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58. Design of a Battery Intermediate Storage System for Rep-Rated Pulsed Power Loads

Author

NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV, Huhman, Brett M, Neri, Jesse M, Wetz, David A, NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV, Huhman, Brett M, Neri, Jesse M, and Wetz, David A

Abstract

The U.S. Naval Research Laboratory (NRL) is developing a battery-powered, rep-rate charger for a 60-kJ capacitor bank. The capacitor will be charged with a bank of LiFePO4 batteries in conjunction with a DC-DC converter. During discharge, the batteries will generate heat from the internal resistance. If the heat is not addressed, damage to the cell may occur, leading to degraded cell lifetime and the potential for cell venting. NRL has developed an integrated cooling system for high power batteries that can limit the residual heat in the battery cells. Results from experiments will be presented, both at the cell and the module level., See also ADA581781. Presented at the IEEE Electric Ship Technologies Symposium (IEEE ESTS 2013) held in Arlington, Virginia on 22-24 April 2013. Published in the Proceedings of the IEEE Electric Ship Technologies Symposium (IEEE ESTS 2013), p1-5, April 2013. U.S. Government or Federal Purpose Rights License.

Published
2013

85. Evaluation of the switching surges generated during the installation of legacy and smart electric metering equipment.

Author

Zhenyuan Zhang, Shrestha, Biju, Honang, Haniel, Wei-Jen Lee, Jie Shi, Fielder, Jerry, Wetz, David A., and Jackson, Ashley

Abstract

Recently, electric utility customers have voiced concerns that some electronic devices inside their home were damaged during the replacement of their traditional solid state or mechanical electric meter with a new ‘Smart’ meter. In an effort to understand if and how this could occur, research has been performed to analyze the transients that are induced downstream as the meters are swapped out. The meters are swapped out in a mechanical fashion without turning off the electricity from the utility. Experiments were setup and performed to as closely as possible mimic the installation process. A number of experiments have been performed under different loading conditions. Additionally, controllable surges have been introduced to the input of the meters to observe the ability each different type of meter has on suppressing them. In the experiments, all of the different types of meters have been tested with and without various different types of loads including pure resistance, pure inductance, parallel resistance/inductance, and electronic loads such as a home personal computer. [ABSTRACT FROM PUBLISHER]

Published
2012
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86. Development of a power electronic test stand for the elevated rate recharge of electrochemical energy storage devices.

Author

Wetz, David A., Novak, Peter M., and Shrestha, Biju

Abstract

There is a high desire to recharge electrochemical energy storage devices, such as rechargeable batteries, supercapacitors, and lithium-ion capacitors, at a faster rate. However, recharging at an elevated rate is traditionally thought of as being catastrophic to the lifetime of the devices. Research has been performed charging batteries at few times the cell's rated C value in a steady state application with findings that the recharge time can be significantly reduced [1]. New research in this area is being conducted at the University of Texas at Arlington. The aim of the research is to understand the charge rate limitations of the devices mentioned above, when the elevated charge is applied in a pulsed fashion. The effect these types of elevated recharge rates have on the fundamental material properties inside the cells is being researched as well. This paper describes the development of a power electronic based test stand that can be used to transfer charge from a larger battery storage system into an individual cell using pulsed currents as high as a few kA. The rationale behind the experiments, the experimental setup developed, and some of the research progress made thus far will be discussed. [ABSTRACT FROM PUBLISHER]

Published
2012
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87. Evaluating the use of a MicroGrid as a power solution for Africa's rural areas.

Author

Ding, Zhaohao, Lee, Wei-Jen, Wetz, David, and Tsai, Chin-Chu

Abstract

Energy availability and reliability is critical to the development of a region, especially for those still in the development phase. Africa, which is the largest and most populous continent after Asia, has only 2% of the world's industrial capacity. Africa's per capita income is roughly 15% of the world average and it consumes roughly 3% of world's energy. Approximately one-third of the estimated 1.6 billion people worldwide that do not have access to electricity currently reside in Africa. Insufficient energy supply has been one of the main factors that have negatively impacted the development of Africa, especially in its rural areas. There are many options that exist for increasing the availability of electricity in this region of the world. The implementation of a MicroGrid is one such option. The intent of this paper is to evaluate the different MicroGrid concepts which could serve as an energy solution for Africa's rural areas. [ABSTRACT FROM PUBLISHER]

Published
2012
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88. A 40-Stage Synchronous Distributed Energy Railgun.

Author

Karhi, Ryan W., Wetz, David A., Giesselmann, Michael, Mankowski, John J., Diehl, Jeff P., and Kelly, Patrick M.

