Balancing the charge of an electric battery

Abstract

The present invention relates to a system (400) comprising an electric battery (401) composed of N elementary cells in series (C1, C2, C3, C4) and Z power transfer modules (M1, M2) each having first and second nodes (A, B) which are connected by corresponding K+1 cells in series, and a third node (D) connected to the first node (A) by only one of the K+1 cells. The third node (D) of each module (M1, M2) is not shared with that of any other module. K is an integer greater than or equal to 2 which is the same for all of the modules (M1, M2).

Description

DESCRIPTION Load balancing in an electric battery

[0001] This application is based on, and claims priority from, French patent application FR2201038 filed on February 7, 2022 and entitled "Charge balancing in an electric battery", which is considered to form an integral part of this description within the limits provided by law. technical field

[0002] This description relates generally to electronic circuits, and, more specifically, to a system comprising an electric battery and energy transfer modules to balance the charge levels of elementary battery cells. Previous technique

[0003] An electric battery typically comprises a group of several elementary cells (accumulators, etc.) connected in series between two nodes or terminals supplying a direct current voltage. To maximize battery performance and increase its lifespan, energy transfer modules can be connected to the intermediate nodes of the series connection of battery cells to balance the charge levels of the cells. These energy transfer modules then form part of a battery balancing circuit. Various configurations of battery balancing circuits and connections of these balancing circuits to the battery cells have been proposed. However, these configurations each have their own drawbacks. Summary of the invention

[0004] There is a need for a system that addresses all or part of the drawbacks of known systems, including a battery and energy transfer modules connected to the battery's elementary cells.

[0005] One embodiment overcomes all or part of the disadvantages of known systems comprising a battery and energy transfer modules connected to the elementary cells of the battery.

[0006] One embodiment provides a system comprising: an electric battery consisting of a series arrangement of N elementary cells; and Z are first energy transfer modules, each first module having a first node and a second node connected by a corresponding set of K+l elementary cells in series, and a third node connected to the first node by a single K+l elementary cells of said corresponding set. Each first module has its third node not shared with the third node of every other first module. K is an integer greater than or equal to 2, identical for all first modules. Z is an integer greater than or equal to 2. N is an integer greater than or equal to K+2. An elementary cell is connected between the first and third nodes of one of the first modules, and to another elementary cell connected between the first and third nodes of another of the first modules, the third node of said one of the first modules being connected to the first node of said other of the first modules.

[0007] According to one embodiment, Z is equal to N-2 and N is even. Furthermore, a connection of the first half of the first N-2 modules to ((N-2) / 2)+K elementary cells in series from a first end of the association of N elementary cells in series, and a connection of the second half of the first N-2 modules to ((N-2) / 2)+K elementary cells in series from a second end of the association of N elementary cells in series. series are symmetrical to each other with respect to a midpoint of the association of the N elementary cells in series.

[0008] In one embodiment, the system comprises a second energy transfer module having a first node and a second node connected by a corresponding set of H elementary cells in series, and a third node connected to the midpoint of the association of N elementary cells in series, the midpoint of said corresponding set of H elementary cells being the midpoint of the association of N elementary cells in series. The second module has its third node not in common with the third node of each first module. H is strictly less than N.

[0009] According to one embodiment, K is odd and H is equal to K+l.

[0010] According to one embodiment, Z is equal to Nl and N is odd. Furthermore, a connection of a first half of the first Nl modules to ((Nl) / 2)+K elementary cells in series from a first end of the association of N elementary cells in series and a connection of a second half of the first Nl modules to ((Nl) / 2)+K elementary cells in series from a second end of the association of N elementary cells in series are symmetric to each other with respect to a central elementary cell of the association of N elementary cells in series.

[0011] According to one embodiment, Z is less than or equal to Nl.

[0012] According to one embodiment, Z is equal to Nl.

[0013] According to one embodiment, Z is equal to NK and the system further comprises Kl second energy transfer modules. Each second module has a first node and a A second node is connected by a corresponding set of P elementary cells in series, and a third node is connected to the first node by only one of the P elementary cells of said corresponding set. P is an integer less than or equal to K, P is greater than or equal to 2, and P has a different value for each of the second modules. Each second module has its third node not in common with the third node of each first module and each other second module.

