FR2986383A1 - Method for managing lithium ion notebook battery in car, involves selecting two energy storage elements belonging to two separate branches, and assembling selected energy storage elements directly in parallel arrangement - Google Patents

Abstract

The method involves interconnecting a set of branches (Bj) electrically in a parallel arrangement, where each branch comprises a set of energy storage elements that are connected in a series arrangement. The two energy storage elements belonging to the two separate branches are selected, where voltages across the branches are different. The selected energy storage elements are directly assembled in the parallel arrangement. Electric currents within the assembly of the selected energy storage elements are estimated. A terminal voltage of commutation elements (Cij) is determined. An independent claim is also included for a device for managing an electrical energy storage battery.

Description

The invention relates to a method for managing an electric energy storage battery comprising a plurality of branches electrically connected to one another. in a parallel arrangement and each having a plurality of storage elements electrically connected to each other in a series connection. The invention also relates to a management device which implements the management method and a motor vehicle comprising such a device. State of the art The batteries used in electric vehicles, for example of the Lithium-Ion type, consist of a set of storage elements, for example electrochemical cells, which are connected in series to reach the voltage level required by the application. On the other hand, to achieve a level of capacity required by the application, a battery may include a parallel assembly of the storage elements. That is why it frequently happens that an electric energy storage battery comprises a plurality of branches electrically connected to each other in a parallel connection and each having a plurality of storage elements electrically connected to each other in a series connection. . The number of branches depends on the capacity sought. The number of elements associated in series along each branch depends on the desired tension. The existing manufacturing processes today do not allow to obtain perfectly identical storage elements, especially for characteristics such as their capacity and their internal resistance. In addition, these elements undergo, during the life of the battery, different temperature variations due to their location in the battery, which causes them to age heterogeneously. When these elements having different characteristics are crossed by the same current, they are out of balance, in that their charge states are different. Battery management devices are known for correcting such imbalances, in order to allow the optimal use of the energy contained in the battery (the range of use being determined by the elements respectively the most charged and the least charged). The balancing can be done from the information of the state of charge of the elements (called "SOC" later, for "State Of Charge" in English terminology) or their voltage or their voltage to empty. The balancing methods currently used are active or passive: passive balancing (or dissipative) discharges the most loaded storage elements in dissipative elements (resistors, for example) so that they all have the same state load; - Active balancing (or non-dissipative) transfers the energy of the most charged elements to the most unloaded, in order to converge to the same state of charge. Balancing solutions are disclosed in US5631534, US20110068744 and WO2004049540, for example, but they are complex and expensive with the use of a large number of electronic components.

Another balancing solution is known from EP1869748B1 which describes the principle of paralleling the plurality of cells contained in each of the modules of the battery, then paralleling all the modules. This balancing is practiced in the situation of discharging the battery to make voltage balancing cells between them, and modules between them. But this solution is not very flexible because all modules and cells are balanced independently of the specific needs of each of the cells. OBJECT OF THE INVENTION The object of the present invention is to propose a method of managing a battery that overcomes the disadvantages listed above. A first object is in particular to be able to balance a battery in a non-dissipative manner, that is to say, by charge transfer. A second object is to provide a simpler solution at a lower cost than current solutions in the "non-sensing balancing" class.

A third object is to provide a flexible solution allowing the transfer of energy between any elements of the battery, whether the battery is in use or not.

A first aspect of the invention relates to a method for managing an electric energy storage battery comprising a plurality of branches electrically connected to each other in a parallel connection and each comprising a plurality of storage elements electrically connected to each other. in a series connection. The management method comprises a step of balancing the states of charge of all or part of said storage elements. The balancing step comprises: a step of selecting at least two storage elements belonging to two distinct branches and at the terminals of which the electrical voltages are different; and a connection step in a directly parallel assembly of the elements. storage selected in the selection step. The connection step may comprise a step of electrical connection between the two branches to which the two storage elements selected in the selection step belong, said connection being made, with respect to the current flow direction in said branches, upstream. and downstream of the selected storage elements.