Subjects
*PLASMA gases, *ELECTRONIC probes, *ELECTRIC switchgear, *ELECTROMAGNETIC waves, *ELECTRIC lines, *CAPACITORS, *HYPERVELOCITY
Abstract

The development process pertaining to the design, fabrication, and testing of a 40-stage free-running arc synchronous distributed energy railgun is presented. Research efforts are still ongoing to suppress the restrike phenomenon that is responsible for causing a velocity ceiling around 6 km/s to exist on plasma armature breech-fed railguns. Numerous solutions have been theorized as viable methods of restrike prevention but lack experimental verification. In collaboration on an AFOSR Multidisciplinary University Research Initiative project, the team at Texas Tech University is responsible for characterizing a functional scale model of a synchronous distributed energy railgun to investigate the effectiveness of a distributed energy scheme to suppress the plasma restrike phenomenon and increase plasma armature railgun performance. The distributed energy scheme is theorized to suppress restrike arc formation because the back-EMF voltage is localized to active stage regions. Synchronous operation refers to the speed of an electromagnetic wave in the LC transmission line formed by the rails and capacitors being matched to the velocity of the armature. The railgun drives a hypervelocity (8 km/s) plasma armature, with no payload, to emulate the conditions of a high-altitude microsatellite launch while relieving the financial burden of a large stored energy facility. Experimental data collected from a seven-stage prototype distributed energy system are discussed which will mimic the design and operation of the first seven stages associated with the final 40-stage system, which is currently under construction. The data collected from this prototype as well as the final 40-stage system will be analyzed for secondary arc formation in an attempt to verify the distributed energy scheme's success in suppressing restrike formation. [ABSTRACT FROM AUTHOR]

Published
2011
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89. Degradation Behavior in Lithium Iron Phosphate Secondary Cells Under High Rate Pulsed Discharge

Author

Wong, Derek Nathan, Wetz, David Alan, Heinzel, John M, and Mansour, Azzam

Abstract

Three 26650 LiFePO4 (LFP) cells cycled at 15C (40 A) under a pulsed discharge (PD) profile showed an abrupt drop in their 15C recharge capacity to 0 Ahr within a 60 cycle span. EIS at 100% state of charge (SOC) shows separation in the mid-frequency semi-circle indicating rapid increase of one electrochemical component’s impedance. XAS analyses on cycled cathodes show 85% retention of active material at the bulk level and almost 100% in the surface region. XPS on PD anodes show surface films that are rich in LiF which have high impedance compared to Li2CO3 rich films. LiF rich films on the anode cause the real impedance of the anodic half-cell to increase faster than the other, slowing the charge transfer kinetics of the battery dramatically. Results indicate the bipolar PD profile increases the rate of LiF deposition on the surface of the anode compared to high rate continuous cycling.

Published
2015
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90. Study of the Impedance Growth and Capacity Fade of High Power Lithium-Iron Phosphate, Valve Regulated Lead Acid, and Nickel Metal Hydride Batteries When Cycled in High Rated Pulsed Profiles

Author

Williams, Christopher, Martin, Matthew Jene, Wetz, David Alan, and Gnegy-Davidson, Clint Gerhard

Abstract

Electrochemical energy storage has become more power and energy dense in recent years. Many applications demanding energy storage operate in a pulsed manner. The most common chemistries considered for use in these applications include valve regulated lead acid (VRLA), nickel metal hydride (NiMH), and lithium-ion (LI). The University of Texas at Arlington’s (UTA’s) Pulsed Power and Energy Laboratory (PPEL) has assembled three batteries, one of each chemistry, with ~60 V open circuit potentials (OCPs) and is in the process of experimentally characterizing their capacity fade and impedance growth when they are used to drive a high current pulsed load in a 5 seconds on / 5 seconds off pulsed profile. All of the batteries are being discharged and recharged at rates much higher than thier 1C rating. Using standard voltage, current, and thermal diagnostics as well as periodic electrochemical impedance spectroscopy (EIS) measurements, the capacity fade and impedance growth of each chemistry is being studied to understand how the high rate pulsed profile ages the cells. Empirical and lumped element models of the impedance rise will be developed to better understand what is aging internally and how it impacts the usable life of the batteries compared with manufacturers rated life predictions. The experimental and modeling efforts will be summarized and conclusions will be drawn to provide the audience with a better understanding of how each of these technologies ages when used in high rate, pulsed applications.

Published
2015
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91. The Impact of High Pulsed Loading on the Fatigue of Electrochemical Energy Storage Devices

Author

Shrestha, Biju, Wetz, David Alan, and Novak, Peter Michael

Abstract

UT Arlington is researching the impact high pulsed loading has on high power electrochemical energy storage devices. Fundamental effects on aging due to high pulsed loading are being investigated by studying the capacity fade and changes in the cells electrochemical impedance [1]. Experiments have been performed in which a 3Ah LiNixCoyAl1-x-yO2cell is discharged at rates as high as 83C (250 A) in a 10 kHz pulsed fashion for 140s. A 1C recharge procedure is used between discharge cycles. The experimental results obtained when cycling at elevated rates are compared to results obtained from a second identical cell which is charged using a 1C constant current (CC) - constant voltage (CV) procedure and discharged at a constant 1C rate. This paper describes the experiments performed and shows the impact high pulsed loading has on the aging and capacity fade of a high power lithium-ion battery after fifty cycles have been performed.

