• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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    • 专利摘要:
    The invention relates to a method for determining the state of health of a first elementary cell of a battery, comprising the steps of: measuring the voltage across the cell under a reference current at several instants of a phase charging or discharging the cell between first and second state of charge states; and detecting a passage of the voltage by a particular predetermined value (UA), corresponding to a predetermined specific charge value (QA) of the cell.
    公开号:FR3018608A1
    申请号:FR1452182
    申请日:2014-03-17
    公开日:2015-09-18
    发明作者:Laurent Vinit；Fathia Karoui
    申请人:Commissariat a lEnergie Atomique CEA；Decathlon SA；Commissariat a lEnergie Atomique et aux Energies Alternatives CEA；
    IPC主号:
    专利说明:

    [0001] B13053 - DD15002ST 1 METHOD FOR ESTIMATING THE HEALTH STATUS OF A BATTERY CELL Field The present application relates to the field of electric batteries in general, and more particularly to the determination of the state of health or state of aging. of an elementary cell of a battery. DISCUSSION OF THE PRIOR ART An electric battery is a group of several rechargeable elementary cells (batteries, accumulators, etc.) connected in series and / or in parallel between two nodes or voltage supply terminals. A battery is often associated with a management device connected to the cells of the battery, which can implement various functions such as cell balancing functions, protection functions, and so on. In some systems, the management device manages gauges or indicators allowing it to know at any time the state of charge, also called SOC (of the English "State of Charge") of each elementary cell of the battery, c that is, the ratio of the charge contained in the cell to the total capacity of the cell at the instant in question. The management device can for example estimate the state of charge B13053 - DD15002ST 2 of each cell from predefined algorithms and / or measurements made by sensors connected to the cells of the battery. In some systems, the management device furthermore manages a complementary indicator of cell aging, commonly referred to as SOH, of the English "State of Health" for health status. At a given instant in the life of a cell, the SOH is equal to the ratio of the capacity of the cell at the instant considered to the capacity of the cell in the new state. The knowledge of the SOH of each cell can, for example, make it possible to identify defective cells for isolating or replacing them, or to readjust or readjust the cell state of charge gauges to take account of the aging of the cells, so as to allow to continue to provide a relatively reliable estimate. The known techniques for determining the SOH of a cell pass through the measurement of the capacity of this cell. For this, the cell can be completely discharged then fully recharged, or fully recharged and complete discharged. During the complete recharge or full discharge phase, the charge accumulated in the cell or extracted from the cell can be measured by coulometric counting, which amounts to measuring the real capacity of the cell. Knowing the real capacity of the cell, the management device can then calculate the SOH of the cell by dividing this real capacity by the capacity of the cell in the new state or by the nominal capacity of the cell, which can be memorized. in the management device. A disadvantage of these SOH determination techniques is that they require a complete discharge of the cell followed by a complete charge, or a complete charge followed by a complete discharge, which is relatively restrictive and can be problematic in some applications.
