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    • 专利摘要:
    This method of estimating the state of charge of a cell comprises the following steps: the complete execution of an algorithm for estimating the capacity Cn, k3 of the cell is inhibited (164) as long as the value of a parameter does not exceed a predetermined threshold, this parameter being chosen from the group consisting of the measured value yk of a voltage at the terminals of the cell, the estimated state of charge SOCk of the cell and a quantity Qk current delivered by the cell between a time k and a previous instant, then - the complete execution of the capacity estimation algorithm Cn, k3 is triggered (164) in response to the fact that this parameter goes below of the predetermined threshold if the parameter is the measured value yk or the estimation of the state of charge SOCk, or rises above the predetermined threshold if this parameter is the quantity Qk of the current flow.
    公开号:FR3029298A1
    申请号:FR1461617
    申请日:2014-11-28
    公开日:2016-06-03
    发明作者:Vincent Heiries；Sylvain Leirens
    申请人:Renault SAS；
    IPC主号:
    专利说明:

    [0001] The invention relates to an automatic method for estimating the state of charge of a cell of a battery as well as to a method for estimating the state of charge of a battery cell. a recording medium and a battery management system for carrying out this method. The invention also relates to a motor vehicle comprising this battery management system. [002] Known methods for estimating the state of charge of a cell of a battery comprise: - the repetition of the following steps at times k: a) the acquisition, at time k, of the measured value yk of the voltage between the terminals of the cell, and the measured intensity ik of the charging or discharging current of the cell, b) the estimation of the state of charge SOCk of the cell, at l instant k, from the measured value yk, the measured intensity ik and a capacitance Cn, k3 of the cell, this capacitance Cn, k3, expressed in Ah, representing the maximum quantity of storable electrical energy in the cell at time k3, the instant k3 being the instant at which the capacitance Cn, k3 has been estimated to be closest to instant k, and - the complete execution, by an electronic calculator, of a estimation algorithm 20 of the capacity Cn, k3 from the measured intensity i k3 at time k3, the times k3 being less frequent than the s instants k. [003] Such a method is described in Part 3 of the following article: L. Plett, et al. : "Extended Kalman filtering for battery management systems of LiPB-based HEV battery packs", Journal of Power Sources, 2004, page 252-292. Later this article is referred to as "Plett 2004". [004] In particular, Plett 2004 indicates that parameters of the state model used to estimate the state of charge of the cell, such as the capacity Cn, k3, vary much more slowly than the state of charge of the cell. This therefore makes it possible to perform the estimation of the capacitance C n, k 3 at a frequency smaller than the frequency at which the estimations of the state of charge of the cell are carried out. Indeed, it is possible to reduce the computing power necessary to execute the method without degrading the accuracy of the estimation of the state of charge of the cell. However, it is not easy to set the frequency at which this estimate of the capacity Cn, k3 must be performed. Moreover, it has been found that the choice of the frequency at which the estimate of the capacitance C n, k 3 is carried out has direct consequences on the accuracy of the estimate obtained and that there is no simple relation between the frequency of estimation of the capacitance Cn, k3 and the accuracy of the estimate of the state of charge of the cell. The invention aims to remedy this disadvantage. It therefore relates to an automatic method for estimating the state of charge of a cell in which: the complete execution of the capacity estimation algorithm Cn, k3 is inhibited as long as the value of a parameter does not cross a first predetermined threshold, this parameter being chosen from the group consisting of the measured value yk, the estimated state of charge SOCk and a quantity Qk of current delivered by the cell between the instant k and a previous moment, then - the complete execution of the capacity estimation algorithm Cn, k3 is triggered in response to the fact that this parameter falls below the first predetermined threshold if the parameter is the measured value yk or l estimating the state of charge SOCk, or rising above the first predetermined threshold if this parameter is the amount Qk of current flow. [6] Triggering the estimate of the capacity Cn, k3 automatically in response to the crossing of a threshold makes it possible to automatically adapt the frequency of execution of this estimate to the current use of the cell. In addition, the choice of the predetermined threshold in the claimed method makes it possible in particular to avoid estimating the capacity Cn, k3 when this is not necessary. This therefore limits the computing power required to perform this process without deteriorating the accuracy of the estimate of this capacity. In addition, triggering the estimation of the capacitance Cn, k3 only when a threshold of state of charge or of voltage or of quantity of current flow is crossed makes it possible to be limited to a single estimate per cycle of charge and discharge of the cell, which is more than enough to accurately estimate this capacity. [7] The embodiments of this automatic estimation method may comprise one or more of the following features: the complete execution of the capacity estimation algorithm Cfl, k3 comprises: the calculation of a predicting the capacitance Cfl, k3 by means of a state model which relates the capacitance Cn, k3 to the capacitance Cn, k3-1 of this same cell at a previous instant k3-1, and then - the correction of the prediction of the capacitance Cfl, k3 as a function of the measured intensity ik3 at the instant k3, and at each instant k when the complete execution of the capacitance estimation algorithm Cfl, k3 is inhibited, the method comprises calculating the prediction of the capacitance Cfl, k3, without making the correction of this prediction of the capacitance Cfl, k3, and the use of this uncorrected prediction of the capacitance Cfl, k3 during the estimation the SOCk state of charge of the cell at this instant k; The estimation of the charge state SOCk of the cell is also a function of an internal resistance R0k2, this internal resistance R0k2 being the internal resistance of the cell at the instant k2, the instant k2 being the instant which is estimated this nearest internal resistance of the instant k, and the method comprises the inhibition of the complete execution, by the electronic calculator, 40 of an internal resistance estimation algorithm R0k2 as long as the measured intensity ik is below a predetermined current threshold, then triggering the complete execution of this internal resistance estimation algorithm ROk2en in response to the fact that the intensity ik rises above the predetermined current threshold; the complete execution of the estimation algorithm of the internal resistance R0k2 comprises: calculating a prediction of the internal resistance R0k2 using a state model which links the internal resistance R0k2 to the internal resistance R0k24 of this same cell at a previous instant k2-1, - the acquisition, at the instant k2, of a measurable physical quantity uk2 defined by the following relation: t. Yk ni = kN where k is the nearest instant of the instant k2 and N is an integer greater than or equal to zero, uk2 being equal to yk when N is equal to zero, - calculating a prediction Û k2 of the measurable physical size uk2 using the following observation model: [OC SOC ni = k pr where: - k is the instant closest to the instant k2, - OCV (S0Cm) is a function that returns the no-load voltage between the terminals of the cell as a function of the charge state SOCm of the cell at time m, - VD, m is a voltage at the terminal of a parallel RC circuit, and - R0k2 is, in this observation model, the prediction of the internal resistance of the cell at the instant k2 calculated just before being corrected, and the correction of the prediction of the internal resistance R0k2 as a function of the difference between the acquired physical magnitude uk2 and calculated prediction ûk2; at each instant k when the complete execution of the estimation algorithm of the internal resistance R0k2 is inhibited, the method comprises the calculation of the prediction of the internal resistance R0k2, without proceeding to correct this prediction of the resistance internal R0k2, and the use of this uncorrected prediction of the internal resistance R0k2 when estimating the SOCk charge state of the cell; N is strictly greater than one. [008] These embodiments of the estimation method also have the following advantages: - Estimate the capacity Cn, k3 at each instant k by only performing the calculation of a prediction of this capacity, without proceeding to its correction, allows to benefit every moment k from an updated estimate of the capacity Cn, k3. This increases the accuracy of the estimation of the state of charge of the cell. In addition, this does not substantially increase the computing power required because the calculation step of the prediction requires much less computing power than the step of correcting this prediction. Triggering the estimation of the internal resistance R0k2 only when the measured intensity ik exceeds a predetermined threshold makes it possible to increase the accuracy of the estimate of this internal resistance. Indeed, it is used here that the measurements of an ammeter are more accurate when the intensity of the measured current is higher. Therefore, estimating