacitances and relaxation resistances. Remarkably, we find that the thermocurrent can lead or lag the applied temperature depending on the gate voltage applied to a quantum RC circuit...

  7. Radio Frequency Characteristics of Printed Meander Inductors and Interdigital Capacitors

    Science.gov (United States)

    Myllymaki, Sami; Teirikangas, Merja; Nelo, Mikko; Tulppo, Joel; Sobociński, Maciej; Juuti, Jari; Jantunen, Heli; Sloma, Marcin; Jakubowska, Malgorzata

    2013-05-01

    Radio frequency (RF) characterizations of printed silver ink inductors manufactured at low (150 °C) and high (850 °C) temperatures and interdigital capacitors manufactured at high (850 °C) temperatures were carried out in the 500 MHz to 6 GHz range. The S-parameter responses of the components were measured with a probe station and an Agilent 8510C network analyzer. Electrical parameters such as inductance, capacitance, and a quality factor were estimated from experimental results and numerical calculation. Component parameters are dependent on physical dimensions and material properties. The components were created in a 4 ×4 mm2 area with line widths/gaps of 500/500, 250/250, and 200/200 µm. Windings in the coils varied from 2 to 5 turns and finger counts in the capacitors, from 5 to 11 within the defined area and line widths. As a result, low-T-cured (150 °C) silver ink meander line inductors achieved 8 to 18 nH inductances at 1 and 2 GHz with a quality value of 10-25. High-T-cured (850 °C) silver ink meander line inductors had 6-15 nH inductances and quality values were around 100, indicating a conductivity challenge with low-T-cured inks. Interdigital capacitors with 1 to 4 pF capacitances and sufficient quality values were created. A low-loss BaTiO3 coating was printed over the interdigital capacitors; they exhibited suitable electrical characteristics to allow decreasing the physical size of the component.

  8. High Speed Capacitor-Inverter Based Carbon Nanotube Full Adder

    OpenAIRE

    Rashtian M; Khatir A; Keshavarzian P; Navi K; Hashemipour O

    2010-01-01

    Abstract Carbon Nanotube filed-effect transistor (CNFET) is one of the promising alternatives to the MOS transistors. The geometry-dependent threshold voltage is one of the CNFET characteristics, which is used in the proposed Full Adder cell. In this paper, we present a high speed Full Adder cell using CNFETs based on majority-not (Minority) function. Presented design uses eight transistors and eight capacitors. Simulation results show significant improvement in terms of delay and power-delay...

  9. Alignment and testing of the NIST calculable capacitor

    Czech Academy of Sciences Publication Activity Database

    Wang, Y.; Cervantes, F. G.; Stambaugh, C.; Šmíd, Radek; Calvo, H.; Koffman, A.; Pratt, J. R.; Lawall, J.

    Piscataway : IEEE, 2014 , s. 476-477. ISBN 978-1-4799-5205-2. ISSN 0589-1485. [Conference on Precision Electromagnetic Measuerements /29./ CPEM 2014 . Rio de Janeiro (BR), 24.08. 2014 -29.08. 2014 ] R&D Projects: GA ČR(CZ) GPP102/12/P962 Institutional support: RVO:68081731 Keywords : Fabry-Perot interferometers * capacitors * electrodes * motion control Subject RIV: BH - Optics, Masers, Lasers

  10. Soft capacitor fibers using conductive polymers for electronic textiles

    OpenAIRE

    Gu, Jian Feng; Gorgutsa, Stephan; Skorobogatiy, Maksim

    2010-01-01

    A novel, highly flexible, conductive polymer-based fiber with high electric capacitance is reported. In its crossection the fiber features a periodic sequence of hundreds of conductive and isolating plastic layers positioned around metallic electrodes. The fiber is fabricated using fiber drawing method, where a multi-material macroscopic preform is drawn into a sub-millimeter capacitor fiber in a single fabrication step. Several kilometres of fibers can be obtained from a single preform with ...

  11. Synchronous Voltage Reversal Control of Thyristor Controlled Series Capacitor

    OpenAIRE

    Ängquist, Lennart

    2002-01-01

    Series compensation of transmission lines is an effectiveand cheap method of improving the power transmission systemperformance. Series capacitors virtually reduces the length ofthe line making it easier to keep all parts of the power systemrunning in synchronism and to maintain a constant voltage levelthroughout the system. In Sweden this technology has been inuse since almost 50 years. The possibility to improve the performance of the ACtransmission system utilizing power electronic equipme...

  12. Out-of-plane CMOS-MEMS variable capacitor

    OpenAIRE

    2009-01-01

    To be able to create small integrated wireless radio front ends, variable capacitors that can be monolithically integrated on the same chip as the electronic circuits are needed. Today’s radio front ends are based on solidstate diode varactors which suffer from poor tuning range and phase noise and do not meet the requirements for a fully integrated wide band radio front end. In this thesis we will look at possibilities for implementation of a monolithic integrated MEMS vara...

  13. Solid state capacitor discharge pulsed power supply for railguns

    OpenAIRE

    Black, Jesse H.

    2007-01-01

    This thesis presents a solid state thyristor switched power supply capable of providing 50 kJ from a high voltage capacitor to a railgun. The efficiency with which energy is transferred from a power supply to a projectile depends strongly on power supply characteristics. This design will provide a better impedance match to the railgun than power supplies utilizing spark gap switches. This supply will cost less and take up less volume than a similar supply using spark gap switches; it wil...

  14. Thermo-charged capacitors and the Second Law of Thermodynamics

    International Nuclear Information System (INIS)

    In this Letter we describe a vacuum spherical capacitor that generates a macroscopic voltage between its spheres harnessing the heat from a single thermal reservoir at room temperature. The basic idea is trivial and it makes use of two concentric spherical electrodes with different work functions. We provide a mathematical analysis of the underlying physical process and discuss its connections with the Second Law of Thermodynamics.

  15. Comparison of topologies suitable for Capacitor Charging Systems

    CERN Document Server

    Maestri, S; Uicich, G; Benedetti, M; Cravero, JM

    2014-01-01

    This paper presents a comparison between topologies suitable for capacitor charging systems. The topologies under evaluation are a flyback converter, a half-bridge series resonant converter and a full-bridge phase-shifted converter. The main features of these topologies are highlighted, which allows the proper topology selection according to the application requirements. Moreover, the performed analysis permits to characterize the operational range of the main components thus allowing their appropriate sizing and selection. Simulation results are provided.

  16. Two-cavity MEMS variable capacitor for power harvesting

    International Nuclear Information System (INIS)

    Novel 2 × 2 mm2 MEMS capacitive plates with two cavities (two capacitors) have been designed, modeled and fabricated for power harvesting by utilizing residual mechanical vibration in the environment using the electrostatic mechanism. The device is unique in the use of an innovative two-cavity design and electroplated nickel as the main structural material. When the capacitance increases for one capacitor, it will decrease for the other. This allows us to use both up and down directions to generate energy. The two-cavity design has achieved higher average power than conventional single-cavity devices under a wide range of vibration frequencies and amplitudes based on the time-domain simulations using Matlab. The movable plate was designed to vibrate without deformation and with resonance frequencies of around 900 Hz and lower using COMSOL finite element tool. The prototype two-cavity MEMS variable capacitor has been successfully fabricated using surface micromachining. The initial testing to investigate the electrical dynamic behavior and power generation from the fabricated devices was also implemented. (paper)

  17. PEO nanocomposite polymer electrolyte for solid state symmetric capacitors

    Indian Academy of Sciences (India)

    Nirbhay K Singh; Mohan L Verma; Manickam Minakshi

    2015-10-01

    Physical and electrochemical properties of polyethylene oxide (PEO)-based nanocomposite solid polymer electrolytes (NPEs) were investigated for symmetric capacitor applications. Nanosize fillers, i.e., Al2O3 and SiO2 incorporated polymer electrolyte exhibited higher ionic conductivity than those with filler-free composites. The composites have been synthesized by the completely dry (solution-free) hot-press method. The addition of filler in fractional amount to the solid polymer matrix at room temperature further enhances the ionic conductivity. Nature of the NPEs were studied using X-ray diffraction and energy-dispersive spectra analyses. Thermal stability of the resulting electrolyte was analysed by thermogravimetric analysis and differential scanning calorimetric studies. Morphology changes occurred during the addition of fillers was evidenced by scanning electronic microscope images. Solid polymer electrolytes exhibiting these parameters was found to be suitable for solid state capacitors. The results obtained from the electrolytes with an optimum compositions (PEO70AgI30)93 (Al2O3)7 and (PEO70AgI30)95 (SiO2)5 used in the (PEO70AgI30)70 (AC)30 electrodes for symmetric capacitor applications and their performances were analysed by impedance spectroscopic, Bode plot, cyclic voltammetry, discharge characteristics and leakage current profile.

  18. Research of on-line detection system for power capacitor

    Science.gov (United States)

    Yao, Junda; Qian, Zheng; Yu, Hao; Xia, Jiuyun

    2016-01-01

    The hidden danger exists in the power capacitor of power system due to long-time operation under the environment of high voltage. Thus, it is possible to induce serious fault, and the on-line detection system is urgently required. In this paper, two methods of the on-line detection system are compared in order to realize the better real-time condition detection. The first method is based on the STM microprocessor with an internal 12 bit A/D converter, which converts analog signals which is arrived from the sample circuit into digital signals, and then the FFT algorithm is used to accomplish the measurement of the voltage and current values of the capacitor. The second method is based on the special electric energy metering IC, which can obtain RMS (Root Mean Square) of voltage and current by processing the sampled data of the voltage and current, and store RMS of voltage and current in its certain registers. The operating condition of the capacitor can be obtained after getting the values of voltage and current. By comparing the measuring results of two methods, the second method could achieve a higher measurement accuracy and more simple construction.

  19. Random Vibration Testing of Advanced Wet Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander

    2015-01-01

    Advanced wet tantalum capacitors allow for improved performance of power supply systems along with substantial reduction of size and weight of the systems that is especially beneficial for space electronics. Due to launch-related stresses, acceptance testing of all space systems includes random vibration test (RVT). However, many types of advanced wet tantalum capacitors cannot pass consistently RVT at conditions specified in MIL-PRF-39006, which impedes their use in space projects. This requires a closer look at the existing requirements, modes and mechanisms of failures, specifics of test conditions, and acceptance criteria. In this work, different lots of advanced wet tantalum capacitors from four manufacturers have been tested at step stress random vibration conditions while their currents were monitored before, during, and after the testing. It has been shown that the robustness of the parts and their reliability are mostly due to effective self-healing processes and limited current spiking or minor scintillations caused by RVT do not increase the risk of failures during operation. A simple model for scintillations events has been used to simulate current spiking during RVT and optimize test conditions. The significance of scintillations and possible effects of gas generation have been discussed and test acceptance criteria for limited current spiking have been suggested.

  20. 50V All-PMOS Charge Pumps Using Low-Voltage Capacitors

    KAUST Repository

    Emira, Ahmed

    2012-10-06

    In this work, two high-voltage charge pumps are introduced. In order to minimize the area of the pumping capacitors, which dominates the overall area of the charge pump, high density capacitors have been utilized. Nonetheless, these high density capacitors suffer from low breakdown voltage which is not compatible with the targeted high voltage application. To circumvent the breakdown limitation, a special clocking scheme is used to limit the maximum voltage across any pumping capacitor. The two charge pump circuits were fabricated in a 0:6m CMOS technology with poly0-poly1 capacitors. The output voltage of the two charge pumps reached 42:8V and 51V while the voltage across any capacitor did not exceed the value of the input voltage. Compared to other designs reported in the literature, the proposed charge pump provides the highest output voltage which makes it more suitable for tuning MEMS devices.

  1. A Humidity-Dependent Lifetime Derating Factor for DC Film Capacitors

    DEFF Research Database (Denmark)

    Wang, Huai; Reigosa, Paula Diaz; Blaabjerg, Frede

    2015-01-01

    Film capacitors are widely assumed to have superior reliability performance than Aluminum electrolytic capacitors in DC-link design of power electronic converters. However, the assumption needs to be critically judged especially for applications under high humidity environments. This paper proposes...... a humidity-dependent lifetime derating factor for a type of plastic-boxed metallized DC film capacitors. It overcomes the limitation that the humidity impact is not considered in the state-of-the-art DC film capacitor lifetime models. The lifetime derating factor is obtained based on a total of 8......,700 hours accelerated testing of film capacitors under different humidity conditions, enabling a more justified lifetime prediction of film capacitors for DC-link applications under specific climatic environments. The analysis of the testing results and the detailed discussion on the derating factor with...

  2. Subsynchronous resonance performance tests of the Slatt thyristor-controlled series capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Piwko, R.J.; Wegner, C.A. [GE Power Systems Engineering, Schenectady, NY (United States); Kinney, S.J. [Bonneville Power Administration, Portland, OR (United States); Eden, J.D. [Portland General Electric, OR (United States)

    1996-04-01

    A thyristor-controlled series capacitor (TCSC) has been designed, installed, and field tested on the BPA 500 kV transmission system. The Slatt TCSC is a variable series capacitor with high control bandwidth. Field test results demonstrate that this TCSC does not participate in or contribute to subsynchronous resonance (SSR). It is SSR neutral in itself, and it can reduce SSR effects due to other nearby conventional series capacitors.

  3. Neural network for optimal capacitor placement and its impact on power quality in electric distribution systems

    International Nuclear Information System (INIS)

    Capacitors are widely installed in distribution systems for reactive power compensation to achieve power and energy loss reduction, voltage regulation and system capacity release. The extent of these benefits depends greatly on how the capacitors are placed on the system. The problem of how to place capacitors on the system such that these benefits are achieved and maximized against the cost associated with the capacitor placement is termed the general capacitor placement problem. The capacitor placement problem has been formulated as the maximization of the savings resulted from reduction in both peak power and energy losses considering capacitor installation cost and maintaining the buses voltage within acceptable limits. After an appropriate analysis, the optimization problem was formulated in a quadratic form. For solving capacitor placement a new combinatorial heuristic and quadratic programming technique has been presented and applied in the MATLAB software. The proposed strategy was applied on two different radial distribution feeders. The results have been compared with previous works. The comparison showed the validity and the effectiveness of this strategy. Secondly, two artificial intelligence techniques for predicting the capacitor switching state in radial distribution feeders have been investigated; one is based on basis Radial Basis Neural Network (RBNN) and the other is based on Adaptive Neuro-Fuzzy Inference System (ANFIS). The ANFIS technique gives better results with a minimum total error compared to RBNN. The learning duration of ANFIS was very short than the neural network case. It implied that ANFIS reaches to the target faster than neural network. Thirdly, an artificial intelligence (RBNN) approach for estimation of transient overvoltage during capacitor switching has been studied. The artificial intelligence approach estimated the transient overvoltages with a minimum error in a short computational time. Finally, a capacitor switching

  4. Digital Realization of Capacitor-Voltage Feedback Active Damping for LCL-Filtered Grid Converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang;

    2015-01-01

    The capacitor voltage of an LCL-filter can also be used for active damping, if it is fed back for synchronization. By this way, an extra current sensor can be avoided. Compared with the existing active damping techniques designed with capacitor current feedback, the capacitor voltage feedback...... overcome their drawbacks, a new derivative method is then proposed, based on the non-ideal generalized integrator. The performance of the proposed derivative has been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately, as...

  5. Enhanced DC-Link Capacitor Voltage Balancing Control of DC–AC Multilevel Multileg Converters

    DEFF Research Database (Denmark)

    Busquets-Monge, Sergio; Maheshwari, Ram Krishan; Nicolas-Apruzzese, Joan;

    2015-01-01

    This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc-link vol......This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc...

  6. THE QUALITY CONTROL OF ELECTROLYTIC TANTALUM CAPACITORS BY USING THE STRESS TEST

    OpenAIRE

    P. L. Kuznetsov; V. V. Muraviev

    2015-01-01

    The article discusses the accelerated method of analysis the electrolytic tantalum capacitors quality on the basis of the change equivalent series resistance forecast while conducting the STRESS TEST.

  7. Integration and Electrical Properties of Novel Ferroelectric Capacitors for 0.25 μm 1 Transistor 1 Capacitor Ferroelectric Random Access Memory (1T1C FRAM)

    Science.gov (United States)

    Song, Y. J.; Jang, N. W.; Jung, D. J.; Kim, H. H.; Joo, H. J.; Lee, S. Y.; Lee, K. M.; Joo, S. H.; Park, S. O.; Kim, Kinam

    2002-04-01

    Since the space margin between capacitors has been greatly reduced in 32 Mb high-density ferroelectric random access memory (FRAM) with a 0.25 μm design rule, considering the limitation of current etching technology, the stack height of ferroelectric capacitors should be minimized for stable node separation. In this paper, novel capacitors with a total thickness of 4000 Å were prepared using a seeding layer, low temperature processing, and optimal top electrode annealing. The 1000 Å Pb(Zr1-xTix)O3 (PZT) films showed excellent structural and ferroelectric properties such as strong (111) orientation and large remanent polarization of 40 μC/cm2. The low stack capacitors were then implemented into 0.6 μm and prototype 0.25 μm FRAM. Compared to a conventional capacitor stack, the ferroelectric capacitors exhibited adequate sensing margin of 250 fC, thus giving rise to a fully working die of 4 Mb FRAM. Therefore, it was clearly demonstrated that the novel capacitors can enable the realization of a high-density 32 Mb FRAM device with a 0.25 μm design rule.

  8. Vibration and Audible Noise of Filter Capacitors in HVDC Converter Stations%Vibration and Audible Noise of Filter Capacitors in HVDC Converter Stations

    Institute of Scientific and Technical Information of China (English)

    ZHU Ling-yu; JI Sheng-chang

    2011-01-01

    The filter capacitor stack is one of the main acoustic noise sources in high-voltage DC (HVDC) converter stations. As HVDC systems are built more and more recently, it is significant to research the audible noise of filter capacitors. In this paper, the current situation of research on vibration and audible noise of filter capacitors in HVDC converter stations, which is departed into three parts--generation mechanism, prediction methods, and reduction measures, is presented and the research achievements are discussed. Scholars have built the model that the alternating electric force caused by the voltage conduces to the vibration, which propagates to the enclosure and radiates audible noise. As a result, the parts contributing most to the generation of audible noise are the top and the bottom of capacitors. In the noise level prediction respect, several methods have been prospected including impact hammer, sweep frequency, impact current, monopole and Kirchhoff formula method, which are suitable for single capacitors or capacitors stacks individually. However, the sweep frequency method is restricted by experiment condition, and the impact current method needs further research and verified. On the other hand, CIGRE WG14.26 provides three sound reduction measures, but all of them are not so practicable, while MPP absorber and compressible space absorber prospected by Dr. Wu Peng are proved to be effective. The sound barriers are also considered by scholars, and the acoustic directivity performance of capacitors is also researched. Besides, the developing direction of each research field is prospected in corresponding part.

  9. Anti-Ferroelectric Ceramics for High Energy Density Capacitors

    Directory of Open Access Journals (Sweden)

    Aditya Chauhan

    2015-11-01

    Full Text Available With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

  10. Using Averaged Modeling for Capacitors Voltages Observer in NPC Inverter

    Directory of Open Access Journals (Sweden)

    Bassem Omri

    2012-01-01

    Full Text Available This paper developed an adaptive observer to estimate capacitors voltages of a three-level neutral-point-clamped (NPC inverter. A robust estimated method using one parameter is proposed, which eliminates the voltages sensors. An averaged modeling of the inverter was used to develop the observer. This kind of modeling allows a good trade-off between simulation cost and precision. Circuit model of the inverter (implemented in Simpower Matlab simulator associated to the observer algorithm was used to validate the proposed algorithm.

  11. Novel Megalo-capacitance Capacitor Using Graphitic Carbons

    Institute of Scientific and Technical Information of China (English)

    Yoshio; Masaki; Nakamura; Hiroyoshi

    2007-01-01

    1 Results During the past years,EDLC (electric double layer capacitors) using activated carbon (AC) as polarizable electrodes have receive great attention in the electric energy storage community because of the advantages of high power density,long cycle life and benignity towards environment,etc..However,one disadvantage must be solved before its further applications.That is the low energy density.Many attempts have been tried to increasing the surface area between 1 000-2 000 m2/g using alkaline or wa...

  12. Capacitors on the basis of intercalate GaSe

    Directory of Open Access Journals (Sweden)

    Kovalyuk Z. D.

    2010-06-01

    Full Text Available The compound GaSe is obtained by the technique of intercalation of a GaSe single crystal in a melt of the ferroelectric salt KNO3. The x-ray analysis of its crystal structure has been carried out and dielectric frequency characteristics of samples has been measured. It is estab-lished, that accumulation of electric charges occurs in the examined examples in frequency area 100—1000 Hz. A sample of filter capacitor has been created on the basis of the re-ceived compounds.

  13. Graphene-Based Flexible and Transparent Tunable Capacitors

    OpenAIRE

    Man, Baoyuan; Xu, Shicai; Jiang, Shouzheng; Liu, Aihua; Gao, Shoubao; Zhang, Chao; Qiu, Hengwei; Li, Zhen

    2015-01-01

    We report a kind of electric field tunable transparent and flexible capacitor with the structure of graphene-Bi1.5MgNb1.5O7 (BMN)-graphene. The graphene films with low sheet resistance were grown by chemical vapor deposition. The BMN thin films were fabricated on graphene by using laser molecular beam epitaxy technology. Compared to BMN films grown on Au, the samples on graphene substrates show better quality in terms of crystallinity, surface morphology, leakage current, and loss tangent. By...

  14. Capacitor discharge welding: Analysis through ultrahigh-speed photography

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, R.D. Jr.; Woodyard, J.R. (Bureau of Mines, Albany, NY (United States)); Devletian, J.H. (Oregon Graduate Inst. of Science and Technology, Beaverton (United States))

    1993-03-01

    Ultrahigh-speed photography of 44,000 frames/s was used to investigate the capacitor discharge welding (CDW) process. The objective of the study was to use high-speed photography and a finite element computer program to help describe the heat flow characteristics of the CDW cycle. The photos revealed that the plasma jet from the cathode was responsible for expelling metal from the anode rather than being squeezed out on contact. Photographic evidence suggested that the unequal anode/cathode heating ratio is primarily due to heat transfer from the anode to the expelled metal particles.

  15. High energy density capacitors for low cost applications

    Science.gov (United States)

    Iyore, Omokhodion David

    Polyvinylidene fluoride (PVDF) and its copolymers with trifluoroethylene, hexafluoropropylene and chlorotrifluoroethylene are the most widely investigated ferroelectric polymers, due to their relatively high electromechanical properties and potential to achieve high energy density. [Bauer, 2010; Zhou et al., 2009] The research community has focused primarily on melt pressed or extruded films of PVDF-based polymers to obtain the highest performance with energy density up to 25 Jcm-3. [Zhou et al., 2009] Solution processing offers an inexpensive, low temperature alternative, which is also easily integrated with flexible electronics. This dissertation focuses on the fabrication of solution-based polyvinylidene fluoride-hexafluoropropylene metal-insulator-metal capacitors on flexible substrates using a photolithographic process. Capacitors were optimized for maximum energy density, high dielectric strength and low leakage current density. It is demonstrated that with the right choice of solvent, electrodes, spin-casting and annealing conditions, high energy density thin film capacitors can be fabricated repeatably and reproducibly. The high electric field dielectric constants were measured and the reliabilities of the polymer capacitors were also evaluated via time-zero breakdown and time-dependent breakdown techniques. Chapter 1 develops the motivation for this work and provides a theoretical overview of dielectric materials, polarization, leakage current and dielectric breakdown. Chapter 2 is a literature review of polymer-based high energy density dielectrics and covers ferroelectric polymers, highlighting PVDF and some of its derivatives. Chapter 3 summarizes some preliminary experimental work and presents materials and electrical characterization that support the rationale for materials selection and process development. Chapter 4 discusses the fabrication of solution-processed PVDF-HFP and modification of its properties by photo-crosslinking. It is followed by a

  16. High Speed Capacitor-Inverter Based Carbon Nanotube Full Adder

    Directory of Open Access Journals (Sweden)

    Rashtian M

    2010-01-01

    Full Text Available Abstract Carbon Nanotube filed-effect transistor (CNFET is one of the promising alternatives to the MOS transistors. The geometry-dependent threshold voltage is one of the CNFET characteristics, which is used in the proposed Full Adder cell. In this paper, we present a high speed Full Adder cell using CNFETs based on majority-not (Minority function. Presented design uses eight transistors and eight capacitors. Simulation results show significant improvement in terms of delay and power-delay product in comparison to contemporary CNFET Adder Cells. Simulations were carried out using HSPICE based on CNFET model with 0.6 V VDD.

  17. Switched capacitor arrays analog memory for sparse data sampling

    International Nuclear Information System (INIS)

    We present the design and the test performed on ADeLinel, a Full-Custom Analog Memory for sparse data sampling. It has been designed as an array of switched capacitors. It is only one channel of 8 cells. The control part of the ADeLine chip is custom designed for the size reduction, high speed performance and low power dissipation. The memory has been integrated in double poly, double metal AMS 0.8 μm CMOS. It has 3.5 V input and output swings, a linearity within ± 6 mV in a 2 V range and 11 bits of resolution. (author)

  18. Zeolite-coated interdigital capacitors for humidity sensing

    OpenAIRE

    Urbiztondo, M.; Pellejero, I.; Rodríguez Martínez, Ángel; Pina Iritia, María Pilar; Santamaría Ramiro, Jesús Marcos

    2011-01-01

    Inter-digital capacitors (IDCs) with electrode gaps of 10 or 50 microns have been coated with zeolite films consisting of different zeolites with Si/Al ratios ranging from 1.5 (zeolite A) to infinite (silicalite). The performance of the sensor in the measurement of humidity has been related to the electrical properties of the zeolites (relative permittivity, ɛr), which in turn is a function of their Si/Al ratio. With zeolites of a high Al content the limit of detection was under 0.5 ppmV.

  19. Tantalum-niobium-alloys as electrolyte capacitor materials

    Energy Technology Data Exchange (ETDEWEB)

    Chamdawalla, N.; Ettmayer, P.; Leuprecht, R.; Aschenbrenner, W.; Bildstein, H.

    1986-07-01

    The properties of Na-Nb-alloys with respect to their use in electrolytic foil condensers were examined by measuring the etching factor, the formability of Ta-Nb foils and the residual current of Ta-Nb alloy wires used for contact leads. Alloys with Nb contents up to 25 wt.-% can be used instead of unalloyed Ta without loss of quality. If the etching and forming procedures were optimized for different compositions, the use of alloys with up to 50 wt.-% Nb for capacitors might be feasible.

  20. Switched-capacitor multiply-by-two amplifier with reduced capacitor mismatches sensitivity and full swing sample signal common-mode voltage

    International Nuclear Information System (INIS)

    A switched-capacitor amplifier with an accurate gain of two that is insensitive to component mismatch is proposed. This structure is based on associating two sets of two capacitors in cross series during the amplification phase. This circuit permits the common-mode voltage of the sample signal to reach full swing. Using the charge-complement technique, the proposed amplifier can reduce the impact of parasitic capacitors on the gain accuracy effectively. Simulation results show that as sample signal common-mode voltage changes, the difference between the minimum and maximum gain error is less than 0.03%. When the capacitor mismatch is increased from 0 to 0.2%, the gain error is deteriorated by 0.00015%. In all simulations, the gain of amplifier is 69 dB. (semiconductor integrated circuits)

  1. Hybrid Evolutionary-Heuristic Algorithm for Capacitor Banks Allocation

    Science.gov (United States)

    Barukčić, Marinko; Nikolovski, Srete; Jović, Franjo

    2010-11-01

    The issue of optimal allocation of capacitor banks concerning power losses minimization in distribution networks are considered in this paper. This optimization problem has been recently tackled by application of contemporary soft computing methods such as: genetic algorithms, neural networks, fuzzy logic, simulated annealing, ant colony methods, and hybrid methods. An evolutionaryheuristic method has been proposed for optimal capacitor allocation in radial distribution networks. An evolutionary method based on genetic algorithm is developed. The proposed method has a reduced number of parameters compared to the usual genetic algorithm. A heuristic stage is used for improving the optimal solution given by the evolutionary stage. A new cost-voltage node index is used in the heuristic stage in order to improve the quality of solution. The efficiency of the proposed two-stage method has been tested on different test networks. The quality of solution has been verified by comparison tests with other methods on the same test networks. The proposed method has given significantly better solutions for time dependent load in the 69-bus network than found in references.

  2. Degradation of Leakage Currents and Reliability Prediction for Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander

    2016-01-01

    Two types of failures in solid tantalum capacitors, catastrophic and parametric, and their mechanisms are described. Analysis of voltage and temperature reliability acceleration factors reported in literature shows a wide spread of results and requires more investigation. In this work, leakage currents in two types of chip tantalum capacitors were monitored during highly accelerated life testing (HALT) at different temperatures and voltages. Distributions of degradation rates were approximated using a general log-linear Weibull model and yielded voltage acceleration constants B = 9.8 +/- 0.5 and 5.5. The activation energies were Ea = 1.65 eV and 1.42 eV. The model allows for conservative estimations of times to failure and was validated by long-term life test data. Parametric degradation and failures are reversible and can be annealed at high temperatures. The process is attributed to migration of charged oxygen vacancies that reduce the barrier height at the MnO2/Ta2O5 interface and increase injection of electrons from the MnO2 cathode. Analysis showed that the activation energy of the vacancies' migration is 1.1 eV.

  3. Soft capacitor fibers using conductive polymers for electronic textiles

    CERN Document Server

    Gu, Jian Feng; Skorobogatiy, Maksim

    2010-01-01

    A novel, highly flexible, conductive polymer-based fiber with high electric capacitance is reported. In its crossection the fiber features a periodic sequence of hundreds of conductive and isolating plastic layers positioned around metallic electrodes. The fiber is fabricated using fiber drawing method, where a multi-material macroscopic preform is drawn into a sub-millimeter capacitor fiber in a single fabrication step. Several kilometres of fibers can be obtained from a single preform with fiber diameters ranging between 500um -1000um. A typical measured capacitance of our fibers is 60-100 nF/m and it is independent of the fiber diameter. For comparison, a coaxial cable of the comparable dimensions would have only ~0.06nF/m capacitance. Analysis of the fiber frequency response shows that in its simplest interrogation mode the capacitor fiber has a transverse resistance of 5 kOhm/L, which is inversely proportional to the fiber length L and is independent of the fiber diameter. Softness of the fiber materials...

  4. New zero voltage switching DC converter with flying capacitors

    Science.gov (United States)

    Lin, Bor-Ren; Shiau, Tung-Yuan

    2016-04-01

    A new soft switching converter is presented for medium power applications. Two full-bridge converters are connected in series at high voltage side in order to limit the voltage stress of power switches at Vin/2. Therefore, power metal-oxide-semiconductor field-effect transistors (MOSFETs) with 600 V voltage rating can be adopted for 1200 V input voltage applications. In order to balance two input split capacitor voltages in every switching cycle, two flying capacitors are connected on the AC side of two full-bridge converters. Phase-shift pulse-width modulation (PS-PWM) is adopted to regulate the output voltage. Based on the resonant behaviour by the output capacitance of MOSFETs and the resonant inductance, active MOSFETs can be turned on under zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. Two full-bridge converters are used in the proposed circuit to share load current and reduce the current stress of passive and active components. The circuit analysis and design example of the prototype circuit are provided in detail and the performance of the proposed converter is verified by the experiments.

