scholarly journals A Simple Internal Resistance Estimation Method Based on Open Circuit Voltage Test Under Different Temperature Conditions

2018 ◽  
Author(s):  
Qi Yao ◽  
Dylan Dah-Chuan Lu ◽  
Gang Lei
Keyword(s):  
Open Circuit Voltage ◽  
Estimation Method ◽  
Internal Resistance ◽  
Open Circuit ◽  
Temperature Conditions

Estimating the Internal Resistance of Li-Ion Battery with Joule's Law to find the Open Circuit Voltage

2021 ◽  
Author(s):  
Venkata Nagarjun PM ◽  
Hirshik Ram S ◽  
Pratik Uthan ◽  
Veeramani V ◽  
Senthilkumar Subramaniam
Keyword(s):  
Open Circuit Voltage ◽  
Internal Resistance ◽  
Open Circuit ◽  
Li Ion Battery ◽  
Li Ion

Thermoelectric Modules For High Temperature Waste Heat

2005 ◽  
Vol 886 ◽  
Author(s):  
Ryoji Funahashi ◽  
Toshiyuki Mihara ◽  
Masashi Mikami ◽  
Saori Urata
Keyword(s):  
Room Temperature ◽  
Open Circuit Voltage ◽  
Waste Heat ◽  
Thermal Strain ◽  
Thermoelectric Module ◽  
Internal Resistance ◽  
Open Circuit ◽  
Cold Side ◽  
Adhesive Material ◽  
Thermoelectric Modules

ABSTRACTA new adhesive material has been developed in order to obtain practically usable thermoelectric modules composed of oxide thermoelectric legs. The thermoelectric module composed of 8-pair oxide legs has been fabricated. Both hot- and cold-sides of the module were covered by alumina plates. Open circuit voltage VO and maximum power Pmax reach 0.38 V and 0.30 W, respectively at 803 K of a hot-side temperature TH and 362 K of a temperature differential ΔT between TH and cold-side temperature TC. Generating power was repeated 11 times at 873-993 K of TH and at 200-290 K of ΔT. The module was cooled down to room temperature after each generation. At third measurement internal resistance RI of the module increased by 30 %. This is due to destruction of junctions because of thermal strain. No deterioration, however, was observed in thermoelectric properties for the oxide legs.

scholarly journals Impact of flux gap upon dynamic resistance of a rotating HTS flux pump

2021 ◽  
Author(s):  
Zhenan Jiang ◽  
Christopher Bumby ◽  
Rodney Badcock ◽  
HJ Sung ◽  
Nicholas Long ◽  
...  
Keyword(s):  
Open Circuit Voltage ◽  
Internal Resistance ◽  
Open Circuit ◽  
Dynamic Resistance ◽  
Coated Conductor ◽  
Simple Circuit ◽  
Output Performance ◽  
Magnet Coil ◽  
Good Agreement ◽  
Flux Pump

HTS flux pumps enable superconducting currents to be directly injected into a magnet coil without the requirement for thermally inefficient current leads. Here, we present results from an experimental mechanically rotating HTS flux pump employing a coated-conductor stator and operated at 77 K. We show the effect of varying the size of the flux gap between the rotor magnets and coated conductor stator from 1 to 7.5 mm. This leads to a corresponding change in the peak applied perpendicular magnetic field at the stator from approximately 350 to 50 mT. We observe that our experimental device ceases to maintain a measurable output at flux gaps above 7.5 mm, which we attribute to the presence of screening currents in the stator wire. We show that our mechanically rotating flux pump is well described by a simple circuit model which enables the output performance to be described using two simple parameters, the open-circuit voltage Voc and the internal resistance, Rd. Both of these parameters are found to be directly proportional to magnet-crossing frequency and decrease with increasing flux gap. We show that the trend in Rd can be understood by considering the dynamic resistance experienced at the stator due to the oscillating amplitude of the applied rotor field. We adopt a literature model for the dynamic resistance within our coated-conductor stator and show that this gives good agreement with the experimentally measured internal resistance of our flux pump. This is the Accepted Manuscript version of an article accepted for publication in 'Superconductor Science and Technology". IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/0953-2048/28/11/115008.