the internal resistance only when the intensity of the current is high, it increases the accuracy of the estimate of this internal resistance while decreasing the computing power required to perform this estimation method. - Estimating the internal resistance R0k2 at each instant k by performing only the calculation of a prediction of this internal resistance, without making its correction, makes it possible to benefit at each instant k from an updated estimate of the internal resistance. This increases the accuracy of the estimation of the state of charge of the cell. In addition, this does not substantially increase the computing power required because the calculation step of the prediction requires much less computing power than the step of correcting this prediction. - Using N measured values yk realized between two successive estimates of the internal resistance R0k2 to estimate this internal resistance makes it possible to increase the precision of this estimate. [009] The invention also relates to an information recording medium comprising instructions for the execution of the automatic estimation method above when these instructions are executed by an electronic computer. The invention also relates to a management system of a battery equipped with at least one cell, this system comprising an electronic computer programmed to: - repeat the following steps at times k: 35 a) the acquiring, at instant k, the measured value yk of the voltage between the terminals of the cell, and the measured intensity ik of the charging or discharging current of the cell, b) the estimation of the state SOCk of the cell, at time k, from the measured value yk, the measured intensity ik and a capacitance Cn, k3 of the cell, this capacitance Cn, k3, expressed in Ah, representing the maximum amount of storable electrical energy in the cell at time k3, time k3 being the instant at which the capacity Cn, k3 has been estimated to be closest to time k, and - completely executing an algorithm estimating the capacitance C n, k3 from the measured intensity i k3 at the instant k3, the ins tants k3 being less frequent than instants k, in which the electronic computer is also programmed to: - inhibit the complete execution of the capacity estimation algorithm C n, k3 as long as the value of a parameter does not cross not a first predetermined threshold, this parameter being chosen from the group consisting of the measured value yk, the estimated state of charge SOCk and a quantity Q k of current delivered by the cell between the instant k and a previous instant , then - triggering the complete execution of the capacity estimation algorithm C n, k3 in response to the fact that this parameter falls below the first predetermined threshold if the parameter is the measured value yk or the estimation of the state of charge SOCk, or rises above the first predetermined threshold if this parameter is the quantity Q k of current flow. Finally, the invention also relates to a motor vehicle comprising: - at least one drive wheel, - an electric motor adapted to drive in rotation this drive wheel to move the motor vehicle, - a battery comprising at least one cell (18-21) adapted to store electrical energy and, alternately, to restore electrical energy to power the electric motor, this cell having two terminals (30, 32) through which it is electrically connected to the electric motor, - a voltmeter electrically connected between the terminals of the cell for measuring the voltage between these terminals, - an ammeter connected in series with the electric cell for measuring the intensity of the charging or discharging current of that cell , and - the claimed system of battery management connected to the voltmeter and the ammeter, this management system comprising a progra electronic calculator mmable able to estimate the state of charge of the battery cell from the 30 voltmeter and ammeter measurements. The invention will be better understood on reading the description which follows, given solely by way of nonlimiting example and with reference to the drawings in which: - Figure 1 is a partial schematic illustration of a motor vehicle equipped with an electric battery; FIG. 2 is a schematic illustration of an electric model of a cell of the battery of the vehicle of FIG. 1; FIG. 3 is a schematic illustration of an estimator arrangement used to estimate the state of charge of a cell of the vehicle battery of FIG. 1; FIGS. 4 to 9 represent equations of different models; state and observation used by the estimators of Figure 3; FIG. 10 is a flowchart of a method for estimating the state of charge of a cell using the estimators of FIG. 3; FIG. 11 is a flowchart of a method for determining the state of charge of the battery of the vehicle of FIG. 1; FIG. 12 is a flowchart of a method for scheduling refresh times of the estimates of the charge states of different cells of a battery; FIG. 13 is a timing chart illustrating different refresh times planned using the method of FIG. 12; FIG. 14 is a schematic illustration of another estimator arrangement used to estimate the state of charge of a cell of the vehicle battery of FIG. 1; FIGS. 15 and 16 show, respectively, a state model and an observation model used by the estimators of FIG. 14; FIG. 17 is a flowchart of a method for estimating the state of charge of a cell using the estimators of FIG. 14; FIG. 18 is an illustration of another possible state model for predicting the capacity and internal resistance of a cell of a battery. In these figures, the same references are used to designate the same elements. In the remainder of this description, the features and functions well known to those skilled in the art are not described in detail. In this description, the term "computing power" designates the number of operations to be performed by an electronic computer. Thus, reducing the computing power means decreasing the number of operations to be performed to achieve the same result or a result of the same nature. [0015] Figure 1 shows a motor vehicle 2 electric traction more known under the term "electric vehicle". Electric vehicles are well known and only the structural elements necessary to understand the rest of this description are presented. The vehicle 2 comprises: - an electric motor 4, capable of driving the driving wheels 6 in rotation to make the vehicle 2 roll on a roadway 8, and - a battery 10 which supplies the motor 4 with electrical energy. [0016] Battery 10 comprises two terminals 12, 14 for electrical connection and several electrical cells electrically connected between these terminals 12 and 14. Terminals 12 and 14 are connected to the electrical loads to be powered. Here, they are therefore in particular connected to the electric motor 4. To simplify FIG. 1, only four electric cells 18 to 21 are shown. Typically, these electric cells are grouped into several stages and these stages are connected in series between the terminals 12 and 14. Here, only two stages are represented. The first stage comprises the cells 18 and 19, and the second stage comprises the cells 20 and 21. Each stage has several branches connected in parallel. Each branch of a stage comprises an electric cell or several electric cells in series. Here, the first stage has two branches, and each branch has a single electric cell. The second stage is structurally identical to the first stage in the example shown in FIG. 1. Here, all the cells of the battery 10 are structurally identical to the manufacturing tolerances. Therefore, only the cell 18 is now described in more detail. The cell 18 comprises two electrical connection terminals 30, 32 which electrically connects it to the other cells and terminals 12 and 14 of the battery 10.
    [0002] The cell 18 is also mechanically fixed without any degree of freedom to the other cells of the battery 10 to form what is often called a "pack" of cells. Cell 18 is capable of storing electrical energy when not in use. This stored electrical energy is then used to power the motor 4, which discharges the cell 18. In alternation, the cell 18 can also receive electrical energy which charges it. The complete discharge of a cell followed by its complete recharge constitutes what is called a charge / discharge cycle, which is simply called a "cycle of a cell". The cell 18 is a known type of cell, for example, it is a LiPB cell (Lithium-ion Polymer Battery) or other. The cell 18 is characterized by an initial nominal capacity Cn'n ', an initial internal resistance RO' ', a current intensity Imax, a maximum voltage Umax, a minimum voltage Um, n and an OCV function (FIG. Sock). The capacity Cn'n 'is the initial capacity of the cell 18. The capacity of a cell represents the maximum amount of electrical energy that can be stored in that cell. This capacity is expressed in Ah. As the cell 18 ages, i.e. as the number of charge and discharge cycles increases, the capacity of the cell decreases. At the moment k, the nominal capacity of the cell 18 is noted Cn, k thereafter. The initial internal resistance RO '' is the value of the internal resistance of the cell 18 before it begins to age. The internal resistance of a cell is a physical quantity found in most electrical models of an electric cell. As the cell ages, typically, the internal resistance increases. At time k, the internal resistance of cell 18 is denoted ROk. Imax is the maximum current that can be delivered by cell 18 without damaging it. Umax is the maximum voltage that can be present permanently between the terminals 30 and 32 of the cell without damaging it. The voltage Umia is the minimum voltage between the terminals 30 and 32 when the cell 18 is completely discharged. Subsequently, Imax, Umax, Umia are considered to be constant physical magnitudes that do not change over time. OCV (SOCk) is a predetermined function which