Two of the storage elements selected in the selection step and belonging to distinct branches may in particular be located at locations of the same rank within the series connection in their respective branches.

At the end of the selection step, at least one storage element can be selected. The selection of the storage elements in the selection step may be a function of selection criteria taking into account a desired dynamic of the balancing and / or a threshold value of the electrical intensity in the directly parallel connection. storage elements. The balancing step may comprise a step of estimating the balancing electric currents within the directly parallel assembly of the storage elements selected in the selection step. The estimation step may comprise a step of determining the voltage across at least one switching element provided on at least one electrical connection link interconnecting two branches to which storage elements selected in the step belong. Selection. The method may comprise a step of protecting against an excessive discharge of any storage element of the battery, comprising: a step of identifying at least one storage element of the battery at the terminals of which the electrical voltage is less than a predetermined low threshold, then a balancing step whose selection step is such that at least the storage element identified in the identification step is selected and all storage elements implanted at locations of the same rank as the rank of the storage element identified in the identification step are selected. It may comprise a step of protecting against an excessive load of any storage element of the battery, comprising a step of automatic dissipation of the energy stored in at least one storage element of the battery when the electrical voltage at the terminals of this battery Storage element is greater than a predetermined high threshold.

A second aspect of the invention relates to a device for managing an electric energy storage battery comprising a plurality of branches electrically connected to each other in a parallel connection and each comprising a plurality of storage elements electrically connected to each other. in a series arrangement, the device comprising software and / or hardware means that implement such a management method. The software and / or hardware means may comprise electrical connection links each connecting two branches to each other between two storage elements and each comprising a switching element, the connection links being configured so that each branch is electrically connected to at least another branch.

The software and / or hardware means may in particular comprise a control unit generating actuation commands controlling the switching elements so as to perform the connection step.

They may also comprise a Zener diode connected in parallel with each of the storage elements and configured to become on when the electric voltage at its terminals is greater than the predetermined high threshold of excessive load of the storage elements, part of the stored energy being dissipated in a resistor connected in series with the diode. BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention given by way of nonlimiting examples and shown in the accompanying drawings, in which: FIG. 1 represents the electrical structure of a first storage battery for which the management method according to the invention can be applied, - Figure 2 shows a part of the management device adapted to the case of Figure 1, - Figure 3 explains the principle of balancing states of charge applied to two storage elements, - Figure 4 details the four states that can adopt the management device adapted to a second storage battery for which the management method according to the invention can be applied; FIGS. 5 to 8 show the curves of evolution of the state of charge of each of the storage elements over time the second battery respectively in the four states, from identical initial conditions, - Figure 9 illustrates similar curves, in the case of a combination in time of several of the four states of the management device, - FIG. 10 illustrates the principle of estimating the balancing currents, and FIG. 11 represents an exemplary embodiment of means for protecting against an excessive load of the storage elements of a given branch of the battery.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION FIG. 1 represents on the one hand the electrical structure of a storage battery for which the detailed management method can be applied later and on the other hand a part of a management device which implements this method. This part of the management device will be better understood with reference to FIG. 2. Thus, the electric energy storage battery comprises a plurality of branches 13i (here j varying between 1 and m since the battery comprises m branches) electrically connected between they in a parallel arrangement and each comprising a plurality of storage elements Ei (here i varying between 1 and n because each branch comprises n series elements) electrically connected to each other in a series connection along each branch. From the terminal A to the terminal D of the battery, the storage elements Ei, 1 are thus implanted along their respective branches in an orderly manner at locations having a given rank i. An element Ei j is therefore implanted at a location of rank i along the branch j. The battery, in addition to the storage elements Ei, j, comprises this electrical structure which ensures such a mounting elements between them and branches between them. This structure includes direct electrical connections connecting, two to two, two adjacent storage elements of the same branch. All the storage elements implanted at locations of the same rank i, for all the branches of the battery, are thus distributed on the same line Li (i varying between 1 and n), forming generally a matrix arrangement (i , j) the battery. The empty voltages of the storage elements Ei j are quite low, of the order of a few volts. Thus, to reach the nominal operating voltage of an electric circuit powered by the battery, it is necessary to put in series a number of electrochemical storage elements, defining the number n. Another design criterion of the battery corresponds to the autonomy it achieves, defined by the capacity of the storage elements. Putting two storage elements of the same type in parallel makes it possible, for example, to double the storage capacity. Thus, the number m of branches makes it possible to define the overall capacity of the battery. Each storage element Ei, 1 is unique in design. The process of manufacturing the storage elements does not make it possible to obtain completely identical elements. The capacity and the internal resistance in particular may differ. In addition, the aging phenomena of these storage elements lead to losses of capacity and increases in internal resistance which tend to increase these differences in characteristics. Thus two elements in series which are crossed by the same current can see their state of charge evolve differently and must be balanced to allow optimal use of the battery. To answer these problems which arise in the case of the matrix-type electrical structure of FIG. 1, the management device comprises software and / or hardware means which implement a management method which will be detailed later, which is intended to balance the states of charge of all or part of the storage elements that includes the battery after elements to balance voltage have previously been selected. Each storage element Ei j of the battery is constituted in the rest of the description by either a supercapacity, or an electrochemical unit cell, or a member with at least one pair of such cells mounted in parallel electrically, or a module comprising at least two such members electrically connected in series with each other, or else an assembly comprising at least two such modules electrically connected in series or in parallel with each other.