  5. Reliability of Capacitors for DC-Link Applications in Power Electronic Converters

    DEFF Research Database (Denmark)

    Wang, Huai; Blaabjerg, Frede

    2014-01-01

    DC-link capacitors are an important part in the majority of power electronic converters which contribute to cost, size and failure rate on a considerable scale. From capacitor users' viewpoint, this paper presents a review on the improvement of reliability of dc link in power electronic converters...

  6. Simulation and analysis of transient over voltages due to capacitor banks switching

    International Nuclear Information System (INIS)

    The switching of any capacitor bank produces over voltages. Transient overvoltage will always occur in the switching device, the switching of shunt capacitor bank has become the most common source of transient voltage on power systems. Transient over voltages due to switching the capacitor bands hurt not only to the capacitor banks, but also to other equipment, such as circuit breakers and transformers. Several methods are available for reducing energising transients. These devices include pre-insertion resistors, pre-insertion inductors,synchronous closing, and MOV arresters. However, not all are practical or economical. The other important problem is existence of capacitor banks in presence of harmonics.Capacitors do not produce harmonics;however,the addition of capacitors to the electrical system will change the frequency response characteristics of the system will change the frequency response characteristics of the system, and in some cases can result in magnification of the voltage and current distortion in the system. In other word in presence of harmonic-producing loads,the capacitors used for power factor correction,may cause parallel resonance with the system inductance, so they increase the total harmonic distortion of voltage and current waveforms

  7. Microcomputer Based System to control the Load of a Capacitor Array in the TJ-1 Tokamak

    International Nuclear Information System (INIS)

    The power to create the magnetic fields in the TJ-1 Tokamak is provides by an array of 16 capacitor sets. The total capacity of this array is 8. 1F. This work describes a computer system based on the Motorola M-6800 micro- processor which controls the load of the capacitor set and stablished the conditions for the reactor trigger. (Author)

  8. The application of structural nonlinearity in the development of linearly tunable MEMS capacitors

    International Nuclear Information System (INIS)

    Electrostatically actuated parallel-plate tunable capacitors are the most desired MEMS capacitors because of their smaller sizes and higher Q-factors. However, these capacitors suffer from low tunability and exhibit high sensitivity near the pull-in voltage which counters the concept of tunability. In this paper, a novel design for parallel-plate tunable capacitors with high tunability and linear capacitance–voltage (C–V) response is developed. The design uses nonlinear structural rigidities to relieve intrinsic electrostatic nonlinearity in MEMS capacitors. Based on the force–displacement characteristic of an ideally linear capacitor, a real beam-like nonlinear spring model is developed. The variable stiffness coefficients of such springs improve the linearity of the C–V curve. Moreover, because the structural stiffness increases with deformations, the pull-in is delayed and higher tunability is achieved. Finite element simulations reveal that capacitors with air gaps larger than 4 µm and supporting beams thinner than 1 µm can generate highly linear C–V responses and tunabilities over 120%. Experimental results for capacitors fabricated by PolyMUMPs verify the effect of weak nonlinear geometric stiffness on improving the tunability for designs with a small air gap and relatively thick structural layers

  9. Microcomputer based system to control the load of a capacitor array in the TJ-1 Tokamak

    International Nuclear Information System (INIS)

    The power to create the magnetic field in the TJ-1 TOKAMAK is provide by an array of 16 capacitor sets. The total capacity of this array is 8.1F. This work describes a computer system based on the Motorola M-6800 microprocessor which controls the load of the capacitor set-and establishes the conditions for the reactor trigger. (author)

  10. On battery-less autonomous polygeneration microgrids: Investigation of the combined hybrid capacitors/hydrogen alternative

    International Nuclear Information System (INIS)

    Highlights: • A battery-less autonomous polygeneration microgrid is technically feasible. • Laboratory testing of hybrid capacitors. • Investigation of hybrid capacitors utilization along with hydrogen subsystem. - Abstract: The autonomous polygeneration microgrid topology aims to cover holistically the needs in remote areas as far as electrical power, potable water through desalination, fuel for transportation in the form of hydrogen, heating and cooling are concerned. Deep discharge lead acid batteries are mostly used in such systems, associated with specific disadvantages, both technical and environmental. This paper investigated the possibility of replacing the battery bank from a polygeneration microgrid with a hybrid capacitor bank and more intensive utilization of a hydrogen subsystem. Initially commercial hybrid capacitors were tested under laboratory conditions and based on the respective results a case study was performed. The optimized combination of hybrid capacitors and higher hydrogen usage was then investigated through simulations and compared to a polygeneration microgrid featuring deep discharge lead acid batteries. From the results it was clear that it is technically possible to exchange the battery bank with a hybrid capacitor bank and higher hydrogen utilization. From the economic point of view, the current cost of the hybrid capacitors and the hydrogen components is high which leads to higher overall cost in comparison with deep discharge lead acid batteries. Taking into account, though, the decreasing cost prospects and trends of both the hybrid capacitors and the hydrogen components it is expected that this approach will become economically competitive in a few years

  11. Design and modeling of inductors, capacitors and coplanar waveguides at tens of GHz frequencies

    CERN Document Server

    Aryan, Naser Pour

    2015-01-01

    This book describes the basic principles of designing and modelling inductors, MIM capacitors and coplanar waveguides at frequencies of several tens of GHz. The author explains the design and modelling of key, passive elements, such as capacitors, inductors and transmission lines that enable high frequency MEMS operating at frequencies in the orders of tens of GHz.

  12. A Different Approach to Studying the Charge and Discharge of a Capacitor without an Oscilloscope

    Science.gov (United States)

    Ladino, L. A.

    2013-01-01

    A different method to study the charging and discharging processes of a capacitor is presented. The method only requires a high impedance voltmeter. The charging and discharging processes of a capacitor are usually studied experimentally using an oscilloscope and, therefore, both processes are studied as a function of time. The approach presented…

  13. Current status of environmental, health, and safety issues of electrochemical capacitors for advanced vehicle applications

    Energy Technology Data Exchange (ETDEWEB)

    Vimmerstedt, L J; Hammel, C J

    1997-04-01

    Electrochemical capacitors are a candidate for traction power assists in hybrid electric vehicles (HEVs). Other advanced automotive applications, while not the primary focus of current development efforts, are also possible. These include load leveling high-energy batteries, power conditioning electronics, electrically hated catalysts, electric power steering, and engine starter power. Higher power and longer cycle life are expected for electrochemical capacitors than for batteries. Evaluation of environmental, health, and safety (EH and S) issues of electrochemical capacitors is an essential part of the development and commercialization of electrochemical capacitors for advanced vehicles. This report provides an initial EH and S assessment. This report presents electrochemical capacitor electrochemistry, materials selection, intrinsic material hazards, mitigation of those hazards, environmental requirements, pollution control options, and shipping requirements. Most of the information available for this assessment pertains to commercial devices intended for application outside the advanced vehicle market and to experiment or prototype devices. Electrochemical capacitors for power assists in HEVs are not produced commercially now. Therefore, materials for advanced vehicle electrochemical capacitors may change, and so would the corresponding EH and S issues. Although changes are possible, this report describes issues for likely electrochemical capacitor designs.

  14. A Review of the Condition Monitoring of Capacitors in Power Electronic Converters

    DEFF Research Database (Denmark)

    Soliman, Hammam Abdelaal Hammam; Wang, Huai; Blaabjerg, Frede

    Capacitor is one of the reliability critical components in power electronic systems. In the last two decades, many efforts in the academic research have been devoted to the condition monitoring of capacitors to estimate their health status. Industry applications demand more reliable power electro...

  15. Two-layer radio frequency MEMS fractal capacitors in PolyMUMPS for S-band applications

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-23

    In this Letter, the authors fabricate for the first time MEMS fractal capacitors possessing two layers and compare their performance characteristics with the conventional parallel-plate capacitor and previously reported state-of-the-art single-layer MEMS fractal capacitors. Explicitly, a capacitor with a woven structure and another with an interleaved configuration were fabricated in the standard PolyMUMPS surface micromachining process and tested at S-band frequencies. The self-resonant frequencies of the fabricated capacitors were close to 10GHz, which is better than that of the parallel-plate capacitor, which measured only 5.5GHz. Further, the presented capacitors provided a higher capacitance when compared with the state-of-the-art-reported MEMS fractal capacitors created using a single layer at the expense of a lower quality factor. © 2012 The Institution of Engineering and Technology.

  16. Optimum capacitor allocation in unbalanced distribution systems by using genetic algorithms; Alocacao otima de capacitores em sistemas de distribuicao desequilibrados usando algoritmos geneticos

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Paulo Augusto N.; Carneiro Junior, Sandoval [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. E-mail: pgarcia@fusoes.com.br; sandoval@dee.ufrj.br; Pereira, Jose Luiz R. [Juiz de Fora Univ., MG (Brazil). Faculdade de Engenharia. E-mail: jluiz@lacee.ufjf.br

    1999-07-01

    This paper presents a methodology for capacitor optimum determination in unbalanced distribution systems. The methodology aims to minimize losses of energy and power during the peak hours considering the capacitor costs. Restrictions were adopted for voltage limits representation and unbalancing between phases. A three phase modelling is presented, allowing the precise representation of the elements constituting the distribution systems. Tests are presented of a three phase system consisted of single, two and three phases, resulting in significant efficiency of the study methodology.

  17. Degradation failure model of self-healing metallized film pulse capacitor

    International Nuclear Information System (INIS)

    The high energy density self-healing metallized film pulse capacitor has been applied to all kinds of laser facilities for their power conditioning systems, whose reliability and expense are straightforwardly affected by the reliability level of the capacitors. Based on the related research in literature, this paper analyses the degradation mechanism of the capacitor, and presents a new degradation failure model--the Gauss-Poisson model. The Gauss-Poisson model divides degradation of capacitor into naturalness degradation and outburst one. Compared with traditional Weibull failure model, the new model is more precise in evaluating the lifetime of the capacitor, and the life tests for this model are simple in design, and lower in the cost of time or expense. The Gauss-Poisson model will be a fine and widely used degradation disable model. (author)

  18. Improvement of the mechanical and thermal properties of the metallized polycarbonate capacitor

    Science.gov (United States)

    Kellerman, H. J.

    1977-01-01

    Changes were studied which enable polycarbonate metallized film capacitors to withstand 500 thermal shock cycles while maintaining electrical characteristic integrity without becoming intermittent, and without losing hermeticity. The task was for metallized polycarbonate film capacitors designed to meet MIL-C-39022/9 and MIL-C-83421/1. The capacitor design improvements implemented were the insertion of a rubber washer between spray cap and end seal and the utilization of a flexible lead assembly. One hundred fifty capacitors incorporating the design improvements were manufactured and subsequently underwent 500 thermal shock cycles. One hundred forty nine capacitors survived the test. Failure analysis revealed that the lone failure was due to a poor solder joint, initially detected in pre-screening tests as having poor dissipation factor and equivalent series resistance measurement readings.

  19. Influence of Electrolyte on ESR of Medium Voltage Wet Tantalum Capacitors

    Institute of Scientific and Technical Information of China (English)

    刘仲娥; 宋金荣; 陈晓静; 李忆莲; 桂娟

    2004-01-01

    In this paper, the influence of working electrolyte on high-frequency electrical performance of wet tantalum capacitors is studied. Emphasis is especially put on the study of the contribution of depolariser in reducing Equivalent Series Resistance(ESR). According to the theory of depolarization in electrochemistry and the theory of cathode capacitance of electrolytic capacitor, different kinds of depolarisers are added separately into the foregone electrolyte. Then capacitors are assembled with tantalum cores dipped with the compounded electrolytes. The best depolariser and its concentration in the whole electrolyte could be selected according to the test results of the capacitance and ESR of the capacitors. The results of our experiment show that depolariser Fe2(SO4)3 used in working electrolyte of 100 V/100 μF wet tantalum capacitors can help to obtain lower ESR and higher capacitance at frequency from 0.1 kHz to 100 kHz.

  20. Optimal Capacitor Placement in Radial Distribution Feeders Using Fuzzy-Differential Evolution for Dynamic Load Condition

    Science.gov (United States)

    Kannan, S. M.; Renuga, P.; Kalyani, S.; Muthukumaran, E.

    2015-12-01

    This paper proposes new methods to select the optimal values of fixed and switched shunt capacitors in Radial distribution feeders for varying load conditions so as to maximize the annual savings and minimizes the energy loss by taking the capacitor cost into account. The identification of the weak buses, where the capacitors should be placed is decided by a set of rules given by the fuzzy expert system. Then the sizing of the fixed and switched capacitors is modeled using differential evolution (DE) and particle swarm optimization (PSO). A case study with an existing 15 bus rural distribution feeder is presented to illustrate the applicability of the algorithm. Simulation results show the better saving in cost over previous capacitor placement algorithm.

  1. High energy density capacitors for power electronic applications using nano-structure multilayer technology

    Energy Technology Data Exchange (ETDEWEB)

    Barbee, T.W. Jr.; Johnson, G.W.

    1995-09-01

    Power electronics applications are currently limited by capacitor size and performance. Only incremental improvements are anticipated in existing capacitor technologies, while significant performance advances are required in energy density and overall performance to meet the technical needs of the applications which are important for U.S. economic competitiveness. One application, the Power Electronic Building Block (PEBB), promises a second electronics revolution in power electronic design. High energy density capacitors with excellent electrical thermal and mechanical performance represent an enabling technology in the PEBB concept. We propose a continuing program to research and develop LLNL`s nano-structure multilayer technologies for making high voltage, high energy density capacitors. Our controlled deposition techniques are capable of synthesizing extraordinarily smooth sub-micron thick layers of dielectric and conductor materials. We have demonstrated that, with this technology, high voltage capacitors with an order of magnitude improvement in energy density are achievable.

  2. Determination of the operating voltage for non-linear capacitors as turn-off snubbers in power electronic switches

    OpenAIRE

    A. G. K. Lutsch; J. J. Schoeman; J. D. van Wyk

    1988-01-01

    The use of non-linear capacitors improves the efficiency of turn-off snubbers for power electronic switches. The parameters for the determination of non-linear ferro-electric capacitors are discussed and a novel measuring method for the determination of the maximum operating voltage is suggested. The procedure to select ferro-electric capacitors is also discussed.

  3. Determination of the operating voltage for non-linear capacitors as turn-off snubbers in power electronic switches

    Directory of Open Access Journals (Sweden)

    A. G. K. Lutsch

    1988-03-01

    Full Text Available The use of non-linear capacitors improves the efficiency of turn-off snubbers for power electronic switches. The parameters for the determination of non-linear ferro-electric capacitors are discussed and a novel measuring method for the determination of the maximum operating voltage is suggested. The procedure to select ferro-electric capacitors is also discussed.

  4. Polymer--Ionic liquid Electrolytes for Electrochemical Capacitors

    Science.gov (United States)

    Ketabi, Sanaz

    Polymer electrolyte, comprised of ionic conductors, polymer matrix, and additives, is one of the key components that control the performance of solid flexible electrochemical capacitors (ECs). Ionic liquids (ILs) are highly promising ionic conductors for next generation polymer electrolytes due to their excellent electrochemical and thermal stability. Fluorinated ILs are the most commonly applied in polymer-IL electrolytes. Although possessing high conductivity, these ILs have low environmental favorability. The aim of this work was to develop environmentally benign polymer-ILs for both electrochemical double layer capacitors (EDLCs) and pseudocapacitors, and to provide insights into the influence of constituent materials on the ion conduction mechanism and the structural stability of the polymer-IL electrolytes. Solid polymer electrolytes composed of poly(ethylene oxide) (PEO) and 1-ethyl-3-methylimidazolium hydrogen sulfate (EMIHSO4) were investigated for ECs. The material system was optimized to achieve the two criteria for high performance polymer-ILs: high ionic conductivity and highly amorphous structure. Thermal and structural analyses revealed that EMIHSO4 acted as an ionic conductor and a plasticizer that substantially decreased the crystallinity of PEO. Two types of inorganic nanofillers were incorporated into these polymer electrolytes. The effects of SiO2 and TiO2 nanofillers on ionic conductivity, crystallinity, and dielectric properties of PEO-EMIHSO 4 were studied over a temperature range from -10 °C and 80 °C. Using an electrochemical capacitor model, impedance (complex capacitance) and dielectric analyses were performed to understand the ionic conduction process with and without fillers in both semi crystalline and amorphous states of the polymer electrolytes. Despite their different nanostructures, both SiO2 and TiO2 promoted an amorphous structure in PEO-EMIHSO 4 and increased the ionic conductivity 2-fold. While in the amorphous state, the

  5. Principal considerations in large energy-storage capacitor banks

    International Nuclear Information System (INIS)

    Capacitor banks storing one or more megajoules and costing more than one million dollars have unique problems not often found in smaller systems. Two large banks, Scyllac at Los Alamos and Shiva at Livermore, are used as models of large, complex systems. Scyllac is a 10-MJ, 60-kV theta-pinch system while Shiva is a 20-MJ, 20-kV energy system for laser flash lamps. A number of design principles are emphasized for expediting the design and construction of large banks. The sensitive features of the charge system, the storage system layout, the switching system, the transmission system, and the design of the principal bank components are presented. Project management and planning must involve a PERT chart with certain common features for all the activities. The importance of the budget is emphasized

  6. Capacitor Discharge and Vacuum Resistance in Massless QED_2

    CERN Document Server

    Chu, Yi-Zen

    2010-01-01

    A charged parallel plate capacitor will create particle-antiparticle pairs by the Schwinger process and discharge over time. We consider the full quantum discharge process in 1+1 dimensions including backreaction, when the electric field interacts with massless charged fermions. We recover oscillatory features in the electric field observed in a semiclassical analysis and find that the amplitude of the oscillations falls off as t^{-1/2} and that stronger coupling implies slower decay. Remarkably, Ohm's law applies to the vacuum and we evaluate the quantum electrical conductivity of the vacuum to be 2e/\\pi^{1/2}, where e is the fermionic charge. Similarities and differences with black hole evaporation are mentioned.

  7. Switched Capacitor Network Analysis by Means of TCM

    Institute of Scientific and Technical Information of China (English)

    徐静波; 徐望人

    2004-01-01

    The totally coded method (TCM) reveals the same objective law, which governs the gain calculating for signal flow graph as Mason formula does. This algorithm is carried out merely in the domain of code operation. Based on pure code algorithm, it is more efficient because figure searching is no longer necessary. The code-series ( CS ), which are organized from node association table, have the holoinformation nature, so that both the content and the sign of each gain-term can be determined via the coded method.The principle of this method is obvious and it is suited for computer programming. The capability of the computeraided analysis for Switched Capacitor (SCN) can be enhanced.

  8. Aspirated capacitor measurements of air conductivity and ion mobility spectra

    CERN Document Server

    Aplin, K L

    2005-01-01

    Measurements of ions in atmospheric air are used to investigate atmospheric electricity and particulate pollution. Commonly studied ion parameters are (1) air conductivity, related to the total ion number concentration, and (2) the ion mobility spectrum, which varies with atmospheric composition. The physical principles of air ion instrumentation are long-established. A recent development is the computerised aspirated capacitor, which measures ions from (a) the current of charged particles at a sensing electrode, and (b) the rate of charge exchange with an electrode at a known initial potential, relaxing to a lower potential. As the voltage decays, only ions of higher and higher mobility are collected by the central electrode and contribute to the further decay of the voltage. This enables extension of the classical theory to calculate ion mobility spectra by inverting voltage decay time series. In indoor air, ion mobility spectra determined from both the novel voltage decay inversion, and an established volt...

  9. Fabrication and characterization of thermally drawn fiber capacitors

    Science.gov (United States)

    Lestoquoy, Guillaume; Chocat, Noémie; Wang, Zheng; Joannopoulos, John D.; Fink, Yoel

    2013-04-01

    We report on the fabrication of all-in-fiber capacitors with poly(vinylidene fluoride) (PVDF) as the dielectric material. Electrodes made of conductive polymer are separated by a PVDF thin film within a polycarbonate casing that is thermally drawn into multiple meters of light-weight, readily functional fiber. Capacitive response up to 20 kHz is measured and losses at higher-frequencies are accounted for in a materials-based model. A multilayered architecture in which a folded PVDF film separates interdigitated electrodes over an increased area is fabricated. This structure greatly enhances the capacitance, which scales linearly with the fiber length and is unaffected by fiber dimension fluctuations.

  10. A review on electrochemical double-layer capacitors

    International Nuclear Information System (INIS)

    Various energy storage technologies have been developed in the market for various applications. Batteries flywheels, fuel cells are a few which are much common, those are being used in several countries and also research is also carrying on these technologies to make much better them. The electrochemical double-layer capacitor (EDLC) is an emerging technology, which really plays a key part in fulfilling the demands of electronic devices and systems, for present and future. This paper presents the historical background, classification, construction, modeling, testing, and voltage balancing of the EDLC technology. The applications of EDLC in electrical vehicles, power quality, and others are also discussed and their advantages over other storages technologies are also discussed.

  11. Hybridization of rechargeable batteries and electrochemical capacitors: Principles and limits

    International Nuclear Information System (INIS)

    The demand for electrochemical energy sources is nowadays extremely large and it addresses very different application, from small portable devices, over electric vehicles, to large stationary applications. The requirements for the electrochemical energy sources are therefore extremely various in terms of cost, specific power and energy, cycle life, safety. In spite of the large variety of electrochemical energy storage systems available today they may not fulfil all of the requirements requested. The need of achieving both high energy density and power density has been pointed out in the last decade and, among the different possible approaches, the hybridization of two types of electrochemical energy storage devices, rechargeable battery and electrochemical double layer capacitor, has been strongly investigated. This work reviews the different approaches to the hybridization, such as internal and external, serial and parallel and provides a collection of today's achievements.

  12. Nanostructure multilayer dielectric materials for capacitors and insulators

    Science.gov (United States)

    Barbee, Jr., Troy W.; Johnson, Gary W.

    1998-04-21

    A capacitor is formed of at least two metal conductors having a multilayer dielectric and opposite dielectric-conductor interface layers in between. The multilayer dielectric includes many alternating layers of amorphous zirconium oxide (ZrO.sub.2) and alumina (Al.sub.2 O.sub.3). The dielectric-conductor interface layers are engineered for increased voltage breakdown and extended service life. The local interfacial work function is increased to reduce charge injection and thus increase breakdown voltage. Proper material choices can prevent electrochemical reactions and diffusion between the conductor and dielectric. Physical vapor deposition is used to deposit the zirconium oxide (ZrO.sub.2) and alumina (Al.sub.2 O.sub.3) in alternating layers to form a nano-laminate.

  13. X-ray irradiation of ion-implanted MOS capacitors

    International Nuclear Information System (INIS)

    He+ ion-implanted metal-oxide-semiconductor (MOS) capacitors with two different oxide thickness have been irradiated by X-rays and the depth distribution of the implant damage in the Si-SiO2 structures have been examined. The efficiency of X-ray annealing of electronic traps caused by implantation and changes in charge populations are reported. The experiment shows that (in the case when defects introduced by implantation are located at the Si-SiO2 interface) only defects corresponding to the deep levels in the Si can be affected by X-ray irradiation. When defects introduced by ion implantation are located deeper within the Si substrate complete annealing of these defects is observed

  14. Evolution of recrystallization textures in high voltage aluminum capacitor foils

    Institute of Scientific and Technical Information of China (English)

    刘楚明; 张新明; 周鸿章; 陈志永; 邓运来; 周卓平

    2001-01-01

    The evolution of recrystallization textures in high voltage aluminum capacitor foils which are produced with a high level of cold reduction was tracked by analysis of microstructure and crystallographic texture. The results show that the deformation textures are mainly composed of S-orientation, Cu-orientation and a little Bs-orientation. During the low temperature stages of final annealing, the iron precipitates first along the sub-grain boundaries, and the Fe concentration in the matrix becomes low. Then, the cube grains nucleate preferably into the sub-grains. At high temperature stages, the cube nuclei can grow preferably because of their 40°〈111〉 orientation relationship to the S orientation, the main component of the rolling texture. Finally, the cube texture is sharply strong and the R orientation is very weak in the foils.

  15. Carbon additives for electrical double layer capacitor electrodes

    Science.gov (United States)

    Weingarth, D.; Cericola, D.; Mornaghini, F. C. F.; Hucke, T.; Kötz, R.

    2014-11-01

    Electrochemical double layer capacitors (EDLCs) are inherently high power devices when compared to rechargeable batteries. While capacitance and energy storage ability are mainly increased by optimizing the electrode active material or the electrolyte, the power capability could be improved by including conductive additives in the electrode formulations. This publication deals with the use of four different carbon additives - two carbon blacks and two graphites - in standard activated carbon based EDLC electrodes. The investigations include: (i) physical characterization of carbon powder mixtures such as surface area, press density, and electrical resistivity measurements, and (ii), electrochemical characterization via impedance spectroscopy and cyclic voltammetry of full cells made with electrodes containing 5 wt.% of carbon additive and compared to cells made with pure activated carbon electrodes in organic electrolyte. Improved cell performance was observed in both impedance and cyclic voltammetry responses. The results are discussed considering the main characteristics of the different carbon additives, and important considerations about electrode structure and processability are drawn.

  16. 64-Channel, 5 GSPS ADC Module with Switched Capacitor Arrays

    International Nuclear Information System (INIS)

    We present a 5 GSPS ADC/Data processing module with up to 64 channels and 2048 cells per channel, designed for fast-sampling, front-end applications. This is a 6U VME board that incorporates 16 pieces DRS4 ( (http://drs.web.psi.ch), [1]) Switched Capacitor Array chips developed at Paul Scherrer Institut, Switzerland. The 16 DRS4 chips are grouped in four independent input blocks. A block, with a geometric size of 43×120 mm, has four pieces DRS4 chips, four pieces AD9222 converters, and one Altera Stratix III FPGA. Each DRS4 chip has eight channels and each channel has 1024 sampling cells, which can be daisy-chained for larger sampling depth. This feature allows for a great level of flexibility in choosing the number of channels relative to capacitor array size, for a particular application. The first prototype Printed Circuit Board (PCB) was designed for a sampling depth of 2048 cells and 16 channels in a 42 mm wide block, i.e. 64 channels for the 6U VME board. This compact form factor allows for these input blocks to be used as front-end electronics for the Cherenkov Telescope Array (CTA) cameras. In this VME board, the four blocks are fully independent and can run each in different modes without any conflict. A global FPGA, also a Stratix III device, provides control and interfacing. The module can run with a local oscillator or with input system clocks in the range of 20–550 MHz. The front panel is fitted with a 2.5 Gbps serial link transceiver

  17. Advanced Proton Conducting Polymer Electrolytes for Electrochemical Capacitors

    Science.gov (United States)

    Gao, Han

    Research on solid electrochemical energy storage devices aims to provide high performance, low cost, and safe operation solutions for emerging applications from flexible consumer electronics to microelectronics. Polymer electrolytes, minimizing device sealing and liquid electrolyte leakage, are key enablers for these next-generation technologies. In this thesis, a novel proton-conducing polymer electrolyte system has been developed using heteropolyacids (HPAs) and polyvinyl alcohol for electrochemical capacitors. A thorough understanding of proton conduction mechanisms of HPAs together with the interactions among HPAs, additives, and polymer framework has been developed. Structure and chemical bonding of the electrolytes have been studied extensively to identify and elucidate key attributes affecting the electrolyte properties. Numerical models describing the proton conduction mechanism have been applied to differentiate those attributes. The performance optimization of the polymer electrolytes through additives, polymer structural modifications, and synthesis of alternative HPAs has achieved several important milestones, including: (a) high proton mobility and proton density; (b) good ion accessibility at electrode/electrolyte interface; (c) wide electrochemical stability window; and (d) good environmental stability. Specifically, high proton mobility has been addressed by cross-linking the polymer framework to improve the water storage capability at normal-to-high humidity conditions (e.g. 50-80% RH) as well as by incorporating nano-fillers to enhance the water retention at normal humidity levels (e.g. 30-60% RH). High proton density has been reached by utilizing additional proton donors (i.e. acidic plasticizers) and by developing different HPAs. Good ion accessibility has been achieved through addition of plasticizers. Electrochemical stability window of the electrolyte system has also been investigated and expanded by utilizing HPAs with different heteroatoms

  18. Modeling of stored charge in metallized biaxially oriented polypropylene film capacitors based on charging current measurement.

    Science.gov (United States)

    Li, Hua; Wang, Bowen; Li, Zhiwei; Liu, De; Lin, Fuchang; Dai, Ling; Zhang, Qin; Chen, Yaohong

    2013-10-01

    Metallized biaxially oriented polypropylene film (BOPP) capacitors are widely used in pulsed power systems. When the capacitor is used as the energy storage equipment under high electric field, more charges should be provided to maintain the voltage of the capacitor. This should be ascribed to the completion of the slow polarization which may take several hours or even longer. This paper focuses on the stored charge in metallized BOPP film capacitors. The modeling of the stored charge by the equivalent conversion of circuits is conducted to analyse the slow polarization in the BOPP film. The 3-RC network is proposed to represent the time-dependent charge stored in the capacitor. A charging current measurement system is established to investigate the charge storage property of the capacitor. The measurement system can measure the long time charging current with a sampling rate of 300 Hz. The total charge calculated by the charging current indicates that the stored charge in the capacitor under the electric field of 400 V/μm is 13.5% larger than the product of the voltage and the capacitance measured by the AC bridge. The nonlinear effect of the electric field on the slow polarization charge is also demonstrated. And the simulation of charge storage based on the 3-RC network can match well with the trend of the stored charge increasing with the time. PMID:24182144

  19. Effect of an Additional, Parallel Capacitor on Pulsed Inductive Plasma Accelerator Performance

    Science.gov (United States)

    Polzin, Kurt A.; Sivak, Amy D.; Balla, Joseph V.

    2011-01-01

    A model of pulsed inductive plasma thrusters consisting of a set of coupled circuit equations and a one-dimensional momentum equation has been used to study the effects of adding a second, parallel capacitor into the system. The equations were nondimensionalized, permitting the recovery of several already-known scaling parameters and leading to the identification of a parameter that is unique to the particular topology studied. The current rise rate through the inductive acceleration coil was used as a proxy measurement of the effectiveness of inductive propellant ionization since higher rise rates produce stronger, potentially better ionizing electric fields at the coil face. Contour plots representing thruster performance (exhaust velocity and efficiency) and current rise rate in the coil were generated numerically as a function of the scaling parameters. The analysis reveals that when the value of the second capacitor is much less than the first capacitor, the performance of the two-capacitor system approaches that of the single-capacitor system. In addition, as the second capacitor is decreased in value the current rise rate can grow to be twice as great as the rise rate attained in the single capacitor case.

  20. Series multilayer internal electrodes for high energy density glass-ceramic capacitors

    Institute of Scientific and Technical Information of China (English)

    LUO Jun; DU Jun; TANG Qun; MAO ChangHui

    2009-01-01

    The glass-ceramic dielectrics and internal electrode structures are investigated for improving the general energy storage density of capacitors.Calculation indicates that glass-ceramics acquired from glass matrix annealing at 850℃ for 3 hours can be approximately up to 17 J/cm3 in energy storage density.They are appropriately chosen as the dielectrics for preparing high energy storage density capacitors (HESDCs).A series multilayer structure of internal electrode is developed for the HESDCs,in which each layer is a combination of gold film and silver paste.This electrode structure promises the capacitor immune from the residual porosity defects inevitably brought by electrode paste sintering process,and specifically improves the electrical breakdown strength of the capacitor.Based on this new electrode structure,the energy storage densities of capacitors are increased by more than one order of magnitude compared with those traditional ones with only single layer of internal electrode.Thus,HESDCs based on the optimized glass-ceramic dielectrics can potentially achieve 7.5 J/cm3 in energy storage density,even taking into consideration the enlargement of total capacitor volumes while encapsulating practicable capacitors from dielectrics media.