returns the empty voltage of the cell 18 according to its state of charge SOCk. The no-load voltage is the measurable voltage between terminals 30 and 32 after the cell 18 has been electrically isolated from any electrical load for two hours. The state of charge at the instant k of the cell 18 is SOCk noted. The state of charge represents the filling rate of cell 18. It is equal to 100% when the amount of electrical energy stored in cell 18 is equal to its capacity Cn, k. It is equal to 0% when the amount of energy stored in the cell 18 is zero, that is to say that it can no longer be extracted from the electrical energy of the cell 18 to supply an electric charge. The parameters Cn'n ', Imax, Umax, Unn and OCV function (SOCk) are known parameters of the cell. For example, they are given by the constructor of the cell or are determined experimentally from measurements made on this cell. The battery 10 also comprises for each cell: a voltmeter which measures the voltage between the terminals of this cell, and an ammeter which measures the intensity of the charging or discharging current of this cell. To simplify FIG. 1, only a voltmeter 34 and an ammeter 36 of the cell 18 have been shown. Unlike the various parameters of the cell 18 introduced previously, the SOCk charge state of the cell 18 is not measurable. It must therefore be estimated. For this purpose, the vehicle 2 comprises a battery management system 40, better known by the acronym BMS ("Battery Management System"). One function of this system 40 is to determine the state of charge of the battery as well as the state of health of this battery. To determine this state of charge and this state of health, the system 40 is able to estimate the state of charge and the state of health of each cell of the battery 10. The state of health of a cell represents the progress of aging of this cell. Here, the state of health of a cell, at time k, is denoted SOHk. Subsequently, it is measured by the ratio Cn, k / Cn'n '. To calculate the state of health of a cell, the system 40 is also able to estimate the capacity Cn, k of this cell at the current time k. To achieve these various estimates, the system 40 is electrically connected to each voltmeter and each ammeter of the battery 10 to acquire the measurements of the voltage and the intensity of the current between the terminals of each cell. Here, the system 40 includes a memory 42 and a programmable electronic computer 44, able to execute instructions stored in the memory 42. For this purpose, the memory 42 includes the instructions necessary for the execution of the 40 methods of the figures 10 to 12 and / or Figure 17. This memory 42 also includes the initial values of the various parameters necessary for the execution of these methods. The structure of the system 40 is therefore identical or similar to those of known battery management systems and is not described in more detail. [0034] Figure 2 shows an electric model 50 of the cell 18. This model is known under the term "Thevenin model of the first order" or "Lumped 5 parameter model". It comprises successively connected in series starting from the terminal 32 to the terminal 30: - a generator 52 of the empty voltage OCV (SOCk), - a parallel RC circuit 54, and - an internal resistance 56 called thereafter at time k, "internal resistance ROk". The circuit 54 comprises a capacitor CD capacitor connected in parallel with a resistance RD value. Subsequently, it is considered that these two parameters CD and RD of the model 50 are known and constant over time. The voltage at the instant k across the circuit 54 is denoted VD, k. The value at instant k of the voltage between the terminals 30 and 32 of the cell 18 is denoted yk and the intensity, at the same instant, of the charging or discharging current of the cell 18 is denoted ik. FIG. 3 represents a first embodiment of an estimator arrangement implemented in the system 40 for estimating the state of charge and the state of health of the cell 18. Each estimator is implemented in the form of an estimation algorithm executed by the calculator. Thus, we will not talk about the sequence of "execution of an estimator" as "execution of an estimation algorithm". In this first embodiment, the system 40 comprises an estimator 60 of the charge state SOCk and the voltage VD, k from the measured value yk of the voltage and the measured intensity ik. The estimator 60 is here implemented as a Kalman filter. It therefore uses a state model 62 (FIG. 4) and an observation model 64 (FIG. 5). In these figures 4 and 5, the equations of these models are represented using the previously defined notations. Notations R0k2 and Cn, k3 represent, respectively, the capacity and internal resistance of cell 18, respectively, at times k2 and k3. These moments k2 and k3 are defined later. Moreover, in the model 62, xk designates the state vector [SOCk, VD, k] T at time k. In this description, the symbol "T" designates the transposed mathematical operation. The multiplication operation is represented by the operator ". " or " * ". Subsequently, it is considered that the origin of the time corresponds to the zero value of the instant k. Under these conditions, the instant k current is equal to kTe, where T, is the sampling period of the ammeter and voltmeter measurements of the battery 10. Thus, Te is the period of time which separates any two successive instants k and k-1 acquisition of the voltage and current intensity by the system 40. The period Te is typically a constant between 0.1 s and 10 s. Here, the period Te is equal to 1 s to plus or minus 20%. For example, Te is 40 equal to one second. In the model 62, wk is a state noise vector. Here, the noise wk is a Gaussian white noise centered. This noise represents the uncertainty on the model used. The covariance matrix, at the instant k, of the noise wk is denoted by Qk It is defined by the following relation: Qk = E (Wk * WkT), where E (...) is the expected expectation function. Model 62 is also written as Xk + 1 = FkXk Bkik Wk, where - Fk is the state transition matrix at time k, - Bk is the control vector at time k. The model 62 allows in particular to predict the state of charge SOCk + i at time k + 1 from the state of charge preceding SOCk. The model 64 can be used to predict the value yk of the voltage at instant k from the state of charge SOCk, the voltage VD, k and the measured intensity ik. In this model, vk is a Gaussian white measurement noise centered. The covariance matrix of the noise vk at time k is noted Rk thereafter. In the particular case described here, this matrix Rk is a single-column, single-row matrix. It is defined by the relation Rk = E (Vk * VkT). This noise vk is independent of the noise wk and the initial state vector xo. It will be noted that the model 64 is non-linear, since the OCV function (SOCk) is generally nonlinear. Because of this, the estimator 60 implements the extended version of the Kalman filter, better known by the acronym EKF (Extended Kalman Filter). In this extended version, we come back to a linear observation model of the form yk = Hkxk + ROk2.ik + vk by linearizing the model 64 in the vicinity of the vector xk. Typically, the model 64 is developed in Taylor series in the vicinity of the vector xk. Then we neglect the contributions of derivatives from the second order. Here, the matrix Hk is therefore equal to the first derivative of the OCV function in the vicinity of the SOCk charge state. This linearization of the model 64 is typically performed for each new value of the state of charge SOC k. The estimator 60 needs to know the capacitance C n, k3 and the internal resistance R0k2 to be able to estimate the state of charge SOCk.i. The capacity and the internal resistance of the cell 18 vary as it ages. To account for this aging, the capacity and the internal resistance of the cell 18 are estimated, respectively, at times k3 and k2. Here, an estimator 66 estimates the internal resistance R0k2 from the measured value yk2, the measured intensity ik2 and the state of charge SOCk2. Another estimator 68 estimates the capacitance C n, k3 from the intensity i k3 and the state of charge SOCk3. The internal resistance and the capacity of the cell 18 vary more slowly than its state of charge. Thus, to limit the computing power required to estimate the state of charge of the cell without degrading the accuracy of this estimate, estimators 66 and 68 are executed less frequently than estimator 60. Thereafter, Execution times of the estimators 66 and 68 are noted, respectively, k2 and k3 to distinguish them from the instants k. Here, the set of instants k2 and the set of instants k3 are subsets of the set of 40 instants k. Between two successive instants k2 and k2-1 and between two successive instants k3 and k3-1, several periods Te and several instants k elapse. These estimators 66 and 68 are also implemented each in the form of a Kalman filter. The estimator 66 uses a state model 70 (FIG. 6) and an observation model 72 (FIG. 7). In these models, the noises w - 2, k2 and v 2, k2 are Gaussian white centered noises. The covariances of the noise W - 2, k2 and V2, k2 are noted, respectively, 0 -2, k2 and R2, k2 thereafter. The observation model 72 makes it possible to predict the value of a directly measurable physical quantity uk2. The physical quantity uk2 is here the sum of the last N measured values yk. It is defined by the following relation: N. = Y k ni = k- [0045] N is an integer strictly greater than one which is counted as will be described later. In the relation above and in the model 72, the instant k is equal to the instant k2. The model 72 takes into account not only the charge state SOCk, the voltage VD, k and the measured intensity ik at the instant k = k2 but also the previous N estimates of the estimator 60 and N previously measured