    [0002] B13053 - DD15002ST 3 Summary Thus, an embodiment provides a method for determining the health status of a first elementary cell of a battery, comprising the steps of: measuring the voltage across the cell under a current reference at several instants of a charging or discharging phase of the cell between first and second state of charge levels; and detecting a passage of the voltage by a particular predetermined value, corresponding to a particular predetermined load value of the cell. According to one embodiment, the particular values of charge and voltage correspond to the coordinates of a point of intersection of at least two curves representative of the evolution of said voltage as a function of the charge contained in the cell, to distinct aging states of the cell. According to one embodiment, the method further comprises the determination and storage of load variations of the cell between the voltage measurements. According to one embodiment, the load variations are measured by a coulomb counter or a current integrator. According to one embodiment, the load variations are estimated taking into account the time elapsed between the voltage measurements. According to one embodiment, the method comprises a step of determining the slope of the curve representative of the evolution of the voltage as a function of the charge variation of the cell, passing through the particular value of voltage. According to one embodiment, the method comprises a step of calculating the average value of the voltage between the first and second charge levels of the cell, the first and second charge levels being both greater than the value of the value of B13053 - DD15002ST 4 value load or both below the particular load value. According to one embodiment, the method further comprises, after detecting the passage of the voltage by the predetermined specific value, a step of fully recharging the cell, and measuring the charge injected into the cell during this recharging step . According to one embodiment, the particular value of charge is between 20% and 60% of the nominal capacity of full load of the cell. According to one embodiment, the cell is a lithium-ion type cell, and the particular value of charge is between 38% and 42% of the full load nominal capacity of the cell. According to one embodiment, the cell has a nominal capacity of 2.2 Ah and a full load rated voltage of 4.2 V, and the particular voltage value is in the range of 3.5 V to 3 V. According to one embodiment, the method further comprises a preliminary characterization phase comprising the acquisition, for a second elementary cell of the same type as the first cell, of at least two characteristic curves representative of the evolution of the voltage across the second cell under the reference current 25 as a function of the charge contained in the second cell, to at least two distinct aging states of the second cell. According to one embodiment, the prior characterization phase further comprises a step of determining a cross point of the two characteristic curves in the load range ranging from 20% to 60% of the nominal capacity of the cell. Another embodiment provides a system comprising: a battery having a plurality of elementary cells and a battery management device, in which B13053 - DD15002ST the management device is adapted to determine the state of health of an elementary cell by a process of the aforementioned type. According to one embodiment, the battery is a dynamically reconfigurable architecture battery, and the management device is adapted to dynamically disconnect and reconnect cells of the battery so that the battery provides an AC voltage to its terminals. According to one embodiment, the reference current 10 is zero, and the steps of measuring the voltage across the first cell are implemented during periods of disconnection of the first cell by the management device in view of the generating an alternating voltage across the battery. BRIEF DESCRIPTION OF THE DRAWINGS These features and their advantages, as well as others, will be set forth in detail in the following description of particular embodiments in a non-limiting manner with reference to the accompanying figures in which: FIG. diagram illustrating the evolution with the aging of the behavior of an elementary battery cell; Figure 2 is a diagram illustrating the evolution with aging of a characteristic value of a battery cell; and FIG. 3 illustrates, in block form, an example of an embodiment of a method for determining the state of health of an elementary battery cell. DETAILED DESCRIPTION FIG. 1 is a diagram comprising three curves 101a, 101b and 101c representing, for three states of aging or distinct states of health of an elementary cell of a battery, the evolution of the voltage, in volts (V ) at the terminals of the cell under a reference current iref 35 (that is to say the voltage across the cell when the cell is traversed by the current iref), depending on the load contained in the cell. The curves of FIG. 1 have been plotted for a lithium-ion cell of NMC (nickel cobalt manganese) / graphite type, having a nominal capacity, that is to say displayed by the manufacturer, of 2.2 Ah, and a full load nominal voltage of 4.2 V. The curve 101a represents the behavior of the cell in the new state, the curve 101b corresponds to the same cell after about 600 charge / discharge