With reference to FIG. 2, the management device comprises electrical connection links, each connecting two branches 13i and 131 + 1 to one another at two links between two adjacent storage elements of the two branches thus connected. On each of the inter-branch connection links, a switching element Ci j is arranged. The connection links are configured (by their number and by the choice of connection points to the electrical structure of the battery) so that each branch is electrically connected at least once to at least one other branch at the level of the direct electrical connections . A connection link interconnects two direct electrical links inter-storage elements belonging to two different branches. The switching element C 1, 1 which is mounted on a given connection link makes it possible to selectively control the opening or closing of this connection link. Thus, the switching element Ci j makes it possible to put in or not in electrical contact the direct electrical connection connecting the element Ei and the element Ei + 1,1 and the direct electrical connection connecting the element Ei, j + 1 and the element Ei + 1, i + 1. As a result, the simultaneous closing of the switching elements Ci j and C; _1,1 makes it possible to electrically parallel the element Eijet element Ei, i ± i.

For the implementation of the management method, the management device comprises a control unit (not shown) generating control commands individually controlling the switching elements Ci, j, these commands being chosen so as to connect elements of storage (previously selected by the control unit according to given criteria), belonging to different branches, in a parallel assembly for performing a step of balancing the charge states of the selected storage elements. The storage elements implemented by the balancing operation are therefore selectable, thanks to the arrangement of the plurality of inter-branch connection links and the plurality of switching elements Ci, i, from the set storage elements that includes the battery. Advantageously, the switching elements Ci, i are insulated gate field effect transistors more commonly referred to as "MOSFET" in the English terminology for "Metal Oxide Semiconductor Field Effect Transistor". This variant has the advantage of being controlled in voltage to control the current in the circuit. However, the switching elements can be of any other nature, such as relays or other, insofar as they are controllable and oppose a low resistance to the passage of the current once closed. According to an essential characteristic, the management device therefore implements a method of managing the electric energy storage battery including in particular a step of balancing the states of charge of all or part of said storage elements, this step comprising itself: - a step of selecting, among at least two branches Bi and 131 + 1 different, at least two storage elements Ei, i and Ei, i + 1 at the terminals 20 of which the electrical voltages (and therefore the charge states "SOC") are different, - and a step of electrical connection of the storage elements selected in the selection step to at least one mounting directly in parallel with each other. The term "directly parallel mounting" means that two selected storage elements have their terminals directly connected in pairs, excluding a series arrangement. The connection step comprises in particular a step of electrical connection between the two branches to which belong the two storage elements selected in the selection step, said connection being made, with respect to the direction of current flow in said branches, in upstream and downstream of the selected storage elements.