intensities, between instants k2 and k2-1. Taking into account the measurements and intermediate estimates between the instants k2 and k2-1, makes it possible to increase the precision of the estimation of the internal resistance R0k2. The estimator 68 uses a state model 74 (FIG. 8) and an observation model 76. In the models 74 and 76, the noises W3, k3 and V3, k3 are centered Gaussian white noises. The covariances of the noises W3, k3 and V3, k3 are noted respectively Q3, k3 and R3, k3 thereafter. It will be noted that the model 76 is a linear model so that a simple Kalman filter can be used for the estimator 68 instead of an extended Kalman filter. The observation model 76 makes it possible to estimate a directly measurable physical quantity zk3. The physical quantity zk3 is here the sum of the N last measured intensities ik. It is defined by the following relation: [0049] In the above relation and in the model 76, the instant k is equal to the instant k3. This physical quantity zk3 takes into account not only the measured intensity ik-1 at the instant k-1 preceding the instant k3, but also the previous N of the intensities measured between the instants k3 and k3-1. Here, N is an integer strictly greater than one which is counted as will be described later. It is not necessarily equal to the N introduced in the model 72. The fact of taking into account measurements and intermediate estimates between the instants k3 and k3-1, makes it possible to increase the precision of the estimate of the capacity Cn, k3. The operation of the estimators 60, 66 and 68 will now be described using the method of FIG. 10 and in the particular case of estimating the state of charge of the cell 18. [0051] The method starts with a phase 100 of adjusting the different covariance matrices necessary to execute the estimators 60, 66 and 68. More specifically, during an operation 102, the covariance matrices Qk and Rk of the estimator 60 are automatically adjusted. using the following relations: Qk = [NoGo, k (No)] - 1 and Rk = 10 I, where - No is a predetermined integer strictly greater than 1, - I is the identity matrix, and - Go, k (No) is defined by the following relation: N0-1 Fk 15 [0052] No is generally chosen during the design of the system 40 and then fixed once and for all. Generally, No is less than 100. For example, No is between Set 15. Here, No is chosen equal to 10. Using the above relationships greatly simplifies the setting of the matrices Qo and Ro as well as the setting the matrices Qk and Rk as will be seen later. Indeed, the only parameter to be chosen is the value of the integer No. [0054] During an operation 104, the covariances Q2,0 and R2,0 are also set. For example, Q2,0 is chosen equal to [(13 * ROini) / (3 * NCe0ms)] 2, where - [3 is a chosen constant greater than or equal to 0.3 or 0.5 and, preferably, greater than at 0.8 and generally less than three, 25 - Nice °, is the expected number of charging and discharging cycles of cell 18 before it reaches its end of life, and - Ns is the number of times the internal resistance is estimated per charge and discharge cycle of the cell18. The constant [3 represents, expressed as a percentage divided by 100, the difference 30 between the value of the initial internal resistance RO '' and its end-of-life value. Typically, [3 is set by the user or measured experimentally. Nceol is a number of cycles which can be measured experimentally or obtained from the data of the constructor of the cell 18. Ns is set by the state of charge estimation method implemented by the computer 44. As will be seen later, the internal resistance is estimated only once per cycle. Therefore, Ns is taken equal to 1. By way of illustration, the covariance R2,0 is chosen equal to (2cniU'x / 300) 2, where Cm is the maximum error of the voltmeter 34 expressed as a percentage . Subsequently, the covariances 0 -2, k2 and R2, k2 are considered to be constant and equal, respectively, to Q2.0 and R2.0. In an operation 106, the covariances Q3,0 and R3,0 are set. For example, the covariance Q3,0 is taken equal to [y * Cn'n '/ (3 * Nce0I * Ns)] 2, where y represents, expressed as a percentage divided by 100, the difference between the capacity Cn'n and the capacity of the cell 18 at the end of its life. y is a constant selected by the user between 0.05 and 0.8 and preferably between 0.05 and 0.3. Here, y = 0.2. The covariance R3.0 is for example chosen to be equal to [2 * E, m * Imax / 300] 2, where En is the maximum error of the ammeter 36 expressed as a percentage. Subsequently, the covariances Q3, k3 and R3, k3 are considered constant and taken equal, respectively, to Q3,0 and R3,0. Once the covariance matrices have been set, the estimation of the state of charge of the cell 18 can begin. During a phase 110, at each instant k, the voltmeter 34 and the ammeter 36 measure, respectively, the value yK and the intensity ik and these measurements are immediately acquired by the system 40 and stored in the memory 42. Phase 110 is repeated every moment k. In parallel, the estimator 60 executes a phase 114 for estimating the state of charge at the instant k of the cell 18. For this, during a step 116, the estimator 60 calculates a prediction SOCkik-i and a prediction VD, k / k_i of, respectively, the state of charge of the cell 18 and the voltage VD at the terminals of the circuit 54 at the instant k. In the notations used herein, the index k / k-1 indicates that this prediction is made taking into account only the measurements made between times 0 and k-1. This is called prediction a priori. The index kik indicates that the prediction at the instant k takes into account all the measurements made between the instants 0 and k. This is called a posteriori prediction. Predictions SOC1 and VD, k / k-1 are calculated using model 62, intensity measured ik-1 and capacity Cn, k3. It should be noted that in the model 62, the state transition matrix F k_i is constant regardless of k and therefore does not need to be reevaluated at each instant k. In a step 117, the estimator 60 also calculates the prediction Pkik_i of an estimation error covariance matrix on the state vector xk.
    [0003] Typically, this is accomplished using the following relationship: Pk / k-1 = Fk-1Pk-1 / k-1Fk-1T + Qk-1 [0066] These various matrices Fk-1, Pk-1 / k-1 and Qk-1 have already been previously defined. Then, in a step 118, the estimator 60 constructs the matrix H k by 40 linearizing the model 64 around predictions SOCkik_i and VD, k / k-1. In a step 120, the covariance matrices Q k and Rk are automatically updated. Here, for this, the step 120 is identical to the operation 102 taking into account this time the matrix H k constructed during the step 118. [0099] After that, during a step 122, the estimator 60 corrects the SOCkik-i and VD, k / k-1 predictions as a function of a difference between the measured value yk and a predicted j / k value from the model 64. This difference is known as "Innovation". This step 122 typically comprises: an operation 124 for calculating the prediction S / k, then an operation 126 for correcting the predictions SOCkik-i and VD, k / k-1 and the matrix Pk / k-1 for obtain the corrected predictions SÔC k / k, VD, k / k and Pk / k. In the operation 124, the prediction j / k is calculated using the model 64 in which the value of the state of charge is taken equal to SOCk / k_i and the value of the voltage VD, k is taken equal to VD, k / ki. The difference between the measured value yk and its prediction j / k is noted Ek thereafter. Numerous methods exist to correct the SOCkik-i and VD, k / k-1 prior estimates from the E k innovation. For example, in step 126, these estimates are corrected using the Kalman Kk gain. The gain Kk is given by the following relation Kk = Pk / k-1 Krk (H kPk / k-1 Krk + Rk) 1. Then, the predictions a priori are corrected with the following relation: xkik = KkEk. The matrix Pk / ki is corrected using the following relation: Pk / k = Pk / k-1 -KkF1 kPk / k-1 - Steps 116 to 122 are repeated at each instant where a new estimate of the state of charge of the cell 18 is to be made. During each new iteration, the state vector xk_i is initialized with the values obtained during the previous iteration of the phase 114 for the cell 18. In parallel, during a step 130, the calculator 44 compares each new measurement of the intensity ik at a threshold SH, of predetermined current. As long as the measured intensity does not exceed this threshold SH 'the execution of the estimator 66 and inhibited. On the other hand, as soon as the measured intensity ik exceeds this threshold SH 'then the estimator 66 is immediately executed. The threshold SH, is generally greater than lmax / 2 and advantageously greater than 0.8 * Imax or 0.91max. The estimator 66 executes a phase 140 for estimating the internal resistance R0k2 at the instant k2. Here, the instant k2 is equal to the instant k where the intensity ik crosses the threshold SH ,. For this, during a step 142, the estimator 66 calculates the a priori prediction RO of the internal resistance from the model 70. [0077] Then, during a step 144, the estimator 66 calculates the prediction P - 2, k2 / k2-1 of the covariance matrix of the estimation error on the internal resistance. For example, this prediction is calculated using the following relationship: P - 2, k2 / k2-1 = P2, k2 - 40 1 / k2-1 ± Q2.0. It will be noted that here, the model 72 is a linear function of the state variable. It is therefore not necessary to linearize it in the vicinity of the prediction R k2 / k2-1 to obtain the matrix H2, k2. Here, this matrix H2, k2 is equal to -N. In a step 148, the estimator 66 corrects the prediction R0 k2 / k2-1 as a function of the difference between the measured physical quantity uk2 and a prediction Ûk2 of this same physical quantity. Here, N is a predetermined