  1. An innovative ultra-capacitor driven shape memory alloy actuator with an embedded control system

    International Nuclear Information System (INIS)

    In this paper, an innovative ultra-capacitor driven shape memory alloy (SMA) actuator with an embedded control system is proposed targeting high power high-duty cycle SMA applications. The ultra-capacitor, which is capable of delivering massive amounts of instantaneous current in a compact dimension for high power applications, is chosen as the main component of the power supply. A specialized embedded system is designed from the ground up to control the ultra-capacitor driven SMA system. The control of the ultra-capacitor driven SMA is different from that of a regular constant voltage powered SMA system in that the energy and the voltage of the ultra-capacitor decrease as the system load increases. The embedded control system is also different from a computer-based control system in that it has limited computational power, and the control algorithm has to be designed to be simple while effective so that it can fit into the embedded system environment. The problem of a variable voltage power source induced by the use of the ultra-capacitor is solved by using a fuzzy PID (proportional integral and derivative) control. The method of using an ultra-capacitor to drive SMA actuators enabled SMA as a good candidate for high power high-duty cycle applications. The proposed embedded control system provides a good and ready-to-use solution for SMA high power applications. (paper)

  2. Phase shift PWM with double two-switch bridge for high power capacitor charging

    International Nuclear Information System (INIS)

    Pulse power supply systems working at higher voltage and high repetition rate demands for higher power from capacitor chargers. Capacitor charging requirement become more challenging in such cases. In pulse power circuits, energy storage capacitor should be charged to its desired voltage before the next switching occurs. It is discharged within a small time, delivering large pulse power. A capacitor charger has to work with wide load variation repeatedly. Many schemes are used for this purpose. The proposed scheme aims at reducing stresses on switches by reducing peak current and their evils. A high voltage power supply is designed for capacitor charging. The proposed scheme is based on a Phase-Shifted PWM without using any extra component to achieve soft switching. Indirect constant average current capacitor charging is achieved with a simple control scheme. A double two-switch bridge is proposed to enhance reliability. Power supply has been developed to charge a capacitor of 50 μF to 2.5 kV at 25 Hz. (author)

  3. Fabrication and Characterization of Multilayer Capacitors Buried in a Low Temperature Co-Fired Ceramic Substrate

    OpenAIRE

    G. Y. Li; Y. C. Chan

    1998-01-01

    Multilayer ceramic capacitors designed to be embedded in a low temperature co-fired ceramic substrate have been successfully fabricated. Low and high value capacitors were respectively embedded in the low K multilayer substrate and high K dielectric layer. The buried capacitor has a capacitance density range (1 kHz) from about 220 pF/cm2 to 30 nF/cm2. The design took material compatibility and shrinkage characteristics specifically into account. The effects of heating rate and peak temperatur...

  4. Ultra-capacitors in power conversion systems analysis, modeling and design in theory and practice

    CERN Document Server

    Grbovic, Petar J

    2014-01-01

    Divided into five parts, this book is focused on ultra-capacitors and their applications in power conversion systems. It discusses ultra-capacitor analysis, modelling and module design from a macroscopic (application) perspective. It also describes power conversion applications, interface dc-dc converter design and entire conversion system design. Part One covers the background of energy storage technologies, with particular attention on state-of-the-art ultra-capacitor energy storage technologies. In Chapter four of this part, power conversion systems with integrated energy storage is discus

  5. Digital Control of a power conditioner for fuel cell/super-capacitor hybrid system

    DEFF Research Database (Denmark)

    Caballero, Juan C Trujillo; Gomis-Bellmunt, Oriol; Montesinos-Miracle, Daniel;

    2014-01-01

    This article proposes a digital control scheme to operate a proton exchange membrane fuel cell module of 1.2 kW and a super-capacitor through a DC/DC hybrid converter. A fuel cell has been proposed as a primary source of energy, and a super-capacitor has been proposed as an auxiliary source of...... energy. Experimental validation of the system implemented in the laboratory is provided. Several tests have been performed to verify that the system achieves excellent output voltage (V0) regulation and super-capacitor voltage (V SC) control under disturbances from fuel cell power (PFC) and output power...

  6. Voltage ripple compensation for grid connected electrolyser power supply using small DC link capacitor

    DEFF Research Database (Denmark)

    Török, Lajos; Mathe, Laszlo; Munk-Nielsen, Stig

    2014-01-01

    The purpose of this work was to investigate a three-phase-grid connected power supply using small DC link capacitor for electrolyser application. The hydrogen generation system requires low voltage and high current power supply. Thus the structure of the 3-phase power supply is defined as follows......: a three phase rectification, a small DC-link capacitor and a phase-shifted full-bridge converter with current doubler rectification. Design constraints and control problems are investigated. The advantages and problems caused by the use of small DC link capacitor are presented. The control of the...

  7. Optimal Value of Series Capacitors for Uniform Field Distribution in Transmission Line MRI Coils

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy

    2016-01-01

    Transmission lines are often used as coils in high field magnetic resonance imaging (MRI). Due to the distributed nature of transmission lines, coils based on them produce inhomogeneous field. This work investigates application of series capacitors to improve field homogeneity along the coil. The...... equations for optimal values of evenly distributed capacitors are derived and expressed in terms of the implemented transmission line parameters.The achieved magnetic field homogeneity is estimated under quasistatic approximation and compared to the regular transmission line resonator. Finally, a more...... practical case of a microstrip line coil with two series capacitors is considered....

  8. Optimal Capacitor For Maximum Output Power Tracking Of Self Excited Induction Generator Using Fuzzy Logic Approach

    Directory of Open Access Journals (Sweden)

    Mr.M.Senthilkumar

    2010-08-01

    Full Text Available This paper aims to determine the optimal capacitors required for maximum output power of a single phase self excited induction generator (SEIG. This paper deals with theoretical, fuzzy logic and practical approach in order to extract the values of optimal capacitor for maximum output power .To find this capacitor value, nonlinear equations have to be solved from the equivalent circuit of SEIG. The advantages of using fuzzy logic approach are universal control algorithm, fast converging, accepting of noise and inaccurate signals. At the end of the paper the theoretical and fuzzy logic results are verified with experimental values.

  9. Capacitor Voltage Ripple Suppression for Z-Source Wind Energy Conversion System

    OpenAIRE

    Shoudao Huang; Yang Zhang; Zhikang Shuai

    2016-01-01

    This paper proposes an improved pulse-width modulation (PWM) strategy to reduce the capacitor voltage ripple in Z-source wind energy conversion system. In order to make sure that Z-source capacitor voltage has symmetrical maximum and minimum amplitudes in each active state, the shoot-through time is divided into six unequal parts. According to the active state and zero state, the shoot-through time is rearranged to match the charging time and discharging time of the Z-source capacitors. Theor...

  10. Iron–carbon hybrid capacitor: A proof-of-concept study

    Indian Academy of Sciences (India)

    V R Chari; S R Aravamuthan; A K Shukla

    2014-10-01

    In the present study, cost-intensive Ni electrode is replaced by high surface-area activated carbon (AC) cathode and the possibility of the Fe anode, used in Ni–Fe battery, to function as Fe–C hybrid capacitor has been examined. The electrochemical properties of Fe–C hybrid capacitor assembly are studied using cyclic voltammetry (CV) and galvanostatic charge–discharge cycles. Over 100 galvanostatic charge–discharge cycles for Fe–C hybrid capacitor are carried out and a maximum capacitance of 24 F g-1 is observed.

  11. DC-Voltage Fluctuation Elimination Through a DC-Capacitor Current Control for DFIG Converters Under Unbalanced Grid Voltage Conditions

    DEFF Research Database (Denmark)

    Liu, Changjin; Xu, Dehong; Zhu, Nan;

    2013-01-01

    Unbalanced grid voltage causes a large second-order harmonic current in the dc-link capacitors as well as dc-voltage fluctuation, which potentially will degrade the lifespan and reliability of the capacitors in voltage source converters. This paper proposes a novel dc-capacitor current control...... method for a grid-side converter (GSC) to eliminate the negative impact of unbalanced grid voltage on the dc-capacitors. In this method, a dc-capacitor current control loop, where a negative-sequence resonant controller is used to increase the loop gain, is added to the conventional GSC current control...... loop. The rejection capability to the unbalanced grid voltage and the stability of the proposed control system are discussed. The second-order harmonic current in the dc capacitor as well as dc-voltage fluctuation is very well eliminated. Hence, the dc capacitors will be more reliable under unbalanced...

  12. Graphene double-layer capacitor with ac line-filtering performance.

    Science.gov (United States)

    Miller, John R; Outlaw, R A; Holloway, B C

    2010-09-24

    Electric double-layer capacitors (DLCs) can have high storage capacity, but their porous electrodes cause them to perform like resistors in filter circuits that remove ripple from rectified direct current. We have demonstrated efficient filtering of 120-hertz current with DLCs with electrodes made from vertically oriented graphene nanosheets grown directly on metal current collectors. This design minimized electronic and ionic resistances and produced capacitors with RC time constants of less than 200 microseconds, in contrast with ~1 second for typical DLCs. Graphene nanosheets have a preponderance of exposed edge planes that greatly increases charge storage as compared with that of designs that rely on basal plane surfaces. Capacitors constructed with these electrodes could be smaller than the low-voltage aluminum electrolyte capacitors that are typically used in electronic devices. PMID:20929845

  13. Mission Profile Translation to Capacitor Stresses in Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Ma, Ke; Wang, Huai;

    2014-01-01

    DC capacitors are widely adopted in grid-connected PhotoVoltaic(PV) systems for power stabilization and control decoupling. They have become one of the critical components in grid-connected PV inverters in terms of cost, reliability and volume. The electrical and thermal stresses of the DC...... capacitors are varying along with the intermittent solar PV energy (i.e. of weather-dependency) and also the grid conditions (e.g. voltage fault transients). This paper serves to translate real-field mission profiles (i.e. solar irradiance and ambient temperature) into voltage, current, and temperature...... stresses of the DC capacitors under both normal and abnormal grid conditions. As a consequence, this investigation provides new insights into the sizing and reliability prediction of those capacitors with respect to priorart studies. Two study cases on a single-stage PV inverter and a two-stage PV inverter...

  14. Physics Based Electrolytic Capacitor Degradation Models for Prognostic Studies under Thermal Overstress

    Data.gov (United States)

    National Aeronautics and Space Administration — Electrolytic capacitors are used in several applications rang- ing from power supplies on safety critical avionics equipment to power drivers for electro-mechanical...

  15. A Review of the Condition Monitoring of Capacitors in Power Electronic Converters

    DEFF Research Database (Denmark)

    Soliman, Hammam Abdelaal Hammam; Wang, Huai; Blaabjerg, Frede

    2015-01-01

    Capacitor is one of the reliability critical components in power electronic systems. In the last two decades, many efforts in the academic research have been devoted to the condition monitoring of capacitors to estimate their health status. Industry applications demand more reliable power...... electronics products with preventive maintenance. Nevertheless, most of the developed capacitor condition monitoring technologies are rarely adopted by industry due to the complexity, increased cost and other relevant issues. An overview of the prior-art research in this area is therefore needed to justify...... opportunities. Therefore, this paper firstly classifies the capacitor condition monitoring methods into three categories, then the respective technology evolution from 1993 to 2015 is summarized. Remarks on the state-of-the-art research and the future opportunities targeting for practical industry applications...

  16. Condition Monitoring for DC-link Capacitors Based on Artificial Neural Network Algorithm

    DEFF Research Database (Denmark)

    Soliman, Hammam Abdelaal Hammam; Wang, Huai; Gadalla, Brwene Salah Abdelkarim;

    2015-01-01

    In power electronic systems, capacitor is one of the reliability critical components . Recently, the condition monitoring of capacitors to estimate their health status have been attracted by the academic research. Industry applications require more reliable power electronics products with...... preventive maintenance. However, the existing capacitor condition monitoring methods suffer from either increased hardware cost or low estimation accuracy, being the challenges to be adopted in industry applications. New development in condition monitoring technology with software solutions without extra...... hardware will reduce the cost, and therefore could be more promising for industry applications. A condition monitoring method based on Artificial Neural Network (ANN) algorithm is therefore proposed in this paper. The implementation of the ANN to the DC-link capacitor condition monitoring in a back...

  17. A General Reliability Model for Ni-BaTiO3-Based Multilayer Ceramic Capacitors

    Science.gov (United States)

    Liu, Donhang

    2014-01-01

    The evaluation of multilayer ceramic capacitors (MLCCs) with Ni electrode and BaTiO3 dielectric material for potential space project applications requires an in-depth understanding of their reliability. A general reliability model for Ni-BaTiO3 MLCC is developed and discussed. The model consists of three parts: a statistical distribution; an acceleration function that describes how a capacitor's reliability life responds to the external stresses, and an empirical function that defines contribution of the structural and constructional characteristics of a multilayer capacitor device, such as the number of dielectric layers N, dielectric thickness d, average grain size, and capacitor chip size A. Application examples are also discussed based on the proposed reliability model for Ni-BaTiO3 MLCCs.

  18. A Model-Based Prognostics Methodology For Electrolytic Capacitors Based On Electrical Overstress Accelerated Aging

    Data.gov (United States)

    National Aeronautics and Space Administration — A remaining useful life prediction methodology for electrolytic capacitors is presented. This methodology is based on the Kalman filter framework and an empirical...

  19. A Model-based Prognostics Methodology for Electrolytic Capacitors Based on Electrical Overstress Accelerated Aging

    Data.gov (United States)

    National Aeronautics and Space Administration — A remaining useful life prediction methodology for elec- trolytic capacitors is presented. This methodology is based on the Kalman filter framework and an empirical...

  20. Effect of structure and morphology on thermal and electrical properties of polycarbonate film capacitors

    Science.gov (United States)

    Yen, S. P. S.; Lewis, C. R.

    1990-01-01

    Research is reported to identify polycarbonate (PC) film characteristics and fabrication procedures which extend the reliable performance range of PC capacitors to 125 C without derating, and establish quality control techniques and transfer technology to US PC film manufacturers. The approach chosen to solve these problems was to develop techniques for fabricating biaxially oriented (BX) 2 microns or thinner PC film with a low dissipation factor up to 140 C; isotropic dimensional stability; high crystallinity; and high voltage breakdown strength. The PC film structure and morphology was then correlated to thermal and electrical capacitor behavior. Analytical techniques were developed to monitor film quality during capacitor fabrication, and as a result, excellent performance was demonstrated during initial capacitor testing.

  1. Active control of flying capacitor currents in multilevel voltage-source inverters

    Czech Academy of Sciences Publication Activity Database

    Kokeš, Petr; Semerád, Radko

    2013-01-01

    Roč. 58, č. 4 (2013), s. 393-410. ISSN 0001-7043 Institutional support: RVO:61388998 Keywords : voltage source inverter (VSI) * multilevel inverter * flying capacitor Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  2. Helping students understand real capacitors: measuring efficiencies in a school laboratory

    International Nuclear Information System (INIS)

    A recent reform in the Portuguese secondary school curriculum reintroduced the study of capacitors. Thus we decided to implement some experimental activities on this subject with our undergraduate students in physics education courses. A recent announcement of a new kind of capacitor being developed by a team of scientists at Massachusetts Institute of Technology (MIT), which makes use of nanotechnologies, was a great motivation for the study of a topic that could easily be considered 'out of time'. Since this new kind of capacitor is being seen as the battery of the future, our focus was essentially on efficiency measurements, motivating students to obtain, respectively, the time constant and the energies stored and supplied during the charge and discharge processes, from experimental graphics representing the power as a function of time in real capacitors

  3. Physics of Failure Models for Capacitor Degradation in DC-DC Converters

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper proposes a combined energy-based model with an empirical physics of failure model for degradation analysis and prognosis of electrolytic capacitors in...

  4. METHODS FOR DETERMINING THE POLYCHLORINATED BIPHENYL EMISSIONS FROM INCINERATION AND CAPACITOR AND TRANSFORMER FILLING PLANTS

    Science.gov (United States)

    Described are methods to measure the polychlorinated biphenyl (PCB) emissions from the stacks of municipal waste, industrial waste, and sewage sludge incinerators and from capacitor and transformer filling plants. The PCB emissions from the incineration plants are collected by im...

  5. Contribution to dimensioning a pack of super-capacitors for 12/42 V application

    Energy Technology Data Exchange (ETDEWEB)

    Rafik, F.; Karmous, M. [Ecole d' Ingenieurs de l' Arc Jurassien, CH (Switzerland); Gualous, H.; Berthon, A. [Universite de Franche-Comte, Lab. en Electronique, Electrotechnique et Systemes (L2ES), UTBM, 90 - Belfort (France); Gallay, R. [Maxwell Technologies, CH (Switzerland)

    2004-07-01

    Increase power demands on automotive are making current 12/14 V electrical systems inadequate. The total power demand will triple in some cars from 800 W today to an average of 2500 W and into kW range for peak demand in the future. Super-capacitor can be used for energy storage and for peak power requirement in order to increase the efficiency and the life cycle of the system. However, the sizing of energy storage with super-capacitors is very important for embedded applications, because of the weight and the volume of the system. This paper presents a sizing method of a pack of super-capacitors. The proposed method is based on the power and energy demand. In order to validate this method, a model of the Maxwell cell BCAP0010 of super-capacitors is presented and implemented in the SIMPLORER software. (authors)

  6. Physics Based Electrolytic Capacitor Degradation Models for Prognostic Studies under Thermal Overstress

    Science.gov (United States)

    Kulkarni, Chetan S.; Celaya, Jose R.; Goebel, Kai; Biswas, Gautam

    2012-01-01

    Electrolytic capacitors are used in several applications ranging from power supplies on safety critical avionics equipment to power drivers for electro-mechanical actuators. This makes them good candidates for prognostics and health management research. Prognostics provides a way to assess remaining useful life of components or systems based on their current state of health and their anticipated future use and operational conditions. Past experiences show that capacitors tend to degrade and fail faster under high electrical and thermal stress conditions that they are often subjected to during operations. In this work, we study the effects of accelerated aging due to thermal stress on different sets of capacitors under different conditions. Our focus is on deriving first principles degradation models for thermal stress conditions. Data collected from simultaneous experiments are used to validate the desired models. Our overall goal is to derive accurate models of capacitor degradation, and use them to predict performance changes in DC-DC converters.

  7. Modeling and fabrication of an RF MEMS variable capacitor with a fractal geometry

    KAUST Repository

    Elshurafa, Amro M.

    2013-08-16

    In this paper, we model, fabricate, and measure an electrostatically actuated MEMS variable capacitor that utilizes a fractal geometry and serpentine-like suspension arms. Explicitly, a variable capacitor that possesses a top suspended plate with a specific fractal geometry and also possesses a bottom fixed plate complementary in shape to the top plate has been fabricated in the PolyMUMPS process. An important benefit that was achieved from using the fractal geometry in designing the MEMS variable capacitor is increasing the tuning range of the variable capacitor beyond the typical ratio of 1.5. The modeling was carried out using the commercially available finite element software COMSOL to predict both the tuning range and pull-in voltage. Measurement results show that the tuning range is 2.5 at a maximum actuation voltage of 10V.

  8. Location and determination of steps of capacitors in shunt for distribution power lines; Localizacion y determinacion de pasos de capacitores en derivacion para lineas de distribucion

    Energy Technology Data Exchange (ETDEWEB)

    Pampin Vergara, Gabriela; Sarmiento Uruchurtu, Hector [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2001-07-01

    A methodology is presented to determine the optimal location of the capacitor banks in shunt for distribution networks. The proposed tool allows knowing the bank type to install (fixed, disconnect able or of pass), as well as the electrical parameters of the feeder and the economic benefit that the banks of capacitors represent, with a minimum of input data. Its development in a spreadsheet allows the analysis of numerous alternatives in an easy way. The method is based on that the structure of the feeders of distribution is, generally, of radial type, with which, and by means of an iterative process, the optimal location of the capacitor banks in shunt is looked for. The type of bank is determined based of the demand, as well as the number of steps. The results of the analysis in feeders of the network of the central area are shown. [Spanish] Se presenta una metodologia para determinar la localizacion optima de los bancos de capacitores en derivacion en redes de distribucion. La herramienta propuesta permite conocer el tipo de banco a instalar (fijo, desconcectable o de paso), asi como los parametros electricos del alimentador y el beneficio economico que representan los bancos de capacitores, con un minimo de datos de entrada. Su desarrollo en una hoja de calculo permite el analisis de numerosas alternativas de manera facil. El metodo se basa en que la estructura de los alimentadores de distribucion es, por lo general, de tipo radial, con lo cual, y por medio de un proceso iterativo, se busca la localizacion optima de los bancos de capacitores en derivacion. Se determina el tipo de banco en funcion de la demanda, asi como el numero de pasos. Se muestran resultados del analisis en alimentadores de la red del area central.

  9. Characterization of silicon carbide metal oxide semiconductor capacitors

    Science.gov (United States)

    Marinella, Matthew J.

    Only a few years after the invention of the transistor, William Shockley considered silicon carbide (SiC) an excellent material for high temperature semiconductor devices. Over a half century later, SiC technology is nearly mature enough that it may be considered for use in commercial electronic devices. Furthermore, since SiC has the ability to grow thermal silicon dioxide, significant research has been directed toward the creation of a commercial SiC metal oxide semiconductor field effect transistor (MOSFET). However, a number of significant hurdles still must be overcome before SiC devices can become commercially competitive, including the relatively high cost and low quality of materials. Another significant problem is the lack of understanding of factors which limit the minority carrier lifetime. The primary purpose of this work was to use the pulsed metal oxide semiconductor capacitor (MOS-C) technique to measure generation lifetime in SiC materials. It was found that many nonidealities corrupt the results obtained by this technique. One very interesting nonideality was negative bias temperature instability (NBTI), which has also been widely studied by the silicon industry in recent years. Methods to understand and minimize the effect of these nonidealities were developed. Furthermore, these methods allowed for further study of the oxide properties, such as leakage current. Even after accounting for nonidealities, generation lifetimes showed several peculiarities, such as a variation of as much as a factor of 1000 within a square cm area. In addition, the ratio of generation to recombination lifetime is less than unity, which is not predicted by classic theory, nor typically observed in silicon devices. Possible explanations are put forth to explain these observations. In addition, to further investigate these abnormalities, Schottky diodes were fabricated and characterized. When applied to the SiC MOS capacitor, the pulsed MOS-C technique involves

  10. Effect of cerium addition on microstructure and texture of aluminum foil for electrolytic capacitors

    Institute of Scientific and Technical Information of China (English)

    王海燕; 李文学; 任慧平; 黄丽颖; 王向阳

    2010-01-01

    Anode foil of aluminum electrolytic capacitor,which requires large surface area for high capacitance,were prepared by rolling,annealing and electrochemical etching.Effects of cerium addition on the capacitance of aluminum electrolytic capacitors were investigated.Microstructure of the aluminum foil surface was observed by optical microscopy(OM) and scanning electron microscopy(SEM).Electron back scattered diffraction(EBSD) was also employed to reveal texture evolvement of cold-rolled aluminum foil after ann...

  11. Diagnostics system for the 67 MJ, 50 kV pulsed power capacitor bank

    International Nuclear Information System (INIS)

    The diagnostics system is designed for charging and discharging to the load of the large 67 MJ and 50 kV capacitor bank for the iodine laser pulse power of ISKRA-5 facility. Discharging diagnostics of the capacitor bank uses a technique to measure a sequence of times between representative discharge events for 665 discharge circuits of the bank. Benefits of the measurement techniques are discussed. (author). 3 figs., 3 refs

  12. Reactive Compensation Capability Of Fixed Capacitor Thyristor Controlled Reactor For Load Power Factor Improvement A Review

    OpenAIRE

    Harpreet Singh; Durga Sharma

    2015-01-01

    Abstract Reactive power compensation capability of a fixed capacitor thyristor controlled reactor type static VAr compensator is being investigated in this paper. The TCR has the power transfer controlling capability only in the lagging power factor range. The range of TCR can be extended by connecting a fixed capacitor in shunt with the TCR. The compensated reactive power can be selectively controlled by appropriately changing the firing angle of the TCR circuit in lagging as well as the lea...

  13. Fabrication and Electrochemical Properties of Carbon Nanotube-based Composite Electrodes for Electrochemical Capacitor Applications

    Institute of Scientific and Technical Information of China (English)

    Kwang; Bum; Kim

    2007-01-01

    1 Results Electrochemical capacitors (ECs) are expected to be used in hybrid electric vehicles in combination with batteries or fuel cells because of their higher power density than batteries. ECs using electrical double layer capacitance of carbon based materials and pseudocapacitance of transition metal oxides are called electrochemical double layer capacitors (EDLC) and supercapacitors (or pseudocapacitor), respectively. Transition metal oxides are considered the best candidates for high energy dens...

  14. INTRODUCING FICTITIOUS CURRENTS FOR CALCU- LATING ANALYTICALLY THE ELECTRIC FIELD IN CYLINDRICAL CAPACITORS

    OpenAIRE

    Ravaud, Romain; Lemarquand, Guy; Slobodan, Babic,

    2009-01-01

    International audience The aim of this paper is to show the interest of using equivalence models for calculating the electric field produced by cylindrical capacitors with dielectrics. To do so, we use an equivalent model, based on the dual Maxwell's Equations for calculating the two electric field components created inside the capacitor and outside it. This equivalent model uses fictitious currents generating a electric vector potential that allows us to determine the electric field compo...

  15. Reversible post-breakdown conduction in aluminum oxide-polymer capacitors

    OpenAIRE

    CHEN, Qian; Gomes, HL; Rocha, PRF; De Leeuw,; Meskers, SCJ Stefan

    2013-01-01

    Aluminum/Al2O3/polymer/metal capacitors submitted to a low-power constant current stress undergo dielectric breakdown. The post-breakdown conduction is metastable, and over time the capacitors recover their original insulating properties. The decay of the conduction with time follows a power law (1/t) α . The magnitude of the exponent α can be raised by application of an electric field and lowered to practically zero by optical excitation of the polyspirofluorene polymer. The metastable condu...

  16. Recent Developments in Fault Detection and Power Loss Estimation of Electrolytic Capacitors

    OpenAIRE

    Braham, Ahmed; Lahyani, Amine; VENET, Pascal; Rejeb, Nejla

    2010-01-01

    International audience This paper proposes a comparative study of current-controlled hysteresis and pulsewidth modulation (PWM) techniques, and their influence upon power loss dissipation in a power-factor controller (PFC) output filtering capacitors. First, theoretical calculation of low-frequency and high-frequency components of the capacitor current is presented in the two cases, as well as the total harmonic distortion of the source current. Second, we prove that the methods already us...

  17. Radiation response and electrical properties of polymer energy storage capacitors: PVF2, Polysulfone, and Mylar

    Science.gov (United States)

    Edwards, L. R.

    1981-01-01

    Efforts were made to develop a polymer film capacitor that is tolerant to radiation. The capacitors are to be utilized in a high voltage pulse discharge application. Radiation response data at high dose/dose rate levels are presented for polyvinylidene fluoride (PVF2), polysulfone, and Mylar. The results show that PVF2 is the most radiation tolerant while Mylar is the least tolerant. The data also show that the radiation response is quite dependent on operating electric stress.

  18. Electrical Properties of Thin-Film Capacitors Fabricated Using High Temperature Sputtered Modified Barium Titanate

    OpenAIRE

    Robert Mamazza; Heinz Felzer; Martin Dubs; Glyn J. Reynolds; Martin Kratzer

    2012-01-01

    Simple thin-film capacitor stacks were fabricated from sputter-deposited doped barium titanate dielectric films with sputtered Pt and/or Ni electrodes and characterized electrically. Here, we report small signal, low frequency capacitance and parallel resistance data measured as a function of applied DC bias, polarization versus applied electric field strength and DC load/unload experiments. These capacitors exhibited significant leakage (in the range 8–210 μA/cm2) and dielectric loss. Measur...

  19. Capacitor electrode stimulates nerve or muscle without oxidation-reduction reactions.

    Science.gov (United States)

    Guyton, D L; Hambrecht, F T

    1973-07-01

    Porous tantalum disks, available as "slugs" from the capacitor industry, have large available surface area and a thin insulating coating of tantalum pentoxide. When implanted, they fill with extracellular fluid and operate as capacitor-stimulating electrodes having high capacitance per unit volume. Capable of stimulating excitable tissute without generating electrochemical by-products, these electrodes should provide a safer interface between neural prosthetic devices and human tissue. PMID:4197450

  20. A Novel Approach for Optimal Capacitor Placement Model in Power Distribution Systems

    OpenAIRE

    K.S.Ravichandran; Salem Saleh Saeed Alsheyuhi; Venugopal Chitra

    2012-01-01

    This study deals with the design of distributed power systems and optimal capacitor placement based on the ANFIS (Adaptive Network Fuzzy Inference Systems) using Mamdani-type fuzzy inference model. Traditionally, this problem of optimal capacitor placement has been solved through various optimization techniques, but it is less accuracy of finding placement and more time consuming. This can be avoided by defining the system stochastically. In this study, we introduce ANFIS architecture for the...

  1. Three-level Converter in Offshore Wind Energy Systems: New Strategy for Unbalancing in Capacitors Voltage

    OpenAIRE

    Seixas, Mafalda; Melicio, Rui; Mendes, Victor,; Figueiredo, Joao

    2014-01-01

    This paper is on an offshore wind energy conversion system equipped with full-power three-level converter and permanent magnet synchronous generator. Multi-level converters, namely three-level converters, are limited by unbalance voltage in the direct current link capacitors. A new control strategy for the selection of the output voltage vectors is proposed in order to improve balance of voltage in the capacitors.

  2. Distance Protection Aspects of Transmission Lines Equipped with Series Compensation Capacitors

    OpenAIRE

    Summers, Clinton Thomas

    1999-01-01

    In order to meet the high demand for power transmission capacity, some power companies have installed series capacitors on power transmission lines. This allows the impedance of the line to be lowered, thus yielding increased transmission capability. The series capacitor makes sense because it's simple and could be installed for 15 to 30% of the cost of installing a new line, and it can provide the benefits of increased system stability, reduced system losses, and better voltage regulation....

  3. Influence of the fringe field on moving of the charged particles in flat and cylindrical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Doskeyev, G.A.; Edenova, O.A. [Aktobe State University named after K. Zhubanov, Br. Zhubanov Street 263, 030000 Aktobe (Kazakhstan); Spivak-Lavrov, I.F., E-mail: spivakif@rambler.ru [Aktobe State University named after K. Zhubanov, Br. Zhubanov Street 263, 030000 Aktobe (Kazakhstan)

    2011-07-21

    This paper describes different analytic approaches to describe the fringe fields of flat and cylindrical capacitor structures. A method for the calculation of deflection of charged particles from the optical axis is developed. The behavior of a charged particle beam in a flat capacitor is approximated by using a sharp cut-off boundary for the field, which has the provision of taking fringe fields into account.

  4. Influence of the fringe field on moving of the charged particles in flat and cylindrical capacitors

    International Nuclear Information System (INIS)

    This paper describes different analytic approaches to describe the fringe fields of flat and cylindrical capacitor structures. A method for the calculation of deflection of charged particles from the optical axis is developed. The behavior of a charged particle beam in a flat capacitor is approximated by using a sharp cut-off boundary for the field, which has the provision of taking fringe fields into account.

  5. Analysis of Capacitor Placement in Power Distribution Networks Using Body Immune Algorithm

    OpenAIRE

    Majid Davoodi; Mohsen Davoudi; Iraj Ganjkhany; Morteza Arfand; Ali Aref

    2012-01-01

    In this study we present a new technique for analysis of capacitor placement in the power distribution systems considering the most of the parameters affected in this problem. Detection of capacitance and optimal placement of capacitors in power distribution system can lead to decrement in losses, enhancement in voltage profile, increment of power factor and freeing up generation capacityand energy distribution. The majority of literatures pay more attention to solve this problem considering ...