cycles representative of a typical use of the cell, and the curve 101c corresponds to the same cell after about 1200 charge / discharge cycles representative of a typical use of the cell. In this example, the voltage measurements were performed under a reference current iref zero. In addition, in FIG. 1, the charge of the cell, on the abscissa, was represented in the remaining standard ampere-hours (Ah NORM), that is to say as a percentage of the nominal capacity of the cell. It is therefore a representative quantity of the physical load actually contained in the cell, or the number of remaining Ahs, and not the state of charge (SOC) of the cell, which is a percentage of the actual total capacity of the cell that can vary with the aging of the cell. The tests carried out by the inventors have shown that the characteristic curves of the voltage at the terminals of the cell, under a constant reference current, as a function of the charge of the cell, to the various states of aging of the cell, are all monotonous ( that is to say, continuously increasing or decreasing) in the range of use of the cell, and all intersecting at the same characteristic point of the cell, here designated by the reference A. In the particular example of the figure 1, the point A corresponds to a voltage UA of 3.55 V and a load QA of 40% of the nominal capacity of the cell (ie 0.88 Ah in this example). The tests carried out by the inventors have furthermore shown that similar behavior is observable when the voltage measurements are carried out under a non-zero reference current, for example a negative current-that is, say a discharge current of the cell - or a positive current that is to say a charge current of the cell. In this case, the coordinates UA and QA of point A may change with respect to the example of FIG. 1, but the same phenomenon as in the example of FIG. 1 occurs, i.e. all the characteristic voltage / charge curves at different aging states of the cell intersect at one point A. The inventors have furthermore found that this same phenomenon is observable for other types of cells than lithium-ion cells. of the example of FIG. 1, for example lithium-ion cells having a nominal capacity other than 2.2 Ah and / or a nominal full charge voltage other than 4.2 V, or cells exhibiting different chemistry. , provided that these cells have monotonic voltage / charge characteristics (without a plateau), for example LMO (LiMn 2 O 4) / graphite lithium ion cells. The position of the point A then depends on the characteristics of the cell and the reference current iref considered, and is typically in the range of charge levels ranging from 20% to 60% of the nominal capacity of the cell. For a given type of cell, a characterization phase can be implemented, making it possible to determine the position of the point A for a reference current iref that one chooses, for example iref = 0 A. A non-limiting example of A method of characterizing a cell type will now be described. At first, a cell of the type to be characterized, having a first state of aging, can be completely discharged. This cell can then be recharged completely by periodically measuring the voltage of the cell under the current during the charging. The actual physical charge contained in the cell can be measured during the charging phase, for example at the same time. using a coulometric counter or a current integrator. It is thus possible to correspond to each measured voltage value a measured value of charge contained in the cell, so as to obtain a remaining voltage / charge characteristic curve of the type shown in FIG. 1. It will be noted that if the charging current is different from iref (especially in the case iref-0), it is possible periodically to force the current through the cell to the value iref for a short time, for example less than 1 ms and preferably less than 10 ps, the time to perform a measurement the voltage across the cell. Alternatively, the voltage / charge characteristic curve can be acquired during a complete discharge phase of the cell, rather than during a charging phase.
    [0003] The cell can then be "aged" by being subjected to charge / discharge cycles representative of a typical use of the cell. The aforementioned steps may be repeated at least once to obtain at least a second voltage / charge characteristic curve of the type shown in FIG. 1, at least one second aging state of the cell. When at least two voltage / load characteristic curves corresponding to different aging states of the cell have been recorded, the point A can be determined from these curves, for example by looking for the point of intersection between these two characteristic curves in the load range from 20% to 60% of the rated capacity of the cell. The voltage measurements as a function of the load 30 carried out during the characterization phase may optionally be smoothed before the determination of the point A. As a non-limiting numerical example, points of the voltage / load characteristic curves may be acquired at a predetermined time. frequency 100 kHz (one point every 10 ps), then averaged over a sliding window of 2000 points (20 ms).
    [0004] B13053 - DD15002ST 9 Once the coordinates of the point A are known for a cell type and a reference current iref, they can be memorized by a device for managing a battery comprising elementary cells of this type.