constant selected strictly at one and, preferably, greater than 10 or 30. The magnitude uk2 is acquired by the estimator 66 as the values yk are measured and acquired. More specifically, during an operation 150, the computer 44 acquires the measured quantity uk2 and calculates the prediction Ûk2. The acquisition of the size uk2 is carried out by summing the last N measures of the measured value yk. The prediction Ûk2 is calculated using the model 72. In this model 72, the value RO k2 is taken equal to the value ROk2 / k2-1 previously calculated. Then, in an operation 152, the estimator 66 corrects the prediction R0 k2 / k2-1 as a function of the innovation E k2. The innovation E k2 is equal to the difference between the measured quantity uk2 and the predicted quantity Ûk2. For example, during the operation 152, the same method as that implemented during the operation 126 is used. Thus, this operation 152 is not described here in more detail. Then, the new estimate RO k2 / k2 is used in the subsequent executions of the estimator 60 in place of the previous estimate R0k2-1 / k2-1. Triggering the execution of the estimator 66 only when the measured intensity ik is high makes it possible to increase the accuracy of the estimation of the internal resistance while at the same time decreasing the computing power necessary to implement this method. Indeed, the accuracy of the ammeter measurement is higher when the intensity ik is higher. Also in parallel with the phases 110 and 114, the method comprises a step 160 in which at each instant k, the estimate SOCk is compared to a predetermined high threshold SHs'. If the estimate SOCk falls below this threshold SH0, then the process is continued immediately by steps 162 and 164. In the opposite case, step 160 is repeated at the next instant k. Typically, the threshold S Elsoc is between 90% and 100%. In step 162, the computer 44 starts by initializing a counter to zero and then increments it by 1 to each new measurement of the intensity ik since the beginning of this step. Moreover, at each instant k, the measured intensity ik and the estimate SOCk generated at the same time are recorded, associated with this instant k, in a database. In parallel with step 162, during step 164, the calculator 44 compares each new estimate SOCk with a predetermined threshold SLs'. The threshold SLs' is for example between 0% and 10%. As long as the estimate SOCk remains above this threshold SLs', step 162 is repeated at the instant k following. In the opposite case, as soon as the estimate SOCk for the cell 18 falls below this threshold SLs' then, the computer 44 immediately triggers the execution of the estimator 68 and stops incrementing the counter. Thus, as long as this threshold SLs' is not crossed, the execution of the estimator 68 is inhibited. The estimator 68 estimates, during a phase 166, capacity C n, k3 at time k3. The instant k3 is therefore equal to the instant k when the execution of the estimator 68 is triggered. As for phase 140, since estimator 68 is not executed at each instant k, time k3-1 does not correspond to time k-1. In contrast, the instants k3 and k3-1 are separated by a time interval greater than or equal to NT, where N is the number counted in step 162. The parameters of the Kalman filter of the estimator 68 are initialized with the previous values of these parameters obtained at the end of the previous iteration at the instant k3-1 of phase 166. [0088] Phase 166 comprises: the calculation, during a step 170, of the prediction Cri, k3 / k34 using the model 74, - the computation, during a step 172, of the prediction P - 3, k3 / k3-1 of the covariance matrix of the error of estimation of the capacity, and 15 - the correction, during a step 174, of the predictions Cn, k3 / k3-1 and P-3, k3 / k3-1 - [0089] In the steps 172 and 174, the matrix of observability H 3, k3 is equal to [(SOCk - SOCk_N)] * 3600 / (NT,). Here is the number of times k elapsed between the moment when the estimated state of charge has dropped below the threshold SHs 'and the moment when the estimated state of charge has dropped below the threshold SLs'. The value N is equal to the value counted in step 162. [0090] Step 174 comprises an operation 176 for acquiring the measured physical quantity zk3 and calculating the prediction 2k3 of the quantity zk3. The acquisition of the magnitude zk3 here consists in calculating the sum of the N last intensities measured between the instants k-1 and k-N. The prediction 2k3 is obtained from the model 76. [0091] Then, during an operation 178, the estimator 68 corrects the prediction C n, k3 / k3-1 as a function of the difference between the measured quantity zk3 and the predicted magnitude k3 to obtain the posterior estimate of the capacity C n, k3 / k3. This correction is, for example, carried out as described in step 126. Next, the capacity C r 1, k 3 / k 3 is transmitted to the estimator 60 which uses it to estimate the state of charge of the cell 18. at the following moments. Triggering the execution of the estimator 68 only after the cell 18 has been largely discharged makes it possible to increase the accuracy of the estimate while at the same time decreasing the computing power required for the evaluation. implement this method. At the end of phase 166, during a step 180, the calculator calculates the state of health SOHk3 at time k3 using the following formula: SOHk3 = Cn, k3 / Cn'n . FIG. 11 represents a method for determining the state of charge of the battery 10. At the instant k, the state of charge of the battery 10 is determined from 40 the state of charge of each cells of this battery. For example, this is done as follows. During a step 190, the computer 44 determines the state of charge of each stage of the battery by adding the state of charge of each cell of this stage. Then, during a step 192, the state of charge of the battery is taken equal to the smallest of the states of charge of a given stage during step 190. As illustrated by the method of FIG. 11, the determination of the charge state of charge of the battery at each instant k requires having an estimation of the state of charge for each of the cells at time k. A first solution therefore consists in executing in parallel, for each of the cells, the estimation method of FIG. 10 by executing at each instant k phase 114. However, in order to limit the computing power required, without degrading the accuracy of FIG. determined state of charge for the battery, it is also possible to plan the execution of the estimations of the states of charge of the cells as described with reference to the method of FIG. 12. The method of FIG. 12 is described in FIG. Simplified case where only three levels of priority are used, called high level, medium level and low priority level respectively. Moreover, it is assumed that the state of charge of a cell whose priority level is high must be estimated at each instant k and therefore at a frequency fe. The state of charge of a cell whose priority level is average must only be estimated with a frequency three times lower and therefore at a frequency fe / 3. Finally, the state of charge of the cells of low priority level must be estimated at a frequency ten times lower is therefore at a frequency fe / 10. In this example, for the high and medium priority levels, there are a limited number of known places in advance. In other words, the number of cells assigned to the high priority level is limited to a predetermined maximum number in advance. The same is true for the number of cells assigned to the medium priority level. In order to plan the times at which the estimates of the state of charge of each of the cells must be refreshed, the computer first assigns, in a step 198, a priority level to each cell. Step 198 begins with an operation 200 in which the system 40 acquires the measured value yk of the voltage between the terminals of each of the cells. Then, during an operation 202, if the measured value yk is above a high threshold SHy or, conversely, below a low threshold SLy, then the computer 44 assigns to this cell the high priority as long as there is enough room in this level. The threshold SHy is greater than or equal to 0.9 * Umax and, preferably, greater than 0.95 * Umax. The threshold SLy is greater than or equal to Um, 'and less than 1.1 * Unr' or 1.05 * Unn. It is important to frequently refresh the estimation of the state of charge of cells whose voltage is close to Umax or unlike Unn. Indeed, an error in the estimation of the state of charge of a cell in such a situation can lead to a degradation of the electrical and mechanical properties of this cell. Then, for the other cells, during an operation 204, the computer 44 calculates the voltage difference between the current measured value yk and a previous value yk-x, where X is a predetermined integer greater than or equal to one and generally less than 5 or 10. Here, X = 1. [00103] In an operation 205, the computer 44 identifies twin cells. Cells are considered to be "binocular" if, at the same instant k, they have the same voltage difference and the same measured value yk. For this, during step 205, the computer 44 compares the voltage difference and the measured value yk for a cell at the voltage differences and at the measured values yk for the other cells at the same instant in order to identify, among these other cells, the cell or cells of this cell. The identifier of this cell and the identifiers of the cell or cells identified as being its binoculars are then grouped together in a set that is stored in the memory 42. The above comparison is for example made for each of the cells of the battery 10. whose identifier has not already been incorporated into one of the registered twin cell sets. Subsequently, a priority level is assigned to only one of the cells in each set