WO2024130355A1 - Procédé d'estimation de l'état de charge par spectroscopie d'impédance électrochimique dans des batteries en fonctionnement et système associé de surveillance de batteries - Google Patents

Procédé d'estimation de l'état de charge par spectroscopie d'impédance électrochimique dans des batteries en fonctionnement et système associé de surveillance de batteries Download PDF

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Publication number
WO2024130355A1
WO2024130355A1 PCT/BR2023/050411 BR2023050411W WO2024130355A1 WO 2024130355 A1 WO2024130355 A1 WO 2024130355A1 BR 2023050411 W BR2023050411 W BR 2023050411W WO 2024130355 A1 WO2024130355 A1 WO 2024130355A1
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Prior art keywords
charge
battery
state
eis
parameters
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Portuguese (pt)
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Rodolfo Castanho FERNANDES
Érick Alves SANTOS
Hudson Giovani Zanin
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Universidade Estadual de Campinas UNICAMP
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Universidade Estadual de Campinas UNICAMP
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]

Definitions

  • the present invention falls within the field of Electronic Engineering. More specifically, the present invention relates to a method and device for determining the remaining energy stored in an electrochemical charge accumulator that is in operation, especially a battery during its operation.
  • Another conventional method consists of testing the battery in a laboratory, obtaining its voltage x state of charge curve and the equation for this curve. Then, in the application outside the laboratory, measure the instantaneous voltage of the battery, substitute this value in the equation obtained and determine the state of charge.
  • This technique also has limitations. For example, it only works for batteries whose voltage varies widely with the state of charge, and is not functional for batteries where the voltage curve varies. Voltage approaches a straight line (plateau) throughout charging or discharging.
  • Another classic method consists of measuring the internal impedance of the battery through the application of the electrochemical impedance spectroscopy technique, but with the battery at rest and not in use. This technique is not useful in a real-time application, i.e., it does not allow determining the state of charge when the battery is being used.
  • Yet another conventional method consists of measuring the battery's internal impedance and, based on previously carried out experiments, correlating this impedance measurement with the battery's state of charge.
  • the impedance measurement technique is done by monitoring the electrical current injected into the battery during charging or extracted from the battery during discharging and the respective voltage measured at the battery terminals.
  • the disadvantage of this technique is that the voltage measured by the battery terminals, fundamental for the impedance measurement, changes with a series of factors, such as temperature, battery life, discharge or charge condition, and therefore, provides an estimate that may not be sufficiently accurate for critical applications, where the state of charge must be estimated with high accuracy so as not to compromise the use and user of the battery, such as in automotive applications.
  • the prior art also teaches a method in which, during the battery charging stage and upon application of a current pulse, the electrochemical impedance spectroscopy technique is performed.
  • the impedance results are used to evaluate the internal behavior of the battery, as an indication of useful life and not for the purpose of determining the state of charge.
  • this technique applies if only for the battery charging stage, being a major disadvantage.
  • Some electrochemical cells such as Lithium-sulfur and Lithium-Iron-Phosphate cells, exhibit voltage curves per state of charge that contain flat or almost flat regions, where the state of charge varies without the voltage varying significantly. This is illustrated in Figure 2, especially in the plateaus formed in regions 200, 201 and 202, which occur even for different charging and discharging conditions. In these cases, when measuring the voltage at the battery terminals, one does not have a precise estimate of the corresponding state of charge, in the plateau region (which in the case of Figure 2, is established between 30 and 80%).
  • Electrochemical Impedance Spectroscopy is a consolidated tool in scientific and industrial circles for evaluating diffusion processes of different natures.
  • the technique can be used to model ion diffusion processes inside batteries (i.e., how ions are transported from one electrode to another throughout battery charging or discharging), allowing comparison between batteries of different chemicals and also measuring their performance under more or less aggressive conditions of use.
  • the technique is also very useful in evaluating corrosion processes on surfaces, evaluating interfaces between different materials, characterizing electrochemical sensors and many other cases.