  6. Fast control technique based on peak current mode control of the output capacitor current

    OpenAIRE

    Alou Cervera, Pedro; García Suárez, Oscar; Oliver Ramírez, Jesús Angel; Cobos Márquez, José Antonio; Viejo de Frutos, Miriam del

    2010-01-01

    The control proposed and analyzed in this paper is based on the peak current mode control of the output capacitor current of a Buck converter. The output capacitor current loop provides fast dynamic response to the control since it behaves as a feed-forward of the load current while the voltage loop provides accurate steady state regulation. A simulation oriented averaged model of the proposed control has been developed to design the external voltage loop. As shown in simulations, with the co...

  7. Performance of AC/graphite capacitors at high weight ratios of AC/graphite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongyu [IM and T Ltd., Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Yoshio, Masaki [Advanced Research Center, Department of Applied Chemistry, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan)

    2008-03-01

    The effect of negative to positive electrode materials' weight ratio on the electrochemical performance of both activated carbon (AC)/AC and AC/graphite capacitors has been investigated, especially in the terms of capacity and cycle-ability. The limited capacity charge mode has been proposed to improve the cycle performance of AC/graphite capacitors at high weight ratios of AC/graphite. (author)

  8. An auxiliary capacitor based ultra-fast drive circuit for shear piezoelectric motors

    OpenAIRE

    Chatterjee, Kamalesh; Boyer, Michael C.; Wise, W. D.; Hudson, Eric

    2009-01-01

    Shear piezoelectric motors frequently require large voltage changes on very short time scales. Since piezos behave electrically as capacitors, this requires a drive circuit capable of quickly sourcing or sinking a large amount of current at high voltages. Here we describe a novel circuit design using a high voltage amplifier, transistor switching stage, and auxiliary capacitor. This circuit can drive piezoelectric motors at higher speeds and lower costs than conventional methods and with grea...

  9. NASA's Evolutionary Xenon Thruster (NEXT) Power Processing Unit (PPU) Capacitor Failure Root Cause Analysis

    Science.gov (United States)

    Soeder, James F.; Pinero, Luis; Schneidegger, Robert; Dunning, John; Birchenough, Art

    2012-01-01

    The NASA's Evolutionary Xenon Thruster (NEXT) project is developing an advanced ion propulsion system for future NASA missions for solar system exploration. A critical element of the propulsion system is the Power Processing Unit (PPU) which supplies regulated power to the key components of the thruster. The PPU contains six different power supplies including the beam, discharge, discharge heater, neutralizer, neutralizer heater, and accelerator supplies. The beam supply is the largest and processes up to 93+% of the power. The NEXT PPU had been operated for approximately 200+ hours and has experienced a series of three capacitor failures in the beam supply. The capacitors are in the same, nominally non-critical location the input filter capacitor to a full wave switching inverter. The three failures occurred after about 20, 30, and 135 hours of operation. This paper provides background on the NEXT PPU and the capacitor failures. It discusses the failure investigation approach, the beam supply power switching topology and its operating modes, capacitor characteristics and circuit testing. Finally, it identifies root cause of the failures to be the unusual confluence of circuit switching frequency, the physical layout of the power circuits, and the characteristics of the capacitor.

  10. OPTIMAL CAPACITORS PLACEMENT IN DISTRIBUTION NETWORKS USING GENETIC ALGORITHM: A DIMENSION REDUCING APPROACH

    Directory of Open Access Journals (Sweden)

    S.NEELIMA

    2011-08-01

    Full Text Available A distribution system is an interface between the bulk power system and the consumers. Among these systems, radial distributions system is popular because of low cost and simple design. In distribution systems, the voltages at buses reduces when moved away from the substation, also the losses are high. The reason for decrease in voltage and high losses is the insufficient amount of reactive power, which can be provided by the shunt capacitors. But the placement of the capacitor with appropriate size is always a challenge. Thus the optimal capacitor placement problem is to determine the location and size of capacitors to be placed in distribution networks in an efficient way to reduce the power losses and improve the voltage profile of the system. For this purpose, in this paper, two stage methodologies are used. In first stage, the load flow of pre-compensated distribution system is carried out using ‘dimension reducing distribution load flow algorithm (DRDLFA’. On the basis of this load flow the potential locations of compensation are computed. In the second stage, Genetic Algorithm (GA technique is used to determine the optimal location and size of the capacitors such that the cost of the energy loss and capacitor cost to be a minimum. The above method is tested on IEEE 69 bus system and compared with other methods in the literature.

  11. Powering microbial electrolysis cells by capacitor circuits charged using microbial fuel cell

    KAUST Repository

    Hatzell, Marta C.

    2013-05-01

    A microbial electrolysis cell (MEC) was powered by a capacitor based energy storage circuit using energy from a microbial fuel cell (MFC) to increase MEC hydrogen production rates compared to that possible by the MFC alone. To prevent voltage reversal, MFCs charged the capacitors in a parallel configuration, and then the capacitors were discharged in series to boost the voltage that was used to power the MECs. The optimal capacitance for charging was found to be ∼0.01 F for each MFC. The use of the capacitor charging system increased energy recoveries from 9 to 13%, and hydrogen production rates increased from 0.31 to 0.72 m3 m-3-day-1, compared to coupled systems without capacitors. The circuit efficiency (the ratio of the energy that was discharged to the MEC to the energy provided to the capacitor from the MFCs) was ∼90%. These results provide an improved method for linking MFCs to MECs for renewable hydrogen gas production. © 2012 Elsevier B.V. All rights reserved.

  12. High-energy power capacitors, their applied technology and the trends

    International Nuclear Information System (INIS)

    High-voltage and high-energy-density power capacitors called high-power ones such as film or electrolytic capacitors, have been used in large quantities for the pulse power technology such as an impulse current or voltage generator and a laser power supply, and for the power electronics one with progress of the power semiconductor device and the inverter technology. Recently, electric double layer capacitors (EDLC) with remarkable technical progress have been applied for the equipments of electric power and industrial field for the purpose of energy saving or electric power quality improvement, which have come to link to the electric power system. Thus, using a lot of high-power capacitors near our life would require to know the structure, the principle and the characteristic of capacitors, and also to consider suitable directions for use, maintenance and safety and so on, when carrying out a system and a facility design. In the technical report, while describing the dielectric and the feature of some high-power capacitors, and introducing the application examples to the laser-fusion power supply and some systems with EDLC, the trend of standardization of EDLC and the directivity of the examination about installation and maintenance of the applied equipments are described. (author)

  13. Analysis of Capacitor Placement in Power Distribution Networks Using Body Immune Algorithm

    Directory of Open Access Journals (Sweden)

    Majid Davoodi

    2012-08-01

    Full Text Available In this study we present a new technique for analysis of capacitor placement in the power distribution systems considering the most of the parameters affected in this problem. Detection of capacitance and optimal placement of capacitors in power distribution system can lead to decrement in losses, enhancement in voltage profile, increment of power factor and freeing up generation capacityand energy distribution. The majority of literatures pay more attention to solve this problem considering only some of the parameters related to the capacitor placement. In this study for the analysis and formulation of the problem we consider six distinct objectives related to the cost of losses, cost of voltage profile, cost of power factor, cost of utilities development and cost of capacitors including the purchase and installation cost. To find the optimum location and capacitance of the capacitors, a proposed method based on the Immune algorithm has been employed in simulations. The important advantage of the Immune algorithm rather than the other methods is its performance in multifunction manner that can investigate many parameters in the target function. The proposed capacitor placement and detecting optimum capacitance method has been implemented and tested in a 9-bus IEEE sample network in DIGSILENT and MATLAB environments.

  14. Geometric optimization of self-healing power capacitor with consideration of multiple factors

    Science.gov (United States)

    Wang, Zijian; Yan, Fei; Hua, Zheng; Qi, Lingna; Hou, Zhijian; Xu, Zhiniu

    2016-08-01

    To decrease temperature rise in self-healing power capacitor and lay foundation for improvement of applied voltage and lifetime, the influence of elements orientation on the temperature distribution of self-healing capacitor is investigated using Fluent15.0 and validated by thermal stability test. Based on the above investigations, the influences of parameters of film, electrode and element on power loss and temperature rise of capacitor are systematically investigated. The results reveal that if geometry and volume of capacitor remain constant, orientation of spray coating has little influence on temperature rise. In view of manufacturing processes, the mode of spray coating close to the large surface should be selected. The power loss will decrease with increasing/decreasing in film thickness/width. Therefore, thicker film should be selected and its width should be less than 75 mm. Temperature rise decreases slowly with element diameter. However, the element diameter should be a moderate value because of the influence of it on the number of self-healing point. A capacitor group with rated voltage of 11/ √{ 3} kV and capacity of 334 kvar is designed and the scheme with the lowest temperature rise is selected. This study provides a reference to self-healing capacitor geometric optimization and lifetime improvement.

  15. Pulse Power Capability Of High Energy Density Capacitors Based on a New Dielectric Material

    Science.gov (United States)

    Winsor, Paul; Scholz, Tim; Hudis, Martin; Slenes, Kirk M.

    1999-01-01

    A new dielectric composite consisting of a polymer coated onto a high-density metallized Kraft has been developed for application in high energy density pulse power capacitors. The polymer coating is custom formulated for high dielectric constant and strength with minimum dielectric losses. The composite can be wound and processed using conventional wound film capacitor manufacturing equipment. This new system has the potential to achieve 2 to 3 J/cu cm whole capacitor energy density at voltage levels above 3.0 kV, and can maintain its mechanical properties to temperatures above 150 C. The technical and manufacturing development of the composite material and fabrication into capacitors are summarized in this paper. Energy discharge testing, including capacitance and charge-discharge efficiency at normal and elevated temperatures, as well as DC life testing were performed on capacitors manufactured using this material. TPL (Albuquerque, NM) has developed the material and Aerovox (New Bedford, MA) has used the material to build and test actual capacitors. The results of the testing will focus on pulse power applications specifically those found in electro-magnetic armor and guns, high power microwave sources and defibrillators.

  16. Miniature photoconducting capacitor array as a source for tunable THz radiation

    Science.gov (United States)

    Hashimshony, D.; Zigler, A.; Papadopoulos, K.

    2000-06-01

    The prospects of a miniature photoconducting capacitor array as a source for THz radiation are discussed. The device consists of an alternately biased capacitor array built on a semiconductor substrate and illuminated by a short laser pulse. The laser pulse creates a propagating plasma front inside the crystal volume by side illumination, and triggers the discharging of the capacitor by shorting out the photoconducting material between each capacitor plate. The sequential discharge of the capacitor array inside the expending plasma region can be considered as an interaction between a static wave and a superluminous ionizing front. In the present article we have demonstrated production of two cycle pulses with a center frequency of up to 1.5 THz. The device combines elements from the well-known "frozen-wave" generator and from the photoconducting switches array. The underlying physics of this radiation mechanism is very similar to the dc-to-ac conversion mechanism inside a gas-filled capacitor array which generates coherent microwave radiation.

  17. Unravelling and controlling hidden imprint fields in ferroelectric capacitors

    Science.gov (United States)

    Liu, Fanmao; Fina, Ignasi; Bertacco, Riccardo; Fontcuberta, Josep

    2016-04-01

    Ferroelectric materials have a spontaneous polarization that can point along energetically equivalent, opposite directions. However, when ferroelectric layers are sandwiched between different metallic electrodes, asymmetric electrostatic boundary conditions may induce the appearance of an electric field (imprint field, Eimp) that breaks the degeneracy of the polarization directions, favouring one of them. This has dramatic consequences on functionality of ferroelectric-based devices such as ferroelectric memories or photodetectors. Therefore, to cancel out the Eimp, ferroelectric components are commonly built using symmetric contact configuration. Indeed, in this symmetric contact configuration, when measurements are done under time-varying electric fields of relatively low frequency, an archetypical symmetric single-step switching process is observed, indicating Eimp ≈ 0. However, we report here on the discovery that when measurements are performed at high frequency, a well-defined double-step switching is observed, indicating the presence of Eimp. We argue that this frequency dependence originates from short-living head-to-head or tail-to-tail ferroelectric capacitors in the device. We demonstrate that we can modulate Eimp and the life-time of head-to-head or tail-to-tail polarization configurations by adjusting the polarization screening charges by suitable illumination. These findings are of relevance to understand the effects of internal electric fields on pivotal ferroelectric properties, such as memory retention and photoresponse.

  18. Carbon aerogels for electric double-layer capacitors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lin; LIU Hongbo; WANG Ming; LIU Wei

    2006-01-01

    In this study, carbon aerogels were derived via the pyrolysis of resorcinol-formaldehyde (RF) aerogels, which were cost-effectively manufactured from RF wet gels by an ambient drying technique instead of conventional supercritical drying. By varying the R/C ratio (molar ratio of resorcinol to catalyst), mesoporous carbon aerogels with high specific surface area were prepared successfully and further investigated as electrode materials for electric double-layer capacitors (EDLCs). The textural properties of carbon aerogels obtained were characterized by nitrogen adsorption/desorption analysis and SEM. The electrochemical performances of carbon aerogels were investigated by impedance spectroscopy, galvanostatic charge/discharge and cyclic voltammetry methods. The results show that BET surface area and specific capacitance increase with R/C ratio, the maximum values of 727 m2·g-1 and 132 F·g-1 are achieved at R/C ratio will of 300. Increasing R/C ratio increase the average pore size of carbon aerogel electrode, which has improved the rate capability. Furthermore, EDLC with carbon aerogel electrodes has an excellent stability at large discharge current and long cycle life.

  19. Unravelling and controlling hidden imprint fields in ferroelectric capacitors.

    Science.gov (United States)

    Liu, Fanmao; Fina, Ignasi; Bertacco, Riccardo; Fontcuberta, Josep

    2016-01-01

    Ferroelectric materials have a spontaneous polarization that can point along energetically equivalent, opposite directions. However, when ferroelectric layers are sandwiched between different metallic electrodes, asymmetric electrostatic boundary conditions may induce the appearance of an electric field (imprint field, Eimp) that breaks the degeneracy of the polarization directions, favouring one of them. This has dramatic consequences on functionality of ferroelectric-based devices such as ferroelectric memories or photodetectors. Therefore, to cancel out the Eimp, ferroelectric components are commonly built using symmetric contact configuration. Indeed, in this symmetric contact configuration, when measurements are done under time-varying electric fields of relatively low frequency, an archetypical symmetric single-step switching process is observed, indicating Eimp ≈ 0. However, we report here on the discovery that when measurements are performed at high frequency, a well-defined double-step switching is observed, indicating the presence of Eimp. We argue that this frequency dependence originates from short-living head-to-head or tail-to-tail ferroelectric capacitors in the device. We demonstrate that we can modulate Eimp and the life-time of head-to-head or tail-to-tail polarization configurations by adjusting the polarization screening charges by suitable illumination. These findings are of relevance to understand the effects of internal electric fields on pivotal ferroelectric properties, such as memory retention and photoresponse. PMID:27122309

  20. Cylindrical Asymmetrical Capacitors for Use in Outer Space

    Science.gov (United States)

    Campbell, Jonathan W.

    2007-01-01

    A report proposes that cylindrical asymmetrical capacitors (CACs) be used to generate small thrusts for precise maneuvering of spacecraft on long missions. The report notes that it has been known for decades that when high voltages are applied to CACs in air, thrusts are generated - most likely as a result of ionization of air molecules and acceleration of the ions by the high electric fields. The report goes on to discuss how to optimize the designs of CACs for operation as thrusters in outer space. Components that could be used to enable outerspace operation include a supply of gas and a shroud, partly surrounding a CAC, into which the gas would flow. Other elements of operation and design discussed in the report include variation of applied voltage and/or of gas flow to vary thrust, effects of CAC and shroud dimensions on thrust and weight, some representative electrode configurations, and several alternative designs, including one in which the basic CAC configuration would be modified into something shaped like a conventional rocket engine with converging/diverging nozzle and an anode with gas feed in the space that, in a conventional rocket engine, would be the combustion chamber.

  1. EMBEDDED CAPACITOR SENSOR FOR MONITORING CORROSION OF REINFORCEMENT IN CONCRETE

    Directory of Open Access Journals (Sweden)

    SITI FATIMAH ABDUL RAHMAN

    2012-04-01

    Full Text Available Corrosion of reinforcement can affect durability and integrity of reinforced concrete structures. Repair cost for a badly corroded structure can be very costly and time consuming. In this paper, several capacitor sensors were developed to monitor corrosion potential of reinforcement in concrete. The impedance capacitive of sensors was tested in various acid and alkali solutions using Agilent 4284A Precision LCR meter. The other sensors were tied to reinforcements and embedded in concrete specimen contaminated with 5% chloride to measure corrosion potential. The specimens were exposed to the corrosion chamber and indoor environments. From the research, it was found that the sensor can measure the impedance capacitive at different frequencies in the aggressive solutions. Besides, it was observed that the patterns of corrosion potential shown by the embedded sensors were similar to the SRI sensor. The output values from embedded sensor are in a range of recommendation by the ASTM-C876. Eventually, the bars were found corroded from the broken specimens that confirmed the detection of corrosion activities as recorded by the sensors.

  2. Finite element analysis of underwater capacitor micromachined ultrasonic transducers.

    Science.gov (United States)

    Roh, Yongrae; Khuri-Yakub, Butrus T

    2002-03-01

    A simple electro-mechanical equivalent circuit model is used to predict the behavior of capacitive micromachined ultrasonic transducers (cMUT). Most often, cMUTs are made in silicon and glass plates that are in the 0.5 mm to 1 mm range in thickness. The equivalent circuit model of the cMUT lacks important features such as coupling to the substrate and the ability to predict cross-talk between elements of an array of transducers. To overcome these deficiencies, a flnite element model of the cMUT is constructed using the commercial code ANSYS. Calculation results of the complex load impedance seen by single capacitor cells are presented, then followed by a calculation of the plane wave real load impedance seen by a parallel combination of many cells that are used to make a transducer. Cross-talk between 1-D array elements is found to be due to two main sources: coupling through a Stoneley wave propagating at the transducer-water interface and coupling through Lamb waves propagating in the substrate. To reduce the cross-talk level, the effect of structural variations of the substrate are investigated, which includes a change of its thickness and etched trenches or polymer walls between array elements. PMID:12322877

  3. A high energy density relaxor antiferroelectric pulsed capacitor dielectric

    International Nuclear Information System (INIS)

    Pulsed capacitors require high energy density and low loss, properties that can be realized through selection of composition. Ceramic (Pb0.88La0.08)(Zr0.91Ti0.09)O3 was found to be an ideal candidate. La3+ doping and excess PbO were used to produce relaxor antiferroelectric behavior with slim and slanted hysteresis loops to reduce the dielectric hysteresis loss, to increase the dielectric strength, and to increase the discharge energy density. The discharge energy density of this composition was found to be 3.04 J/cm3 with applied electric field of 170 kV/cm, and the energy efficiency, defined as the ratio of the discharge energy density to the charging energy density, was 0.920. This high efficiency reduces the heat generated under cyclic loading and improves the reliability. The properties were observed to degrade some with temperature increase above 80 °C. Repeated electric field cycles up to 10 000 cycles were applied to the specimen with no observed performance degradation

  4. Hybrid nanostructured materials for high-performance electrochemical capacitors

    KAUST Repository

    Yu, Guihua

    2013-03-01

    The exciting development of advanced nanostructured materials has driven the rapid growth of research in the field of electrochemical energy storage (EES) systems which are critical to a variety of applications ranging from portable consumer electronics, hybrid electric vehicles, to large industrial scale power and energy management. Owing to their capability to deliver high power performance and extremely long cycle life, electrochemical capacitors (ECs), one of the key EES systems, have attracted increasing attention in the recent years since they can complement or even replace batteries in the energy storage field, especially when high power delivery or uptake is needed. This review article describes the most recent progress in the development of nanostructured electrode materials for EC technology, with a particular focus on hybrid nanostructured materials that combine carbon based materials with pseudocapacitive metal oxides or conducting polymers for achieving high-performance ECs. This review starts with an overview of EES technologies and the comparison between various EES systems, followed by a brief description of energy storage mechanisms for different types of EC materials. This review emphasizes the exciting development of both hybrid nanomaterials and novel support structures for effective electrochemical utilization and high mass loading of active electrode materials, both of which have brought the energy density of ECs closer to that of batteries while still maintaining their characteristic high power density. Last, future research directions and the remaining challenges toward the rational design and synthesis of hybrid nanostructured electrode materials for next-generation ECs are discussed. © 2012 Elsevier Ltd.

  5. SIMULATIONS OF THE AGS MMPS STORING ENERGY IN CAPACITOR BANKS

    International Nuclear Information System (INIS)

    The Brookhaven AGS Main Magnet Power Supply (MMPS) is a thyristor control supply rated at 5500 Amps, +/-9000 Volts. The peak magnet power is 50 MWatts. The power supply is fed from a motor/generator manufactured by Siemens. The generator is 3 phase 7500 Volts rated at 50 MVA. The peak power requirements come from the stored energy in the rotor of the motor/generator. The motor generator is about 45 years old, made by Siemens and it is not clear if companies will be manufacturing similar machines in the future. We are therefore investigating different ways of storing energy for future AGS MMPS operations. This paper will present simulations of a power supply where energy is stored in capacitor banks. Two dc to dc converters will be presented along with the control system of the power section. The switching elements will be IGCT's made by ABB. The simulation program used is called PSIM version 6.1. The average power from the local power authority into the power supply will be kept constant during the pulsing of the magnets at +/-50 MW. The reactive power will also be kept constant below 1.5 MVAR. Waveforms will be presented

  6. SIMULATIONS OF THE AGS MMPS STORING ENERGY IN CAPACITOR BANKS

    Energy Technology Data Exchange (ETDEWEB)

    MARNERIS,I.; BADEA, V.S.; BONATI, R.; ROSER, T.; SANDBERG, J.

    2007-06-25

    The Brookhaven AGS Main Magnet Power Supply (MMPS) is a thyristor control supply rated at 5500 Amps, +/-9000 Volts. The peak magnet power is 50 MWatts. The power supply is fed from a motor/generator manufactured by Siemens. The generator is 3 phase 7500 Volts rated at 50 MVA. The peak power requirements come from the stored energy in the rotor of the motor/generator. The motor generator is about 45 years old, made by Siemens and it is not clear if companies will be manufacturing similar machines in the future. We are therefore investigating different ways of storing energy for future AGS MMPS operations. This paper will present simulations of a power supply where energy is stored in capacitor banks. Two dc to dc converters will be presented along with the control system of the power section. The switching elements will be IGCT's made by ABB. The simulation program used is called PSIM version 6.1. The average power from the local power authority into the power supply will be kept constant during the pulsing of the magnets at +/-50 MW. The reactive power will also be kept constant below 1.5 MVAR. Waveforms will be presented.

  7. Elaboration of a microstructured inkjet-printed carbon electrochemical capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Pech, David; Brunet, Magali; Fabre, Norbert; Mesnilgrente, Fabien; Conedera, Veronique; Durou, Hugo [LAAS-CNRS, Universite de Toulouse, 7 av. du Colonel Roche, F-31077 Toulouse (France); Taberna, Pierre-Louis; Simon, Patrice [CIRIMAT-CNRS, Universite de Toulouse, 118 route de Narbonne, F-31062 Toulouse (France)

    2010-02-15

    Carbon-based micro-supercapacitors dedicated to energy storage in self-powered modules were fabricated with inkjet printing technology on silicon substrate. An ink was first prepared by mixing an activated carbon powder with a PTFE polymer binder in ethylene glycol stabilized with a surfactant then deposited by inkjet on patterned gold current collectors with the substrate heated at 140 C in order to assure a good homogeneity. Electrochemical micro-capacitors with electrodes in an interdigital configuration were fabricated, and characterized using electrochemical techniques in 1 M Et{sub 4}NBF{sub 4} propylene carbonate electrolyte. These micro-devices show an excellent capacitive behavior over a wide potential range of 2.5 V for a cell capacitance of 2.1 mF cm{sup -2}. The newly developed technology will allow the integration of the storage device as close as possible to the MEMS-based energy harvesting device, minimizing power losses through connections. (author)

  8. A high energy density relaxor antiferroelectric pulsed capacitor dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Hwan Ryul; Lynch, Christopher S. [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles (UCLA), Los Angeles, California 90095 (United States)

    2016-01-14

    Pulsed capacitors require high energy density and low loss, properties that can be realized through selection of composition. Ceramic (Pb{sub 0.88}La{sub 0.08})(Zr{sub 0.91}Ti{sub 0.09})O{sub 3} was found to be an ideal candidate. La{sup 3+} doping and excess PbO were used to produce relaxor antiferroelectric behavior with slim and slanted hysteresis loops to reduce the dielectric hysteresis loss, to increase the dielectric strength, and to increase the discharge energy density. The discharge energy density of this composition was found to be 3.04 J/cm{sup 3} with applied electric field of 170 kV/cm, and the energy efficiency, defined as the ratio of the discharge energy density to the charging energy density, was 0.920. This high efficiency reduces the heat generated under cyclic loading and improves the reliability. The properties were observed to degrade some with temperature increase above 80 °C. Repeated electric field cycles up to 10 000 cycles were applied to the specimen with no observed performance degradation.

  9. Some properties of castor oil affecting its performance as a capacitor impregnant and their significance to future impregnant research

    International Nuclear Information System (INIS)

    For a considerable time castor oil and polychlorinated biphenyl (PCB) have been the principal impregnants used in energy-storage capacitors. Castor oil has proven to be better than PCB for pulsed applications. PCB's have come under attack as an environmental hazard, while castor oil is a vegetable product and its supply and quality are subject to fluctuation. These two facts make the development of new impregnants desirable. The properties of PCB as a capacitor impregnant are well known. This paper first compares a number of properties of castor oil and PCB's. A comparison is made between the lives of castor oil capacitors and comparable PCB energy-storage capacitors. Some of the physical and chemical properties of castor oil which make it a good pulse capacitor impregnant are examined. These properties can be used as a guide for future research on new pulse capacitor impregnants

  10. Guidelines for Selection, Screening and Qualification of Low-Voltage Commercial Multilayer Ceramic Capacitors for Space Programs

    Science.gov (United States)

    Teverovsky, Alexander A.

    2012-01-01

    This document has been developed in the course of NASA Electronic Parts and Packaging (NEPP) program and is not an official endorsement of the insertion of commercial capacitors in space programs or an established set of requirements for their testing. The purpose of this document is to suggest possible ways for selection, screening, and qualification of commercial capacitors for NASA projects and open discussions in the parts engineering community related to the use of COTS ceramic capacitors. This guideline is applicable to commercial surface mount chip, simple parallel plate design, multi-layer ceramic capacitors (MLCCs) rated to voltages of 100V and less. Parts with different design, e.g. low inductance ceramic capacitors (LICA), land grid array (LGA) etc., might need additional testing and tailoring of the requirements described in this document. Although the focus of this document is on commercial MLCCs, many procedures discussed below would be beneficial for military-grade capacitors

  11. A module for forming stabilization levels of the voltage of a capacitor bank at the setup SLON

    International Nuclear Information System (INIS)

    The unit for forming stabilization levels of the voltage of capacitor bank at the setup SLON is described. It operates in conjunction with the CHSH-1513 digital voltmeter and is used to control the operation of rectifiers in a charging circuit of the capacitor bank. The unit provides a possibility of voltage stabilization of the capacitor bank over a range of 5 kV with an accuracy of ± 0.5 V. 3 refs.; 3 figs

  12. Sputtered Modified Barium Titanate for Thin-Film Capacitor Applications

    Directory of Open Access Journals (Sweden)

    Robert Mamazza

    2012-04-01

    Full Text Available New apparatus and a new process for the sputter deposition of modified barium titanate thin-films were developed. Films were deposited at temperatures up to 900 °C from a Ba0.96Ca0.04Ti0.82Zr0.18O3 (BCZTO target directly onto Si, Ni and Pt surfaces and characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM and X-ray photoelectron spectroscopy (XPS. Film texture and crystallinity were found to depend on both deposition temperature and substrate: above 600 °C, the as-deposited films consisted of well-facetted crystallites with the cubic perovskite structure. A strongly textured Pt (111 underlayer enhanced the (001 orientation of BCZTO films deposited at 900 °C, 10 mtorr pressure and 10% oxygen in argon. Similar films deposited onto a Pt (111 textured film at 700 °C and directly onto (100 Si wafers showed relatively larger (011 and diminished intensity (00ℓ diffraction peaks. Sputter ambients containing oxygen caused the Ni underlayers to oxidize even at 700 °C: Raising the process temperature produced more diffraction peaks of NiO with increased intensities. Thin-film capacitors were fabricated using ~500 nm thick BCZTO dielectrics and both Pt and Ni top and bottom electrodes. Small signal capacitance measurements were carried out to determine capacitance and parallel resistance at low frequencies and from these data, the relative permittivity (er and resistivity (r of the dielectric films were calculated; values ranged from ~50 to >2,000, and from ~104 to ~1010 Ω∙cm, respectively.

  13. A 1.5 bit/s Pipelined Analog-to-Digital Converter Design with Independency of Capacitor Mismatch

    Institute of Scientific and Technical Information of China (English)

    LI Dan; RONG Men-tian; MAO Jun-fa

    2007-01-01

    A new technique which is named charge temporary storage technique (CTST) was presented to improve the linearity of a 1.5 bit/s pipelined analog-to-digital converter (ADC).The residual voltage was obtained from the sampling capacitor, and the other capacitor was just a temporary storage of charge.Then, the linearity produced by the mismatch of these capacitors was eliminated without adding extra capacitor error-averaging amplifiers.The simulation results confirmed the high linearity and low dissipation of pipelined ADCs implemented in CTST, so CTST was a new method to implement high resolution, small size ADCs.

  14. An RF power amplifier with inter-metal-shuffled capacitor for inter-stage matching in a digital CMOS process

    Institute of Scientific and Technical Information of China (English)

    Feng Xiaoxing; Zhang Xing; Ge Binjie; Wang Xin'an

    2009-01-01

    One challenge of the implementation of fully-integrated RF power amplifiers into a deep submicro digital CMOS process is that no capacitor is available, especially no high density capacitor. To address this problem, a twostage class-AB power amplifier with inter-stage matching realized by an inter-metal coupling capacitor is designed in a 180-nm digital CMOS process. This paper compares three structures of inter-metal coupling capacitors with metal-insulator-metal (MIM) capacitor regarding their capacitor density. Detailed simulations are carried out for the leakage, the voltage dependency, the temperature dependency, and the quality factor between an inter-metal shuffled (IMS) capacitor and an MIM capacitor. Finally, an IMS capacitor is chosen to perform the inter-stage matching.The techniques are validated via the design and implement of a two-stage class-AB RF power amplifier for an UHF RFID application. The PA occupies 370 X 200 μm2 without pads in the 180-nm digital CMOS process and outputs 21.1 dBm with 40% drain efficiency and 28.1 dB power gain at 915 MHz from a single 3.3 V power supply.