[0014] According to one embodiment, the system comprises exactly Nl energy transfer modules in total.

[0015] According to one embodiment, none of the first modules has its first and second nodes in common with the respective first and second nodes of each of the other first modules.

[0016] According to one embodiment, each energy transfer module is adapted to transfer electrical energy from the cell or cells connecting its first and third nodes to the cell or cells connecting its third and second nodes, and vice versa. Brief description of the drawings

[0017] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the attached figures, among which:

[0018] Figure 1 illustrates an example of an embodiment of a system comprising an electric battery and a balancing circuit;

[0019] Figure 2 illustrates an example of another embodiment of a system comprising an electric battery and a balancing circuit;

[0020] Figure 3 illustrates yet another embodiment of a system comprising an electric battery and a balancing circuit; and

[0021] Figure 4 illustrates yet another example of a system comprising an electric battery and a balancing circuit. Description of the implementation methods

[0022] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0023] In the description that follows, when referring to absolute positional qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative positional qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientational qualifiers, such as the terms "horizontal", "vertical", etc., unless otherwise specified, it refers to the orientation of the figures.

[0024] Unless otherwise specified, the expressions "approximately", "roughly", "about", and "on the order of" mean within 10%, preferably within 5%.

[0025] Unless otherwise specified, when referring to two connected elements, this means directly connected without any intermediate elements other than conductors, and when referring to two coupled elements, this means that these two elements can be connected or linked through one or more other elements.

[0026] For the sake of clarity, only the steps and elements necessary for understanding the described embodiments have been shown and are detailed. In particular, known battery balancing algorithms, from which energy transfer modules can be controlled to balance the charge levels of the battery cells, have not been detailed, as the described embodiments are compatible with these known algorithms. Furthermore, known implementations of energy transfer modules and their control circuits have not been detailed, as the described embodiments are compatible with these known implementations.

[0027] In the following description, we consider energy transfer modules each having first, second and third nodes, and each adapted to transfer electrical energy from the cell(s) linking the first and third nodes of the module to the cell(s) linking the third and second nodes of the module.

[0028] For example, such modules each include: - a switch, for example a MOS (Metal Oxide Semiconductor) transistor, one conduction terminal of which is connected, for example, to the first node of the module and another conduction terminal of which is connected, for example, to an internal node of the module, - a switch, for example a MOS transistor, one conduction terminal of which is connected, for example, to the second node of the module and another conduction terminal of which is connected, for example, to the internal node of the module, and - an inductive element one terminal of which is connected, for example, to the internal node of the module, and another terminal is linked, for example connected, to the third node of the module. Examples of modules of this type are, for example, illustrated by Figures 3, 6A, 6B and 6C of patent EP 29440008 or US patent 9847655, the content of these two patents being incorporated into the present application within the limits provided by law, and the embodiments described being compatible with these examples of modules.

[0029] As an example, each module of the type described above may further include a control circuit for its switches. The control of the module's switches by its control circuit may be active or passive. An example of a module control circuit is described in relation to Figure 4 of the two aforementioned patents.

[0030] Systems are known in which each module has its first node connected to the first terminal of the battery, its second node connected to the second terminal, and its third node connected to an intermediate node in the series-connected battery cell array. However, each module then sees the entire available DC voltage between the battery terminals, which is undesirable. An example of such a system is described in relation to Figure 2 of the two aforementioned patents.

[0031] Furthermore, systems are known in which each module has its first and second nodes connected by exactly two elementary battery cells, and its third node connected to the midpoint of these two elementary cells. These systems are very efficient at transferring energy between two neighboring cells, but are no longer efficient enough when energy needs to be transferred between two distant cells, particularly due to energy losses in the modules under load. transfer. An example of such a system is described, for instance, in relation to Figure 1 of the two aforementioned patents.