  • the EIS technique presupposes that the sample to be analyzed is excited by two simultaneously applied electrical signals: the first being a constant voltage or current level, and the second being an alternating sinusoidal signal of variable frequency typically between 1 MHz and 1 mHz and with constant amplitude.
  • the constant signal and the alternating signal add up when applied to the sample, exciting it in such a way that electrochemical processes occur in it.
  • the frequency of the sinusoidal alternating electrical signal is changed, performing a frequency sweep such that different processes are revealed depending on the different excitations imposed on the sample.
  • the EIS device then captures the resulting electrical signals, in the form of amplitudes and phases, and composes a resulting graph containing on one axis the real impedance of the sample and on the other the imaginary impedance of the sample.
  • This graph is called by technicians in the subject the Nyquist graph or even Nyquist Plot, as the international literature prefers, and is illustrated in Figure 4, through (300) , where the regions of high frequency (301) , medium frequencies are indicated. (302) and low frequencies (303) for a typical battery curve with only two electrodes.
  • the EIS technique as it uses frequency scanning, can become very time-consuming for applications outside the laboratory. Assuming that the frequency sweep starts at 1 MHz, ends at 1 mHz, considering that usually 10 different measurement points are carried out per decade on the logarithmic scale (from 106 Hz to 10-3 Hz), we have 90 points measurement. In the high frequency region, 1 MHz to 10 kHz for example, EIS run times range from 1 ps to 100 ps and each point is therefore experimentally tested very quickly. In the medium frequency region, 10 kHz to 100 Hz, for example, each EIS occurs in a time between 100 ps and 10 ms. And in the low frequency region, 100 Hz to 1 mHz, execution times vary from 10 ms to 1000 s (approximately 17 minutes), per point.
  • the state of the art lacks a method and system capable of estimating with high precision the state of charge of a battery during its operation.
  • An EIS circuit comprises at least two current regulators and an electrical energy storage device, which are connected with one or more electrochemical cells in a configuration that decouples the energy flowing to the respective current regulators.
  • the presence of the electrical energy storage device allows each regulator to simultaneously operate at lower power levels while inducing the desired EIS disturbance current.
  • Low power operation allows for lower volume and cost for the same current compared to dissipative-only or non-dissipative current regulators.
  • the electrical energy storage device allows the energy flowing through the current regulators to be varied independently to achieve the desired EIS disturbance current while a minimum amount of heat is generated in the circuit, thus allowing the circuit occupies a minimum size and incurs minimum cost.
  • the present invention can be applied to determine the energy remaining in the battery both during charging and discharging, which is already more than some existing techniques allow.
  • the battery voltage is not used as an estimation parameter, but rather the parameters of an equivalent electrical circuit of the battery, to estimate the state of charge. Therefore, this invention applies even to those batteries that have a voltage vs . flat or nearly flat state of charge.
  • this invention provides that the electronic circuit for carrying out electrochemical impedance measurement can be simplified to the point of being embedded inside the battery, next to its protection circuit.
  • this invention proposes that electrochemical impedance spectroscopy (EIS), a traditional laboratory technique that requires many minutes or even hours to be carried out, be carried out only at medium frequencies, simplifying the electrical circuit (by not need high frequency signals) and making the process very fast (a few seconds, by eliminating the analysis at low frequencies).
  • EIS electrochemical impedance spectroscopy
  • this invention suggests that, as the electrochemical impedance spectroscopy technique reveals many distinct parameters and that each of them can be related differently to the charge state, sometimes one of them is used for estimation, sometimes another, always obtaining good results. accuracy in estimating state of charge.
  • Figure 1 illustrates hypothetical voltage curves per state of charge for Lithium-ion batteries
  • Figure 2 illustrates hypothetical voltage curves per state of charge for Lithium-sulfur and Lithium-Iron-Phosphate batteries
  • FIG. 3 is a flowchart of the method according to the present invention.
