LARGE HIGH ENERGY DENSITY PULSE DISCHARGE CAPACITORCHARACTERIZATION

Fred MacDougall, Joel Ennis, Xiao Hui Yang, Ken Seal, Sanjay Phatak,Brian Spinks, Nathan Keller, Chip Naruo

General Atomics Energy ProductsGeneral Atomics Electronic Systems, Inc.

4949 Greencraig Lane, San Diego, CA 92123-1675 USA

T. Richard JowArmy Research Laboratory

2800 Powder Mill Road, Adelphi, MD 20783

Abstract II. Applications for Pulse Power Capacitors

The energy density of film capacitors continues to The high power energy discharge market is relativelyincrease. This paper discusses the performance issues small compared to other capacitor markets. Itof limited life pulsed discharge capacitors operating includes applications for medical equipment likeat better than 2 J/cc (2MJ/m3) in the 5kV to 20kV defibrillators and X-Ray equipment. Large sciencerange. Self-healing metallized electrodes have been experiments like the Z upgrade at Sandia Nationalutilized in these designs to provide graceful aging at Labs or NIF at LLNL are another major segment ofelectric fields greater than 500 MV/m. A variety of the market. Presently there is significant activity onpolymer films have been evaluated for use in these the part of the military for capacitors that will meetcapacitors. The pulse rise times where the capacitors the needs of Future Combat Systems (FCS).find application are in the range of microseconds to The requirements for the capacitors needed for FCSmilliseconds. Life tests have been performed with are more taxing than that of other segments of thethe goal of achieving at least 1000 charge/discharge market for several reasons. The two primary reasonscycles at maximum energy density. Failure modes in are that the systems are mobile rather than fixednormal charge/discharge pulse service, and short- emplacements; and the systems operate in hostilecircuit fault conditions have been evaluated. Design environments rather than a laboratory. In recognitionmodifications to increase life and energy density of this, a number of development programs have beenwere made based on those analyses. Capacitors initiated to meet these special needs. Since thedelivering greater than 1OOkJ above 2 J/cc have been platforms are mobile, there is a premium placed onbuilt, tested, and shipped. the energy density of the capacitors. Since the

environment is hostile, a premium is placed onI. Acknowledgements achieving a wide range of operating conditions.

The research reported in this document/presentation These are the primary requirements that separatewas performed in connection with contract military from commercial pulse power capacitors.W91 IQX-04-D-0003 with the U.S. Army ResearchLaboratory. The views and conclusions contained in III. Recent History of Capacitor Developmentthis document/presentation are those of the authorsand should not be interpreted as presenting the The capacitor development process has beenofficial policies or position, either expressed or evolutionary rather than revolutionary. Earlyimplied, of the U.S. Army Research Laboratory or development was primarily driven by the need forthe U.S. Government unless so designated by other banks of low cost energy storage capacitors used inauthorized documents. Citation of manufacturer's or large pulse power systems, such as those used intrade names does not constitute an official simulating EMP and radiation effects of nuclearendorsement or approval of the use thereof. The U.S. weapons. In the early 1980's the 5Ok high energyGovernment is authorized to reproduce and distribute . J vo o

reprnts orGvernent urpoes ntwitstaning11, 22, 33, 44, and up to 66 kV. These capacitorsanyopyigh nottio heeon were based on high-density Kraft paper, extended

aluminum foil electrodes, and castor oil

0-7803-9189-6/05/$20.00 ©C 2005 IEEE. 1215

impregnation. In the early 1990's, lOOkJ metallized A comparison of some of the milestone-settingelectrode capacitors became available at energy capacitors that have been developed over the years isdensities of about 1 J/cc for equivalent life given in Table 1. It should be noted that while theperformance. These capacitors had lower peak PVdF capacitors built in 1993 has a relatively highcurrent capability than the foil capacitors, and higher energy density in terms of J/cc, the M.114 capacitor isinductance, but were well-suited for millisecond- >50% higher in energy density in terms of J/g.discharge applications, such as railguns andflashlamps. Mde"t S ng - M s '

Also, in the same time period, high energy density | _Ene y Di' g Ccapacitors using high dielectric constant PVdF film | inwere manufactured in significant quantities with YihrWririuAhpIJoenergy densities of 2.4J/cc. The PVdF dielectric Fir L; ;my lIdcapacitors were expensive, suffered from a high 19 EIa Lr= a d 0ESdielectric losses, had difficulty in operating at high byLL_______ h_repetition rates, and delivered significantly less | Cap P V

energy for fast pulses. These advances in energy _____ NSWdensity were driven by military research in directed .___ __=. E == nNo__==_L_energy weapons and kinetic energy weapons, such as | 2S1(3unC|drailguns. United Defens

2HA5 j 4 EM 2un92 &64 2_6The major driver for the development of large energy -storage capacitors in the mid- to late-1990's was the T 19 ~~~~~~~~~~~~~Table1- Millilsecond Discharge CapacitorsNational Ignition Facility (NIF), a U.S. Departmentof Energy facility now being built at LawrenceLivermore National Laboratory in California. The All of the capacitors listed in Table 1 are of the self-NIF system requires 4800 units of high reliability, healing construction using metallized electrodes.low cost capacitors, each storing about 83 kJ at 24 This type of construction allows the capacitors tokV, to drive flashlamps used in laser beam energy operate close to their average breakdown voltageamplification. stress rather than below their minimum breakdown

stress. End of life results from the slow loss ofIn the last few years, military interest in directed and capacitance as the dielectric breaks down and thekinetic energy weapons, as well as in EM armor electrodes are consumed in the self-healing process.concepts, has again begun to drive development ofhigher energy density capacitors. In 2004 thedelivery of 1 OOk, 2.2 J/cc capacitors for theArmy/United Defense ETIPPS program was reportedat the IEEE Power Modulator Conference [1].