    [0005] The detection, by the management device, of the passage of a cell of the battery at point A when the battery is in use, allows the management device to reliably know the load available in this cell, independently of possible drift of the battery gauges related to cell aging or other phenomena. The battery management device is, for example, adapted to implement, for each cell of the battery, a method of detecting a passage at point A comprising the following steps: measuring the voltage across the cell under the reference current iref at several instants of a phase of charging or discharging the cell between first and second state of charge levels of the cell, for example between 20% and 80% of the SOC of the cell; and detecting a particular predefined value UA of this voltage, stored in the management device, this voltage corresponding to the voltage coordinate of the predetermined point A during the characterization phase. The charging or discharging phase of the point A detection method may correspond to a charging or discharging of the cell by normal use of the battery by a system including the battery, for example an electrically assisted vehicle. If the normal charging or discharging current of the cell is different from the reference current iref, the management device may periodically force the current through the cell to the iref value for a duration preferably sufficiently short so as not to interfere with the operation. of the system, for example for a period of less than 1 ms and preferably less than 10 ps, the time B13053 - DD15002ST 10 to measure the voltage across the cell. This duration is preferably chosen, if necessary, identical or similar, for example equal to 20%, to the period during which the current is periodically forced to the value iref 5 during the characterization phase to acquire characteristic curves of the cell. Alternatively, the point A detection method may comprise a dedicated phase of charging or discharging the cell, which may be implemented by the battery management device specifically to cause a passage of the cell through point A and thus enable the detection of the passage at point A. The above-mentioned method of detecting the passage to the point A of a cell of a battery may for example be used by the management device for recalibrating or readjusting a load cell gauge of the cell. The battery management device may, for example, implement a method for evaluating the state of charge of a cell of the battery, this method comprising phases for estimating the state of charge of the cell, and, between estimation phases, recalibration phases of the estimation method making it possible to compensate for any drifts, for example drifts related to aging of the cell or drifts of the measurements made by sensors of the management system. these resetting phases may comprise phases of detection of the passage at point A of the cell. For example, a load state gauge of the cell may be reset following a phase of detection of a passage at point A of the cell, to compensate for any discrepancy between an estimated load value of the cell. and the real load value known at point A, at the moment of detection of point A. An advantage is that the resetting of a charge state gauge of the cell by detecting a passage at point A of the cell does not require a complete discharge or a complete charge of the cell. This makes it possible to make the registration phases much less restrictive than with known B13053-DD15002ST 11 state of charge load resetting solutions. In particular, it is possible to provide more frequent readjustments than in existing systems. This can for example make it possible to use simpler state of charge estimation algorithms than in existing systems, since a possible decrease in the reliability of the estimation algorithms can be compensated by more frequent readjustments. According to one aspect of the described embodiments, detection by the management device of the passage of a cell from the battery at point A may be used to determine the health status or SOH of the cell. An exemplary method for determining the SOH of a cell of a battery, which can be implemented by a battery management device, will now be described. This method comprises a phase of measuring the voltage across the cell under the reference current at several instants of a charging or discharging phase of the cell between first and second charge levels of the cell. The first and second charge levels are such that the range from the first to the second charge level comprises the charge level QA of point A of the cell. For example, the voltage measurements are made over a range of charge levels ranging from 20% to 60% of the nominal capacity of the cell, or over a range of state of charge levels (SOC) ranging from from 20% to 80%. The charging or discharging phase of the SOH determination method may correspond to charging or discharging the cell by normal use of the battery by a system including the battery. If the charging or normal discharging current of the cell is different from the reference current iref, the management device may periodically force the current through the cell to the iref value for a duration preferably sufficiently short so as not to interfere with the current. For example, for a period of less than 1 msec and preferably less than 10 μs, the time required to measure a voltage across the cell terminals. This duration is preferably chosen, where appropriate, identical or similar, for example equal to 20%, to the period during which the current is periodically forced to the value iref during the characterization phase. Alternatively, the SOH determination method may include a dedicated charge or discharge phase of the cell, which may be implemented by the battery management device specifically to determine the SOH of the cell.
    [0006] In this example, during the process of determining the SOH, the management device measures the charge accumulated in the cell or extracted from the cell between the different voltage measurements, for example by means of a coulomb counter or an integrator current. Note that if the charge or discharge rate of the cell during the SOH determination process is considered stable and known, the charge variation in the cell between two voltage measurements is proportional to the time elapsed between the two measurements. The management circuit can then estimate the load variations by the simple knowledge of the time elapsed between the voltage measurements, which can for example be measured by means of a clock. An advantage is that the SOH of the cell can then be determined without current measurement. The voltage values measured under the current iref, as well as the load variations of the cell between the different voltage measurements, can be stored, for example in a memory of the management device. The method for determining the SOH of the cell further comprises a step of detecting the passage of the voltage across the cell under the reference current iref, by the particular value of voltage V of the point A. According to a first example of realization, once the passage of the cell by the voltage UA has been detected, the SOH can be estimated by the battery management device by calculating a magnitude representative of the slope, at the point of B13053 - DD15002ST 13 voltage UA , of the characteristic curve of the voltage under the current iref as a function of the load variations of the cell. By way of example, this magnitude may be the directing coefficient of the linear interpolation of the characteristic at the voltage point UA, the directing coefficient of the derivative of the characteristic at the voltage point UA, the angle of the direction vector of the Linear interpolation of the characteristic at the voltage point UA, etc. The inventors have indeed observed (as appears in FIG. 1) that the slope, at the point of voltage UA, of the curve representative of the voltage of the cell under the current iref as a function of the charge variation of the cell, varies substantially monotonically with the SOH of the cell. In particular, in the case of lithium-ion cells, the inventors have found that the slope, at the voltage point UA, of the curve representative of the voltage of the cell under the current iref as a function of the charge variation of the cell , varies substantially linearly with the SOH of the cell.