of twin cells. Thus, step 206 and subsequent steps 208 and 210 are performed only for cells that do not have a twin cell and for a single cell in each set of twin cells. During an operation 206, the computer classifies the cells in decreasing order of absolute value of the difference calculated during the operation 204. Then, it assigns to the first cells of this classification the remaining places associated with the levels. of high priority. Then, it assigns the remaining places associated with an average priority level to the next cells in that ranking. Finally, it assigns to the last cells of this classification the low priority level. Once a priority level has been assigned to each cell, during a step 208, the computer 44 schedules the refresh times of the estimations of the charge states of the cells according to their priority level. Step 208 is performed so as to respect the refresh frequency of the estimates associated with each of the priority levels. For this purpose, for example, the computer 44 first reserves the times at which the estimates of the cells of high priority level must be refreshed. Then, it reserves the moments at which the estimates of the state of charge of the cells of average priority level must be refreshed taking into account the times of refreshment already reserved. Finally, it does the same with cells assigned a low priority level. [00106] To illustrate this, it is assumed that a high priority level was assigned to the cell 18, that a mean priority level was assigned to the cells 19 and 20 and that a low priority level was assigned. in cell 21. In addition, it is required that during a period T ,, the computer executes at most twice the phase 114 of the method of FIG. 10. The result obtained with these hypotheses is shown in FIG. the instants k to k + 11 have been represented on the abscissa. Above each of these instants k, two boxes symbolize the fact that the computer 44 can, at each instant k, perform twice the phase 114 of the method of FIG. 10. In each of these boxes, the number is indicated. of the cell for which phase 114 is executed. When no number is in this box, this means that the method of FIG. 10 is not executed and therefore the saved computing power can be used for other purposes such as, for example, the execution of the estimators. Finally, in a step 210, for each cell assigned a priority level, the computer 44 executes the phase 114 at the scheduled time for this cell. Outside these scheduled times, the computer inhibits the complete execution of the phase 114 for that cell. Similarly, the execution of phase 114 for twin cells to which no priority level has been assigned is also inhibited. In parallel, during a step 212, for each twin cell to which no priority level has been assigned, the estimation of the state of charge of this cell is taken equal to the last estimate calculated during of step 210 for a twin cell of this cell. Thus, phase 114 is executed for only one of the twin cells. This reduces the computing power required to determine the state of charge of battery without degrading the accuracy of this determination. Optionally, in parallel with step 210, at each instant k, calculator 44 also performs a state of charge prediction step 214 for each of the cells that are not processed during step 210. at this moment k. Step 214 consists in executing only the prediction step 116, without performing the correction step 122, for all the cells for which, at the same time, the complete estimation phase 114 is not executed. Indeed, the prediction step 116 is much less computationally intensive than the step 122 and can therefore be executed, for example, at each instant k. Thus, when step 214 is implemented, there is at each moment k of a new estimation of the state of charge for each of the cells of the battery. Steps 198 and 208 are repeated at regular intervals to update the priority level assigned to each of these cells and therefore the refresh rates of the estimate of the state of charge of these cells. This method for scheduling refresh times of the estimates of the charge states of the cells makes it possible to limit the computing power required without degrading the accuracy of the state of charge determined for the battery. In fact, the method of FIG. 12 exploits the fact that the cells whose voltage deviations are small are cells that discharge or charge little and therefore whose state of charge does not vary rapidly. It is therefore possible to estimate the state of charge of these cells at a lower frequency without degrading the accuracy of the state of charge determined for the battery. During the execution of the methods of FIGS. 10 and 11, whenever the SOCk state of charge of a cell at a given instant is to be used for a calculation, the state of charge SOCk is taken equal to the last estimated or predicted charge state for that cell. In other words, it is considered that the state of charge remains constant between two successive instants where it is estimated or predicted. It will also be noted that each time the calculator 44 executes the estimation phase 114 for a cell, it retrieves the information necessary for this execution from the values obtained at the end of the previous execution of this phase. for the same cell. This is the case, for example, for state variables. Note, however, that the previous execution time is not necessarily the time k-1 but may be the time k-3 or k-10 depending on the priority level assigned to this cell. [00113] Many other embodiments of the method for estimating the state of charge of a cell are possible. For example, Fig. 14 shows another arrangement of estimators. This other arrangement is identical to that of FIG. 3 except that the estimators 66 and 68 are replaced by a single estimator 230. The estimator 230 simultaneously estimates the capacity and the internal resistance of the cell 18. The estimator 230 is executed less The estimator 60. Here, we note k4 the execution times of the estimator 230 and hence C n, k4 and R0k4 the capacity and the estimated internal resistance at time k4. The set of instants k4 is a subset of instants k. The estimator 230 estimates at the same time the capacity Cn, k4 and the internal resistance ROka. This estimator 230 implements a Kalman filter that uses a state model 232 (FIG. 15) and an observation model 234 (FIG. 16). The operation of this estimator 230 will now be described with reference to the method of FIG. 17 and in the particular case of the cell 18. This method of FIG. 17 is identical to the preceding one of FIG. 10 except that the steps 25 130 to 174 are replaced by steps 240, 242, 244 and a phase 246 for estimating the capacitance and the internal resistance. In step 240, the computer 44 compares at each instant k the measured value yk to a high threshold SHy2. Typically, this threshold SHy2 is greater than or equal to 0.8 * Umax or 0.9 * Umax. Steps 242 and 244 are executed only if measured value yk falls below this threshold SHy2. In step 242, the computer 44 starts by initializing a counter to zero and then increments this counter by 1 at each new instant k. Moreover, at each of these instants k, the measured intensity ik, the value yk, the state of charge SOCk and the estimated voltage VD, k are recorded, associated at this instant k, in a database. In parallel with step 242, during step 244, the computer 44 compares, at each instant k, the new measured value yk at a low voltage threshold SLy2. This threshold SLy2 is less than or equal to 1.2 * Um ,, or 1.1 * Um, n and greater than or equal to Umm [00119] As soon as the measured value yk goes below the threshold SLy2, 40 the incrementation the counter in step 242 is stopped and the execution of the estimator 230 is started. On the other hand, as long as the measured value yk remains above this threshold SLy2, the execution of the estimator 230 is inhibited. The estimator 230 executes the phase 246. As previously, it is noted that the instants ka and k4-1 are separated by a time interval greater than or equal to NTe, where N is the value of the counter incremented during the Step 242. The operation of the estimator 230 is deduced from the operation described above for the estimators 66 and 68. It will therefore not be described here in more detail. Other electrical models and therefore other state models can be used to estimate the state of charge of the cell 18. For example, in a simplified variant, the circuit 54 is omitted. Conversely, a more complex electric model may contain several parallel RC circuits electrically connected in series with each other. The state model of the cell 18 must then be modified accordingly to correspond to this new electrical model of the cell. However, everything described above applies without difficulty with such a modified state model. For examples of modified state models, the reader may refer to application WO2006057468. The RD and CD parameters of the model 50 can also be estimated instead of being considered as predetermined constant parameters. For this purpose, these two parameters RD and CD are for example introduced into the state vector xk which then becomes [SOCk, VD, k, RD, k and CD, k] T. For example, the state model is modified to incorporate the two following RD equations, k + 1 = RD, k and CD, k + 1 = CD, k. The state vector xk can also be supplemented by the temperature of the cell so as to estimate this temperature at the same time as the state of charge of this cell. The cell may also be equipped with additional sensors such as a temperature sensor. In this case, the observation model is modified to take into account these additional measured physical quantities. The reader can refer to application WO2006057468 for examples of modified observation models. [00125] Other possible electrical models for modeling the electric cell 30 are also