  • Figure 4 is an exemplary Nyquist plot according to the present invention.
  • Figure 5 is an exemplary equivalent electrical circuit of a battery according to the present invention.
  • Figures 6a, 6b and 6c are graphs of the behavior of the parameters Re, Rct and Cdl during the discharge of a lithium-sulfur battery
  • FIG. 7 is a representation of an energy storage module comprising an EIS circuit in accordance with the present invention
  • Figure 8 is a representation of an EIS circuit according to the present invention.
  • the method of the present invention is carried out in two distinct stages: the first being carrying out laboratory tests of the cell or battery that will be monitored, and the second being the monitoring itself carried out by the electronic system embedded in the cell or battery.
  • an SOI step is carried out to perform an electrochemical impedance spectroscopy (EIS) on a representative sample of the battery to be used in the definitive or real application, at regular intervals of state of charge, for example of 5% by 5%, and exploring the entire range of charge states (from 0 to 100%).
  • EIS electrochemical impedance spectroscopy
  • the constant current component in the EIS technique is assumed null, so that there is effectively only sinusoidal alternating current of fixed amplitude and variable frequency being applied to the sample under test. In this way, the state of charge of the sample under test is not changed during the EIS run, allowing very precise characterization of the battery's internal parameters.
  • the frequency range for performing the EIS can be chosen based on sample-specific criteria, without prejudice to the method described here, however it is typically advisable to perform the sweep at a frequency of at least 10 kHz to 100 Hz, that is, at medium frequencies. More preferably, the frequency sweep can be carried out from 10 kHz to 1 kHz. Even more preferably, the frequency sweep can be carried out from 5 kHz to 2 kHz. For each charge state, a Nyquist plot is obtained. An exemplary and non-limiting Nyquist plot is seen in Figure 4.
  • Varying the state of charge in a controlled and precise manner is a task that can be carried out by applying a constant current and regulated at high precision through a battery testing device that applies such current for a known interval of time, of in such a way that the multiplication of current by time (which results in Ampere-hours, A.h) corresponds to the desired fraction of the battery's state of charge.
  • the second step S02 of the method described in the present invention consists of extracting the parameters for composing equivalent electrical circuits from each Nyquist graph.
  • the present invention does not presuppose a specific equivalent electrical circuit and, among the many possible ones, the concept is discussed here using the circuit in Figure 5.
  • Figure 5 illustrates an exemplary and non-limiting equivalent electrical circuit called a Randles-Ershler circuit
  • parameter 401 is a pure resistor, Re, which models the total electrical resistance of the battery (electrolyte, current collectors, electrical connections ) .
  • Parameter 402 is a pure electrical resistor, Rct, which models the electrical resistance associated with charge transfer within the battery during the charging or discharging stage.
  • Parameter 403 is a pure capacitor, Cdl, which models the double-layer capacitance of the two-electrode cell.
  • parameter 404 is the open Warburg parameter, Wo, which represents the finite and linear diffusion of species.
  • the third step S03 of the method consists of tabulation, that is, organizing in the form of reference tables (look-up tables, in international literature) or any other form, the values of each parameter of the equivalent circuit, for the charging and discharging, and individually correlating them to the state of charge.
  • Figures 6a, 6b and 6c show the behavior of the parameters Re, Rct and Cdl during the discharge of a lithium-sulfur battery, taken here only as an example.
  • the mathematical regression that is, the characteristic polynomial
  • the polynomial is obtained using data from only part of the experimental curve. This is obtained by observing the plotted data and limiting the polynomial to regions where there is actually a very expressive behavior of the parameter in question depending on the charge state. In this way, the polynomial becomes more precise in calculating the parameter for any load state. Evidently, with this approach the polynomial will only represent part of the range of charge states.
  • the fourth step S04 foreseen for the present invention consists of performing the fusion of the mathematical regressions (trend lines) of all the parameters involved, so that one or another of these regressions can be used to accurately establish the state of charge battery current.