  15. A capacitor pulser for plasma focus soft X-ray sources

    International Nuclear Information System (INIS)

    A capacitor pulser to be used as high voltage, high-current pulse generator (30 kV, 50 kA) for plasma physics (generation of dense transient plasmas), plasma X-ray source and pulse power technology research has been developed. The main components of the pulser are the energy storage capacitor bank and the high voltage, high current switch. The capacitor bank consists of 2 Maxwell high voltage low inductance pulse capacitors (C=0.2 μF; L=0.025 μH; U=40 kV). The working voltage is of +30 kV, the maximum energy is 180 J, the peak current is 50 kA. The capacitor bank is discharged by means of a high voltage spark gap switch developed in IPTRD. It is a 3-electrode, high pressure switch triggered by field distortion. The trigger pulse is provided by master spark gap switch of similar design and has a maximum amplitude of -60 kV with about 5 ns rise-time. (authors)

  16. Performance of a combined capacitor based on ultrafine nickel oxide/carbon nanotubes composite electrodes

    Institute of Scientific and Technical Information of China (English)

    Xiaofeng Wang; Yanqiu Cao; Yiqiang Lu; Qiqian Sha; Ji Liang

    2004-01-01

    A new sol-gel process for the preparation of ultrafine nickel hydroxide electrode materials was developed. The composite electrodes consisting of carbon nanotubes and Ni(OH)2 were developed by mixing the hydroxide and carbon nanotubes together in different mass ratios. In order to enhance energy density, a combined type pseudocapacitor/electric double layer capacitor was considered and its electrochemical properties were characterized by cyclic voltammetry and dc charge/discharge test. The combined capacitor shows excellent capacitor behavior with an operating voltage up to 1.6 V in KOH aqueous electrolyte. Stable charge/discharge behaviors were observed with much higher specific capacitance values of 24 F/g compared with that of EDLC (12F/g) by introducing 60% Ni(OH)2 in the anode material. By using the modified anode of a Ni(OH)2/carbon nanotubes composite electrode, the specific capacitance of the cell was less sensitive to discharge current density compared with that of the capacitor employing pure nickel hydroxide as anode. The combined capacitor in this study exhibits high energy density and stable power characteristics.

  17. A capacitor-clamped inverter based torsional oscillation damping method for electromechanical drivetrains

    Directory of Open Access Journals (Sweden)

    Shagar Viknash

    2016-01-01

    Full Text Available A typical electromechanical drivetrain consists of an electric motor, connecting shafts and gears. Premature failures of these shafts and gears have been reported which are mainly due to fatigue caused by extreme loads and torsional oscillations. Overdesign and passive damping are the common approaches taken to increase the fatigue life. Nevertheless, they increase the system cost, weight and volume. Alternatively, active damping through advanced inverter control of the motor drive has been identified as a promising solution that does not require overdesign or alterations to the existing system. Even with the active damping control, oscillations propagate into the dc side of the power converter and subsequently to the upstream power bus. Generally, a large capacitor or an additional energy storage system is placed to suppress these oscillations. This paper proposes to use the clamping capacitors of the capacitor-clamped inverter as energy storage elements and thereby eliminate the need for a large dc side capacitor or an additional energy storage system. The efficacy of the proposed method has been verified with computer simulations. Simulation results show that the clamping capacitors are capable of containing torsional oscillations within the inverter without passing them to the upstream power bus.

  18. High-dielectric-constant ferroelectric thin film and bulk ceramic capacitors for power electronics.

    Energy Technology Data Exchange (ETDEWEB)

    Auciello, O. H.; Baldo, P.; Baumann, P.; Erck, R. A.; Giumarra, J.; Im, J.; Kaufman, D. Y.; Lanagan, M. T.; Pan, M. J.; Streiffer, S. K.; Zebrowski, J.

    1999-08-10

    Significant effort is presently focused on reducing the size and weight of power electronic modules. To achieve these goals in high-power capacitors, alternative materials and fabrication processes are needed. Thin film (<0.5 {micro}m) and bulk capacitors that use perovskite-based ferroelectric dielectrics are promising alternative technologies. Ferroelectrics possess high dielectric constants, thus offering substantial increases in volumetric capacitance. In thin film form, these materials display low loss and high breakdown strength. The unique properties of some of these materials, such as a nonlinear dielectric response or a high energy-storage capacity accompanying a phase change, can be exploited for power electronic capacitors. Prototype capacitors of two such materials, (Ba,Sr)TiO{sub 3} and PbZrO{sub 3}, have been fabricated in both thin film and bulk ceramic form. The influence of fabrication conditions on dielectric properties has been studied. Initial studies have demonstrated the viability of perovskite ferroelectrics for next-generation capacitor components.

  19. Electrode dependent interfacial layer variation in metal-oxide-semiconductor capacitor

    International Nuclear Information System (INIS)

    The interfacial layer between oxide and semiconductor in metal-oxide-semiconductor (MOS) capacitors depends on the metal electrode material. The metal/HfO2/Si and metal/HfO2/Ge capacitor were made using an atomic layer deposited HfO2 dielectric films and Mo, Ru, and Pt electrodes above Si substrate and Ti, Ru, and Pt electrodes above Ge substrate. The measured saturation capacitance was varied with electrode and evaluated to capacitance equivalent thickness (CET). In Si-based MOS capacitor, the CET value of the capacitor with Pt electrode is larger than those with Mo and Ru electrode. In addition, the CET is 27.4 A, 38.2 A, and 30.8 A for Ti, Ru, and Pt electrode, respectively, for Ge-based MOS capacitors. The CET variation with electrode is attributed the variation of dielectric constant of HfO2 dielectric and the difference of interfacial layer. The CET variation is well in agreement with the interfacial layer thickness taken by a transmission electron microscopy. The thickness variation of interfacial layer results from the oxygen gettering ability of the electrode even though they are apart

  20. Physics Based Degradation Models for Capacitor Prognostics under Thermal Overstress Conditions

    Directory of Open Access Journals (Sweden)

    Kai Goebel

    2013-01-01

    Full Text Available Electronics subsystems for monitoring, control, and enhanced functionality play an increasingly important role in safety critical systems. Electrolytic capacitors are an important component in several key subsystems that range from power supplies on safety critical avionics equipment to power drivers for electro-mechanical actuators. These capacitors are known to have comparatively low reliability, and given their criticality in electronics subsystems they are a good candidate for component level monitoring and prognostics. Prognostics provides a way to assess remaining useful life of components and systems based on their current state of health and their anticipated future use and operating conditions. Past experiences have shown that capacitor degradation and failures are quite prevalent under high electrical and thermal stress conditions that they are often subjected to during operations. Our focus in this work is on deriving a physics-based degradation model for electrolytic capacitors under thermal stress conditions. As part of our methodology, we study the effects of accelerated aging due to thermal stress on a batch of identically manufactured capacitors operating at different temperatures. This provides a framework for supplementing theoretical modeling with data collected from simultaneous experiments, which is then used to validate the derived models.

  1. Electrochemical performance of nickel oxide/KOH/active carbon super-capacitor

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The fabrication and characterization of new type Nickel oxide/KOH/Active carbon super-capacitor have been described. Porous nickeloxide was prepared by hydrolysis of nickel acetate and heated in air at 300℃. The resulting nickel oxide behaved as an electrochemical capacitor electrode with a specific capacitance (50-70F/g) superior to most active carbon electrodes. This kind of nickel oxide maintained highutilization at high rate of discharge (i.e., high power density) and had excellent cycle life more than 1000 times, while the capacitance of the cell composed of two identical nickel oxide electrodes was poor at high discharge current density and the maximum operational voltage of this type capacitor was limited to 0.5V. A new type super-capacitorwas designed in which the nickel oxide and the active carbon were applied to the positive and negative electrodes respectively. The breakdown voltage of this type super-capacitor was improved effectively to 0.8V and excellent characteristic of high power discharge was attained in this way. The Nickel oxide/KOH/Active carbon super-capacitor has promising potentials in portable telecommunications, uninterruptable power supplies and battery load leveling applications.

  2. Depollution benchmarks for capacitors, batteries and printed wiring boards from waste electrical and electronic equipment (WEEE)

    Energy Technology Data Exchange (ETDEWEB)

    Savi, Daniel, E-mail: d.savi@umweltchemie.ch [Dipl. Environmental Sci. ETH, büro für umweltchemie, Zurich (Switzerland); Kasser, Ueli [Lic. Phil. Nat. (Chemist), büro für umweltchemie, Zurich (Switzerland); Ott, Thomas [Dipl. Phys. ETH, Institute of Applied Simulation, Zurich University of Applied Sciences, Wädenswil (Switzerland)

    2013-12-15

    Highlights: • We’ve analysed data on the dismantling of electronic and electrical appliances. • Ten years of mass balance data of more than recycling companies have been considered. • Percentages of dismantled batteries, capacitors and PWB have been studied. • Threshold values and benchmarks for batteries and capacitors have been identified. • No benchmark for the dismantling of printed wiring boards should be set. - Abstract: The article compiles and analyses sample data for toxic components removed from waste electronic and electrical equipment (WEEE) from more than 30 recycling companies in Switzerland over the past ten years. According to European and Swiss legislation, toxic components like batteries, capacitors and printed wiring boards have to be removed from WEEE. The control bodies of the Swiss take back schemes have been monitoring the activities of WEEE recyclers in Switzerland for about 15 years. All recyclers have to provide annual mass balance data for every year of operation. From this data, percentage shares of removed batteries and capacitors are calculated in relation to the amount of each respective WEEE category treated. A rationale is developed, why such an indicator should not be calculated for printed wiring boards. The distributions of these de-pollution indicators are analysed and their suitability for defining lower threshold values and benchmarks for the depollution of WEEE is discussed. Recommendations for benchmarks and threshold values for the removal of capacitors and batteries are given.

  3. Evaluation of gamma and neutron irradiation effects on the properties of mica film capacitors

    Indian Academy of Sciences (India)

    Rajesh Roy; Arun Pandya

    2005-12-01

    We present an investigation of gamma and neutron radiation effects on mica film capacitors from an electrical point of view. We have studied quantitatively the effects of gamma and neutron irradiation on mica film capacitors of thickness, 20 and 40 m (0.7874 and 1.5748 mil) with two different areas, 01 and 04 cm2. The capacitance has been measured at room temperature in the frequency range 100 Hz–10 MHz. Negligible change in the capacitance due to high gamma dose of 60Co, 15 kGy at dose rate 0.25 kGy/h, has been observed. However, appreciable change in the capacitance has been observed due to low doses of fast neutrons (cumulative dose, 115 cGy) with flux ∼ 9.925 × 107 neutrons/cm2 h from 252Cf neutron source of fluence, 2.5 × 107 neutrons/s. We have also observed that the impact of gamma and neutron irradiation is more at frequencies higher than 10 kHz. These results show that the mica capacitors do not show any radiation response below 10 kHz. The study shows the radiation response of mica film capacitors to gamma and fast neutron radiations. Mica capacitors show low gamma radiation response in comparison to fast neutron radiation, because a total dose of kGy order has been given by gamma source and only few cGy dose has been given by fast neutron source.

  4. Depollution benchmarks for capacitors, batteries and printed wiring boards from waste electrical and electronic equipment (WEEE)

    International Nuclear Information System (INIS)

    Highlights: • We’ve analysed data on the dismantling of electronic and electrical appliances. • Ten years of mass balance data of more than recycling companies have been considered. • Percentages of dismantled batteries, capacitors and PWB have been studied. • Threshold values and benchmarks for batteries and capacitors have been identified. • No benchmark for the dismantling of printed wiring boards should be set. - Abstract: The article compiles and analyses sample data for toxic components removed from waste electronic and electrical equipment (WEEE) from more than 30 recycling companies in Switzerland over the past ten years. According to European and Swiss legislation, toxic components like batteries, capacitors and printed wiring boards have to be removed from WEEE. The control bodies of the Swiss take back schemes have been monitoring the activities of WEEE recyclers in Switzerland for about 15 years. All recyclers have to provide annual mass balance data for every year of operation. From this data, percentage shares of removed batteries and capacitors are calculated in relation to the amount of each respective WEEE category treated. A rationale is developed, why such an indicator should not be calculated for printed wiring boards. The distributions of these de-pollution indicators are analysed and their suitability for defining lower threshold values and benchmarks for the depollution of WEEE is discussed. Recommendations for benchmarks and threshold values for the removal of capacitors and batteries are given

  5. Optimal capacitor placement in distribution networks by means of a determinatively initiated genetic algorithm

    International Nuclear Information System (INIS)

    In this paper we present a new approach to the optimal control of reactive power in distribution systems based on genetic algorithms. The problem is treated as a combinative one and details on the procedure for determination of the optimal combination of fixed capacitors with predefined sizes are given. Instead of random initiation as a standard procedure in the genetic algorithms, we use determinative initiation in which for randomly chosen capacitor locations we calculate their sizes using a system of linear equations. That way we give the GA a good starting point. In our GA optimization procedure chromosomes are strings of number equal to the number of capacitors of different sizes placed in the network nodes. We use standard genetic operators: selection, crossover, mutation and the principle of elitism. In the paper chromosomes are divided into sub-chromosomes for each of the nodes. Consequently, a modified crossover operator dealing with genes of one node at a time has been introduced. The objective function takes into account savings due to energy losses and peak load reduction as well as investments for the capacitors divided into two categories: fixed ones and those dependent on the capacitor's size. We utilize the power summation method for simulation of the network operation using staircase approximation of the load duration curve. The results presented in this paper and their comparison with the previous ones show the advantages of the proper sed method. (Original)

  6. A noise level prediction method based on electro-mechanical frequency response function for capacitors.

    Directory of Open Access Journals (Sweden)

    Lingyu Zhu

    Full Text Available The capacitors in high-voltage direct-current (HVDC converter stations radiate a lot of audible noise which can reach higher than 100 dB. The existing noise level prediction methods are not satisfying enough. In this paper, a new noise level prediction method is proposed based on a frequency response function considering both electrical and mechanical characteristics of capacitors. The electro-mechanical frequency response function (EMFRF is defined as the frequency domain quotient of the vibration response and the squared capacitor voltage, and it is obtained from impulse current experiment. Under given excitations, the vibration response of the capacitor tank is the product of EMFRF and the square of the given capacitor voltage in frequency domain, and the radiated audible noise is calculated by structure acoustic coupling formulas. The noise level under the same excitations is also measured in laboratory, and the results are compared with the prediction. The comparison proves that the noise prediction method is effective.

  7. High current 66 kV tests on high stability PFN discharge capacitors for CERN LHC

    CERN Document Server

    Barnes, M J

    1999-01-01

    The European Laboratory for Particle Physics (CERN) is constructing a Large Hadron Collider (LHC) to be installed in an existing 27 km circumference tunnel. The LHC will be equipped with fast pulsed magnet systems for injecting two counter-rotating hadron beams. Two pulsed systems, of 4 magnets and 4 pulse forming networks (PFNs) each, are required for this purpose. TRIUMF will build and test 5 resonant charging power supplies (RCPS) and nine PFNs and the associated thyratron switch units as part of the Canadian contribution to CERN LHC. Failures in the PFN capacitors may lead to incorrect beam deflections that may in turn damage LHC components. For this reason the reliability of the capacitors must be exceptionally high. Hence sample PFN capacitors were purchased and tested. The test procedure included discharging the PFN capacitors from 66 kV, into a 10.1 Ohm resistance, for 500,000 cycles, at a frequency of approximately 1 Hz. Subsequently the PFN capacitors were discharged from 66 kV into a 2.7 Ohm resist...

  8. Preparation of etched tantalum semimicro capacitor stimulation electrodes.

    Science.gov (United States)

    Robblee, L S; Kelliher, E M; Langmuir, M E; Vartanian, H; McHardy, J

    1983-03-01

    The ideal electrode for stimulation of the nervous system is one that will inject charge by purely capacitive processes. One approach is to exploit the type of metal-oxide combination used in electrolytic capacitors, e.g., Ta/Ta2O5. For this purpose, fine tantalum wire (0.25 mm diam) was etched electrolytically at constant current in a methanol solution of NH4Br containing 1.5 wt % H2O. Electrolytic etching produced a conical tip with a length of ca. 0.5 mm and shaft diameters ranging from 0.10 to 0.16 mm. The etched electrodes were anodized to 10 V (vs. SCE) in 0.1 vol % H3PO4. The capacitance values normalized to geometric area of etched electrodes ranged from 0.13 to 0.33 micro F mm-2. Comparison of these values to the capacitance of "smooth" tantalum anodized to 10 V (0.011 micro F mm-2) indicated that the degree of surface enhancement, or etch ratio, was 12-30. The surface roughness was confirmed by scanning electron microscopy studies which revealed an intricate array of irregularly shaped surface projections about 1-2 micrometers wide. The etched electrodes were capable of delivering 0.06-0.1 micro C of charge with 0.1 ms pulses at a pulse repetition rate of 400 Hz when operated at 50% of the anodization voltage. This quantity of charge corresponded to volumetric charge densities of 20-30 micro C mm-3 and area charge densities of 0.55-0.88 micro C mm-2. Charge storage was proportionately higher at higher fractional values of the formation voltage. Leakage currents at 5 V were ca. 2 nA. Neither long-term passive storage (1500 h) nor extended pulsing time (18 h) had a deleterious effect on electrode performance. The trend in electrical stimulation work is toward smaller electrodes. The procedures developed in this study should be particularly well-suited to the fabrication of even smaller electrodes because of the favorable electrical and geometric characteristics of the etched surface. PMID:6841372

  9. The Electrochemical Flow Capacitor: Capacitive Energy Storage in Flowable Media

    Science.gov (United States)

    Dennison, Christopher R.

    Electrical energy storage (EES) has emerged as a necessary aspect of grid infrastructure to address the increasing problem of grid instability imposed by the large scale implementation of renewable energy sources (such as wind or solar) on the grid. Rapid energy recovery and storage is critically important to enable immediate and continuous utilization of these resources, and provides other benefits to grid operators and consumers as well. In past decades, there has been significant progress in the development of electrochemical EES technologies which has had an immense impact on the consumer and micro-electronics industries. However, these advances primarily address small-scale storage, and are often not practical at the grid-scale. A new energy storage concept called "the electrochemical flow capacitor (EFC)" has been developed at Drexel which has significant potential to be an attractive technology for grid-scale energy storage. This new concept exploits the characteristics of both supercapacitors and flow batteries, potentially enabling fast response rates with high power density, high efficiency, and long cycle lifetime, while decoupling energy storage from power output (i.e., scalable energy storage capacity). The unique aspect of this concept is the use of flowable carbon-electrolyte slurry ("flowable electrode") as the active material for capacitive energy storage. This dissertation work seeks to lay the scientific groundwork necessary to develop this new concept into a practical technology, and to test the overarching hypothesis that energy can be capacitively stored and recovered from a flowable media. In line with these goals, the objectives of this Ph.D. work are to: i) perform an exploratory investigation of the operating principles and demonstrate the technical viability of this new concept and ii) establish a scientific framework to assess the key linkages between slurry composition, flow cell design, operating conditions and system performance. To

  10. Experimental determination of harmonic conditions amplification in a distribution network by capacitor bank switching

    DEFF Research Database (Denmark)

    Baloi, Alexandru; Kocewiak, Lukasz Hubert; Bak, Claus Leth;

    2012-01-01

    The paper presents a study comprising laboratory measurements for the evaluation of the harmonic amplification due to capacitor bank switching. The mathematical model of the amplification factors of the current flowing on the circuit elements is presented. Theoretical aspects, regarding the total...... harmonic distortion (THD) of the capacitor current computed using the amplification factor, are originally presented. Nonlinear loads as six pulse rectifier and National Instruments measurement sensors together with LabView software were used on the laboratory set-up. The main instrument of the method is...... the harmonic impedance, “seen” in the bus of the capacitor bank switching. MatLab Simulink is used for the determination of the harmonic impedance....

  11. Bayesian Framework Approach for Prognostic Studies in Electrolytic Capacitor under Thermal Overstress Conditions

    Science.gov (United States)

    Kulkarni, Chetan S.; Celaya, Jose R.; Goebel, Kai; Biswas, Gautam

    2012-01-01

    Electrolytic capacitors are used in several applications ranging from power supplies for safety critical avionics equipment to power drivers for electro-mechanical actuator. Past experiences show that capacitors tend to degrade and fail faster when subjected to high electrical or thermal stress conditions during operations. This makes them good candidates for prognostics and health management. Model-based prognostics captures system knowledge in the form of physics-based models of components in order to obtain accurate predictions of end of life based on their current state of heal th and their anticipated future use and operational conditions. The focus of this paper is on deriving first principles degradation models for thermal stress conditions and implementing Bayesian framework for making remaining useful life predictions. Data collected from simultaneous experiments are used to validate the models. Our overall goal is to derive accurate models of capacitor degradation, and use them to remaining useful life in DC-DC converters.

  12. Magntohydrodynamic behavior of capacitor-coil target toward alternative inertial confinement fusion

    Science.gov (United States)

    Sasaki, T.; Oyama, S.; Sugimoto, Y.; Takahashi, K.; Kikuchi, T.; Harada, N.; Nagatomo, H.; Fujioka, S.; Sunahara, A.

    2016-05-01

    To understand its magnetohydrodynamic behaviors and the electrical properties, we proposed to evaluate both experimental observations and numerical simulations. Electrical conductivity for nickel in warm dense matter (WDM) state has been measured with an exploding wire in a quasi-isochoric vessel. The result shows that the electrical conductivity for nickel in WDM is relatively high from the comparison of the electrical conductivities for several materials in WDM state. However, the skin effect in the capacitor-coil target will be neglected from the estimation. A two-dimensional magnetohydrodynamic simulation for the capacitor-coil target has been demonstrated. The results shows that the distribution of B-field in the capacitor-coil target depends on the electrical conductivity model.

  13. R dump converter without DC link capacitor for an 8/6 SRM: experimental investigation.

    Science.gov (United States)

    Kavitha, Pasumalaithevan; Umamaheswari, Bhaskaran

    2015-01-01

    The objective of this paper is to investigate the performance of 8/6 switched reluctance motor (SRM) when excited with sinusoidal voltage. The conventional R dump converter provides DC excitation with the help of capacitor. In this paper the converter used is the modified R dump converter without DC link capacitor providing AC or sinusoidal excitation. Torque ripple and speed ripple are investigated based on hysteresis current control. Constant and sinusoidal current references are considered for comparison in both DC and AC excitation. Extensive theoretical and experimental investigations are made to bring out the merits and demerits of AC versus DC excitation. It is shown that the constructionally simple SRM can be favorably controlled with simple R dump converter with direct AC excitation without need for DC link capacitor. A 4-phase 8/6 0.5 kW SRM is used for experimentation. PMID:25642452

  14. Investigations on Capacitor Compensation Topologies Effects of Different Inductive Coupling Links Configurations

    Directory of Open Access Journals (Sweden)

    Norezmi Jamal

    2015-06-01

    Full Text Available This paper presents investigations on capacitor compensation topologies with different inductive coupling links for loosely coupled inductive power transfer (IPT system. In general, the main constraint of the loosely coupled IPT system is power losses due to the large leakage inductances. Therefore, to overcome the aforementioned problem, in this work, capacitor compensation is proposed to be used by adding an external capacitor to the system. By using this approach, the resonant inductive coupling can be achieved efficiently and hence the efficiency of the system is also increased significantly. This paper analyzes the performance of two different compensation topologies, which are primary series-secondary series (SS and primary series- secondary parallel (SP topology. The performance of such topologies is evaluated through the experimental results at 1MHz operating frequency for different types of inductive coupling. From the results, SS topology produces a high power transfer but SP topology gives better efficiency.

  15. Integrated decoupling capacitors using Pb(Zr,Ti)O{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dimos, D.; Lockwood, S.J.; Garino, T.J.; Al-Shareef, H.N.; Schwartz, R.W.

    1996-07-01

    Thin-film decoupling capacitors based on ferroelectric PLZT (PbLaZrTiO{sub 3}) films are being developed for advanced packaging. The increased integration that can be achieved by replacing surface- mount capacitors should lead to decreased package volume and improved high-speed performance. For this application, chemical solution deposition is an appropriate fabrication technique since it is a low- cost, high-throughput process. Relatively thick Pt electrodes (1{mu}m) are used to minimize series resistance and inductance in fabricating these devices. Also, important electrical properties are discussed, with emphasis on lifetime measurements, which suggest that resistance degradation will not be a severe limitation on device performance. Finally, some of the work being done to develop methods of integrating these thin-film capacitors with integrated circuits and multichip modules is presented.

  16. Self-assembled nanowire array capacitors: capacitance and interface state profile

    International Nuclear Information System (INIS)

    Direct characterization of the capacitance and interface states is very important for understanding the electronic properties of a nanowire transistor. However, the capacitance of a single nanowire is too small to precisely measure. In this work we have fabricated metal–oxide–semiconductor capacitors based on a large array of self-assembled Si nanowires. The capacitance and conductance of the nanowire array capacitors are directly measured and the interface state profile is determined by using the conductance method. We demonstrate that the nanowire array capacitor is an effective platform for studying the electronic properties of nanoscale interfaces. This approach provides a useful and efficient metrology for the study of the physics and device properties of nanoscale metal–oxide–semiconductor structures. (paper)

  17. On demand single photon source using a nanoscale metal-insulator-semiconductor capacitor

    CERN Document Server

    Hu, B; Yang, M J; Hu, Binhui

    2005-01-01

    We propose an on-demand single photon source for quantum cryptography using a metal-insulator-semiconductor quantum dot capacitor structure. The main component in the semiconductor is a p-doped quantum well, and the cylindrical gate under consideration is only nanometers in diameter. As in conventional metal-insulator-semiconductor capacitors, our system can also be biased into the inversion regime. However, due to the small gate area, at the onset of inversion there are only a few electrons residing in a quantum dot. In addition, because of the strong size quantization and large Coulomb energy, the number of electrons can be precisely controlled by the gate voltage. After holding just one electron in the inversion layer, the capacitor is quickly biased back to the flat band condition, and the subsequent radiative recombination across the bandgap results in single photon emission. We present numerical simulation results of a semiconductor heterojunction and discuss the merits of this single photon source.

  18. A Novel Approach for Optimal Capacitor Placement Model in Power Distribution Systems

    Directory of Open Access Journals (Sweden)

    K.S. Ravichandran

    2012-02-01

    Full Text Available This study deals with the design of distributed power systems and optimal capacitor placement based on the ANFIS (Adaptive Network Fuzzy Inference Systems using Mamdani-type fuzzy inference model. Traditionally, this problem of optimal capacitor placement has been solved through various optimization techniques, but it is less accuracy of finding placement and more time consuming. This can be avoided by defining the system stochastically. In this study, we introduce ANFIS architecture for the first time in this field to obtain an optimal capacitor placement in power distributed systems. The results are compared with a standard 34-bus test system with other models, with respect to the placements, savings and the computational time.

  19. High voltage AC/AC electrochemical capacitor operating at low temperature in salt aqueous electrolyte

    Science.gov (United States)

    Abbas, Qamar; Béguin, François

    2016-06-01

    We demonstrate that an activated carbon (AC)-based electrochemical capacitor implementing aqueous lithium sulfate electrolyte in 7:3 vol:vol water/methanol mixture can operate down to -40 °C with good electrochemical performance. Three-electrode cell investigations show that the faradaic contributions related with hydrogen chemisorption in the negative AC electrode are thermodynamically unfavored at -40 °C, enabling the system to work as a typical electrical double-layer (EDL) capacitor. After prolonged floating of the AC/AC capacitor at 1.6 V and -40°C, the capacitance, equivalent series resistance and efficiency remain constant, demonstrating the absence of ageing related with side redox reactions at this temperature. Interestingly, when temperature is increased back to 24 °C, the redox behavior due to hydrogen storage reappears and the system behaves as a freshly prepared one.

  20. A comparative evaluation of integrated capacitors for AC-coupled microstrip detectors

    International Nuclear Information System (INIS)

    The electrical reliability of integrated capacitors to be used for AC-coupled microstrip detectors has been investigated by characterizing a specially designed test chip. Capacitors employing different stacked dielectrics, including double-layer oxide, oxide-nitride, and oxide-nitride-oxide insulators, have been compared in terms of intrinsic breakdown field and extrinsic failure distributions. Results obtained from two fabrication runs are presented and discussed. The impact of the different technological options adopted on diode leakage current and bulk- and surface-generation parameters is also reported. (orig.)

  1. Design and simulation of charge sensitive preamplifier with CMOS FET implemented as feedback capacitor Cfp

    Institute of Scientific and Technical Information of China (English)

    WEMBE TAFO Evariste; SU Hong; GAO Yanni; WU Ming

    2008-01-01

    In this paper,to design a new preamplifier for optimum performances with charged-particle or heavy-ion detectors,the CMOS FET is implemented as a feedback capacitor Cfp.so that the entire system should be built only with MOSFET.This work is a revolution design because to realize an ASIC for a preamplifier circuit,the capacitor will also be included.We succeed after a simulation to maintain a rise time less than 3 ns,the output resistance less than 94 Ω and the linearity almost good.

  2. Charge storage mechanism in nanoporous carbons and its consequence for electrical double layer capacitors.

    Science.gov (United States)

    Simon, Patrice; Gogotsi, Yury

    2010-07-28

    Electrochemical capacitors, also known as supercapacitors, are energy storage devices that fill the gap between batteries and dielectric capacitors. Thanks to their unique features, they have a key role to play in energy storage and harvesting, acting as a complement to or even a replacement of batteries which has already been achieved in various applications. One of the challenges in the supercapacitor area is to increase their energy density. Some recent discoveries regarding ion adsorption in microporous carbon exhibiting pores in the nanometre range can help in designing the next generation of high-energy-density supercapacitors. PMID:20566518

  3. Transition from Spark Discharge to Constricted Glow Discharge in Atmospheric Air by Capacitor Coupled Discharge

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yutao; REN Chunsheng; XU Zhenfeng; MA Tengcai; QI Bing; WANG Dezhen; WANG Younian

    2007-01-01

    The transition from a spark discharge to a constricted glow discharge in atmospheric air was studied with a capacitor coupled pin-to-water plasma reactor. The reason of the transition is considered to be of various factors, namely the change of the air gap due to the polarization of water molecules by the electric field, the feedback effect of the capacitors, and the ion trapping mechanism. The effects of the frequency of the power supply, inter-electrode gap, and coupled capacitance on the discharge transition were also investigated.

  4. Enhanced Stability of Capacitor-Current Feedback Active Damping for LCL-Filtered Grid Converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang;

    2015-01-01

    The proportional capacitor-current feedback active damping method has been widely used to suppress the LCL-filter resonance. However, the time delay in the damping control loop may lead to non-minimum phase or even unstable responses when the resonance frequency varies in a wide range. To improve...... the robustness of damping, this paper proposes an improved damping controller with the capacitor current feedback loop, which is based on the second-order generalized integrator, instead of a proportional gain, which can effectively mitigate the detrimental effect of the time delay. Robustness of the...

  5. High-performance electrolyte in the presence of dextrose and its derivatives for aluminum electrolytic capacitors

    Science.gov (United States)

    Tsai, Ming-Liao; Lu, Yi-Fang; Do, Jing-Shan

    Dextrose and its derivatives (e.g. glucose, gluconic acid and gluconic lactone) are added to modify the characteristics of electrolytes used in aluminum electrolytic capacitors. The results show that the conductivity and sparking voltage of the electrolytes are severely affected by the concentration of dextrose gluconic acid and gluconic lactone. In addition, the pH of the electrolyte is only slightly affected by the quantity of gluconic acid and gluconic lactone. The capacitance, dissipation factor, and leakage current of capacitors impregnated with the electrolytes prepared in this work are periodically measured under storage conditions and loading at 105 °C.