[0032] Systems are also known in which, with the exception of certain energy transfer modules connected to the battery terminals, each module has its first and second nodes connected by an even number of elementary cells strictly greater than two, and its third node connected to the midpoint of these cells. In other words, except for modules connected to the battery terminals, each module has its first and third nodes connected by X cells, where X is an integer greater than or equal to 2, its third and second nodes connected by X cells, and its first and second nodes connected by 2X cells. Examples of such systems are described, for instance, in relation to Figures 3 and 5 of the aforementioned patents. These systems offer a good compromise between the balancing efficiency between neighboring cells and the balancing efficiency between distant cells, while preventing any one module from receiving the entire DC voltage of the battery.However, to balance any charge imbalance between the battery cells in such a system, the minimum current each module must be able to supply at its third node increases quadratically with the number N of battery cells, which is undesirable. For example, this minimum current is proportional to (N*N) / A, with A equal to 8 when X equals 2, and with A equal to 18 when X equals 3.

[0033] This section proposes systems comprising a battery with N cells in series and Nl balancing modules. Among the Nl modules, there are N-2 modules (called "1-to-Q modules") for each of which the first and second nodes of the module are connected by Q+l cells, where Q is an integer greater than or equal to 2, and the first and The third nodes of the module are connected by only one of the Q+1 cells. Each of the N-2 1-to-Q modules has its third node not shared with the third node of each of the other N-2 1-to-Q modules. Each of the N-2 1-to-Q modules has its first node not shared with the first node of the other N-2 1-to-Q modules and / or its second node not shared with the second node of the other N-2 1-to-Q modules. None of the Nl modules in the system has its first and second nodes connected to the first and second terminals of the battery, respectively, so none of the Nl modules sees the full battery voltage. Among the N-2 1-to-Q modules, there are Z modules, where Z is an integer greater than or equal to 2, for which Q has the same value K.For two consecutive battery cells, one of the two cells connects the first and third nodes of one of the Z modules, and the other of the two cells connects the first and third nodes of another of the Z modules. N is at least equal to 2+K.

[0034] In other words, a system is proposed here comprising an electric battery with an association of N cells in series and Nl energy transfer modules, in which the Nl modules comprise Z modules, for each of which the first and second nodes of the module are connected by a corresponding set of exactly K+l cells in series, and the third node of the module is connected to the first node of the module by a single one of these K+l cells. Each of the Z modules has its third node not shared with the third node of the other modules. Furthermore, one of the N cells is connected between the first and third nodes of the first of the Z modules, and to another of the N cells, said other cell being connected between the first and third nodes of a second of the Z modules, and the third node of the first module being further connected to the first node of the second module. We understand that Z is therefore at least equal to 2, and that N is at least equal to K+2.

[0035] Such a configuration of the connection of the modules to the battery cells allows that the current that each module must be able to supply on its third node to allow the battery to be balanced increases linearly with the number N of battery cells.

[0036] Figure 1 illustrates an embodiment of a system 100 comprising a battery 101 comprising N elementary cells in series, and a charge balancing circuit connected to the battery 101.

[0037] More specifically, Figure 1 illustrates an example of an embodiment in which: - the number Z of energy transfer modules having the same number K of cells between their second and third nodes is equal to N-2, - N is even, and - a connection of half of the Z modules to elementary cells in series from a first terminal of the battery 101 and a connection of the other half of the Z modules to elementary cells in series from a second terminal of the battery 101, are symmetrical to each other with respect to a midpoint of the N elementary cells in series.

[0038] In the example in Figure 1, K equals 3 and N equals 8 (so Z equals 6). In other examples not shown, the number N is different from 8, for example smaller than, or, conversely, greater than, 8, and / or the number K is different from 3, for example smaller than, or, conversely, greater than, 3.

[0039] Battery 101 comprises N elementary cells Ci, with i an integer index from 1 to N, connected in series, in order of increasing index, between the nodes or terminals V+ and V- of battery 101. In this example, the positive terminal of cell Cl and the negative terminal of cell C8 are respectively connected to the V+ and V- terminals of the battery, and each of the intermediate cells C2 to C7 of the battery has its positive terminal connected to the negative terminal of the neighboring cell with a lower index, and its negative terminal connected to the positive terminal of the neighboring cell with a higher index.