  • a careful inspection of Figures 6a, 6b and 6c reveals that the behaviors of Re and Rct are very abrupt for the 100% to 90% load state range, while the Cdl curve indicates that in this In the same range, the variation of said parameter, typically expressed in F.cm- 2 , is smoother and more organized. Therefore, to predict the charge state in operation, it is more convenient, in the example in question, to use curve 506.
  • the estimate can be redone using Re or Rct so that the new estimate is more accurate.
  • This iteration can be repeated as many times as desired until an estimate with satisfactory precision is obtained.
  • more complex circuit models comprising a greater number of parameters could be considered for different types of batteries, thus increasing the number of parameters available for estimating the state of charge, which in turn increases the chances of having a highly correlated parameter that will provide greater precision in such an estimate.
  • the only limitation would be the processing capacity of the physical device that carries it out, and the time spent to carry out the iterations must be observed considering the actual intended application.
  • crossing data from different curves can be used for a more assertive prediction and determination of the state of charge at any given moment.
  • all curves can be considered at the same time, with a specialized algorithm calculating the most precisely determinable state of charge among those possible from said curves.
  • an algorithm containing the traditional mathematical formulation of Butler-Volmer models, which describe the electrochemical behavior of the cell, would make it possible to highlight which of the parameters of the equivalent electrical circuit best serve to correlate with the state of charge.
  • such a solution requires a lot of experimental data.
  • the fifth step S05 of the method of determining the state of charge for batteries in operation revealed by the present invention consists of programming the regression curves or trend lines or, even, the reference tables obtained and exemplified here by curves 502, 504 and 506, in a memory, for example, a ROM or Flash memory, without being limited to these, of a microcontrolled device.
  • a memory for example, a ROM or Flash memory
  • Such a device may be any known in the art, for example, low-cost 8 or 16 bit microcontrollers, processors, processed circuits dedicated to numerical processing, without being limited to these.
  • EIS is performed on the cell or battery in operation.
  • EIS is advantageously performed in the medium frequency range, for example from 10 kHz to 100 Hz, either during a load operation or discharge of the cell or battery.
  • the specific range of frequencies can be appropriately chosen depending on the electrochemical characteristics of the cell or battery, however what is intended here is that it is not necessary to carry out EIS over the entire range that goes from a few mHz to tens of MHz.
  • step S07 the data obtained in the previous step undergoes a decomposition into equivalent real-time parameters, which mathematically can be done in the same way as described in step S02, with the technical difference that in S07 it is an algorithm embedded in the application.
  • the optimization and even the form of this algorithm are beyond the scope of the present invention as they are traditional in the literature and depend mainly on the computational resources (memory, processing) of the microcontrolled device.
  • a simple equivalent electrical circuit such as the one shown in Figure 5 is chosen, where each parameter can be calculated through equations that can be performed on an 8-bit microcontroller, for example.
  • step S08 a regression is performed with pre-programmed data, that is, the data recorded in step S05.
  • pre-programmed data that is, the data recorded in step S05.
  • it is up to the processed or microcontrolled device to carry out the mathematical calculation, using the polynomials previously determined in step S04.
  • polynomials previously determined in step S04.
  • they are easily solvable on low-cost microcontrollers.
  • step S02 it is possible that greater computational power will be necessary here to solve the polynomials in a timely manner, according to what each application demands.
  • step S09 an approximation of the state of charge in real time is carried out, which is the determination of the state of charge result in a range from 0 to 100%.
  • the result of this approximation is sent to a display device, for example a screen, so that it can be read by a user.
  • the second embodiment of the present invention will now be described, embodied in a battery monitoring system configured to perform at least steps S06 to S09 described above.
  • the system must be installed, preferably and without limitation, within the battery assembly, constituting the battery monitoring and management system. In specific applications, the system can be external to the battery assembly.
  • FIG. 7 describes the general organization and architecture proposed for said battery monitoring system, which in international literature is called battery monitoring system (BMS).