  6. Uranium dioxide vapor condensation by rarefaction waves in the ORNL Capacitor Discharge Vaporization tests

    International Nuclear Information System (INIS)

    A spherical shock tube type model with homogeneous nucleation and particle condensation growth in the rarefaction wave fan has been developed and applied to the Capacitor Discharge Vaporization (CDV) experiments conducted at ORNL. In each CDV test, a stack of molten UO2 fuel pellets contained in a quartz tube were partially vaporized in an argon environment by rapid energy deposition through capacitor discharge. A UO2 aerosol was generated during the resulting expansion of the UO2 vapor. The position of the expanding UO2 vapor-argon interface as a function of time was estimated from movies of the CDV tests

  7. Temperature dependent C-V characteristics of YBCO/YSZ/Si MIS capacitors

    International Nuclear Information System (INIS)

    Metal-insulator-semiconductor capacitors are fabricated from a YBa2Cu3O7-δ (YBCO)/yttria-stabilized zirconia (YSZ)/Si structure. Current-voltage (I-V) measurements reveal that thicker YBCO films (lte)1500 Angstrom tend to result in more stable capacitors. In this paper, it is shown that the distribution of mobile ions in YSZ can be set with biases at room temperature and then frozen by lowering the temperature, giving rise to adjustable threshold voltages at 80 K

  8. A novel single phase buck PFC converter in discontinuous capacitor voltage mode operation

    Institute of Scientific and Technical Information of China (English)

    邓超平; 凌志斌; 叶芃生

    2003-01-01

    A novel single-phase Buck converter for power factor correction is proposed. It features simple control due to the constant duty ratio PWM used. It can obtain unity power factor by selecting a suitable LC filter at its input to force the voltage of capacitor to operate in discontinuous capacitor voltage mode. And by using another resonant LC filter at its output, it can not only eliminate the input current distortion at the vicinity of the zero crossing of the supply but also drastically reduce the 100 Hz output voltage ripple. The validity of analysis is confirmed by simulation results and experimental results.

  9. Design and simulation of charge sensitive preamplifier with CMOS FET implemented as feedback capacitor Cfp

    International Nuclear Information System (INIS)

    In this paper, to design a new preamplifier for optimum performances with charged-particle or heavy-ion detectors, the CMOS FET is implemented as a feedback capacitor Cfp, so that the entire system should be built only with MOSFET. This work is a revolution design because to realize an ASIC for a preamplifier circuit, the capacitor will also be included. We succeed after a simulation to maintain a rise time less than 3 ns, the output resistance less than 94 Ω and the linearity almost good. (authors)

  10. Degradation testing and failure analysis of DC film capacitors under high humidity conditions

    DEFF Research Database (Denmark)

    Wang, Huai; Nielsen, Dennis Achton; Blaabjerg, Frede

    2015-01-01

    degradation of the film capacitors is a concern in applications exposed to high humidity environments. This paper investigates the degradation of a type of plastic-boxed metallized DC film capacitors under different humidity conditions based on a total of 8700 h of accelerated testing and also post failure...... analysis. The test results are given by the measured data of capacitance and the equivalent series resistance. The degradation curves in terms of capacitance reduction are obtained under the conditions of 85% Relative Humidity (RH), 70% RH, and 55% RH. The post failure analysis of the degraded samples of...

  11. Research on the Application of the Super Capacitor in the Solar LED Pest Control Light

    Directory of Open Access Journals (Sweden)

    Li Tianhua

    2014-02-01

    Full Text Available Based on the energy storage characteristics of the super-capacitor and solar panels, this study selects the super-capacitor as the storage device to design the solar LED pest control light, which is energy saving, environmentally friendly, safe and reliable. The solar LED pest control light is easy to use and there is no need erecting and maintaining wires. However, the current storage battery is weak in charge control due to the instability of the sun light and this unstable charge state may lead to its premature failure or capacity loss, thus causing the service life of pest control light to be below the designed specification.

  12. Research on the Application of the Super Capacitor in the Solar LED Pest Control Light

    OpenAIRE

    Li Tianhua; Pan Zhengkun

    2014-01-01

    Based on the energy storage characteristics of the super-capacitor and solar panels, this study selects the super-capacitor as the storage device to design the solar LED pest control light, which is energy saving, environmentally friendly, safe and reliable. The solar LED pest control light is easy to use and there is no need erecting and maintaining wires. However, the current storage battery is weak in charge control due to the instability of the sun light and this unstable charge state may...

  13. Synthesis of Cerium Dioxide High-k Thin Films as a Gate Dielectric in MOS Capacitor

    OpenAIRE

    Anil G. Khairnar; Y.S. Mhaisagar; A.M. Mahajan

    2013-01-01

    In the present study, the Al/CeO2 / p-Si MOS capacitor was fabricated by depositing the Aluminium (Al) metal layer by thermal evaporation technique on sol-gel derived CeO2 high-k thin films on p-Si substrate. The deposited CeO2 films were characterized by Ellipsometer to study the refractive index that is determined to be 3.62. The FTIR analysis was carried out to obtain chemical bonding characteristics. Capacitance-voltage measurements of Al/CeO2 /p-Si MOS capacitor were carried out to deter...

  14. Control Strategy of Two Capacitor Voltages for Separate MPPTs in Photovoltaic Systems Using Neutral-Point-Clamped Inverters

    DEFF Research Database (Denmark)

    Choi, Ui-Min; Blaabjerg, Frede; Lee, Kyo-Beum

    2015-01-01

    panel mismatch conditions. In this system, if PV modules are separately connected to the split capacitor voltage, the MPPT efficiency can be improved by the proposed control strategy. By the proposed method, the two capacitor voltages can be controlled asymmetrically to perform the separate MPPTs of...

  15. Capacitor Test, Evaluation. and Modeling Within NASA Electronic Parts and Packaging (NEPP) Program. "Why Ceramic Capacitors Fracture During Manual Soldering and How to Avoid Failures"

    Science.gov (United States)

    Teverovsky, Alexander

    2011-01-01

    Presentation discusses: (1) Why Multi-Layer Ceramic Capacitors(MLCCs) crack during manual soldering? Workmanship and parts issues. (2) Do existing qualification requirements assure crack-free soldering? MIL-spec Thermal Shock (TS) testing. MIL-spec Resistance to Soldering Heat (RSH) test. (3) What test can assure reliable soldering? Mechanical characteristics of ceramics. Comparison of three TS techniques: LND, TSD, and IWT. (4) Simulation of TS conditions.

  16. Conducted EMI Mitigation Schemes in Isolated Switching Mode Power Supply without the Need of a Y-capacitor

    DEFF Research Database (Denmark)

    Bai, Yongjiang; Yang, Xu; Zhang, Dan;

    2016-01-01

    In order to construct a low impedance loop for common mode electromagnetic interference (EMI) signals, traditional method is to use Y-capacitors as filtering components. However, in the commonly used isolated AC-DC switching mode power supplies (SMPS), the Y-capacitors branch also behaves as a....... The goal of this paper is try to meet these two demands at the same time. In this paper, a novel non-Y-capacitor EMI design concept for SMPS is proposed for the first time. By getting rid of traditional EMI filtering component---the Y-capacitors, the leakage current can be eliminated entirely....... Meanwhile, to face with EMI design challenge, optimized transformer architecture is presented. Analysis of the transformer architecture as well as the auxiliary winding has been carried out. Then a novel topology suitable for non-Y-capacitors converter is proposed and the design procedure of the proposed...

  17. Optimal Placement and Sizing of Capacitor and Distributed Generation with Harmonic and Resonance Considerations Using Discrete Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    M. Heydari

    2013-06-01

    Full Text Available Presence of distributed generation (DG in distribution systems has significant impacts on the operational characteristics of these systems, also using capacitor for reactive compensation and loss reduction is so common. Injected harmonic currents from non-linear loads into distribution system distort all of voltages and currents and must be considered when placing the capacitor banks so that the resonance will not occur. In this paper discrete particle swarm optimization (DPSO approach is used for the optimal placement and sizing of distributed generations and capacitors in distribution systems for simultaneous voltage profile improvement, loss and total harmonic distortion (THD reduction. There is a term in the objective function which prevents harmonic resonance between capacitor reactance and system reactance. Constraints include voltage limit, voltage THD, number/ size of capacitors and generators. For evaluating the proposed algorithm, the IEEE 33-bus test system is modified and employed.

  18. An all-inkjet printed flexible capacitor on a textile using a new poly(4-vinylphenol) dielectric ink for wearable applications

    OpenAIRE

    Li, Yi; Torah, Russel; Beeby, Steve; Tudor, John

    2012-01-01

    This paper reports a flexible capacitor for wearable applications which has been all-inkjet printed on a standard 65/35 polyester cotton textile using a new poly(4 vinylphenol)(PVP) dielectric material. Capacitors form the basis of a variety of sensors, such as for proximity and touch, as well as electronic circuits. This paper reports a general fabrication printing process to realize capacitors on textiles. The parallel plate capacitor design uses a combination of heat curable silver ink and...

  19. Liquid electrolyte-free cylindrical Al polymer capacitor review: Materials and characteristics

    Science.gov (United States)

    Yoo, Jeeyoung; Kim, Jaegun; Kim, Youn Sang

    2015-06-01

    The manufacturing methods for liquid electrolyte-free Al polymer capacitors are introduced by using new materials like novel oxidants, separators and negative current collectors. The Al polymer capacitor is constructed by an Al foil as an anode, Al2O3 as a dielectric, and poly(3, 4-ethylenedioxythiophene) (PEDOT) as a cathode. There are also various synthetic methods of 3, 4-ethylenedioxythiophene (EDOT) and the chemical polymerization of PEDOT from EDOT using iron benzenesulfonate as a new oxidant and dopant. Furthermore, various cathodic current collectors such as conventional Al foils, carbon and titanium dioxide deposited on Al foils or substrates, as well as various separators with manila-esparto paper and synthetic fibers (series of acryl, PET, etc.) are studied. The Al polymer capacitors with the newly introduced oxidant (iron benzenesulfonate), separator (aramid based synthetic fibers) and current collector (TiO2) exhibit considerably enhanced capacitance values and the extremely low resistance (7 mΩ), so there is low power consumption and high reliability. Additionally, the newly developed Al polymer capacitor is guaranteed for 5,000 h at 125 °C, which means there is a long life time operation over ∼ 5 × 106 h at 65 °C.

  20. Development of recovery control for magnet power supply with floating capacitor

    International Nuclear Information System (INIS)

    Japan Proton Accelerator Research Complex (J-PARC) aims at achieving a MW-class proton accelerator facility. One of the promising solutions for increasing the beam power is to fasten the repetition rate of Main Ring (MR) from current rating of 2.5 sec to 1 sec in the future. However, in this scheme, the increase of output voltage and the power variation on the electric system are serious concerns for main magnets. We have considered that the energy recovery scheme based on capacitive energy storage is one of the best solution to compensate the power variation induced by a magnet power supply. In order to achieve the idea, we have decided to innovate the floating capacitor method to produce the high output voltage and return the capacitor energy with magnetic energy. However driving power supply with the floating capacitor method needs to establish the charging method of them in each cycle and initialization. In this article, we report about the recovery control of floating capacitor. (author)

  1. Low-dimensional carbon and MXene-based electrochemical capacitor electrodes

    Science.gov (United States)

    Yoon, Yeoheung; Lee, Keunsik; Lee, Hyoyoung

    2016-04-01

    Due to their unique structure and outstanding intrinsic physical properties such as extraordinarily high electrical conductivity, large surface area, and various chemical functionalities, low-dimension-based materials exhibit great potential for application in electrochemical capacitors (ECs). The electrical properties of electrochemical capacitors are determined by the electrode materials. Because energy charge storage is a surface process, the surface properties of the electrode materials greatly influence the electrochemical performance of the cell. Recently, graphene, a single layer of sp2-bonded carbon atoms arrayed into two-dimensional carbon nanomaterial, has attracted wide interest as an electrode material for electrochemical capacitor applications due to its unique properties, including a high electrical conductivity and large surface area. Several low-dimensional materials with large surface areas and high conductivity such as onion-like carbons (OLCs), carbide-derived carbons (CDCs), carbon nanotubes (CNTs), graphene, metal hydroxide, transition metal dichalcogenides (TMDs), and most recently MXene, have been developed for electrochemical capacitors. Therefore, it is useful to understand the current issues of low-dimensional materials and their device applications.

  2. Research of on-line monitoring equipment for power capacitor based on wireless sensor network

    Science.gov (United States)

    Yu, Hao; Qian, Zheng; Yao, Junda; Xia, Jiuyun

    2016-01-01

    As the main electrical component for the reactive power compensation, the power capacitors are widely applied in many fields. And since the insulation condition of power capacitor could be identified accurately by using the on-line monitoring system, it attracts more and more attentions in recent years. In this paper, a novel on-line monitoring equipment for power capacitor based on wireless sensor network is presented. The operation data which includes the current and voltage of every capacitor is collected at first, and then the FFT is utilized to calculate the amplitude and phase of every signal, thus the insulation condition and the fault symptom could all be diagnosed accurately by analyzing the FFT results. In order to realize the effective isolation and the reliable communication between the sensing part and the merging unit, the wireless sensor network is adopted. The high reliability and transmission rate could be realized by using 2.4GHz UHF and 5GHz ISM radio bands. Thus the on-line monitoring system could be manufactured, and the lab test is carried at last. The testing results illustrate that this system could satisfy the requirement of on-site real-time measurement.

  3. Carbon-Based Materials for Lithium-Ion Batteries, Electrochemical Capacitors, and Their Hybrid Devices.

    Science.gov (United States)

    Yao, Fei; Pham, Duy Tho; Lee, Young Hee

    2015-07-20

    A rapidly developing market for portable electronic devices and hybrid electrical vehicles requires an urgent supply of mature energy-storage systems. As a result, lithium-ion batteries and electrochemical capacitors have lately attracted broad attention. Nevertheless, it is well known that both devices have their own drawbacks. With the fast development of nanoscience and nanotechnology, various structures and materials have been proposed to overcome the deficiencies of both devices to improve their electrochemical performance further. In this Review, electrochemical storage mechanisms based on carbon materials for both lithium-ion batteries and electrochemical capacitors are introduced. Non-faradic processes (electric double-layer capacitance) and faradic reactions (pseudocapacitance and intercalation) are generally explained. Electrochemical performance based on different types of electrolytes is briefly reviewed. Furthermore, impedance behavior based on Nyquist plots is discussed. We demonstrate the influence of cell conductivity, electrode/electrolyte interface, and ion diffusion on impedance performance. We illustrate that relaxation time, which is closely related to ion diffusion, can be extracted from Nyquist plots and compared between lithium-ion batteries and electrochemical capacitors. Finally, recent progress in the design of anodes for lithium-ion batteries, electrochemical capacitors, and their hybrid devices based on carbonaceous materials are reviewed. Challenges and future perspectives are further discussed. PMID:26140707

  4. Generalized Multi-Cell Switched-Inductor and Switched-Capacitor Z-source Inverters

    DEFF Research Database (Denmark)

    Li, Ding; Chiang Loh, Poh; Zhu, Miao;

    2013-01-01

    . Their boosting gains are, therefore, limited in practice. To overcome these shortcomings, the generalized switched-inductor and switched-capacitor Z-source inverters are proposed, whose extra boosting abilities and other advantages have already been verified in simulation and experiment....

  5. Characterization and modeling of atomic layer deposited high-density trench capacitors in silicon

    NARCIS (Netherlands)

    Matters-Kammerer, M.K.; Jinesh, K.B.; Rijks, T.G.S.M.; Roozeboom, F.; Klootwijk, J.H.

    2012-01-01

    A detailed electrical analysis of multiple layer trench capacitors fabricated in silicon with atomic-layer-deposited Al 2O 3 and TiN is presented. It is shown that in situ ozone annealing of the Al 2O 3 layers prior to the TiN electrode deposition significantly improves the electric properties of th

  6. An Active Damping Technique for Small DC-Link Capacitor Based Drive System

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Lu, Kaiyuan

    2013-01-01

    A small dc-link capacitor based drive system shows instability when it is operated with large input line inductance at operating points with high power. This paper presents a simple, new active damping technique that can stabilize effectively the drive system at unstable operating points, offering...

  7. A Model-based Prognostics Methodology for Electrolytic Capacitors Based on Electrical Overstress Accelerated Aging

    Science.gov (United States)

    Celaya, Jose; Kulkarni, Chetan; Biswas, Gautam; Saha, Sankalita; Goebel, Kai

    2011-01-01

    A remaining useful life prediction methodology for electrolytic capacitors is presented. This methodology is based on the Kalman filter framework and an empirical degradation model. Electrolytic capacitors are used in several applications ranging from power supplies on critical avionics equipment to power drivers for electro-mechanical actuators. These devices are known for their comparatively low reliability and given their criticality in electronics subsystems they are a good candidate for component level prognostics and health management. Prognostics provides a way to assess remaining useful life of a capacitor based on its current state of health and its anticipated future usage and operational conditions. We present here also, experimental results of an accelerated aging test under electrical stresses. The data obtained in this test form the basis for a remaining life prediction algorithm where a model of the degradation process is suggested. This preliminary remaining life prediction algorithm serves as a demonstration of how prognostics methodologies could be used for electrolytic capacitors. In addition, the use degradation progression data from accelerated aging, provides an avenue for validation of applications of the Kalman filter based prognostics methods typically used for remaining useful life predictions in other applications.

  8. Investigation about decoupling capacitors of PMT voltage divider effects on neutron-gamma discrimination

    International Nuclear Information System (INIS)

    Scintillators are almost used in any nuclear laboratory. These detectors combine of scintillation materials, PMT and a voltage divider. Voltage dividers are different in resistive ladder design. But the effect of decoupling capacitors and damping resistors haven’t discussed yet. In this paper at first a good equilibrium circuit designed for PMT, and it was used for investigating about capacitors and resistors in much manner. Results show that decoupling capacitors have great effect on PMT output pulses. In this research, it was tried to investigate the effect of Capacitor’s value and places on PMT voltage divider in Neutron-Gamma discrimination capability. Therefore, the voltage divider circuit for R329-02 Hamamatsu PMT was made and Zero Cross method used for neutron-gamma discrimination. The neutron source was a 20Ci Am-Be. Anode and Dynode pulses and discrimination spectrum were saved. The results showed that the pulse height and discrimination quality change with the value and setting of capacitors

  9. Capacitor energy needed to induce transitions from the superconducting to the normal state

    International Nuclear Information System (INIS)

    The purpose of this paper is to describe a technique to turn a long length of superconducting wire normal by dumping a charged capacitor into it and justify some formulae needed in the design. The physical phenomenon is described. A formula for the energy to be stored in the capacitor is given. There are circumstances where the dc in an electrical circuit containing superconducting elements has to be turned off quickly and where the most convenient way to switch the current off is to turn a large portion or all of the superconducting wire normal. Such was the case of the Time Projection Chamber (TPC) superconducting magnet as soon as a quench was detected. The technique used was the discharge of a capacitor into the coil center tap. It turned the magnet winding normal in ten milliseconds or so and provided an adequate quench protection. The technique of discharging a capacitor into a superconducting wire should have many other applications whenever a substantial resistance in a superconducting circuit has to be generated in that kind of time scale. The process involves generating a pulse of large currents in some part of the circuit and heating the wire up by ac losses until the value of the wire critical current is smaller than the dc current. Use of low inductance connections to the circuit is necessary. Then the dc gets turned off due to the resistance of the wire as in a magnet quench

  10. Converter Power Density Increase using Low Inductive Integrated DC-link Capacitor/Bus

    DEFF Research Database (Denmark)

    Trintis, Ionut; Franke, Toke; Rannested, Bjørn;

    2015-01-01

    The power losses in switching devices have a direct effect on the maximum converter power. For a voltage source converter, the DC-link bus has a major influence on the power loss and safe operating area of the power devices. The Power Ring Film CapacitorTM integrated with an optimized bus structu...

  11. Effect of Preconditioning and Soldering on Failures of Chip Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander A.

    2014-01-01

    Soldering of molded case tantalum capacitors can result in damage to Ta205 dielectric and first turn-on failures due to thermo-mechanical stresses caused by CTE mismatch between materials used in the capacitors. It is also known that presence of moisture might cause damage to plastic cases due to the pop-corning effect. However, there are only scarce literature data on the effect of moisture content on the probability of post-soldering electrical failures. In this work, that is based on a case history, different groups of similar types of CWR tantalum capacitors from two lots were prepared for soldering by bake, moisture saturation, and longterm storage at room conditions. Results of the testing showed that both factors: initial quality of the lot, and preconditioning affect the probability of failures. Baking before soldering was shown to be effective to prevent failures even in lots susceptible to pop-corning damage. Mechanism of failures is discussed and recommendations for pre-soldering bake are suggested based on analysis of moisture characteristics of materials used in the capacitors' design.

  12. Simulation Study of the Carrier-Based PWM Method in Three- Phase Flying Capacitor Inverters

    OpenAIRE

    Adrian Şchiop

    2008-01-01

    This paper is a simulation study ofmodulation strategies in three-phase flying capacitorinverters. Under investigation are those strategies thatsolve the capacitor voltage balancing problem: phaseshiftPWM method, the saw-tooth rotation PWM methodand carrier redistribution PWM method. The results areshown through simulation.

  13. Simple DCM or CRM analog peak current controller for HV capacitor charge-discharge applications

    DEFF Research Database (Denmark)

    Trintis, Ionut; Dimopoulos, Emmanouil; Munk-Nielsen, Stig

    2013-01-01

    This paper presents a simple analog current controller suitable for buck and boost converter topologies. The controller operates in DCM or CRM, depending on the setup. The experimental results are presented to validate the proposed controller functionality for a high voltage capacitor charge...

  14. Electrostatic micro-actuator with a pre-charged series capacitor: modeling, design, and demonstration

    International Nuclear Information System (INIS)

    As a powerful method to reduce actuation voltage in an electrostatic micro-actuator, we propose and investigate an electrostatic micro-actuator with a pre-charged series capacitor. In contrast to a conventional electrostatic actuator, the injected pre-charges into the series capacitor can freely modulate the pull-in voltage of the proposed actuator even after the completion of fabrication. The static characteristics of the proposed actuator were investigated by first developing analytical models based on a parallel-plate capacitor model. We then successfully designed and demonstrated a micro-switch with a pre-charged series capacitor. The pull-in voltage of the fabricated micro-switch was reduced from 65.4 to 0.6 V when pre-charged with 46.3 V. The on-resistance of the fabricated micro-switch was almost the same as the initial one, even when the device was pre-charged, which was demonstrated for the first time. All results from the analytical models, finite element method simulations, and measurements were in good agreement with deviations of less than 10%. This work can be favorably adapted to electrostatic micro-switches which need a low actuation voltage without noticeable degradation of performance. (paper)

  15. Use of Super-Capacitor to Enhance Charging Performance of Stand-Alone Solar PV System

    KAUST Repository

    Huang, B. J.

    2011-01-01

    Introduction: The battery charging performance in a stand-alone solar PV system affects the PV system efficiency and the load operating time. The New Energy Center of National Taiwan University has been devoted to the development of a PWM charging technique to continue charging the lead-acid battery after the overcharge point to increase the battery storage capacity by more than 10%. The present study intends to use the super-capacitor to further increase the charge capacity before the overcharge point of the battery. The super-capacitor is connected in parallel to the lead-acid battery. This will reduce the overall charging impedance during the charge and increase the charging current, especially in sunny weather. A system dynamics model of the lead-acid battery and super-capacitor was derived and the control system simulation was carried out to predict the charging performance for various weathers. It shows that the overall battery impedance decreases and charging power increases with increasing solar radiation. An outdoor comparative test for two identical PV systems with and without supercapacitor was carried out. The use of super-capacitor is shown to be able to increase the lead-acid charging capacity by more than 25% at sunny weather and 10% in cloudy weather. © Springer-Verlag Berlin Heidelberg 2011.

  16. Electric-Field-Induced Superconductivity Detected by Magnetization Measurements of an Electric-Double-Layer Capacitor

    NARCIS (Netherlands)

    Kasahara, Yuichi; Nishijima, Takahiro; Sato, Tatsuya; Takeuchi, Yuki; Ye, Jianting; Yuan, Hongtao; Shimotani, Hidekazu; Iwasa, Yoshihiro

    2011-01-01

    We report evidence for superconductivity induced by the application of strong electric fields onto the surface of a band insulator, ZrNCl, provided by the observation of a shielding diamagnetic signal. We introduced an electric-double-layer capacitor configuration and in situ magnetization measureme

  17. Alternative interpretations for decreasing voltage with increasing charge in ferroelectric capacitors

    Science.gov (United States)

    Song, Seul Ji; Kim, Yu Jin; Park, Min Hyuk; Lee, Young Hwan; Kim, Han Joon; Moon, Taehwan; Do Kim, Keum; Choi, Jung-Hae; Chen, Zhihui; Jiang, Anquan; Hwang, Cheol Seong

    2016-01-01

    Recent claim on the direct observation of a negative capacitance (NC) effect from a single layer epitaxial Pb(Zr0.2,Ti0.8)O3 (PZT) thin film was carefully reexamined, and alternative interpretations that can explain the experimental results without invoking the NC effect are provided. Any actual ferroelectric capacitor has an interfacial layer, and experiment always measures the sum of voltages across the interface layer and the ferroelectric layer. The main observation of decreasing ferroelectric capacitor voltage (VF) for increasing ferroelectric capacitor charge (QF), claimed to be the direct evidence for the NC effect, could be alternatively interpreted by either the sudden increase in the positive capacitance of a ferroelectric capacitor or decrease in the voltage across the interfacial layer due to resistance degradation. The experimental time-transient VF and QF could be precisely simulated by these alternative models that fundamentally assumes the reverse domain nucleation and growth. Supplementary experiments using an epitaxial BaTiO3 film supported this claim. This, however, does not necessarily mean that the realization of the NC effect within the ferroelectric layer is impractical under appropriate conditions. Rather, the circuit suggested by Khan et al. may not be useful to observe the NC effect directly. PMID:26864751

  18. A Capacitor-Free, Fast Transient Response Linear Voltage Regulator In a 180nm CMOS

    DEFF Research Database (Denmark)

    Deleuran, Alexander N.; Lindbjerg, Nicklas; Pedersen, Martin K.;

    2015-01-01

    A 1.8 V capacitor-free linear regulator with fast transient response based on a new topology with a fast and slow regulation loop is presented. The design has been laid out and simulated in a 0.18 µm CMOS process. The design has a low component count and is tailored for system-on-chip integration...

  19. Design of the individual Marx modules for the Atlas machine 36 megajoule, 25 megampere capacitor bank

    International Nuclear Information System (INIS)

    This paper presents the preliminary electrical and mechanical design of the Atlas machine's 1.8 megajoule, 600 kV Marx modules. The modules are implemented with plastic cased capacitors similar to those developed for the Defense Nuclear Agency (DNA) ACE II and ACE IV machines. The double ended electrode capacitor style has been dubbed ''FASTCAP.'' Electrodes are provided for mounting rail-gaps on one side and flat plate transmission line damping resistors on the other. This provides for an extremely low circuit inductance. A series array of ten capacitors, each rated at 60 kV, 33.5 uF, and 60 kJ, with their five triggered rail-gaps, form a Marx submodule. Three Marx submodules are nested into a large G-10 fiberglass rack to form a complete Marx module. The module support rack has individual capacitor shelves that ease assembly and replacement. The Marx's design also facilitates construction, testing and verification of a modules performance prior to installation. Modules will be repaired or maintained in a separate test bay without affecting machine operation schedules. Railgap maintenance will become part of a regularly-scheduled preventative maintenance program as spare modules are installed and removed from the machine

  20. Ageing behaviour of electrochemical double layer capacitors. Part I. Experimental study and ageing model

    Energy Technology Data Exchange (ETDEWEB)

    Bohlen, Oliver; Kowal, Julia; Sauer, Dirk Uwe [Institute for Power Electronics and Electrical Drives ISEA, RWTH Aachen University, Aachen (Germany)

    2007-10-11

    Different types of commercially available electrochemical double layer capacitors (EDLCs) were analysed in accelerated ageing tests by impedance spectroscopy. From these measurements the parameters of an impedance model were determined. The characteristic change of the impedance parameters is discussed and an ageing model for EDLCs is developed. (author)

  1. Experimental study of charge collection in PN, NP diodes and MOS capacitor struck by heavy ions

    International Nuclear Information System (INIS)

    Charge collection in PN and silicon diodes and MOS capacitor struck by heavy ions, has been experimentally studied. We have analysed a large set of data obtained at GANIL, Saclay and Bruyeres-le-Chatel accelerators. General laws have been deduced to describe the FUNNELING phenomena as function of circuit polarisation and ion penetration

  2. Effect of Reverse Bias Stress on Leakage Currents and Breakdown Voltages of Solid Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander A.