    [0007] This linearity phenomenon is illustrated by FIG. 2 representing the evolution of the directing coefficient, in mVa (on the ordinate), at the voltage point UA, of the curve representative of the voltage of the cell under the current iref as a function of the variation. charge of the cell, as a function of the SOH of the cell, in% (abscissa). For a given cell type, a characterization phase can be implemented, making it possible to determine a variation law of the SOH of the cell as a function of the slope, at the voltage point UA, of the curve representative of the voltage of the cell. cell under the current iref depending on the load variation of the cell. For this, we can measure this characteristic slope for several distinct SOH of the same cell that is voluntarily aged in the laboratory for the purposes of characterization. For example, this characterization can be performed simultaneously with a characterization phase B13053 - DD15002ST 14 performed to determine the position of the point A for the cells of the type in question. The battery management device may comprise a conversion circuit making it possible to provide an estimate of the SOH of the cell as a function of the magnitude representative of the slope, at the voltage point UA, of the characteristic curve of the voltage of the cell under the current iref according to the load variations of the cell. By way of non-limiting example, the conversion circuit may comprise a correspondence table comprising characteristic slope values determined for distinct SOHs during the characterization, and calculation means making it possible to interpolate the SOH for the slope values. not included in the correspondence table. As an alternative, if an analytical expression approximating the law of variation of the characteristic slope as a function of the SOH of the cells was determined during the characterization, this expression can be used by the conversion circuit to estimate the SOH of the cell. According to a second exemplary embodiment, once the passage of the cell by the voltage UA has been detected, the SOH can be estimated by the battery management device by calculating a quantity representative of the average of the measured voltage values of the battery. the cell under the current iref (preferably on a relatively large number of points to overcome any spurious variations of the measured values), in a range of charge levels of the cell excluding the point A, and preferably in a load level range greater than point A, for example in the range from the QA level + 10% of the nominal capacity of the cell to the QA level + 20% of the rated capacity of the cell (ie in the range of 50% to 60% of the nominal capacity of the cell in the example of Figure 1). The inventors have indeed found that the average, in a load level range excluding the point A, of the voltage across the cell under the current iref, varies from B13053 - DD15002ST substantially monotonically with the SOH of the cell. In particular, in a higher charge level range at point A, the average of the voltage across the cell under the iref current is higher the lower the SOH of the cell (i.e. say that aging of the cell is important). For a given cell type, a characterization phase can be implemented, making it possible to determine a variation law of the SOH of a cell as a function of the average of the voltage of the cell under the current iref, in a range of load levels that are chosen and do not include the QA level. For this, we can measure this characteristic average for several SOH distinct from the same cell that is voluntarily aged in the laboratory for the purposes of characterization. By way of example, this characterization can be carried out at the same time as a characterization phase carried out to determine the position of the point A for the cells of the type in question. The battery management device may include a conversion circuit for providing an estimate of the SOH of the cell as a function of the average of the voltage of the cell under the current iref in the range of reference reference levels chosen. By way of nonlimiting example, the conversion circuit may comprise a correspondence table comprising average voltage characteristic values in the range of reference load levels, and calculation means for interpolating the SOH for the values of the reference voltage. average voltage not included in the correspondence table. Alternatively, if an analytical expression approximating the law of variation of the SOH of the cells as a function of the average voltage of the cell under the current iref in the selected reference range, was determined during the characterization, this expression can be used by the conversion circuit to estimate the SOH of the cell.