Published
2013
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92. Cycling Fatigue Induced on Electrochemical Energy Storage Cells as a Result of High C Pulsed Charging

Author

Novak, Peter Michael, Wetz, David Alan, and Shrestha, Biju

Abstract

A 3Ah lithium-ion battery, LiNixCoyAl1-x-yO2, has been repeatedlyrecharged at an elevated C rate in a pulsed fashion to understand theimpact this has on cell lifetime. A peak charge rate of 33C, ~100 A, isapplied in 3 s increments with 6 s of idle time between pulses. Betweenrecharges, the cell is discharged at a constant current (CC) 1C rate. Cellfatigue is determined using electrochemical impedance spectroscopy (EIS)and capacity measurements. During each elevated recharge, the cellsvoltage, current, and temperature are monitored using high speed dataacquisition systems. EIS measurements are made before and after each1C-CC discharge. A second cell of the same type is also cycled on apotentiostat using a 1C-CC, constant voltage (CV) recharge and 1C-CCdischarge. The goal is to compare the aging of the two cells in order tounderstand the differences introduced from elevated recharge rates.

Published
2013
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94. A Single-Frequency Impedance Diagnostic for State of Health Determination in Li-ion 4P1S Battery Packs

Author

Huhman, Brett Michael, Electrical Engineering, Mili, Lamine M., Odendaal, Willem G., Zaghloul, Amir I., Wetz, David Alan, Centeno, Virgilio A., and Brown, Alan J.

Subjects
Electrochemical Impedance Spectroscopy, EIS, Computed Tomography, LiFePO4, Battery, Pulsed Power
Abstract

State-of-Health (SoH), a specified measure of stability, is a critical parameter for determining the safe operating area of a battery cell and battery packs to avoid abuse and prevent failure and accidents. A series of experiments were performed to evaluate the performance of a 4P1S battery array using electrochemical impedance spectroscopy to identify key frequencies that may describe battery state of health at any state of charge. Using a large sample number of cells, the state of health frequency, fSoH, for these LiFePO4 26650 cells is found to be 158 Hz. Four experiments were performed to evaluate the lifetime in different configurations: single-cell at 1C (2.6A), single-cell at 10C (26A), four cells in parallel at 10C (ideal match), and four cells in parallel (manufacturer match). The lifetime for each experiment set degraded substantially, with the final parallel series reaching end of life at 400 cycles, a 75.32% reduction in life compared to operating solo. Analysis of the fSoH data for these cells revealed a change in imaginary impedance at the critical frequency that corresponded to changes in the capacity and current data, supporting the development of a single-frequency diagnostic tool. An electrochemical model of the battery was generated, and it indicated the anode material was aging faster than the SEI layer, the opposite of normal cell degradation. A post-mortem analysis of cells from three configurations (baseline, single-cell, and parallel-cell) supported the modeling, as physical damage to the copper current collector in the anode was visible in the parallel-connected cell. Ph. D.

Published
2017

95. A multi-stage distributed energy plasma arc railgun

Author

Karhi, Ryan W., Giesselmann, Michael G., Bayne, Stephen B., Rasty, Jahan, McNab, Ian, Wetz, David A., and Mankowski, John J.

Subjects
Plasma, Railgun, Plamsa arc, Distributed energy store
Abstract

The development process pertaining to the design, fabrication, coding, and testing of multi-stage distributed energy plasma arc railguns are presented. In collaboration on an Air Force Office of Scientific Research (AFOSR) funded Multidisciplinary University Research Initiative (MURI) project, the Center for Pulsed Power and Power Electronics (P3E) at Texas Tech University is responsible for developing and investigating a functional scale model of a multi-stage distributed energy store (DES) railgun to analyze its effectiveness to suppress a restrike phenomenon and increase plasma armature railgun performance [1]. The term “restrike” denotes the formation of an electrical breakdown in the railgun bore some distance behind a traveling plasma armature. The formation of this secondary arc reduces the driving force on the primary armature and has led to a velocity ceiling of approximately 6 km/s on all breech-fed plasma armature railguns. Numerous solutions have been theorized as viable methods of restrike prevention but lack experimental verification. The primary objective of our research team within the MURI effort is to experimentally test Dr. Jerry Parker’s theoretical restrike suppression technique [2] that was developed at Los Alamos National Laboratory in the 1980’s. The project tasks are organized to identify potential problematic issues and verify theoretical concepts before implementation of a full scale system.

Published
2010

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