The balancing principle by an electrically direct paralleling is presented with reference to Figure 3 in application to two storage elements each consisting of an electrochemical cell. Each cell is unique in design, as previously stated.

The cell manufacturing process does not allow to obtain completely identical cells, especially about the capacity. The paralleling of these cells is accompanied by an equality of electrical tension which generates the flow of a current from the most charged cell to the cell which is less. Figure 3 illustrates the particular case where the cell 1 is the most loaded. Its empty voltage is OCV1. Thus, the current εg will charge the cell 2 whose empty voltage is OCV2. As its state of charge increases, OCV2 also increases and ieg decreases until the cells are balanced in voltage and therefore approximately in state of charge.

The method, through the management device, allows to select certain storage elements of the battery according to predetermined criteria, then connect these previously selected elements in an electrical assembly where they are all directly in parallel electrically. For each of the elements of this parallel assembly, the balancing principle described in FIG. 3 applies, which makes it possible to concretely perform a step of balancing the states of charge of all or part of the storage elements of the battery. , ie those which have been previously selected by the control unit.30 It is in particular possible to provide for an electrical connection link to connect two direct links interposed between storage elements respectively Ei j and Ei, 1.1 of the same rank i from one branch to another. Thus, two storage elements of the same rank i selected in the selection step and belonging to different branches respectively Bi and B1 + 1 are then put in parallel. The selection of the storage elements Ei j at the selection stage is a function of selection criteria taking into account, for example: a desired dynamics of the balancing, and / or a threshold value of the electrical intensity in the parallel connection of the storage elements selected in the selection step. In the first case, it is possible in particular to associate in parallel the storage elements having the lowest voltage with the elements having the highest voltage. In the second case, the choice of elements must take into account a maximum value of the difference in voltage (or state of charge) to be balanced within the assembly.

A particular but non-exclusive application consists in arranging such a management device on board a motor vehicle to control the battery for storing electrical energy supplying an electric traction chain of the vehicle and / or auxiliary electrical components on board the vehicle. vehicle. However, the invention can be applied to any battery system which is composed of at least two electrochemical cells in series, such as laptop batteries, for example, or even the balancing of supercapacities. The management method will be better understood in the context of an exemplary application with reference to FIG. 4, which details a second simplified storage battery with respect to the case of FIG. 1, but for which the management method can also be used. to be applied. This terminal battery A and D comprises two branches 13i (the number m is equal to two) connected in a parallel connection and each of the branches comprises three storage elements Ei, 1 (the number n is equal to three) connected in one series mounting along their respective branch. On the first branch B1, three storage elements E1,1, E2,1 and E3,1 are connected in series. On the second branch B2, three storage elements E1,2, E2,2 and E3,2 are also connected in series. A management device is adapted for implementing the method. The two branches B1 and B2 are electrically connected in parallel with each other. The direct electrical connection between the element E1,1 and the element E2,1 of the first branch is connected to the direct electrical connection between the element E1,2 and the element E2,2 of the second branch by the intermediate of a first connection link on which is arranged a first switching element C1.1. The direct electrical connection between the element E2,1 and the element E3,1 of the first branch is connected to the direct electrical connection between the element E2,2 and the element E3,2 of the second branch by the intermediate of a second connection link on which is arranged a second switching element C2,1. Each of the two switching elements C1,1 and C2,1 can vary between two states respectively open and closed. The management device which comprises the two electrical connection links and the two switching elements C1,1 and C2,1 controlled by a control unit (not shown) can thus adopt four distinct states: the case 1 where the two elements of switching are open, the case 2 where only the switching element C2,1 is closed, the case 3 where only the switching element C1,1 is closed, and the case 4 where the two switching elements are closed. Case 1 corresponds to an inactive state of the management device. In this case, the differences of state of charge of the elements of the battery remain invariant.