GA-ESI has also produced 1 30kJ capacitors for theGeneral Atomics' Navy railgun program in the pastyear, as well as substantial design verification andvalidation data to support a reliable lifetime of morethan 10,000 cycles.

This year, quarter megajoule ("M/4114) capacitors Figure 1 - Small Scale Capacitoroperating at 2.6 J/cc have been demonstrated. Thesecapacitors have a low dissipation factor (DF) andhigh energy efficiency. The self-healing ability has The self-healing capacitors have an advantage in themade it possible to store this amount of energy in a development process. The laboratory investigationsingle component ofreasonable size. of a new dielectric system often starts with small

capacitors where the best performing systems arechosen for further development in larger capacitors.

1216

Figure 1 shows the typical small-scale capacitor used wasted in the form of heat. In fact, measuring theto develop capacitors like that shown in Figure 2. efficiency of a circuit using this type of capacitorSelf-healing capacitors tend to have higher energy may show unexpectedly high output energy. Thisdensities when scaled up in size due to improved can be caused by an increase in capacitance thatpacking factor, whereas foil electrode capacitors occurs in most capacitors when the capacitor is putsuffer from an area scaling effect that reduces under stress. For the quarter-megajoule capacitor,breakdown strength and operating fields with size. the added stored energy associated with the increase

in capacitance, is greater than the thermal lossesIV. Quarter Megajoule Capacitors Mq./4 during a typical charge/discharge cycle. This

phenomenon should be considered when calculatingThe new quarter megajoule capacitors perform well the capacitor efficiency defined as:in high repetition rate applications. Like theirpredecessors they are designed to operate in the Energy Efficiency =Delivered Energy/('2 C V)millisecond time frame but can be designed to Where the capacitance "C" in the equation should beoperate in the microsecond time frame with some based on the capacitance value at the operatingreduction in energy density. voltage. If this is not done, the calculated efficiency

can exceed 100%The first quarter-magajoule capacitor built is shown GENERAL ATOMIC S ELECTRONIC SYSTEM S INCin Figure 2. The dimensions and electrical ratings are MJ CAPACITOR TEST RESULTSlisted in Table 2.

CapacitGr DimensiGnsLength 333 cmWidth 4.0.4 cmH Bight 81-3 icmVolume 109,224 cc

~~~~~~~Electrical ParametersVTest 6,640 VoltsCapacitance @ Vjst 13842 uFStared Energy 306 kioulse

Pulse DischargePeak Current 49A4 kAmnrpRiseTime 180 usscMeasured Delivered Enery 293 kdkulesEnergy Density 2c68Jhbc

Table 2 - Quarter Megajoule Capacitor- MJ/~~~~~~~~~~~~~~A14 Performance

Unlike past advances in capacitors, the developmentof the quarter magajoule capacitor has not resulted inan increase in cost. This new generation ofcapacitors generally cost significantly less than theirpredecessors in termns of $/Joule of stored energy.

Figure 2- First Quarter-MegaJoule Capacitor VI. Conclusions

V. Delivered Energy The development work presently under way in the

with only a small fraction of the energy delivered

1217

particularly for specific military applications. The [2] J.B. Ennis, F. W. MacDougall, R.A. Cooper, J.F.new generation of capacitors is outperforming Bates, N. Ozkan. "Recent Developments In Pulsepervious capacitors in many areas. The capacitors Power Capacitors". In Proc. of 2nd Internationalare higher in energy density, lower in cost, and safer Symposium on Pulsed Power and Plasmato operate than their predecessors. Continued work Applications Korea Electrotechnology Researchin this area will result in continued improvements and Institute Chang-Won, Kyung-Nam, Korea, Octobereven more cost effective capacitors in the future. 2001.More importantly, the capacitors will evolve into theequipment needed for the specific requirements of the [3] J.B. Ennis, F.W. MacDougall, R.A. Cooper, J.F.US military's present and future combat systems. Bates. "Self-Healing Pulse Capacitors For The

National Ignition Facility (NIF)". In Proc. of IEEEPulsed Power Conference, June 1999.

VII. REFERENCES[1] J.B.Ennis, X.H. Yang, F.W. MacDougall, K. Seal [4] F.W. MacDougall, J.B. Ennis, R.A. Cooper, J.F.J Herbig High Energy Density Capacitor Bates, N. Oskan. "Energy Density of Film CapacitorsCharacterization In Proc. 2004 IEEE-Power for ETC Gun Applications". presented at 18thModulator Conference, San Francisco, CA, May, Meeting of the Electric Launcher Association, San2004. Diego, California, October 10th, 2001.

1218

本文献由“学霸图书馆-文献云下载”收集自网络，仅供学习交流使用。

学霸图书馆（www.xuebalib.com）是一个“整合众多图书馆数据库资源，

提供一站式文献检索和下载服务”的24 小时在线不限IP

图书馆。

图书馆致力于便利、促进学习与科研，提供最强文献下载服务。

图书馆导航：

图书馆首页 文献云下载 图书馆入口 外文数据库大全 疑难文献辅助工具