    [0008] B13053 - DD15002ST 16 According to a third exemplary embodiment, once the passage of the cell by the voltage UA has been detected, the cell can be fully charged. During this charging phase, the amount of charge Q1 accumulated in the cell can be measured, for example by means of a coulometric counter or estimated, for example by means of a time measurement if the charging regime is known. When the full charge of the cell is reached, the total capacity of the QTi cell can be calculated by the formula QTi = QA + Q1, which makes it possible to calculate the SOH of the cell. In practice, so that the measurement of the SOH is transparent for the user in the case where a passage of the cell by the voltage UA is detected during a discharge phase of the cell, it is possible, once the passage of 15 the cell by the voltage UA has been detected, to let the user continue to discharge the cell by measuring or estimating the amount of charge Q2 charged from passage to point A. Once the user has finished using the battery, it can be expected to fully recharge the battery. During this charging phase, the amount of charge Q3 accumulated in the cell can be measured or estimated. When the full charge of the cell is reached, the total capacity of the cell QTi can be calculated by the formula QTi = QA - Q2 + Q3, which makes it possible to calculate the SOH of the cell. An advantage of this third embodiment is that it makes it possible to determine the SOH of a cell without having to fully discharge this cell, and without using onboard tables of curves and / or characteristic values. An advantage of the SOH determination methods of a cell of the type described in the present application is that the SOH can be determined without charge or complete discharge of the cell. This makes the SOH determination less compelling than with known solutions. In particular, it is possible to provide SOH determination phases which are more frequent than in existing systems, which makes it possible for B13053 - DD15002ST 17, for example, to increase the reliability of the cell state of charge gauges. The embodiments described in the present application of a method for detecting the passage at point A of a cell, or for resetting a charge state of a cell, or for determining the SOH of a cell, although not limited to this particular case, are of particular interest for use in a dynamically reconfigurable electrical architecture battery. By dynamically reconfigurable electrical architecture battery, here is meant a battery in which the circuit diagram for interconnecting the elementary cells of the battery between the voltage supply terminals of the battery can be dynamically modified during operation of the battery, so that the battery provides at its terminals an alternating voltage, for example for powering an electric motor or any other load that can be powered by an alternating voltage. Examples of embodiments of dynamically reconfigurable electrical architecture batteries are for example described in patent applications FR2972304, FR2972305, FR2972306 and FR2972308 of the applicant. A dynamically reconfigurable electrical architecture battery typically comprises a management device capable of dynamically disconnecting and reconnecting cells of the battery, possibly by changing their position and / or their connection mode (serial or parallel) with respect to the other cells of the battery at a relatively high frequency during battery usage phases. At each disconnection of a cell, the current flowing through this cell is canceled during the disconnection period, for example in the range from 1 ps to 1 ms. Advantageously, the battery management device can exploit these frequent disconnections to implement a method of the aforementioned type for a zero iref reference current. For this, the management system can measure the voltage of the cell during periods of disconnection of the cell forming part of the normal operation of the system, for example in order to detect a passage of the cell by the voltage UA of the cell. point A, and / or to determine the SOH cell by the methods described above. One advantage is that the voltage measurements under the current iref do not require any disturbance of the normal operating mode of the battery. FIG. 3 illustrates, in block form, a nonlimiting example of an embodiment of a method for determining the SOH of a cell of a battery, which can be implemented during a discharge phase of the cell. Note that from the following description, the skilled person will adapt the method of Figure 3 to determine the SOH during a charging phase of the cell. The method of Figure 3 may be triggered by the battery management device during a discharge phase of the cell, before the charge level of the cell reaches the QA value. By way of nonlimiting example, the method of FIG. 3 is triggered when the state of charge of the cell reaches a threshold comprised in the range of 60% to 80% of SOC. The method of FIG. 3 comprises an initial step 201 during which the voltage at the terminals of the cell is measured