In case 2, elements E3,1 and E3,2 are associated in an assembly directly in parallel. The series connection of the elements E1,1 and E2,1 of the first branch is connected in parallel with the series connection of the elements E1,2 and E2,2 of the second branch. The states of charge of the elements E3,1 and E3,2 will be balanced. At the same time, the average charge states of the series assemblies of the elements E1,1 and E2,1 on the one hand, and E1,2 and E2,2 on the other hand, will be balanced. At the end of the connection step corresponding to the closing of the switching element C2,1, the unselected storage elements E1,1, E2,1, E1,2 and E2,2 branches among which d other storage elements E3,1 and E3,2 have been selected remain electrically connected to each other in at least one parallel and / or in series connection. The connection step is configured so that the directly parallel connection of the storage elements E3,1 and E3,2 selected in the selection step is electrically connected in series connection with the at least one parallel connection and or in series formed by said storage elements E1,1, E2,1, E1,2 and E2,2 not selected. In case 3, the elements E1,1 and E1,2 are associated in an assembly directly in parallel. The series connection of elements E2,1 and E3,1 of the first branch is connected in parallel with the series connection of elements E2,2 and E3,2 of the second branch. The states of charge of the elements E1,1 and E1,2 will be balanced. At the same time, the average load states of the series assemblies of the elements E2,1 and E3,1 on the one hand, and E2,2 and E3,2 on the other hand, will be balanced. At the end of the connection step corresponding to the closing of the switching element C1,1, the unselected storage elements E2,1, E3,1, E2,2 and E3,2 branches among which other storage elements E1,1 and E1,2 have been selected remain electrically connected to each other in at least one parallel and / or series connection. The connection step is configured so that the directly parallel connection of the storage elements E1,1 and E1,2 selected in the selection step is electrically connected in a series connection with the at least one parallel connection and or in series formed by said storage elements E2,1, E3,1, E2,2 and E3,2 not selected.

In the case 4 resulting from a connection step where the two switching elements have been closed, the elements E1,1 and E1,2 are associated in a first assembly directly in parallel. Elements E2,1 and E2,2 are associated in a second assembly directly in parallel. Elements E3,1 and E3,2 are associated in a third assembly directly in parallel. The three parallel assemblies, independent in the balancing they provide respectively, are electrically connected together in a series connection. In this case, the states of charge of elements E1,1 and E1,2; E2.1 and E2.2; E3,1 and E3,2 will balance two by two.

FIGS. 5 to 8 show the time evolution curves of the state of charge of each of the elements E1,1, E1,2, E2,1, E2,2, E3,1 and E3,2 respectively in FIGS. Case 1 to 4 from identical initial conditions.

In the case of Figure 5 corresponding to case 1, the charge states of the six storage elements do not change over time, because there is no balancing done.

In the case of FIG. 6 corresponding to case 2, the state of charge of the storage element E3.1 identified SoC_Ce1131 changes inversely with the state of charge of the storage element E3.2 identified SoC_Ce1132 because the terminals of these two storage elements are connected directly in parallel at the end of the connection step in order to achieve rapid dynamic balancing of their states of charge.

In the case of FIG. 7 corresponding to case 3, the state of charge of the storage element E1.1 identified SoC_Ce1111 changes inversely with the state of charge of the storage element E1.2 identified SoC_Ce1112 because the terminals of these two storage elements are connected directly in parallel at the end of the connection step in order to achieve rapid dynamic balancing of their states of charge. In the case of FIG. 8 corresponding to case 4, the state of charge of the storage element E3.1 identified SoC_Ce1131 changes inversely with the state of charge of the storage element E3.2 identified SoC_Ce1132 because the terminals of these two storage elements are connected directly in parallel at the end of the connection step in a first directly parallel assembly in order to achieve a first dynamic balancing of their states of charge. At the same time, the state of charge of the storage element E2,1 identified SoC_Ce1121 changes inversely with the state of charge of the storage element E2,2 identified SoC_Ce1122 because the terminals of these two storage elements are connected directly in parallel at the end of the connection step in a second assembly directly in parallel in order to achieve a second dynamic balancing of their states of charge. Finally, at the same time, the state of charge of the storage element E1,1 identified SoC_Ce1111 changes inversely with the state of charge of the storage element E1,2 identified SoC_Ce1112 because the terminals of these two storage elements are connected directly in parallel at the end of the connection step in a third assembly directly in parallel in order to achieve a third dynamic balancing of their states of charge. The three parallel assemblies are independent and connected together in series. FIG. 9 illustrates identical curves but in the case of a combination in time of several of the states of the management device, here by controlling the switching elements first in case 2, then in case 4 after about 6000 seconds of application of Case 2.