    2011-01-01

    The majority of solid tantalum capacitors are produced by high-temperature sintering of a fine tantalum powder around a tantalum wire followed by electrolytic anodization that forms a thin amorphous Ta2O5 dielectric layer and pyrolysis of manganese nitrite on the oxide to create a conductive manganese dioxide electrode. A contact to tantalum wire is used as anode terminal and to the manganese layer as a cathode terminal of the device. This process results in formation of an asymmetric Ta -- Ta2O5 -- MnO2 capacitor that has different characteristics at forward (positive bias applied to tantalum) and reverse (positive bias applied to manganese cathode) voltages. Reverse bias currents might be several orders of magnitude larger than forward leakage currents so I-V characteristics of tantalum capacitors resemble characteristics of semiconductor rectifiers. Asymmetric I-V characteristics of Ta -- anodic Ta2O5 systems have been observed at different top electrode materials including metals, electrolytes, conductive polymers, and manganese oxide thus indicating that this phenomenon is likely related to the specifics of the Ta -- Ta2O5 interface. There have been multiple attempts to explain rectifying characteristics of capacitors employing anodic tantalum pentoxide dielectrics. A brief review of works related to reverse bias (RB) behavior of tantalum capacitors shows that the mechanism of conduction in Ta -- Ta2O5 systems is still not clear and more testing and analysis is necessary to understand the processes involved. If tantalum capacitors behave just as rectifiers, then the assessment of the safe reverse bias operating conditions would be a relatively simple task. Unfortunately, these parts can degrade with time under reverse bias significantly, and this further complicates analysis of the I-V characteristics and establishing safe operating areas of the parts. On other hand, time dependence of reverse currents might provide additional information for investigation of

  3. Capacitor and rail-gap development for the Atlas machine Marx modules

    International Nuclear Information System (INIS)

    This paper presents the engineering issues and development criteria utilized to evolve the Atlas Marx bank pulse power components. The capacitor and rail-gap required alterations from existing designs to minimize system inductance and component count, maximize reliability, and enhance maintainability. For the capacitors, development has resulted in a plastic cased device with double ended bushings. The design of the capacitors' output electrodes, foil packs, and internal interconnect webbing results in a capacitor with improved performance. The capacitors are rated at 33.5 uF and 60 kV and are housed in a 28 in. x 29 in. x 13 in. fiberglass case. Terminal inductance is less than 15 nH with a design discharge current greater than 650 kA. An improved ''third generation'' rail-gap will be utilized and is a product of the ACE machine developments at Maxwell Laboratories. The gap has a polyurethane body and one piece electrodes. To minimize prefires, a modified internal profile reduces the E-field and increases tracking length between the electrodes. With an individual Marx stage charged ''+'' and ''-'' and a trigger rail with 50/50 grading (mid-plane), external trigger bias or coupling components are not required. This further reduces system component count. To further reduce gap prefires and environmental concerns, high pressure air, instead of the typical Argon/SF6 mixture, will be used. The metallic switching by-products will form insulating oxides and the gap flushing procedures are simplified. To ensure multi-channel discharges, fast dV/dT trigger voltages (∼30 kV/nS), similar to those developed for the Staged Theta-Pinch railgaps (a Scyllac era machine at Los Alamos), will be utilized

  4. Capacitive desalination of ZnO/activated carbon asymmetric capacitor and mechanism analysis

    International Nuclear Information System (INIS)

    ABSTRACT: Zinc oxide/activated carbon composite electrode (ZnO/AC) was prepared by simply mixing ZnO nanoparticles with AC granules in the presence of Teflon emulsion. Scanning electron microscopy shows an even and seamless surface with effective filling of ZnO nanoparticles in between AC granules. Cyclic voltammetry and impedance analysis demonstrate the ideal double-layer capacitor behavior. The desalination behavior of the asymmetric capacitor with ZnO/AC as positive electrode and AC as negative electrode (+ZnO/AC‖AC), or ZnO/AC as negative electrode and AC as positive electrode (−ZnO/AC‖AC) was studied, respectively. As compared with pure AC‖AC capacitor, −ZnO/AC‖AC capacitor showed a very stable desalination behavior with high desalination amount of 9.4 mg/g and charge efficiency of 80.5%; while +ZnO/AC‖AC capacitor showed no obvious difference after several desalination cycles due to poor stability. The mechanism was analyzed based on zeta potential of ZnO particles and pH variation near the electrode surface during charging process. The different desalination properties on positive and negative electrodes due to zeta potential variation of ZnO with pH change at electrode surface were further confirmed by using other metal oxides like CuO, MnO2 and WO3. This study provides a particularly important guidance for screening electrode materials and optimizing operation parameters for capacitive desalination (also called capacitive deionization, CDI)

  5. Voltage stabilization of VSI SMES capacitors and voltage sag compensation by SMES using novel switching strategies

    Energy Technology Data Exchange (ETDEWEB)

    Mohammad Reza, Alizadeh Pahlavani; Abbas, Shoulaie [Department of Electrical Engineering, Iran University of Science and Technology (IUST), Heidarkhani St., Narmak, 16844 Tehran (Iran); Hossine Ali, Mohammadpour [Department of Electrical Engineering, University of South Carolina, Columbia, SC (United States)

    2010-08-15

    This paper presents a novel and optimized switching strategy and control approach for a three-level two-quadrant chopper in a three-level Neutral point clamped (NPC) voltage source inverter (VSI) superconducting magnetic energy storage (SMES). Using the proposed switching strategy, the voltage of the inverter capacitors in SMES can be independently controlled; also, the minimum power and switching losses - as well as the proper convection - can be achieved using this same strategy. The simulation results indicate that when combined with a proportional-integral (PI) control approach the proposed switching strategy can be easily implemented in the power networks and can balance and stabilize the multi-level inverters' capacitor voltage level. The voltage variation of the capacitors in the steady state condition is less than (0.062%) which is 15 times better than the IEEE standard requirement (1%). To investigate the effectiveness and reliability of the proposed approach in stabilizing capacitor voltage, SMES performance using the presented approach is compared with that of SMES when the capacitors of the three-level inverter are replaced with equal and ideal voltage sources. This comparison is carried out from the power-quality point of view, and it is shown that the proposed switching strategy with a PI controller is highly reliable. Considering that the Space Vector Pulse Width Modulation (SVPWM) is highly effective in decreasing low order harmonics (LOH), this article utilizes this type of modulation when it is combined with the most optimized switching strategy. In addition, this study proposes a new algorithm for SMES to compensate the voltage sag in the power networks. Simulation results show that the VSI SMES, when combined with the proposed algorithm, is able to compensate the voltage sag and phase voltage in less than one cycle, which is 5 times better than other voltage sag compensators. (author)

  6. Ni-BaTiO3-Based Base-Metal Electrode (BME) Ceramic Capacitors for Space Applications

    Science.gov (United States)

    Liu, Donhang; Fetter, Lula; Meinhold, Bruce

    2015-01-01

    A multi-layer ceramic capacitor (MLCC) is a high-temperature (1350C typical) co-fired ceramic monolithic that is composed of many layers of alternately stacked oxide-based dielectric and internal metal electrodes. To make the dielectric layers insulating and the metal electrode layers conducting, only highly oxidation-resistant precious metals, such as platinum, palladium, and silver, can be used for the co-firing of insulating MLCCs in a regular air atmosphere. MLCCs made with precious metals as internal electrodes and terminations are called precious-metal electrode (PME) capacitors. Currently, all military and space-level applications only address the use of PME capacitors.

  7. Quantitative impedance characterization of sub-10 nm scale capacitors and tunnel junctions with an interferometric scanning microwave microscope

    International Nuclear Information System (INIS)

    We present a method to characterize sub-10 nm capacitors and tunnel junctions by interferometric scanning microwave microscopy (iSMM) at 7.8 GHz. At such device scaling, the small water meniscus surrounding the iSMM tip should be reduced by proper tip tuning. Quantitative impedance characterization of attofarad range capacitors is achieved using an ‘on-chip’ calibration kit facing thousands of nanodevices. Nanoscale capacitors and tunnel barriers were detected through variations in the amplitude and phase of the reflected microwave signal, respectively. This study promises quantitative impedance characterization of a wide range of emerging functional nanoscale devices. (paper)

  8. Field Experiments on 10 kV Switching Shunt Capacitor Banks Using Ordinary and Phase-Controlled Vacuum Circuit Breakers

    OpenAIRE

    Wenxia Sima; Mi Zou; Qing Yang; Ming Yang; Licheng Li

    2016-01-01

    During the switching on/off of shunt capacitor banks in substations, vacuum circuit breakers (VCBs) are required to switch off or to switch on the capacitive current. Therefore, the VCBs have to be operated under a harsh condition to ensure the reliability of the equipment. This study presents a complete comparison study of ordinary and phase-controlled VCBs on switching 10 kV shunt capacitor banks. An analytical analysis for switching 10 kV shunt capacitor banks is presented on the basis of ...

  9. Mechanical Engineering Safety Note: Analysis and Control of Hazards Associated with NIF Capacitor Module Events

    Energy Technology Data Exchange (ETDEWEB)

    Brereton, S

    2001-08-01

    The NIF capacitor module was reviewed with respect to pressure venting and shrapnel containment during failures. A modified module concept was proposed that would adequately vent the pressure, yet be effective at containing shrapnel. Two large vents are provided on each side of the module. These have fixed vent areas, and are immediately accessible for pressure venting at the beginning of a pressure transient. A shrapnel shield is located on the outside of each vent opening forming a chute. The chute contains a collimator. This increases the number of bounces that shrapnel must take on the way out, and directs the shrapnel to the trap beneath. The trap contains a depth of clear pine, sufficient to completely absorb the energy of even the most energetic fragment considered. Based on a review of the evidence from past capacitor failures at the FANTM facility at Sandia National Laboratory, Albuquerque, and additional theoretical estimates, the peak pressure generated in the module during explosive events was estimated to be less than 40 psig. This internal pressure in the FANTM module appears to be tolerable, as only minor damage to the module and to internal components was observed after events. The new module concept proposed here provides increased venting area, fully available at the initiation of an event. It is expected that even less damage would be observed if an event occurred in a module with this design. The module joints and connections were formally reviewed with respect to their tolerance to a brief internal pressure as high as 40 psig. With minor modifications that have been incorporated into the design, the module was shown to maintain its integrity during such events. Some of the calculations performed estimated the quantity of dielectric oil that could be involved in a capacitor failure. It was determined that a very small amount of the available oil would contribute to the explosive event, on the order of 500 g or less. This is a small fraction of

  10. Substituted Quaternary Ammonium Salts Improve Low-Temperature Performance of Double-Layer Capacitors

    Science.gov (United States)

    Brandon, Erik J.; Smart, Marshall C.; West, William C.

    2011-01-01

    Double-layer capacitors are unique energy storage devices, capable of supporting large current pulses as well as a very high number of charging and discharging cycles. The performance of doublelayer capacitors is highly dependent on the nature of the electrolyte system used. Many applications, including for electric and fuel cell vehicles, back-up diesel generators, wind generator pitch control back-up power systems, environmental and structural distributed sensors, and spacecraft avionics, can potentially benefit from the use of double-layer capacitors with lower equivalent series resistances (ESRs) over wider temperature limits. Higher ESRs result in decreased power output, which is a particular problem at lower temperatures. Commercially available cells are typically rated for operation down to only 40 C. Previous briefs [for example, Low Temperature Supercapacitors (NPO-44386), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), p. 32, and Supercapacitor Electrolyte Solvents With Liquid Range Below 80 C (NPO-44855), NASA Tech Briefs, Vol. 34, No. 1 (January 2010), p. 44] discussed the use of electrolytes that employed low-melting-point co-solvents to depress the freezing point of traditional acetonitrile-based electrolytes. Using these modified electrolyte formulations can extend the low-temperature operational limit of double-layer capacitors beyond that of commercially available cells. This previous work has shown that although the measured capacitance is relatively insensitive to temperature, the ESR can rise rapidly at low temperatures, due to decreased electrolyte conductance within the pores of the high surface- area carbon electrodes. Most of these advanced electrolyte systems featured tetraethylammonium tetrafluoroborate (TEATFB) as the salt. More recent work at JPL indicates the use of the asymmetric quaternary ammonium salt triethylmethylammonium tetrafluoroborate (TEMATFB) or spiro-(l,l')-bipyrrolidium tetrafluoroborate (SBPBF4) in a 1:1 by volume solvent

  11. High performance metal-insulator-metal capacitor using a SrTiO3/ZrO2 bilayer

    Science.gov (United States)

    Jorel, C.; Vallée, C.; Gonon, P.; Gourvest, E.; Dubarry, C.; Defay, E.

    2009-06-01

    Future integration of metal-insulator-metal capacitors requires devices with high capacitance density and low quadratic voltage coefficient of capacitance (α). A major problem is that the increase in capacitance density is usually accompanied by increased voltage nonlinearities. By combining two high-k materials with opposite α, it is demonstrated that it is possible to obtain capacitors with both high capacitance density and minimal nonlinearity. A SrTiO3/ZrO2 bilayer was used to elaborate capacitors displaying a voltage coefficient of -60 ppm/V2 associated with a density of 11.5 fF/μm2. These devices constitute excellent candidates for the next generation of metal-insulator-metal capacitors.

  12. Towards A Model-based Prognostics Methodology for Electrolytic Capacitors: A Case Study Based on Electrical Overstress Accelerated Aging

    Data.gov (United States)

    National Aeronautics and Space Administration — A remaining useful life prediction methodology for elec- trolytic capacitors is presented. This methodology adopts a Kalman filter approach in conjunction with an...

  13. Towards A Model-Based Prognostics Methodology For Electrolytic Capacitors: A Case Study Based On Electrical Overstress Accelerated Aging

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper presents a model-driven methodology for predict- ing the remaining useful life of electrolytic capacitors. This methodology adopts a Kalman filter...

  14. Placement of DG and Capacitor for Loss Reduction, Reliability and Voltage Improvement in Distribution Networks Using BPSO

    Directory of Open Access Journals (Sweden)

    Reza Baghipour

    2012-11-01

    Full Text Available This paper presents multi-objective function for optimally determining the size and location of distributed generation (DG and capacitor in distribution systems for power loss minimization, reliability and voltage improvement. The objective function proposed in this paper includes reliability index, active power loss index, DG's and capacitor's investment cost index and voltage profile index which is minimized using binary particle swarm optimization algorithm (BPSO. The effectiveness of the proposed method is examined in the 10 and 33 bus test systems and comparative studies are conducted before and after DG and capacitor installation in the test systems. Results illustrate significant losses reduction and voltage profile and reliability improvement with presence of DG unit and capacitor.

  15. Li-ion capacitors with carbon cathode and hard carbon/stabilized lithium metal powder anode electrodes

    Science.gov (United States)

    Cao, W. J.; Zheng, J. P.

    2012-09-01

    A lithium-ion capacitor was developed using a mixture of stabilized lithium metal powder and hard carbon as the anode electrode, while activated carbon was used as the cathode. A specific energy of approximately 82 Wh kg-1 was obtained based on the weight of electrode materials; however, when the electrolyte, separator, and current collectors were included, the specific energy of an assembled Li-ion capacitor was about 25 Wh kg-1. The capacitor was able to deliver over 60% of the maximum energy at a discharge C-rate of 44C. Through continuous galvanostatic charge/discharge cycling, the capacitance of the Li-ion capacitor degraded less than 3% over 600 cycles.

  16. SUPER-CAPACITOR APPLICATION IN ELECTRICAL POWER CABLE TESTING FACILITIES IN THERMAL ENDURANCE AND MECHANICAL BRACING TESTS

    Directory of Open Access Journals (Sweden)

    I. V. Oleksyuk

    2015-01-01

    Full Text Available The current-carrying cores of the electrical power cables should be resistant to effects of short-circuit currents whose values depend on the material of the core, its cross-sectional area, cable insulation properties, environment temperature, and the duration of the short-circuit current flow (1 and 3–4 sec. when tested for thermal endurance and mechanical bracing. The facilities for testing the 10 kV aluminum core cables with short-circuit current shall provide mechanical-bracing current 56,82 kA and thermal endurance current 11,16 kA. Although capacitors provide such values of the testing currents to the best advantage, utilizing conventional capacitor-units will involve large expenditures for erecting and  running a separate building. It is expedient to apply super-capacitors qua the electric power supply for testing facilities, as they are capacitors with double-electrical layer and involve the current values of tens of kilo-amperes.The insulation voltage during short-circuit current testing being not-standardized, it is not banned to apply voltages less than 10 kV when performing short-circuit thermal endurance and mechanical bracing tests for electrical power cables of 10 kV. The super-capacitor voltage variation-in-time graph consists of two regions: capacitive and resistive. The capacitive part corresponds to the voltage change consequent on the energy change in the super-capacitors. The resistive part shows the voltage variation due to the active resistance presence in the super-capacitor.The author offers the algorithm determining the number of super capacitors requisite for testing 10 kV-electrical power cables with short-circuit currents for thermal endurance and mechanical bracing. The paper shows that installation of super-capacitors in the facilities testing the cables with short-circuit currents reduces the area needed for the super-capacitors in comparison with conventional capacitors more than by one order of magnitude.

  17. Stability of La2O3 Metal-Insulator-Metal Capacitors under Constant Voltage Stress

    Science.gov (United States)

    Wu, Shu-Hua; Deng, Chih-Kang; Hou, Tuo-Hung; Chiou, Bi-Shiou

    2010-04-01

    In this study, we demonstrate the stability of high-κ La2O3 metal-insulator-metal (MIM) capacitors under constant voltage stress (CVS). It was found that the variation in capacitance caused by CVS strongly depends on the injected charges regardless of stress biases. Furthermore, the quadratic voltage coefficient of capacitance (α) decreases with a logarithmic increase in dielectric loss. Charge trapping contributes to the relative capacitance variation under CVS while the reduced carrier mobility due to the stress-induced traps is responsible for the reduction of α. Additionally, high stability of 10-year lifetime is achieved for a 10-nm La2O3 MIM capacitor with an 11.4 fF/µm2 capacitance density.

  18. Self-healing in segmented metallized film capacitors: Experimental and theoretical investigations for engineering design

    Science.gov (United States)

    Belko, V. O.; Emelyanov, O. A.

    2016-01-01

    A significant increase in the efficiency of modern metallized film capacitors has been achieved by the application of special segmented nanometer-thick electrodes. The proper design of the electrode segmentation guarantees the best efficiency of the capacitor's self-healing (SH) ability. Meanwhile, the reported theoretical and experimental results have not led to the commonly accepted model of the SH process, since the experimental SH dissipated energy value is several times higher than the calculated one. In this paper, we show that the difference is caused by the heat outflow into polymer film. Based on this, a mathematical model of the metallized electrode destruction is developed. These insights in turn are leading to a better understanding of the SH development. The adequacy of the model is confirmed by both the experiments and the numerical calculations. A procedure of optimal segmented electrode design is offered.

  19. Polarization of Bi2Te3 thin film in a floating-gate capacitor structure

    International Nuclear Information System (INIS)

    Metal-Oxide-Semiconductor (MOS) capacitors with Bi2Te3 thin film sandwiched and embedded inside the oxide layer have been fabricated and studied. The capacitors exhibit ferroelectric-like hysteresis which is a result of the robust, reversible polarization of the Bi2Te3 thin film while the gate voltage sweeps. The temperature-dependent capacitance measurement indicates that the activation energy is about 0.33 eV for separating the electron and hole pairs in the bulk of Bi2Te3, and driving them to either the top or bottom surface of the thin film. Because of the fast polarization speed, potentially excellent endurance, and the complementary metal–oxide–semiconductor compatibility, the Bi2Te3 embedded MOS structures are very interesting for memory application

  20. Etch Damage Evaluation in Integrated Ferroelectric Capacitor Side Wall by Piezoresponse Force Microscopy

    Institute of Scientific and Technical Information of China (English)

    WANG Long-Hai; DAI Ying; DENG Zhao

    2008-01-01

    The etch damage in integrated ferroelectrie capacitors side wall fabricated by the typical integrated process (TIPFeCAP) and the innovated integrated process (IIP-FeCAP) are investigated by piezoresponse force microscopy (PFM). The ItP-FeCAP side wail exhibits fine and clear nanoscale domain images and the same piezoresponse signal as the thin film, and the domains can also be easily switched by an external voltage. In the TIP-FeCAP side wall, owing to the effect of etch damage, the very weak piezoresponse signal and some discrete domains can be observed, and the discrete domains cannot be switched by the applied 9 V and -9 V dc voltage. The PFM results reflect the etch damage in the integrated ferroelectrie capacitors and also suggest that the PFM can be used as an ettcacious tools to evaluate the etch damage at nanoscale and spatial variations.

  1. Evaluation and modelling of integral capacitors produced by interdigitated comb electrodes

    Directory of Open Access Journals (Sweden)

    Leandro Alfredo Ramajo

    2008-12-01

    Full Text Available Integral capacitors (IC of one or two-layer printed wiring board (PWB circuits were produced using comb electrodes fixtures and dielectric composites as the inter-electrode material. ICs were fabricated at laboratory scale, using copper comb electrodes and BaTiO3-epoxy composite materials deposited on a glass-Epoxy FR4 board. They were experimentally tested in order to obtain their electrical response. Furthermore, ICs behaviour was modelled through 2-dimensional models applying finite element method (FEM. Results showed that by this laboratory technique it was possible to obtained integral capacitors with low dielectric losses. Moreover, acceptable agreement was found between numerical and experimental capacitance results for all the different analysed ICs. In conclusion, 2D FEM models are a suitable tool to predict electric response of IC devices.

  2. Negative Capacitance in BaTiO3/BiFeO3 Bilayer Capacitors.

    Science.gov (United States)

    Hou, Ya-Fei; Li, Wei-Li; Zhang, Tian-Dong; Yu, Yang; Han, Ren-Lu; Fei, Wei-Dong

    2016-08-31

    Negative capacitances provide an approach to reduce heat generations in field-effect transistors during the switch processes, which contributes to further miniaturization of the conventional integrated circuits. Although there are many studies about negative capacitances using ferroelectric materials, the direct observation of stable ferroelectric negative capacitances has rarely been reported. Here, we put forward a dc bias assistant model in bilayer capacitors, where one ferroelectric layer with large dielectric constant and the other ferroelectric layer with small dielectric constant are needed. Negative capacitances can be obtained when external dc bias electric fields are larger than a critical value. Based on the model, BaTiO3/BiFeO3 bilayer capacitors are chosen as study objects, and negative capacitances are observed directly. Additionally, the upward self-polarization effect in the ferroelectric layer reduces the critical electric field, which may provide a method for realizing zero and/or small dc bias assistant negative capacitances. PMID:27502999

  3. New Carbon Activation Process for Increased Surface Accessibility in Electrochemical Capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Doughty, Daniel H.; Eisenmann, Erhard T.

    1999-03-16

    A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm{sup 3} is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350 C for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

  4. A behavioral simulator for switched-capacitor sigma-delta modulator analog-to-digital converter

    International Nuclear Information System (INIS)

    In this paper, a PC-based simulator for state of the art oversampled switched-capacitor sigma-delta analog-to-digital converters is presented. The proposed simulator employs behavioral model of switched-capacitor integrator and non-linear quantizer to stimulate the system. The behavioral simulation of the integrator is also verified with SPICE. The simulator is fully integrated and standalone. It integrates an input netlist file interpreter, a behavioral simulator, a generic part library and a powerful post-processor to evaluate the SNR, SDR And TSNR. Both passive and active sensitivities can be investigated by the proposed simulator. The simulator is coded in C++, and is very fast

  5. Water-induced dc and ac degradations in TiO2-based ceramic capacitors

    International Nuclear Information System (INIS)

    Water-induced degradations of TiO2-based ceramic capacitors in the presence of dc and ac voltages are reported in this paper. Atomic hydrogen generated by electrolysis of water using dc voltages reduced TiO2-based ceramics at ambient temperature. The resulting degradation was characterized by an increase in capacitance, a large dielectric loss and a dramatic decrease in insulation resistance. Hydrogen and oxygen generated by the electrolysis of water using ac voltages reacted with TiO2-based ceramics. The resulting degradation was characterized by a decrease in capacitance, a large dielectric loss, but no noticeable changes in insulation resistance. Water played a vital role in both dc and ac degradations of TiO2-based capacitors and an effort should be made to prevent water-induced degradations

  6. Effect of Temperature Cycling and Exposure to Extreme Temperatures on Reliability of Solid Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander

    2007-01-01

    In this work, results of multiple temperature cycling (TC) (up to 1,000 cycles) of different types of solid tantalum capacitors are analyzed and reported. Deformation of chip tantalum during temperature variations simulating reflow soldering conditions was measured to evaluate the possibility of the pop-corning effect in the parts. To simulate the effect of short-time exposures to solder reflow temperatures on the reliability of tantalum capacitors, several part types were subjected to multiple cycles (up to 100) between room temperature and 240 C with periodical measurements of electrical characteristics of the parts. Mechanisms of degradation caused by temperature cycling and exposure to high temperatures, and the requirements of MIL-PRF-55365 for assessment of the resistance of the parts to soldering heat are discussed.

  7. Artificial Neural Network Algorithm for Condition Monitoring of DC-link Capacitors Based on Capacitance Estimation

    DEFF Research Database (Denmark)

    Soliman, Hammam Abdelaal Hammam; Wang, Huai; Gadalla, Brwene Salah Abdelkarim; Blaabjerg, Frede

    2015-01-01

    In power electronic converters, reliability of DC-link capacitors is one of the critical issues. The estimation of their health status as an application of condition monitoring have been an attractive subject for industrial field and hence for the academic research filed as well. More reliable...... solutions are required to be adopted by the industry applications in which usage of extra hardware, increased cost, and low estimation accuracy are the main challenges. Therefore, development of new condition monitoring methods based on software solutions could be the new era that covers the aforementioned...... challenges. A capacitance estimation method based on Artificial Neural Network (ANN) algorithm is therefore proposed in this paper. The implemented ANN estimated the capacitance of the DC-link capacitor in a back-toback converter. Analysis of the error of the capacitance estimation is also given. The...

  8. Applications of Silver Nanowires on Transparent Conducting Film and Electrode of Electrochemical Capacitor

    Directory of Open Access Journals (Sweden)

    Yuan-Jun Song

    2014-01-01

    Full Text Available Silver nanowire has potential applications on transparent conducting film and electrode of electrochemical capacitor due to its excellent conductivity. Transparent conducting film (G-film was prepared by coating silver nanowires on glass substrate using Meyer rod method, which exhibited better performance than carbon nanotube and graphene. The conductivity of G-film can be improved by increasing sintering temperature. Electrode of electrochemical capacitor (I-film was fabricated through the same method with G-film on indium tin oxide (ITO. CV curves of I-film under different scanning rates had obvious redox peaks, which indicated that I-film exhibited excellent electrochemical pseudocapacitance performance and good reversibility during charge/discharge process. In addition, the specific capacitance of I-film was measured by galvanostatic charge/discharge experiments, indicating that I-film exhibits high special capacitance and excellent electrochemical stability.

  9. A Simple Strategy of Controlling a Balanced Voltage Capacitor in Single Phase Five-Level Inverter

    Directory of Open Access Journals (Sweden)

    Leonardus Heru Pratomo

    2015-03-01

    Full Text Available The five-level inverter has been used for many applications in renewable energy systems. Even though its harmonic distortion was lower than the conventional two-level inverter. The five-level converter has some disadvantages such as increasing power semiconductor, complex pulse width modulation control methods, and problem with the voltage balancing of the capacitor. This paper aims to propose a modified five-level inverter based on sinusoidal pulse width modulation using phase shifted carrier to enhancing the capacitor voltage balancing. This modified five-level inverter reduces the overall cost and the complexity of the pulse width modulator. Thus making the proposed control system highly simple. The performance and its controller were validated by means of standard laboratory equipments. The analysis, simulation and implementation result showed better performance of five-level inverter.

  10. Analytical modeling of thyristor-controlled series capacitors for SSR studies

    Energy Technology Data Exchange (ETDEWEB)

    Othman, H.A. [ABB Power T and D Co. Inc., Raleigh, NC (United States). Transmission Technology Inst.; Aengquist, L. [ABB Power Systems AB, Vaesteraas (Sweden). Reactive Power Compensation Div.

    1996-02-01

    Thyristor-controlled series capacitors (TCSC) have dynamic characteristics that differ drastically from conventional series capacitors especially at frequencies outside the operating frequency range. Therefore suitable models are needed to properly study the applications of TCSC on a utility system. An accurate analytical model of the TCSC which is valid in the frequency range from 0 Hz to twice the operating frequency is presented. The model incorporates the thyristor triggering logic, the synchronization system, and higher level control loops such as power oscillation damping loop. This model is suited for linearized analyses of a power system using frequency domain methods such as eigenvalues. It is particularly valuable in studying subsynchronous resonance (SSR) and enables the utility industry to better evaluate the interactions between TCSC and other devices.

  11. Patterning of tunable planar ferroelectric capacitors based on the YBCO/BSTO film structure

    Energy Technology Data Exchange (ETDEWEB)

    Karmanenko, S.F.; Dedyk, A.I.; Barchenko, V.T.; Semenov, A.A.; Ter-Martirosyan, L.T. [St Petersburg Electrotechnical University, 197376 St Petersburg (Russian Federation); Chakalov, R.A. [Institute of Electronics, Bulgarian Academy of Sciences, 1784, Sofia (Bulgaria); Lunev, A.V [Ioffe Physico-Technical Institute, 26 Polytekhnicheskaya str., St Petersburg 194021 (Russian Federation)

    1998-03-01

    Superconductor/ferroelectric (SF) and normal conducting metal/ferroelectric (NF) film structures were grown using DC and RF magnetron sputtering of ceramic YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} and Ba{sub x}Sr{sub 1-x}TiO{sub 3} targets. Low-energy ion beam etching was used for patterning an SF planar capacitor with an electrode gap of about 1.5 {mu}m. Ferroelectric films displayed a rather smooth temperature dependence of {epsilon} with a maximal value of about 850 at T {approx} 260 K (tan {delta} {approx} 0.02). Planar ferroelectric capacitors were intended for application in microwave tunable devices, so structures without hysteresis in voltage-capacitance characteristics were demanded. The SF and NF structures demonstrated a high enough coefficient of capacitance tuning (more than 1.5) and lower hysteresis for structures with YBCO electrodes. (author)

  12. New-generation low-power radiation survey instruments. [Powered by capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Waechter, D.A.; Bjarke, G.O.; Wolf, M.A.; Trujillo, F.; Umbarger, C.J.

    1983-01-01

    A number of new, ultra-low-powered radiation instruments have recently been developed at Los Alamos. Among these are two instruments which use a novel power source to eliminate costly batteries. The newly developed gamma detecting radiac, nicknamed the Firefly, and the alpha particle detecting instrument, called the Simple Cordless Alpha Monitor, both use recent advances in miniaturization and power-saving electronics to yield devices which are small, rugged, and very power-frugal. The two instruments consume so little power that the need for batteries to run them is eliminated. They are, instead, powered by a charged capacitor which will operate the instruments for an hour or more. Both line power and mechanical sources are used to charge the storage capacitors which power the instruments.

  13. Low voltage RF MEMS variable capacitor with linear C-V response

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-23

    An RF MEMS variable capacitor, fabricated in the PolyMUMPS process and tuned electrostatically, possessing a linear capacitance-voltage response is reported. The measured quality factor of the device was 17 at 1GHz, while the tuning range was 1.2:1 and was achieved at an actuation DC voltage of 8V only. Further, the linear regression coefficient was 0.98. The variable capacitor was created such that it has both vertical and horizontal capacitances present. As the top suspended plate moves towards the bottom fixed plate, the vertical capacitance increases whereas the horizontal capacitance decreases simultaneously such that the sum of the two capacitances yields a linear capacitance-voltage relation. © 2012 The Institution of Engineering and Technology.

  14. Formation of metal and dielectric liners using a solution process for deep trench capacitors.

    Science.gov (United States)

    Ham, Yong-Hyun; Kim, Dong-Pyo; Baek, Kyu-Ha; Park, Kun-Sik; Kim, Moonkeun; Kwon, Kwang-Ho; Shin, Hong-Sik; Lee, Kijun; Do, Lee-Mi

    2012-07-01

    We demonstrated the feasibility of metal and dielectric liners using a solution process for deep trench capacitor application. The deep Si trench via with size of 10.3 microm and depth of 71 microm were fabricated by Bosch process in deep reactive ion etch (DRIE) system. The aspect ratio was about 7. Then, nano-Ag ink and poly(4-vinylphenol) (PVPh) were used to form metal and dielectric liners, respectively. The thicknesses of the Ag and PVPh liners were about 144 and 830 nm, respectively. When the curing temperature of Ag film increased from 120 to 150 degrees C, the sheet resistance decreased rapidly from 2.47 to 0.72 Omega/sq and then slightly decreased to 0.6 Omega/sq with further increasing the curing temperature beyond 150 degrees C. The proposed liner formation method using solution process is a simple and cost effective process for the high capacity of deep trench capacitor. PMID:22966677

  15. High performance metal-insulator-metal capacitor using a SrTiO(3)/ZrO(2) bilayer

    OpenAIRE

    Jorel, Corentin; Vallée, Christophe; Gonon, Patrice; Gourvest, E.; Dubarry, Christophe; Defay, Emmanuel

    2009-01-01

    Future integration of metal-insulator-metal capacitors requires devices with high capacitance density and low quadratic voltage coefficient of capacitance . A major problem is that the increase in capacitance density is usually accompanied by increased voltage nonlinearities. By combining two high-k materials with opposite , it is demonstrated that it is possible to obtain capacitors with both high capacitance density and minimal nonlinearity. A SrTiO3 /ZrO2 bilayer was used to elaborate capa...