  • BMS battery monitoring system
  • Figure 7 is an illustrative and non-limiting arrangement of an energy storage module 600, which contains electrochemical cells and electronic circuits.
  • the cells are arranged in series and/or parallel associations depending on the voltage and electrical current required for said module 600.
  • Cells 601, 602 and 603 are arranged in series and are respectively the first, second and third cells of the Association.
  • the electrochemical cell 604 illustrates the nth cell of this exemplary association, which results in the battery of cells 605.
  • the electronic monitoring circuit 606 is typically realized on one or multiple printed circuit boards and contains the signal interface circuit 607, known in the literature as analog front-end, responsible by measuring individual cell voltage and providing appropriate electrical insulation between them and the rest of the electronic circuit.
  • state of charge indication circuit 608 responsible for measuring, calculating and visually presenting an estimate of the charge remaining in the battery 605.
  • a state of charge indication circuit 608 responsible for measuring, calculating and visually presenting an estimate of the charge remaining in the battery 605.
  • a microprocessor unit 609 with digital communication capabilities, for integration with other energy storage modules or even with a main electronics unit of the electric vehicle. , for example .
  • Such a unit has the function of equalizing the charge between the cells, whether actively or passively, typically performing this function when the module 600 is at rest.
  • the unit 610 is configured to cause a permanent fuse 611 to blow in critical cases, or just interrupt the charging or discharging process via a switch 612 that can be returned to the state initial if the fault is resolved.
  • the switch may comprise suitably associated electromechanical components and/or semiconductor elements.
  • a resistive element 613 is typically used for monitoring the total electrical current flowing in the energy storage module through the positive terminal 614 and negative terminal 615.
  • the present invention includes a circuit for carrying out the electrochemical impedance spectroscopy 616 . It is preferable that the EIS circuit is embedded with the others that make up the energy storage module 600 because this way EIS can be carried out very close to the electrochemical cells, giving the following advantages to the present invention: a) minimizes effects introduced by long electrical cables, such as unwanted inductive reactances and b) allows it to be possible to perform EIS of individual cells without the need to take all electrical terminations of the electrochemical cells outside of the energy storage module 600 .
  • the positioning of the EIS 616 circuit within the module 600 allows the impedance results to be easily made available to other embedded circuits.
  • the impedance results, already treated and processed within the circuit 616 can be made available to the interface circuit 607 through a data bus 617 for measuring the interface or even made available to the status indication circuit of charge 608 through a data bus 618 to improve precision in calculating the state of charge or to compare two different techniques: one for measuring the state of charge and the other for inferring the state of charge.
  • the data resulting from the EIS circuit 616 can be made available through data buses 619 and 620 respectively to the communication circuits 609 and balancing and security circuits 610.
  • the first can use the information to send to an electronic general monitoring center for the application (electric vehicle, for example) while the second can use the EIS information to adjust the load balancing parameters between cells electrochemistry.
  • the EIS circuit can either be powered by the energy storage module itself where it is installed or externally, through a connection 621. In the case of being powered by an external source, this could be the the same one that powers the application's main electronics center (for example, an electric vehicle).
  • the power supply of the EIS circuit being carried out inside the module 600 itself provides the advantage of eliminating connections and cabling with the outside, resulting in a more robust and compact module.
  • providing the power supply externally allows the EIS circuit not to consume energy from the module where it is installed, therefore minimizing the self-discharge of the energy storage module.
  • the present invention uses electrochemical impedance spectroscopy in its galvanostatic form and adds to this the fact that it is proposed here that there is no direct current throughout the execution of the EIS. This further reinforces the possibility and practical aspects of the present invention, since the EIS 616 circuit will consume very low currents, on the order of a few mA, to carry out the technique proposed here, minimally interfering with the state of charge of the cells and the module. energy storage you want to monitor.