With reference to FIG. 10, the balancing step may comprise a step of estimating the balancing electric currents within the parallel assembly of the storage elements selected in the selection step. In particular, the estimation step may comprise a step of determining the voltage across at least one switching element Ci, 1 arranged on at least one electrical connection link interconnecting two branches, among which storage elements Ei, 1 were selected at the selection stage. Means of measurement are used at each branch to determine the current of the series assembly at the input of branch: respectively 11 for the branch B1, 12 for the branch B2, lm for the branch Bm, etc ... The current passing through it the only closed switching element is such that: 1c = 11 + 12 + let :, where let :, is the balancing current to be determined.

Or: = + =: 1a voltage at the edge of the element E. Tic: the voltage at the connector terminals the resistance of the connector Thus, knowing the resistance 1: 1c of the switching element, the measurement of the voltage 1.1 c at its terminals allows to determine the balancing current leq.

It can also be expected that the management method comprises a step of protection against excessive discharge of any storage element Eijde the battery, this step comprising: a step of identifying at least one storage element Ei, 1 de the battery at the terminals of which the voltage is below a predetermined low threshold (this threshold being itself a function of a risk of deterioration threshold and a safety margin), - then a balancing step as defined previously the selection step is such that at least the storage element identified in the identification step is selected and all the storage elements located at locations of the same rank as the location where the element is implanted storage identified in the identification step are selected. If in use, the control unit, receiving as input the value of the electrical voltages at the terminals of the storage elements, detects that an element Ei, 1 reaches a voltage close to the excessive discharge voltage, it sends a closing command connectors Ci_ 1,1 <j <m-1 and Co <i <mi to put all the elements of the line Li in parallel and therefore, insofar as the states of charge of the other elements are greater than zero, to balance and prevent excessive discharge of the element E;, 1.

Thus, it is possible to provide that during the selection step, at least one storage element Ei j of each branch Bi is selected. With reference to FIG. 11, the management method may also include a step of protecting against an excessive load of any storage element of the battery, comprising a step of automatic dissipation of energy at the level of at least one storage element of the battery when the voltage at the terminals of this storage element is greater than a predetermined high threshold. For this purpose, the software and / or hardware means comprise, for example, a zener diode labeled 4.1 mounted in parallel with each of the storage elements Ei, 1 and configured to become on when the electrical voltage at its terminals is greater than the predetermined high threshold. excessive loading of the storage elements. This threshold is based on a threshold of risk of deterioration and a safety margin. During the dissipation, a part of the energy stored in the element Ei, 1 is dissipated in a resistor Ri j connected in series with the diode 41. The solution previously described makes it possible to have selective balancing circuits, with few components. In addition to a low cost, it eliminates a chain of energy transport and therefore losses of conversion efficiency associated with it. Incidentally, it makes it possible to dispense with a precise measurement of the voltage of the cells, therefore the voltage sensors can be replaced by less efficient sensors but less expensive.

The invention has the following advantages: - it is a non-dissipative balancing, which redirects the energy within the battery, from the most charged elements to the least loaded, - the management device allows select the elements between which the energy transfer is carried out during balancing, - there is no voltage drop across the battery during the balancing step, - any short circuit faults switching elements have no effect, - there is no loss by Joule effect in the switching elements outside the balancing step: indeed in normal operation, the current in the battery is distributed in the different branches without passing through any switching element then all in the open state, - the paralleling of several elements in series with several other elements in series allows low current calls. The inrush current is a function of the voltage difference of the elements in parallel and the equivalent resistance of the mesh created during the paralleling. The paralleling of several elements in series with several other elements in series induces a high equivalent resistance. Consequently, the current draw is weak for a given voltage difference, - in the case of a matrix architecture of the battery whose number of branches is greater than 2, it is possible to realize a mode of operation for which the switching elements are not traversed by the entire battery current and therefore their dimensioning can be less restrictive, to limit the cost of components (switches and associated passive components).