presented in Part 2 of Plett 2004, Chapter 3.3. The continuous automatic adjustment of the covariance matrices Rk and Qk can be performed differently. For example, the so-called "Covariance Matching" method described in the following article can be applied: Mehra, RK: "On the identification of variances and adaptive Kalman Filtering", Automatic Control, IEEE 35 Transaction on, Volume 15, No. 2, pages 175-184, April 1970. This method applies after an initial setting of matrices Ro and Q0, for example, as described in step 102. [00127] In another variant, the matrices Qo, Ro , Qk and Rk are not set as described with reference to operations 102 and 120. For example, these matrices 40 are set using a conventional method. In a simplified case, they are constant. For example, the matrix Ro is then set from the data provided by the sensor manufacturer or from tests performed on these sensors and the matrix Qo by successive tests. The step 122 for correcting the prediction can be performed differently. For example, in a preferred method, the correction of the prediction of the state of charge and of the voltage VD, k, is achieved by minimizing a quadratic cost function J which has two terms: a term related to prediction error of the measured value, and - another term related to the estimation error of the state vector. This method is described in detail in Chapter 10.5.2 of the following book: Y. Bar-10 Shalom, and Al .: "Estimation With Applications to Tracking and Navigation, Theory Algorithms and Software", Wiley Inter-science, 2001. [00129 In another variant, the estimator 60 is not implemented in the form of a Kalman filter. For example, the state of charge is estimated by modeling its evolution over time in the form of a filter RII (infinite impulse response) whose coefficients are estimated by the RLS (Recursive Least Square) method. Other state models can be used to estimate the internal resistance and the capacity of the cell. For example, the model 232 can be replaced by a model 250, shown in FIG. 18. In the model 250, a, 13 and y are constants whose values are obtained from cell manufacturer data or measured. experimentally. Typically: - a is equal to 1 to plus or minus 30% or 10%, -13 is also 1 to plus or minus 30% or 10%, and - y is typically between 0.1 and 0, 5. For example, y is 0.2 to plus or minus 30% or 10%. In the model 250, Nck is equal to the number of charge / discharge cycles of the cell performed before the instant k. This number of cycles is for example measured by counting the number of times the state of charge of the cell falls below the high threshold SHs 'and then below the low threshold SLs'. wad, k is a centered gaussian white noise. y is the difference, expressed as a percentage divided by 100, between the initial capacity Cn '' of the cell and its end-of-life capacity. This model takes into account the fact that: - the internal resistance increases as the cell ages, and - the capacity of the cell decreases as the cell ages. [00132] Similarly, the state model 70 can be replaced by the following state model: R0k2 + 1 = (a + 13Nck2 / NW CEOL, 1R10k2 + - - - 2, k2 where the different symbols of this model have already been previously defined. [00133] The state model 74 can be replaced by the following state model: Cn, k3 + 1 = (1 -YNCk3 / NCEOL) Cn, k3 ± V3, k3 where the different Symbols of this model have already been previously defined [00134] According to the observation model used by the estimator 68, the magnitude zk3 can be calculated differently: For example, the magnitude zk3 is equal to the sum of the N last intensities measured between instants k and k-N + 1. In this case, when N is equal to 1, zk3 = 1k3 [00135] What has been previously described for the initialization of the covariance matrices Qk and Rk can also be applied for the initialization of the covariance matrices of the estimators 68 and 230. [00136] As a variant, the estimator 68 is not implemented as a Kalman filter, for example, the capacity is estimated by modeling its evolution over time in the form of an Infinite Impulse Response (IRN) filter whose coefficients are estimated by the RLS method ( Recursive Least Square). The methods of Figures 10 and 17 can be simplified by taking N equal to a predetermined constant. In this case, N is not counted and steps 160, 162, 240 and 242 may be omitted. For example, N is chosen equal to one or, on the contrary, strictly greater than 1 or S0. In another variant, at each instant k between instants k3 and k3-1, only step 170 of calculation of a prediction Cn, k is executed but the correction step 174 of this prediction is not executed. Thus, we obtain a new prediction of the capacity of the cell at each of these instants k while limiting the computing power required. Similarly, at each instant k between times k4 and k4-1, only the step of calculating the predictions of the capacitance and the internal resistance is executed without performing the step of correcting these predictions. Thus, in these variants, the capacity of the cell is predicted at each instant k but this prediction is corrected only at times k3 or k4. The algorithm for estimating this capacity is therefore only partially executed between the instants k3 and k3-1 or k4 and k4-1 and completely executed only at the instant k3 or k4. At each instant k between the instants k3 and k3-1 or between the instants k4 and k41, the capacitance can be estimated by executing a first algorithm, then at time k3 or k4, the capacity is estimated by executing a second algorithm different from the first algorithm and requiring a larger computing power. The first and second algorithms do not necessarily correspond, as previously described, respectively to the single step 170 and the phase 166 or 246 of a Kalman filter. It can also be two completely different estimation algorithms. [00140] The cell capacity estimation step 166 or 246 may be triggered in response to crossing a threshold on the state of charge, as described with reference to FIG. 10, or in response to FIG. crossing a threshold on the voltage as described with reference to FIG. 17. These steps 166 and 246 can also be triggered in response to crossing a current flow quantity threshold. For this, from the moment when the voltage or the state of charge of the cell has fallen below a predetermined high threshold, at each instant k, the computer 44 calculates the quantity QCk of current delivered using of the following relation: QCk = QCk-1 + kTe. As soon as QCk exceeds a high threshold SHQ, then phase 166 or 246 is executed. On the other hand, as long as the quantity QCk remains greater than the threshold SHQ, the execution of the phases 166 or 246 is inhibited. Alternatively, the quantity QCk can also be calculated on a sliding window containing the last N instants k, where N is a predetermined constant. In another embodiment, the triggering of the estimates of the capacitance and / or of the internal resistance in response to the crossing of a threshold is omitted. For example, these estimates are triggered at regular intervals. This regular interval is equal to Te if the available computing power is sufficient to estimate this capacity and this internal resistance at each instant k. [00142] Many other embodiments of the method of FIG. 12 are possible. For example, operation 205 may be omitted. In this case, no twin cell is identified and step 212 is also omitted. [00143] The operation 202 can be performed differently. For example, only one of the high and low thresholds is used. Operation 202 can also be omitted. [00144] The number of priority levels may be any and greater than at least two or three. Other methods for assigning a priority level to the cells are possible. For example, the priority level of a cell can be calculated using a formula that relates its priority level to its voltage difference and voltage. In the latter case, the comparison operations are omitted. [00145] The method described for associating refresh instants to the cells according to their priority levels is only one example. Any other known method of scheduling tasks according to the priority level of these tasks can be adapted to the case described here of the scheduling of the refresh times of the estimations of the states of charge of the cells. [00146] The planning of the refresh instants of the estimate of the state of charge of each of the cells described with reference to FIG. 12 may be omitted. For example, this will be the case if the computing power necessary for estimating the state of charge of each of the cells at each instant k is available. Alternatively, the computer 44 comprises several programmable sub-computers capable of executing each and in parallel, the estimation method 30 of Figure 10 or 17 for respective cells. The state of health of a cell can also be calculated using the following relation: SOHK = ROK / RO "[00149] The battery 10 can be replaced by any type of battery, for example , in this case, the state model and / or the observation model of the estimator 60 may possibly be adapted to take into account the technology of the lead-in battery, a super-capacitor or a fuel cell. the battery [00150] What has been described above also applies to the hybrid vehicle, that is to say to the vehicle whose driving of the driving wheels is at the same time or, alternatively, provided by an electric motor and an internal combustion engine 40. The vehicle 2 may also be a truck, a motorcycle or a tricycle and in general any vehicle capable of moving by driving driving wheels with the aid of an electric motor powered by For example, it may be a freight elevator. 00151] The battery 10 can be recharged via an electrical outlet which makes it electrically connectable to an electricity distribution network. The battery 10 can also be recharged by an internal combustion engine.