scholarly journals A Time-Efficient and Accurate Open Circuit Voltage Estimation Method for Lithium-Ion Batteries

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1803 ◽  
Author(s):  
Yingjie Chen ◽  
Geng Yang ◽  
Xu Liu ◽  
Zhichao He
Keyword(s):  
Lithium Ion Batteries ◽  
Open Circuit Voltage ◽  
Estimation Method ◽  
Nonlinear Function ◽  
Lithium Ion ◽  
Open Circuit ◽  
Constant Current ◽  
Estimation Accuracy ◽  
Battery Modeling ◽  
The Difference

The open circuit voltage (OCV) of lithium-ion batteries is widely used in battery modeling, state estimation, and management. However, OCV is a function of state of charge (SOC) and battery temperature (Tbat) and is very hard to estimate in terms of time efficiency and accuracy. This is because two problems arise in normal operations: (1) Tbat changes with the current (I), which makes it very hard to obtain the data required to estimate OCV—terminal voltage (U) data of different I under the same Tbat; (2) the difference between U and OCV is a complex nonlinear function of I and is very difficult to accurately calculate. Therefore, existing methods have to design special experiments to avoid these problems, which are very time consuming. The proposed method consists of a designed test and a data processing algorithm. The test is mainly constant current tests (CCTs) of large I, which is time-efficient in obtaining data. The algorithm solves the two problems and estimates OCV accurately using the test data. Experimental results and analyses showed that experimental time was reduced and estimation accuracy was adequate.

scholarly journals Recursive State of Charge and State of Health Estimation Method for Lithium-Ion Batteries Based on Coulomb Counting and Open Circuit Voltage

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1811 ◽  
Author(s):  
Alejandro Gismero ◽  
Erik Schaltz ◽  
Daniel-Ioan Stroe
Keyword(s):  
Open Circuit Voltage ◽  
Estimation Method ◽  
Lithium Ion ◽  
Open Circuit ◽  
Operating Conditions ◽  
State Of Charge ◽  
Recursive Least Squares ◽  
State Of Health ◽  
Operation Conditions ◽  
Extensive Test

The state of charge (SOC) and state of health (SOH) are two crucial indicators needed for a proper and safe operation of the battery. Coulomb counting is one of the most adopted and straightforward methods to calculate the SOC. Although it can be implemented for all kinds of applications, its accuracy is strongly dependent on the operation conditions. In this work, the behavior of the batteries at different current and temperature conditions is analyzed in order to adjust the charge measurement according to the battery efficiency at the specific operating conditions. The open-circuit voltage (OCV) is used to reset the SOC estimation and prevent the error accumulation. Furthermore, the SOH is estimated by evaluating the accumulated charge between two different SOC using a recursive least squares (RLS) method. The SOC and SOH estimations are verified through an extensive test in which the battery is subjected to a dynamic load profile at different temperatures.

EXPERIMENTAL INVESTIGATION ON CHARACTERISTICS OF LOW-CONCENTRATING SOLAR CELLS

2011 ◽  
Vol 25 (09) ◽  
pp. 679-684 ◽  
Author(s):  
W. B. XIAO ◽  
X. D. HE ◽  
J. T. LIU ◽  
Y. Q. GAO
Keyword(s):  
Solar Cells ◽  
Light Intensity ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Incident Light ◽  
Short Circuit Current ◽  
Light Level ◽  
Spot Size ◽  
Internal Resistance ◽  
Open Circuit

At room temperature, the performance of low-concentrating solar cells is investigated experimentally and discussed by theory. The results show that the short-circuit current, which is larger than that of unconcentrated radiation, linearly increases with the light intensity and is directly proportional to the concentration ratio. However, the different behavior is obtained for the open-circuit voltage. The open-circuit voltage is also larger than that at the unconcentrated light level and follows a logarithmic function of the light intensity, showing almost no dependence on the concentration ratios. The main reason is the decrease in internal resistance of solar cell with decreasing spot size, because the increase of incident light intensity leads to an increase of current density. Therefore, an advantage of the low-concentrating photovoltaic systems results from the improvement of the short-circuit current, but not from the open-circuit voltage. This work is very significant for the design of low-concentrating system.

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