Claims (13)

REVENDICATIONS1. A method of managing an electric power storage battery comprising a plurality of branches (Bj, 1m) electrically connected to each other in a parallel arrangement and each having a plurality of connected storage elements (E; j, 1n) electrically between them in a series connection, the management method comprising a step of balancing the charge states (SoC) of all or part of said storage elements (Ei, j), the management method being characterized in that balancing step comprises: a step of selecting at least two storage elements (E; j, Eij + 1) belonging to two distinct branches (Bj, Bi + i) and at the terminals of which the electrical voltages are different, and a connection step in a directly parallel arrangement of the storage elements selected in the selecting step. 2. Management method according to claim 1, characterized in that the connection step comprises a step of electrical connection between the two branches to which belong the two storage elements selected in the selection step, said connection being made by relative to the flow direction of the current in said branches, upstream and downstream of the selected storage elements. 3. Management method according to one of claims 1 or 2, characterized in that two of the storage elements selected in the selection step and belonging to separate branches are located at locations of the same rank (i) within serial assembly in their respective branches. 4. Management method according to one of claims 1 to 3, characterized in that, at the end of the selection step, at least one storage element (Ei, j) is selected. 5. Management method according to one of claims 1 to 4, characterized in that the selection of the storage elements (Ei, j) in the selection step is based on selection criteria taking into account a desired dynamics of balancing and / or a threshold value of the electrical intensity in the directly parallel mounting of the storage elements (Ei, 1). 6. Management method according to one of claims 1 to 5, characterized in that the balancing step comprises a step of estimating the balancing electric currents (leq) within the directly parallel connection of the elements of storage (Ei, j) selected in the selection step. 7. Management method according to claim 6, characterized in that the estimation step comprises a step of determining the voltage across at least one switching element (Ci, j) arranged on at least one connection of electrical connection interconnecting two branches (B1) to which belong storage elements (Ei, j) selected in the selection step. 8. Management method according to one of claims 1 to 7, characterized in that it comprises a step of protection against excessive discharge of any storage element (Ei, j) of the battery, comprising: - a step d identification of at least one storage element (Ei, j) of the battery at the terminals of which the electric voltage is below a predetermined low threshold, then a balancing step whose selection step is such that minus the storage element (Ei, j) identified at the identification step is selected and all the storage elements (Ei, j) located at locations of the same rank (i) as the rank of the element storage (Ei, j) identified at the identification step are selected. 9. Management method according to one of claims 1 to 8, characterized in that it comprises a step of protection against excessive load of any storage element (Ei, j) of the battery, comprising an automatic dissipation step energy stored in at least one storage element (Ei, j) of the battery when the electrical voltage across this storage element (Ei, j) is greater than a predetermined high threshold. 10. Device for managing an electric energy storage battery comprising a plurality of branches (B1, 1 <_j <_rn) electrically connected to each other in a parallel connection and each comprising a plurality of storage elements (E j, 1n) electrically connected to one another in a series connection, the device being characterized in that it comprises software and / or hardware means which implement a management method according to any one of claims 1 to 9 . 11. Management device according to claim 10, characterized in that the software and / or hardware means comprise electrical connection links each connecting two branches (B1, B1 + 1) between them between two storage elements (Eij, Ei, 1,1) and each having a switching element (Ci, j), the connecting links being configured so that each branch is electrically connected to at least one other branch. 12. Management device according to claim 11, characterized in that the software and / or hardware means comprise a control unit generating actuation commands driving the switching elements (Ci, j) so as to perform the step of connection. 13. Management device according to any one of claims 10 to 12, characterized in that the software and / or hardware means comprise a zener diode (4.1) connected in parallel with each of the storage elements (Ei, j). and configured to turn on when the voltage at its terminals is greater than the predetermined high threshold of excessive charge of the storage elements (Ei, j), a portion of the stored energy being dissipated in a resistor (Ri, j) connected in series with the diode (4,1).