  • Figure 8 illustrates a possible non-limiting organization of the EIS 616 circuit with the characteristics necessary to carry out the technique described in the present invention. The following description will be comprehensive, since people skilled in the art will have the necessary basis to choose specific components and/or combinations thereof that meet the particular needs of each practical application.
  • the circuit relating to performing EIS 616 may contain a microcontroller or microprocessor 700 with processing capacity such that it is sufficient to perform the EIS analysis and algorithm described above, particularly steps S 06 to S 09 .
  • the microcontroller or microprocessor 700 also contains the table of experimental data and mathematical regressions described previously and which correlate the EIS parameters with the state of charge previously obtained when testing the battery in question.
  • the microcontroller or microprocessor 700 is further configured to perform calculations pertaining to the EIS in real time.
  • the microcontroller or microprocessor 700 activates or controls a waveform generator 701 which is responsible for generating binary numbers corresponding to the sinusoidal waveform with amplitude and frequency as required by the EIS technique.
  • waveform frequencies are typically in the EIS mid-frequency range, 10 kHz to 100 Hz.
  • the output of the waveform generator 701 is connected to a digital-analog converter 702, responsible for effectively converting binary numbers into an electrical voltage or current signal at high speed. This signal is amplified by an amplifier component 703 and appropriately isolated from the rest of the system through an excitation component 704.
  • a transistor circuit 705 is also included to adapt voltage levels, achievable, for example, through MOSFET type transistors.
  • this circuit serves as an interface with other voltages existing in the application in question (electric vehicles, for example).
  • the sinusoidal electrical signal passes through the transistor circuit 705 and arrives with adequate amplitude and frequency to the battery or electrochemical cells under test.
  • a selector component 706 is used to direct the electrical signal to a specific cell for performing EIS in the same or to the set of cells 605, as necessary.
  • the selector component can be made using high-speed semiconductors and controlled from the microcontroller or microprocessor 700.
  • reception selector 707 is connected to each of the possible EIS performance points. This component is configured to capture the electrical signal originating from the selector component 706 after passing through the electrochemical cell being tested and direct this signal to an analog-to-digital converter 708. The latter converts the electrical response signal, originating from the tested cell, into a binary number that can be processed and used by the microcontroller or microprocessor 700.
  • the microcontroller or microprocessor 700 may also be provided with a form of communication 709, for example I2C or serial, without being limited to these, to establish data exchange with other external circuits.
  • the microcontroller or microprocessor 700 can further be configured to detect whether the battery 605 is in a state of charge or discharge, thereby accurately choosing the reference table recorded in it. Optionally, such detection can be done by the signal interface circuit 607, without being limited to it. For example, another dedicated module could make this determination without departing from the scope of the present invention.
  • this feature of the present invention is particularly advantageous, as it eliminates or at least reduces the need for the electronic circuit to generate (synthesize) and capture signals high-frequency electrical devices, whether current or voltage.
  • Both the electronic circuit (hardware) and the software existing in the BMS can benefit from this approach, possible but not mandatory, which is unique to the technique described here.
  • the present invention has sufficient versatility to be used: a) in the battery as a whole, with a single circuit of EIS assesses the state of charge, b) on each individual module, so that multiple EIS electronic circuits exist in the battery and each is capable of processing the spectroscopy data and estimating the state of charge locally and forward the information to the electric vehicle's electronic control unit in this example.
  • the electronic circuit can perform EIS only at high and medium frequencies, concluding that it in a few seconds and determine the state of charge by comparing the results obtained in real time with the pre-programmed regression curve.
  • the present method can be used alone on a battery as a unique way of determining its state of charge at any time, or it can be used in integration with other methods of calculating and determining the state of charge as a way of improving the accuracy of this determination. Furthermore, there is no limitation on the application of the method proposed here depending on the dimensions, voltage, chemical composition or capacity of the cell or battery in operation. Thus, it proves to be a highly versatile method.