  16. GUARANTEEING THE TROUBLE-FREE OPERATION OF CAPACITOR BANKS IN POWER-SUPPLY SYSTEMS OF INDUSTRIAL ENTERPRISES

    Directory of Open Access Journals (Sweden)

    D.A. Gapon

    2016-03-01

    Full Text Available Purpose. The problem of resonance phenomena in power systems of industrial enterprises using capacitor banks for reactive power compensation was detected. Circuit of the capacitor banks tier to downshift main substation tires is present. But there is no common algorithm to calculate and avoid such trouble. The main goal of this article is to introduce some basics for power supply systems with possible resonant circuits engineering. Methodology. At the first step the data on the change of the current in the chemical company network when changing capacitor banks value are received. For these purposes the oscilloscope function of digital protection relay was used. Current data samples were analyzed by spectrum detection software. Most significant levels of the 3rd and 5th harmonics were achieved. Comparison of harmonic distortion levels with and without capacitor bank is given. Results. Achieved data allow making conclusion about overloading reasons of capacitor banks while higher harmonics currents presence. A voltage and current harmonious composition measuring in the absence of power quality analyzers using digital protection relay terminals or emergencies registers are proposed. The necessity of power quality monitoring near capacitor banks connections to avoid resonance phenomena (current and voltage resonance in industrial power supply systems is proven. The control algorithm of capacitor banks to provide electromagnetic compatibility, while various modes of nonlinear load operation is given. Originality. Using of digital protection relay oscilloscoping for current resonant detection can allow to significally reduce time and cost of solution. Replacement parallel circuit comprising a branch and one active-inductive load to another branch network in the presence of higher harmonics source are proposed. Practical value. A sequence for measuring the levels of harmonic components at the connections of capacitor banks in the absence of specialized

  17. Tube-Super Dielectric Materials: Electrostatic Capacitors with Energy Density Greater than 200 J·cm−3

    OpenAIRE

    Francisco Javier Quintero Cortes; Jonathan Phillips

    2015-01-01

    The construction and performance of a second generation of super dielectric material based electrostatic capacitors (EC), with energy density greater than 200 J·cm−3, which rival the best reported energy density of electric double layer capacitors (EDLC), also known as supercapacitors, are reported. The first generation super dielectric materials (SDM) are multi-material mixtures with dielectric constants greater than 1.0 × 105, composed of a porous, electrically insulating powder filled with...

  18. Tube-Super Dielectric Materials: Electrostatic Capacitors with Energy Density Greater than 200 J cm ˉ³

    OpenAIRE

    Phillips, Jonathan; Quintero Cortes, Francisco Javier

    2015-01-01

    The article of record as published may be found at http://dx.doi.org/10.3390/ma8095301 The construction and performance of a second generation of super dielectric material based electrostatic capacitors (EC), with energy density greater than 200 J cm ˉ³, which rival the best reported energy density of electric double layer capacitors (EDLC), also known as supercapacitors, are reported. The first generation super dielectric materials (SDM) are multi-material mixtures with diele...

  19. High Input Impedance Voltage-Mode Universal Biquadratic Filters With Three Inputs Using Three CCs and Grounding Capacitors

    OpenAIRE

    J. W. Horng; Hsu, C. H.; Tseng, C Y

    2012-01-01

    Two current conveyors (CCs) based high input impedance voltage-mode universal biquadratic filters each with three input terminals and one output terminal are presented. The first circuit is composed of three differential voltage current conveyors (DVCCs), two grounded capacitors and four resistors. The second circuit is composed of two DVCCs, one differential difference current conveyor (DDCC), two grounded capacitors and four grounded resistors. The proposed circuits can realize all the stan...

  20. Design, control and power management of a battery/ultra-capacitor hybrid system for small electric vehicles

    DEFF Research Database (Denmark)

    Li, Zhihao; Onar, Omer; Khaligh, Alireza;

    2009-01-01

    This paper introduces design, control, and power management of a battery/ultra-capacitor hybrid system, utilized for small electric vehicles (EV). The batteries are designed and controlled to work as the main energy storage source of the vehicle, supplying average power to the load; and the ultra......-capacitors are used to meet the peak power demands during transients. Power management system determines the directions of power flow, according to load demand. Presented analyses validate the efficient power management methodology....

  1. Design of aqueous redox-enhanced electrochemical capacitors with high specific energies and slow self-discharge

    OpenAIRE

    Chun, Sang-Eun; Evanko, Brian; Wang, Xingfeng; Vonlanthen, David; Ji, Xiulei; GALEN D. STUCKY; Boettcher, Shannon W.

    2015-01-01

    Electrochemical double-layer capacitors exhibit high power and long cycle life but have low specific energy compared with batteries, limiting applications. Redox-enhanced capacitors increase specific energy by using redox-active electrolytes that are oxidized at the positive electrode and reduced at the negative electrode during charging. Here we report characteristics of several redox electrolytes to illustrate operational/self-discharge mechanisms and the design rules for high performance. ...

  2. Fast Molecular-Dynamics Simulation for Ferroelectric Thin-Film Capacitors Using a First-Principles Effective Hamiltonian

    OpenAIRE

    Nishimatsu, Takeshi; Waghmare, Umesh V.; Kawazoe, Yoshiyuki; Vanderbilt, David

    2008-01-01

    A newly developed fast molecular-dynamics method is applied to BaTiO3 ferroelectric thin-film capacitors with short-circuited electrodes or under applied voltage. The molecular-dynamics simulations based on a first-principles effective Hamiltonian clarify that dead layers (or passive layers) between ferroelectrics and electrodes markedly affect the properties of capacitors, and predict that the system is unable to hop between a uniformly polarized ferroelectric structure and a striped ferroel...

  3. Asymmetry in fatigue and recovery in ferroelectric Pb(Zr,Ti)O3 thin-film capacitors

    OpenAIRE

    Chae, B. G.; Park, C. H.; Yang, Y. S.; Jang, M. S.

    2002-01-01

    We investigate the fatigue and refreshment by dc-electrical field of the electrical properties of Pt/Pb(Ti,Zr)O$_3$/Pt ferroelectric capacitors. We find an asymmetry in the refreshment, that is, the fatigued state can be refreshed by application of negative high dc-voltage to the top electrode, but no refreshment is measured by positive dc-voltage application. We also find that the fatigue can be prevented by driving the capacitor asymmetrically.

  4. Accurate Modeling of the Polysilicon-Insulator-Well (PIW) Capacitor in CMOS Technologies

    OpenAIRE

    JAMASB, Shahriar; MOOSAVİ, Roya

    2015-01-01

    Abstract. A practical method enabling rapid development of an accurate device model for the PIW MOS capacitor is introduced. The simultaneous improvement in accuracy and development time can be achieved without having to perform extensive measurements on specialized test structures by taking advantage of the MOS transistor model parameters routinely extracted in support of analog circuit design activities. This method affords accurate modeling of the voltage coefficient of capacitance over th...

  5. Performance of static var compensator control type thyristor controlled reactor and thyristor switched capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Josias M. de; Yung, Chou Shaw; Rose, Eber H.; Pantoja, Antonio L.A. [ELETRONORTE, Belem, PA (Brazil); Fouesnant, Thomas; Boissier, Luc

    1994-12-31

    This paper has the objective of presenting the philosophy of Static Var Compensator (SVC) Control as well the necessary adjustments in the project of control system to guarantee suitable performance under different operating conditions. The verification on the performance of the SVC control has been done by Transient Network Analyzer (TNA/CEPEL) studies, commissioning tests and a factory tests. The SVC is the type of Thyristor Controlled Reactor (TCR) and Thyristor Switched Capacitor (TSC). (author) 3 refs., 12 figs.

  6. Polarization-induced distortion of ions in the pores of carbon electrodes for electrochemical capacitors

    OpenAIRE

    Ovín Ania, María Concepción; Pernak, J.; Stefaniak, F.; Raymundo-Piñero, Encarnación; Béguin, F.

    2009-01-01

    This paper reports the effect of confining ionic species of the electrolyte inside the porosity of carbon electrodes during the performance of electrochemical capacitors. Solvent-free ionic liquids and a conventional organic medium were used as electrolytes, while two series of carbons with controlled pore sizes – one of them obtained from nanocasting procedure – were used as electrode materials. Our results demonstrate that under the effect of the electric field applied during the polarizati...

  7. A Robust Chaos-Based True Random Number Generator Embedded in Reconfigurable Switched-Capacitor Hardware

    OpenAIRE

    Galajda, P; M. Drutarovsky

    2007-01-01

    This paper presents a new chaos-based True Random Number Generator (TRNG) with a decreased voltage supply sensitivity. Contrary to the traditionally used sources of randomness it uses a well-defined deterministic switched-capacitor circuit that exhibits chaos. The whole design is embedded into a commercially available mixed-signal Cypress PSoC reconfigurable device without any external components. The proposed design is optimized for a reduction of influence of the supply voltage to the quali...

  8. Fast charging techniques and compact intergrated implementations for electrochemical double layer capacitors in portable applications

    OpenAIRE

    Bodnar, Rares

    2014-01-01

    The widespread increase in the range and types of portable electronic devices in the past decades has resulted in higher requirements for energy storage and conversion modules. Most of these devices use rechargeable batteries as energy storage elements. No matter what type of batteries are used (Ni-Cd, Ni-MH, Li-Ion, etc.) they all have one serious drawback in common, in terms of charging time. Electrochemical double layer capacitors (EDLCs) also known as ultracapacitors or supercapacitors se...

  9. A High Power Density Three-level Parallel Resonant Converter for Capacitor Charging

    OpenAIRE

    Sheng, Honggang

    2009-01-01

    This dissertation proposes a high-power, high-frequency and high-density three-level parallel resonant converter for capacitor charging. DC-DC pulsed power converters are widely used in military and medical systems, where the power density requirement is often stringent. The primary means for reducing the power converter size has been to reduce loss for reduced cooling systems and to increase the frequency for reduced passive components. Three-level resonant converters, which combine the mer...

  10. Design of switched-capacitor filter circuits using low gain amplifiers

    CERN Document Server

    Serra, Hugo Alexandre de Andrade

    2015-01-01

    This book describes the design of switched-capacitor filter circuits using low gain amplifiers and demonstrates some techniques that can minimize the effects of parasitic capacitances during the design phase. Focus is given in the design of low-pass and band-pass SC filters, and how higher order filters can be achieved using cascaded biquadratic filter sections. The authors also describe a low voltage implementation of a low-pass SC filter.

  11. Design and Implementation of Integrated Common Mode Capacitors for SiC JFET Inverters

    OpenAIRE

    Robutel, Rémi; Martin, Christian; Buttay, Cyril; Morel, Hervé; Mattavelli, Paulo; Boroyevitch, Dushan; Meuret, Régis

    2013-01-01

    12 pages International audience This paper deals with the issue of electromagnetic interference (EMI) in SiC-JFET inverter power modules, and proposes a solution to limit conducted emissions at high frequencies. SiC-JFET inverters can achieve very fast switching, thereby reducing commutation losses, at the cost of a high level of EMI. In order to limit conducted EMI emissions, it is proposed to integrate small-value common mode (CM) capacitors, directly into the power module. High frequ...

  12. Evaluation and modelling of integral capacitors produced by interdigitated comb electrodes

    OpenAIRE

    Leandro Alfredo Ramajo; Damian Enrique Ramajo; María Marta Reboredo; Diego Hernan Santiago; Miriam Susana Castro

    2008-01-01

    Integral capacitors (IC) of one or two-layer printed wiring board (PWB) circuits were produced using comb electrodes fixtures and dielectric composites as the inter-electrode material. ICs were fabricated at laboratory scale, using copper comb electrodes and BaTiO3-epoxy composite materials deposited on a glass-Epoxy FR4 board. They were experimentally tested in order to obtain their electrical response. Furthermore, ICs behaviour was modelled through 2-dimensional models applying finite elem...

  13. Niobium powder synthesized by calciothermic reduction of niobium hydroxide for use in capacitors

    OpenAIRE

    Baba, Masahiko; Kikuchi, Tatsuya; Suzuki, Ryosuke O.

    2015-01-01

    Metallic niobium powder was produced for applications in electric capacitors via calciothermic reduction of niobium hydroxide in molten CaCl2. Sub-micrometer spherical metallic particles with coral-like morphologies reflected the particle size of the starting oxide powder. A fine powder was obtained from the mixtures of niobium hydroxide and CaO or Ca(OH)2, respectively. Sintered pellets of the metallic powder showed a higher capacitance (CV) than those of the simply reduced powder without pr...

  14. Phenolic carbon cloth-based electric double-layer capacitors with conductive interlayers and graphene coating

    OpenAIRE

    Lei, C.; F. Markoulidis; Wilson, P; Lekakou, C.

    2015-01-01

    Phenolic resin-derived activated carbon (AC) cloths are used as electrodes for large-scale electric double-layer capacitors or supercapacitors. To increase the energy and power density of the supercapacitor, the contact resistance between the carbon cloth and the aluminium foil current collector is reduced by modifying the Al current collectors. Different modified Al current collectors, including Toyal-Carbo®(surface-modified Al), DAG® (deflocculated Acheson™ graphite) coating and poly(3,4-et...

  15. Performance of electric double layer capacitors using nanocarbons produced from nanoparticles of resorcinol-formaldehyde polymers

    OpenAIRE

    Tashima, Daisuke; Taniguchi, Mitsufumi; Fujikawa, Daisuke; Kijima, Tsuyoshi; Otsubo, Masahisa

    2009-01-01

    In this study, nanocarbons produced from nanoparticles of resorcinol-formaldehyde (RF) polymers were used instead of the conventional activated carbon for polarized electrodes in electric double layer capacitors (EDLCs) in order to improve their capacitance. The capacitances and internal resistances of the fabricated EDLCs were evaluated from their discharge characteristics. EDLCs with nanocarbon-based electrodes showed fairly high capacitance and had almost the same internal resistance as th...

  16. Effects of binders on the performance of electric double-layer capacitors of carbon nanotube electrodes

    Institute of Scientific and Technical Information of China (English)

    LI Chensha; WANG Dazhi; ZHANG Baoyou; WANG Xiaofeng; CAO Maosheng; LIANG Ji

    2005-01-01

    Polarizable electrodes of electric double layer capacitor (EDLCs) were made from carhon nanotubes. Effects of different binders, which are phenolic resin (PF) and polytetrafluoroethylene (PTFE), on the properties of polarizable electrodes are studied. Results indicate that the microstructure, pore size distribution and specific capacitance of the electrodes with PTFE binder are superior to those electrodes with PF binder after carbonization. The suitable binder (PTFE) for carbon nanotubes electrodes is proposed.

  17. Evaluation of Constant Potential Method in Simulating Electric Double-Layer Capacitors

    OpenAIRE

    Wang, Zhenxing; Yang, Yang; Olmsted, David L.; Asta, Mark; Laird, Brian B.

    2014-01-01

    A major challenge in the molecular simulation of electric double layer capacitors (EDLCs) is the choice of an appropriate model for the electrode. Typically, in such simulations the electrode surface is modeled using a uniform fixed charge on each of the electrode atoms, which ignores the electrode response to local charge fluctuations induced by charge fluctuations in the electrolyte. In this work, we evaluate and compare this Fixed Charge Method (FCM) with the more realistic Constant Potent...

  18. Improved Field Homogeneity for Transmission Line MRI Coils Using Series Capacitors

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Dong, Yunfeng

    2015-01-01

    High field magnetic resonance imaging (MRI) systems often use short sections of transmission lines for generating and sensing alternating magnetic fields. Due to distributed nature of transmission lines, the generated field is inhomogeneous. This work investigates the application of series capaci...... capacitors to improve the field homogeneity. The resulting magnetic field distribution is estimated analytically and evaluated numerically. The results are compared to a case of a conventional transmission line coil realization....

  19. Oxidation behavior of CNTs and the electric double layer capacitor made of the CNT electrodes

    Institute of Scientific and Technical Information of China (English)

    LI; Chensha; (李辰砂); WANG; Dazhi; (王大志); LIANG; Tongxiang; (梁彤祥); LI; Guitao; (李贵涛); WANG; Xiaofeng; (王晓峰); CAO; Maosheng; (曹茂盛); LIANG; Ji; (梁吉)

    2003-01-01

    The effect of CO2 oxidized carbon nanotubes (CNTs) on the performance of electric double layer capacitors (EDLCs) was studied. CO2 oxidation increased the specific area and improved the dispersity of CNTs. Specific capacitance of the polarizable electrodes in EDLCs based on the oxidized CNTs were obviously improved and the maximum specific capacitance of 47 F/g was obtained. CO2 oxidizing CNTs is hence an effective way to improve the performances of EDLCs based on the CNT electrodes.

  20. Observation of inhomogeneous domain nucleation in epitaxial Pb(Zr,Ti)O3 capacitors

    OpenAIRE

    Kim, D.J.; Jo, J. Y.; Kim, T. H.; Yang, S. M.; Chen, B; Kim, Y. S.; Noh, T. W.

    2007-01-01

    We investigated domain nucleation process in epitaxial Pb(Zr,Ti)O3 capacitors under a modified piezoresponse force microscope. We obtained domain evolution images during polarization switching process and observed that domain nucleation occurs at particular sites. This inhomogeneous nucleation process should play an important role in an early stage of switching and under a high electric field. We found that the number of nuclei is linearly proportional to log(switching time), suggesting a bro...

  1. Electrochemical Properties of Modified Carbon Electrodes for Electric Double Layer Capacitors

    OpenAIRE

    Tashima, D.; Sakamoto, A.; Taniguchi, M.; Sakoda, T; Otsubo, M.

    2008-01-01

    To improve capacitance and energy density of electric double layer capacitors (EDLCs), plasma surface treatments were carried out on surface of activated carbon sheets, and optimal conditions for the treatment were discuused. Operating gas pressure of argon was 20 Pa, and activated carbon sheets were set up so that they were covered with the dc glow discharge at 70 W. Electrochemical properties, including cyclic voltammetry (CV) and cole-cole plot of EDLCs in organic electrolyte, were examine...

  2. Aligned Carbon Nano tubes Array by DC Glow Plasma Etching for Super capacitor

    International Nuclear Information System (INIS)

    To open the end of carbon nano tubes and make these ends connect with functional carboxyl group, aligned carbon nano tubes (CNTs) arrays was etched by DC glow oxygen-argon plasma. With these open-ended carbon nano tubes array as electrode materials to build super capacitor, we found that the capacity (32.2 F/g) increased significantly than that of pure carbon nano tubes (6.7 F/g)

  3. Application of ZnO varistor protection to capacitors of artificially commutated inverter in MTDC system

    Energy Technology Data Exchange (ETDEWEB)

    Manohar, P.; Chandrasekharaiah, H.S. (Indian Inst. of Science, Bangalore (India). Dept. of High Voltage Engineering)

    1991-02-01

    The dynamic analysis of a mesh type multiterminal HVDC (MTDC) transmission system including an artificially commutated inverted (ACI) with varistor protected series capacitors is carried out using digital simulation technique. The study shows that the varistor protection is feasible and improves the performance of normal rated inverters which connect weak ac systems. It reduces the magnitude of dynamic overvoltage and the peak direct current at the ACI during abnormal conditions resulting in a significantly improved dynamic performance of the MTDC system.

  4. Lithium tin phosphate anode partially reduced through prelithiation for hybrid capacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Chien-Ju [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Keelung Road, Section 4, Taipei 10607, Taiwan (China); Tsai, Dah-Shyang, E-mail: dstsai@mail.ntust.edu.tw [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Keelung Road, Section 4, Taipei 10607, Taiwan (China); Chang, Chuan-hua [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Keelung Road, Section 4, Taipei 10607, Taiwan (China); Le, Minh-Vien [Chemical Engineering Department, Ho Chi Minh City University of Technology, Ho Chi Minh City (Viet Nam)

    2015-04-05

    Highlights: • LiSn{sub 2}(PO{sub 4}){sub 3} LSP is prelithiated to yield tin and made steady its electrode capacity. • Several hybrid capacitors are made with negative LSP and positive activated carbon AC. • The effects of LSP prelithiation level and LSP:AC mass ratio are studied. • The plus of metallic tin on capacity is realized only at low current densities. • The LSP-I:AC ratio of 1:1 in mass is superior under most operation conditions. - Abstract: Incorporated as the negative electrode, the LiSn{sub 2}(PO{sub 4}){sub 3} (LSP) crystals requires a prelithiation step to decompose LSP partially and yield tin metal for a relatively steadied capacity in cycling the hybrid capacitor of LiPF{sub 6} electrolyte. The charge transfer reactions of lithium alloying tin at low potentials offer a substantial amount of electrical capacity. Hence, several capacitors of LSP negative and activated carbon (AC) positive are prepared to understand the effects of prelithiation and LSP:AC mass ratio on how to exploit this electrochemical capacity. Among two prelithiation levels and three mass ratios, the combination of LSP-I (10% tin) and 1:1 (LSP:AC) mass ratio stands out as the best choice over a wide range of specific current. On the other hand, the selection of a specific current low enough to match the charge-transfer reaction kinetics enables the LSP electrode of high prelithiation level, LSP-II (45% tin), to utilize its battery-like capacity thoroughly. The maximum energy of hybrid capacitor LSP-II/AC is measured 28.7 W h kg{sup −1} at a minimum specific current 0.03 A g{sup −1}.

  5. Evaluation of 10V Chip Polymer Tantalum Capacitors for Space Applications

    Science.gov (United States)

    Teverovsky, Alexander A.

    2016-01-01

    Due to low ESR and safe failure mode, new technology chip polymer tantalum capacitors (CPTC) have gained popularity in the electronics design community, first in commercial applications, and now in hi-rel and space systems. The major drawbacks of these parts are high leakage currents, degradation under environmental stresses, and a relatively narrow temperature range of operating and storage conditions. Several studies have shown that a certain amount of moisture in polymer cathodes is necessary for a normal operation of the parts. This might limit applications of CPTCs in space systems and requires analysis of long-term exposure to deep vacuum conditions on their performance and reliability. High leakage currents and limited maximum operational temperature complicate accelerated testing that is necessary to assess long-term reliability and require new screening and qualification procedures for quality assurance. A better understanding of behavior of CPTCs as compared to traditional, MnO2, capacitors is necessary to develop adequate approaches for QA system for space applications. A specific of CPTCs is that different materials and processes might be used for low-voltage (10 V and less) and high-voltage (above 10 V) capacitors, so performance and degradation processes in these groups require separate analysis. In this work, that is a part of the NASA Electronic Parts and Packaging (NEPP) program, degradation of AC and DC characteristics under environmental stresses at different temperatures and voltages have been studied in nine lots of commercial and automotive grade capacitors rated to 10 V. Results of analysis of leakage currents, high temperature storage (HTS) up to 5000 hrs in vacuum and air at different temperatures, and Highly Accelerated Life Testing (HALT) in the range from 85 C to 145 C are presented. Temperature and voltage acceleration factors were calculated based on approximation of distributions of degradation rates with a general log-linear Weibull

  6. Electrochemical Properties of PANI as Single Electrode of Electrochemical Capacitors in Acid Electrolytes

    OpenAIRE

    Haihua Zhu; Shunjin Peng; Weijie Jiang

    2013-01-01

    The polyaniline (PANI) powder with globular sponge-like morphology was prepared by chemical solution polymerization, and its morphology and chemical structure were characterized by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The single electrode of electrochemical capacitor was made using the prepared PANI powder as active material and carbon paper as current collector. Electrochemical properties of PANI as a single electrode in 1 M HCl...

  7. STUDY OF STATIC ELECTRICITY CHARGE ACCUMULATION ON SURFACE OF FLUOROPOLYMER-4 PRODUCTS USING VIBRATING CAPACITOR METHOD

    Directory of Open Access Journals (Sweden)

    H. Vershina

    2014-10-01

    Full Text Available The paper presents investigations of processes pertaining to surface charge accumulation and running of fluoropolymer-4 products using vibrating capacitor method. Modification of a measurement technique allowing to register distribution of dielectric surface potential without disturbance of the surface charged state has been described in the paper. The paper contains graphics of spatial distribution of surface potential of fluoropolymer-4 products after various treatments. The paper reveals that thermal treatment (tempering reduces static characteristics of fluoropolymer-4.

  8. Implementation of a Capacitor Less Low Dropout Voltage Regulator on Chip (SOC)

    OpenAIRE

    Shailika Sharma; Himani Mittal

    2014-01-01

    — In this paper we have implemented a linear voltage low drop out regulator for efficient power management considering the fact in mind that voltage regulators provide a constant voltage supply to the circuits. We replace the common drain by common source pass element to improve efficiency and reduce the voltage drop across the device. This research paper includes the process to remove the external capacitor allowing for greater power system (soc) application. A compensation scheme is present...

  9. Miniature wire-shaped solar cells, electrochemical capacitors and lithium-ion batteries

    OpenAIRE

    Shaowu Pan; Zhitao Zhang; Wei Weng; Huijuan Lin; Zhibin Yang; Huisheng Peng

    2014-01-01

    It is critically important to develop miniature energy harvesting and storage devices in modern electronics, for example, for portable and foldable electronic facilities. In this review article, novel miniature solar cells, electrochemical capacitors and lithium-ion batteries as well as their integrated devices are carefully summarized. Particular emphasis has been paid to wire-shape energy devices that exhibit unique and promising advantages such as being lightweight and weaveable compared w...

  10. LTC And Shunt Capacitor Switching In Smart Grid: Sensitivity To Plug-In Electric Vehicle Forecasts

    OpenAIRE

    Sara Deilami

    2015-01-01

    Optimal scheduling of transformer load tap changer (LTC) and switched shunt capacitors (SSCs) in smart grid (SG) with plug-in electric vehicles (PEVs) and nonlinear loads can be performed to reduce system losses, node voltage fluctuations and total harmonic distortion (THD). This paper investigates the effects of vehicles’ plug-in time forecast errors on performance of LTC and SSCs switching. First, a genetic algorithm (GA) is used to determine the optimal switching schedules with...

  11. Shunt-capacitor-assisted synchronization of oscillations in intrinsic Josephson junctions stack

    OpenAIRE

    Martin, I.; Halász, Gábor B.; Bulaevskii, L. N.; Koshelev, A. E.

    2010-01-01

    We show that shunt capacitor stabilizes synchronized oscillations in intrinsic Josephson junction stacks biased by DC current. This synchronization mechanism has an effect similar to the previously discussed radiative coupling between junctions, however, it is not defined by the geometry of the stack. It is particularly important in crystals with smaller number of junctions, where radiation coupling is week, and is comparable with the effect of strong super-radiation in crystal with many junc...

  12. A New Optimization Framework To Solve The Optimal Feeder Reconfiguration And Capacitor Placement Problems

    OpenAIRE

    Mohammad-Reza Askari

    2015-01-01

    Abstract This paper introduces a new stochastic optimization framework based bat algorithm BA to solve the optimal distribution feeder reconfiguration DFR as well as the shunt capacitor placement and sizing in the distribution systems. The objective functions to be investigated are minimization of the active power losses and minimization of the total network costs an. In order to consider the uncertainties of the active and reactive loads in the problem point estimate method PEM with 2m schem...

  13. The Effected Oxide Capacitor in CMOS Structure of Integrated Circuit Level 5 Micrometer Technology

    OpenAIRE

    Rodthong, S.; Burapattanasiri, B.

    2009-01-01

    This article is present the effected oxide capacitor in CMOS structure of integrated circuit level 5 micrometer technology. It has designed and basic structure of MOS diode. It establish with aluminum metallization layer by sputtering method, oxide insulator layer mode from silicon dioxide, n+ and p+ semiconductor layer, it has high capacitance concentrate. From the MOS diode structure silicon dioxide thickness 0.5 micrometer, it will get capacitance between aluminum metal layer and p+ semico...

  14. Invisibility Cloaks Modeled by Anisotropic Metamaterials Based on Inductor-capacitor Networks

    OpenAIRE

    Liu, Xiao; Li, Chao; Yao, Kan; Meng, Xiankun; Li, Fang

    2009-01-01

    Based on the transformation optics, a novel transmission-line (TL) approach to realize invisibility cloaking using planar anisotropic metamaterials (MTMs) is proposed. The two-dimensional cylindrical cloaks are modeled based on inductor-capacitor (L-C) MTMs networks. The three elements of the constitutive parameters are all allowed to be spatially inhomogeneous which lead to the full parameter realization of a cylindrical cloak. As an example, a cloak working at VHF band is modeled and its in...

  15. Lithium tin phosphate anode partially reduced through prelithiation for hybrid capacitor application

    International Nuclear Information System (INIS)

    Highlights: • LiSn2(PO4)3 LSP is prelithiated to yield tin and made steady its electrode capacity. • Several hybrid capacitors are made with negative LSP and positive activated carbon AC. • The effects of LSP prelithiation level and LSP:AC mass ratio are studied. • The plus of metallic tin on capacity is realized only at low current densities. • The LSP-I:AC ratio of 1:1 in mass is superior under most operation conditions. - Abstract: Incorporated as the negative electrode, the LiSn2(PO4)3 (LSP) crystals requires a prelithiation step to decompose LSP partially and yield tin metal for a relatively steadied capacity in cycling the hybrid capacitor of LiPF6 electrolyte. The charge transfer reactions of lithium alloying tin at low potentials offer a substantial amount of electrical capacity. Hence, several capacitors of LSP negative and activated carbon (AC) positive are prepared to understand the effects of prelithiation and LSP:AC mass ratio on how to exploit this electrochemical capacity. Among two prelithiation levels and three mass ratios, the combination of LSP-I (10% tin) and 1:1 (LSP:AC) mass ratio stands out as the best choice over a wide range of specific current. On the other hand, the selection of a specific current low enough to match the charge-transfer reaction kinetics enables the LSP electrode of high prelithiation level, LSP-II (45% tin), to utilize its battery-like capacity thoroughly. The maximum energy of hybrid capacitor LSP-II/AC is measured 28.7 W h kg−1 at a minimum specific current 0.03 A g−1

  16. Microscale electrostatic fractional capacitors using reduced graphene oxide percolated polymer composites

    KAUST Repository

    Elshurafa, Amro M.

    2013-06-14

    We show that graphene-percolated polymer composites exhibit fractional capacitance response in the frequency range of 50 kHz–2 MHz. In addition, it is shown that by varying the loading of graphene within the matrix from 2.5% to 12%, the phase can be controllably tuned from −67° to −31°, respectively. The electrostatic fractional capacitors proposed herein are easy to fabricate and offer integration capability on electronic printed circuit boards.

  17. Voltage Stability of Long Transmission Line Equipped with a Thyristor Controlled Series Capacitor

    OpenAIRE

    Prechanon Kumkratug

    2012-01-01

    Problem statement: Power-Voltage curve provides very important information for voltage stability analysis. The exact long transmission line model consists of the resistance and the reactance. The resistance causes in the active line loss. It is not easy task to achieve the power-voltage curve characteristics of power system with the exact long line model equipeed with a Thyristor Controlled Series Capacitor (TCSC). Approach: This study applies the concept of the Newton-Raphson method to itera...

  18. Voltage Stability of Medium Transmission Line Equipped with a Thyristor Controlled Series Capacitor

    OpenAIRE

    Prechanon Kumkratug

    2012-01-01

    Problem statement: Power-Voltage curve provides very important information for voltage stability analysis. The exact medium transmission line model consists of the resistance and the reactance. The resistance causes in the active line loss. It is not an easy task to achieve the power-voltage curve characteristics of power system with the exact medium line model equipped with a. Thyristor Controlled Series Capacitor (TCSC). Approach: This study applies the concept of the Newton-Raphson method ...

  19. A test protocol to screen capacitors for radiation-induced charge loss.

    Energy Technology Data Exchange (ETDEWEB)

    Zarick, Thomas Andrew; Hartman, E. Frederick

    2008-09-01

    This report presents a test protocol for screening capacitors dielectrics for charge loss due to ionizing radiation. The test protocol minimizes experimental error and provides a test method that allows comparisons of different dielectric types if exposed to the same environment and if the same experimental technique is used. The test acceptance or screening method is fully described in this report. A discussion of technical issues and possible errors and uncertainties is included in this report also.

  20. Powder metallurgical processing and metal purity: A case for capacitor grade sintered tantalum

    Indian Academy of Sciences (India)

    G S Upadhyaya

    2005-07-01

    The paper reviews the role of sintered tantalum as volumetric efficient electrical capacitor. Powder characteristics and sintering aspects are discussed. The role of impurities in influencing the electrical properties has been described. Today’s driving force behind the Ta market is the use of surface mounted versions known as chip types, for applications requiring a wide range of operational temperature, such as automotive electronics.