    权利要求:
    Claims (9)
    [0001]
    REVENDICATIONS1. An automatic method for estimating the state of charge of a cell of a battery, this method comprising: - the repetition of the following steps at times k: a) the acquisition (110), at time k, the measured value yk of the voltage between the terminals of the cell, and the measured intensity ik of the charging or discharging current of the cell, b) the estimation (114) of the state of charge SOCk of the cell, at time k, from the measured value yk, the measured intensity ik and a capacity Cn, k3 of the cell, this capacity Cn, k3, expressed in Ah, representing the maximum quantity of storable electrical energy in the cell at time k3, the time k3 being the instant at which the capacity Cn, k3 has been estimated to be closest to instant k, and - the execution (166; 246) complete, by an electronic calculator, an algorithm 15 for estimating the capacitance Cn, k3 from the measured intensity i k3 at time k3, the instants k3 e so much less frequent than instants k, characterized in that: - the complete execution of the capacity estimation algorithm Cn, k3 is inhibited (164; 244) as long as the value of a parameter does not exceed a predetermined first threshold, this parameter being selected from the group consisting of the measured value yk, the estimated state of charge SOCk and a quantity Qk of current flow. by the cell between the instant k and a previous instant, then - the complete execution of the capacity estimation algorithm Cn, k3 is triggered (164; 244) in response to the fact that this parameter falls below the first predetermined threshold if the parameter is the measured value yk or the estimate of the charge state SOCk, or rises above the first predetermined threshold if this parameter is the amount Qk of the current flow.
    [0002]
    2. The method according to claim 1, wherein: the complete execution of the capacitance estimation algorithm Cn, k3 comprises: calculating (170) a prediction of the capacitance Cn, k3 to the using a state model which links the capacity Cn, k3 to the capacity Cn, k3-1 of this same cell at a previous instant k31, then the correction (174) of the prediction of the capacity Cn, k3 according to of the measured intensity i k3 at time k3, and at each instant k when the complete execution of the capacitance estimation algorithm Cn, k3 is inhibited, the method comprises the calculation of the prediction of the capacitance Cn, k3, without proceeding to correct this prediction of the capacitance Cn, k3, and the use of this uncorrected prediction of the capacitance Cn, k3 during the estimation of the state of charge SOCk of the cell at this moment k.
    [0003]
    3. Method according to any one of the preceding claims, in which: the estimation (114) of the state of charge SOCk of the cell is also a function of an internal resistance R0k2, this internal resistance R0k2 being the internal resistance from the cell to the instant k2, the instant k2 being the instant at which this internal resistor closest to the instant k is estimated, and - the method comprises the inhibition (130; 244) of the execution complete, by the electronic computer, an algorithm for estimating the internal resistance R0k2 as the measured intensity ik is less than a predetermined current threshold, then triggering the complete execution of this estimation algorithm the internal resistance R0k2 in response to the fact that the intensity ik rises above the predetermined current threshold.
    [0004]
    4. The method according to claim 3, wherein the complete execution of the internal resistance estimation algorithm R0k2 comprises: calculating (142) a prediction of the internal resistance R0k2 with the help of a state model which links the internal resistance R0k2 to the internal resistance R0k24 of this same cell at a previous instant k2-1, - the acquisition (150), at the instant k2, of a measurable physical quantity uk2 defined by the following relation: ni = k- where k is the nearest instant of the instant k2 and N is an integer greater than or equal to zero, uk2 being equal to yk when N is equal to zero, - the calculation of a prediction Û k2 of the measurable physical magnitude uk2 using the following observation model: [OC 1150C -RQ Ii in = k- where: - k is the time closest to the time of day , - OCV (S0Cm) is a function that returns the no-load voltage between the terminals of the cell as a function of the charge state SOCm of the cell at the insta m, 30 - VD, m is a voltage at the terminal of a parallel RC circuit, and - R0k2 is, in this observation model, the prediction of the internal resistance of the cell at the instant k2 calculated just before to be corrected, and the correction (152) of the prediction of the internal resistance R0k2 as a function of the difference between the acquired physical quantity uk2 and the calculated prediction ûk2.
    [0005]
    5. Method according to claim 4, wherein at each instant k where the complete execution of the estimation algorithm of the internal resistance R0k2 is inhibited, the method comprises calculating the prediction of the internal resistance R0k2, without proceeding. correcting this prediction of the internal resistance R0k2, and using this uncorrected prediction of the internal resistance R0k2 when estimating the charge state SOCk of the cell.
    [0006]
    6. The method of claim 4, wherein N is strictly greater than one.
    [0007]
    7. Information recording medium (42), characterized in that it comprises instructions for executing an estimation method according to any one of the preceding claims, when these instructions are executed by an electronic calculator.
    [0008]
    8. Management system of a battery equipped with at least one cell, this system comprising an electronic computer (44) programmed to: - repeat the following steps at times k: a) acquisition, at the moment k, the measured value yk of the voltage between the terminals of the cell, and the measured intensity ik of the charging or discharging current of the cell, b) the estimation of the charge state SOCk of the cell at time k, from the measured value yk, the measured intensity ik and a capacitance Cn, k3 of the cell, this capacitance Cn, k3, expressed in Ah, represents the maximum quantity of storable electrical energy in the cell at time k3, time k3 being the instant at which the capacity Cn, k3 has been estimated to be closest to instant k, and - completely executing an algorithm for estimating capacity Cn, k3 from the measured intensity ik3 at the instant k3, the times k3 being less frequent than the instants k, characterized in that the electronic computer (44) is also programmed to: - inhibit the complete execution of the capacity estimation algorithm Cn, k3 as long as the value of a parameter does not pass a threshold first predetermined threshold, this parameter being chosen from the group consisting of the measured value yk, the estimated state of charge SOCk and a quantity Qk of current delivered by the cell between the instant k and a previous instant, and triggering the complete execution of the capacitance estimation algorithm Cn, k3 in response to the fact that this parameter falls below the first predetermined threshold if the parameter is the measured value yk or the estimation of the state charge SOCk, ormonitor above the first predetermined threshold if this parameter is the quantity Qk of current flow.
    [0009]
    9. Motor vehicle comprising: 5 - at least one drive wheel (6), - an electric motor (4) capable of driving this driving wheel in rotation to move the motor vehicle, - a battery (10) comprising at least one cell ( 18-21) adapted to store electrical energy and, alternately, to restore electrical energy to supply the electric motor, said cell having two terminals (30, 32) through which it is electrically connected to the electric motor; - a voltmeter (34) electrically connected between the terminals of the cell for measuring the voltage between these terminals; - an ammeter (36) connected in series with the electric cell for measuring the intensity of the charging current or discharge of this cell, and - a system (40) for managing the battery connected to the voltmeter and to the ammeter, this management system comprising a programmable electronic calculator (44) capable of estimating the state of charge of the battery cell from voltmeter and ammeter measurements, characterized in that the battery management system (40) is in accordance with claim 8.
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    同族专利:
    公开号 | 公开日
    JP6902467B2|2021-07-14|
    KR20170090455A|2017-08-07|
    JP2017538932A|2017-12-28|
    WO2016083756A1|2016-06-02|
    CN107110916A|2017-08-29|
    US10393812B2|2019-08-27|
    FR3029298B1|2016-12-30|
    EP3224636A1|2017-10-04|
    EP3224636B1|2019-05-01|
    US20170269164A1|2017-09-21|
    CN107110916B|2020-02-18|
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1461617A|FR3029298B1|2014-11-28|2014-11-28|AUTOMATIC METHOD OF ESTIMATING THE CHARGING STATE OF A CELL OF A BATTERY|FR1461617A| FR3029298B1|2014-11-28|2014-11-28|AUTOMATIC METHOD OF ESTIMATING THE CHARGING STATE OF A CELL OF A BATTERY|
    EP15808758.5A| EP3224636B1|2014-11-28|2015-11-26|Automatic method for estimating the state of charge of a cell of a battery|
    KR1020177017630A| KR20170090455A|2014-11-28|2015-11-26|Automatic method for estimating the state of charge of a cell of a battery|
    JP2017528428A| JP6902467B2|2014-11-28|2015-11-26|How to automatically estimate the charge status of a battery cell|
    CN201580069827.0A| CN107110916B|2014-11-28|2015-11-26|Method for automatic estimation of the state of charge of the battery cells of a battery pack|
    PCT/FR2015/053242| WO2016083756A1|2014-11-28|2015-11-26|Automatic method for estimating the state of charge of a cell of a battery|
    US15/531,495| US10393812B2|2014-11-28|2015-11-26|Automatic method for estimating the state of charge of a cell of a battery|
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