under the current iref, and the measured voltage value is written in a field U (0), of rank k = 0 of a table U for storing the measured voltage values. In step 201, a field Q (0), of rank k = 0, of a table Q for storing charge quantity values extracted from the cell, is initialized to the value 0. During a step 203 after step 201, the index k pointing in the tables U and Q is incremented by 1, and the voltage across the cell is again measured under the current iref- The measured voltage value is written in the field U (k) of the table U. In addition, during the step 203, B13053 - DD15002ST 19, the charge variation AQ of the cell between the step of measuring the voltage U (k-1) and the The measuring step of the voltage U (k) is determined, for example by coulometric counting, or estimated from the time elapsed between the two measurements. The Q (k-1) + AQ value is written in the Q (k) field of the Q-table. In a step 205, the management device checks whether the voltage U (k) measured in step 203 has crossed the voltage value UA of the characteristic point A of the cell. If, during step 205, the value U (k) is greater than the value UA, steps 203 and 205 are repeated. If, during step 205, the value U (k) is less than or equal to the value UA, a step 207 is implemented during which the management device checks whether the load variation Q (k) of the cell since the beginning of the process has reached a threshold Q5. If, during step 205, the value Q (k) is below the threshold Q5, the steps 203, 205 and 207 are repeated. If, during step 207, the value Q (k) is greater than or equal to the value Q5, a step 209 for determining the SOH of the cell is implemented.
    [0009] In step 209, the SOH can for example be determined from the values contained in the tables U and Q, according to one of the abovementioned methods, namely by calculating a magnitude representative of the slope, at the point of voltage UA, the characteristic curve of the voltage of the cell under the current iref as a function of the load variations of the cell, or by calculation of a magnitude representative of the average of the voltage of the cell under the current iref in a range of cell charge levels greater than point A or lower than point A. At the end of step 209, the method for determining the SOH terminates. Particular embodiments have been described. Various variations and modifications will be apparent to those skilled in the art. In particular, the battery management device can optionally store, in addition to the coordinates B13053 - DD15002ST of the point A, all of one or more of the voltage / charge characteristic curves of the cells at a reference current iref, determined during a characterization phase of the cells. In this case, to evaluate the state of charge of a cell of the battery, the management device can measure the voltage across the cell under the current iref, and estimate the state of charge of the cell. cell from this measurement and memorized characteristic curves. The particular curve used to make a state of charge estimate of a cell can be selected taking into account the SOH of the cell. In addition, during the characterization phase of the cells, the coordinates of point A, as well as the characteristic slopes of the voltage / charge curves at point A, and / or the characteristic averages of the voltage in a range of load levels excluding point A, may optionally be determined for several different reference currents iref. In this case, when the management device implements a phase for determining the SOH by a method of the aforementioned type, it can choose the reference current best suited to the use made of the battery during the phase of determination of SOH.
    权利要求:
    Claims (16)
    [0001]
    REVENDICATIONS1. A method for determining the state of health of a first elementary cell of a battery, comprising the following steps: measuring the voltage (U (k)) across the terminals of the cell 5 under a reference current (iref) at several instants of a charging or discharging phase of the cell between first and second state of charge levels; and detecting a passage of said voltage (U (k)) by a particular predetermined value (UA), corresponding to a predetermined particular charge value (QA) of the cell.
    [0002]
    The method of claim 1, wherein said particular load (QA) and voltage (UA) values correspond to the coordinates of a crossing point (A) of at least two representative curves (101a, 101b, 101c). of the evolution of said voltage (Uk) as a function of the charge contained in the cell, to states of aging distinct from the cell.
    [0003]
    The method of claim 1 or 2, further comprising determining and storing charge variations (AQ) of the cell between said voltage measurements.
    [0004]
    The method of claim 3, wherein said load variations (AQ, Q (k)) are measured by a coulomb counter or a current integrator.
    [0005]
    The method of claim 3, wherein said load variations (AQ, Q (k)) are estimated by taking into account the time elapsed between said voltage measurements.