  • the data obtained in the laboratory testing phase may be such that they include the degradation of the cells or batteries in question, either due to aging at rest, or due to by executing multiple charge and recharge cycles.
  • the respective trend lines can be pre-programmed into the microcontroller or microprocessor 700 in an architecture similar to that described by Figures 7 and 8.
  • the microcontroller or microprocessor 700 has a memory for said programming, for example, a ROM or Flash memory, without being limited to these.
  • the present invention can be applied to determine the remaining energy in the battery both during charging and discharging, which is already more than some existing techniques allow.
  • the battery voltage is not used as an estimation parameter, but rather the parameters of an equivalent electrical circuit of the battery, to estimate the state of charge. Therefore, this invention applies even to those batteries that have a flat or almost flat voltage versus state of charge curve.
  • the present invention provides that the electronic circuit for carrying out electrochemical impedance measurement can be simplified to the point of being embedded inside the battery, next to its protection circuit.
  • the present invention proposes that electrochemical impedance spectroscopy, a traditional laboratory technique that requires many minutes or even hours to be carried out, be carried out only at medium frequencies, simplifying the electrical circuit (as it does not require high frequency signals) and making the process very fast (a few seconds, by eliminating the analysis at low frequencies).
  • electrochemical impedance spectroscopy a traditional laboratory technique that requires many minutes or even hours to be carried out, be carried out only at medium frequencies, simplifying the electrical circuit (as it does not require high frequency signals) and making the process very fast (a few seconds, by eliminating the analysis at low frequencies).
  • the present invention can be used in together with low and high frequency EIS data.
  • the present invention suggests that, as the electrochemical impedance spectroscopy technique reveals many distinct parameters and that each of them can be related differently to the state of charge , each one of them is selectively and strategically used for estimation, in order to obtain satisfactory accuracy in estimating the state of charge.

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Abstract

Dans un premier temps, la présente invention peut être utilisée pour déterminer l'énergie existante dans une batterie aussi bien pendant la charge que pendant la décharge, ce qui va au-delà de ce que permettent quelques techniques existantes. Dans un deuxième temps, la tension de la batterie comme paramètre d'estimation n'est pas utilisée, mais le sont les paramètres d'un circuit électrique équivalent de la batterie pour estimer l'état de charge. Ensuite, cette invention s'applique même aux batteries qui présentent une courbe de tension c.\ un état de charge plane ou quasi plane. Dans un troisième temps, ladite invention prévoit que le circuit électrique pour effectuer la mesure de l'impédance électrochimique peut être simplifié au point d'être embarqué dans la batterie conjointement avec le circuit de protection de celle-ci. Dans un quatrième temps, ladite invention propose que la spectroscopie d'impédance électrochimique (SIE), qui est une technique classique de laboratoire et qui requiert beaucoup de minutes voire d'heures pour être mise en oeuvre, soit exécutée uniquement à moyennes fréquences, simplifiant le circuit électrique (pour ne pas avoir besoin de signaux de haute fréquence) et rendant le processus très rapide (quelques secondes, pour éliminer l'analyse à basses fréquences). Enfin, cette invention suggère que, comme la technique de spectroscopie d'impédance électrochimique (SIE) révèle beaucoup de paramètres distincts et que chacun de ceux-ci peut être associé de manière différente à l'état de charge, tantôt l'un d'eux est alors utilisé pour l'estimation, tantôt un autre, ce qui permet d'obtenir une bonne précision de l'estimation de l'état de charge.
PCT/BR2023/050411 2022-12-21 2023-11-25 Procédé d'estimation de l'état de charge par spectroscopie d'impédance électrochimique dans des batteries en fonctionnement et système associé de surveillance de batteries Ceased WO2024130355A1 (fr)

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BR102022026239-0A BR102022026239A2 (pt) 2022-12-21 Método de estimativa do estado de carga por espectroscopia de impedância eletroquímica em baterias em operação e respectivo sistema de monitoramento de baterias
BR1020220262390 2022-12-21

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