    [0006]
    6. Method according to any one of claims 3 to 5, comprising a step of determining the slope of the curve representative of the evolution of said voltage (U (k)) as a function of the load variation (AQ, Q (k)) of the cell, passing through said particular voltage value (UA).
    [0007]
    7. A method according to any one of claims 3 to 5, comprising a step of calculating the average value of said voltage (Uk) between first and second levels of charge of the cell, said first and second levels of both being greater than said particular load value (QA) or both lower than said particular load value (QA).
    [0008]
    The method of any one of claims 1 to 7 further comprising, after detecting the passage of said voltage (U (k)) by said predetermined particular value (UA), a step of fully recharging the cell, and measuring the charge injected into the cell during this charging step.
    [0009]
    The method of any one of claims 1 to 8, wherein said particular charge value (QA) is between 20% and 60% of the rated full load capacity of the cell.
    [0010]
    The method according to any one of claims 1 to 9, wherein said cell is a lithium-ion type cell, and wherein said particular charge value (QA) is between 38% and 42% of the nominal capacity. full charge of the cell.
    [0011]
    The method of claim 10, wherein said cell has a nominal capacity of 2.2 Ah and a full load nominal voltage of 4.2 V, and wherein said particular voltage value (QA) is within the range of ranging from 3.5 V to 3.6 V.
    [0012]
    12. Method according to any one of claims 1 to 11, further comprising a preliminary characterization phase comprising the acquisition, for a second elementary cell of the same type as the first cell, of at least two characteristic curves (101a, 101b, 101c) representative of the evolution of the voltage across the second cell under the reference current (iref) as a function of the charge contained in the second cell, to at least two distinct aging states of the second cell.
    [0013]
    The method of claim 12, wherein the prior characterization phase further comprises a step of determining a crossing point (A) of said at least two characteristic curves in the load range of 20%. at 60% of the rated capacity of the cell.
    [0014]
    14. System comprising: a battery comprising a plurality of elementary cells; and a battery management device, wherein the management device is adapted to determine the state of health of an elementary cell by a method according to any one of claims 1 to 13.
    [0015]
    The system of claim 14, wherein the battery is a dynamically reconfigurable architecture battery, and wherein the management device is adapted to dynamically disconnect and reconnect cells of the battery so that the battery provides at its terminals a AC voltage.
    [0016]
    The system of claim 15, wherein said reference current (iref) is zero, and wherein said steps of measuring the voltage (U (k)) across the first cell are performed for periods of time. disconnection of the first cell by the management device for the generation of an AC voltage across the battery.
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    同族专利:
    公开号 | 公开日
    EP2944970A1|2015-11-18|
    US20150260795A1|2015-09-17|
    EP2944970B1|2016-12-14|
    CN104965176A|2015-10-07|
    CN104965176B|2020-01-21|
    FR3018608B1|2017-11-24|
    US9759776B2|2017-09-12|
    JP6460860B2|2019-01-30|
    JP2015175854A|2015-10-05|
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    法律状态:
    2015-03-18| PLFP| Fee payment|Year of fee payment: 2 |
    2016-03-25| PLFP| Fee payment|Year of fee payment: 3 |
    2017-03-31| PLFP| Fee payment|Year of fee payment: 4 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1452182A|FR3018608B1|2014-03-17|2014-03-17|METHOD OF ESTIMATING THE HEALTH STATUS OF A BATTERY CELL|FR1452182A| FR3018608B1|2014-03-17|2014-03-17|METHOD OF ESTIMATING THE HEALTH STATUS OF A BATTERY CELL|
    EP15158714.4A| EP2944970B1|2014-03-17|2015-03-11|Method for estimating the state of health of a battery cell|
    US14/658,581| US9759776B2|2014-03-17|2015-03-16|Battery cell state-of-health estimation method|
    CN201510117102.6A| CN104965176B|2014-03-17|2015-03-17|Battery cell state of health estimation method|
    JP2015053840A| JP6460860B2|2014-03-17|2015-03-17|Method for estimating the health of battery cells|
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