[0040] The load balancing circuit comprises Z load balancing modules Mj, with j an integer index from 1 to Z, or, put another way, from 1 to N-2.

[0041] One half of the Z modules Mj is connected to ((N-2) / 2)+K elementary cells in series from the V+ end of the series arrangement of the N cells Ci of battery 101. A second half of the Z modules is connected to ((N-2) / 2)+K elementary cells in series from the V- end of the series arrangement of the N cells Ci of battery 101. In other words, for each module Mj belonging to the first half of the modules Mj, the K+1 cells that connect the first node A of the module to the second node B of the module are cells belonging to the ((N-2) / 2)+K cells that are in series from the terminal V+ of battery 101, and, for each module Mj belonging to the second half of the modules Mj, the K+l cells which connect the nodes A and B of the module are cells belonging to the ( (N-2) / 2)+K cells which are in series from the terminal V- of battery 101.

[0042] More specifically, the modules Mj with index j ranging from 1 to Z / 2 (M1, M2, M3 in the example in Figure 1) are connected to the cells Ci with index i ranging from 1 to ((N-2) / 2)+K (Cl, C2, C3, C4, C5 and C6 in the example in Figure 1), and the modules Mj with index j ranging from (Z / 2)+l to N-2 (M4, M5 and M6 in the example in Figure 1) are connected to the cells Ci with index i ranging from ( (N+2 ) / 2 ) -K+l to N (C3, C4, C5, C6, C7 and C8 in the example in Figure 1).

[0043] For the first half of the Z modules Mj, each module Mj has its first node A and its third node D connected by the cell Ci with index i equal to j, and, for the second half of the Z modules M, each module Mj has its nodes A and D connected by the cell Ci with index i equal to j+2. For example, the module M1 has its nodes A and D connected by the cell Cl, and the module M5 has its nodes A and D connected by the cell C7.

[0044] In addition, for the first half of the Z modules Mj, each module Mj has its node A connected to the terminal of the cell Ci with index i equal to j which is on the side of the terminal of battery 101 connected to cell Cl, and, for the second half of the Z modules Mj, each module Mj has its node A connected to the terminal of the cell Ci with index i equal to j+2 which is on the side of the terminal of battery 101 connected to cell CN (or C8 in the example in Figure 1).

[0045] None of the modules Mj share its D node with the D node of any other module Mj. Furthermore, none of the modules Mj share its A and B nodes with the A and B nodes of each of the other modules Mj, respectively. For example, each module Mj has its A node not shared with the A node of every other module Mj, but may have its B node shared with the B node of another module Mj.

[0046] Since N is greater than or equal to K+2, none of the modules Mj sees all N battery cells between its nodes A and B.

[0047] The 100 system comprises Nl energy transfer modules in total and, as illustrated in Figure 1, the The balancing circuit then includes an energy transfer module Mb in addition to the N-2 modules Mj.

[0048] To maintain a 100% symmetric system, module Mb has its first node A and second node B connected by an even number H of serial cells Ci. Furthermore, module Mb has its third node D connected to the midpoint 104 of the N serial cells Ci, that is, to the point 104 connecting cell Ci with index i equal to N / 2 to cell Ci with index i equal to (N / 2)+1. Point 104 also corresponds to the midpoint of the H serial cells Ci connecting nodes A and B of module Mb. Module Mb has a node D that is not common to the node D of each of the modules Mj.

[0049] Preferably, when K is odd, as in the example in Figure 1, the number H of serial cells Ci connecting nodes A and B of module Mb is equal to K+l. Thus, each of modules Mj and Mb has the same number K+l of cells Ci between its nodes A and B.

[0050] However, in other, unillustrated examples, whether K is even or odd, the module Mb has its nodes A and B connected by an even number H of serial cells Ci that is not equal to K+1. For example, the module Mb shown in Figure 1, which has its nodes A and B connected by H equal to four serial cells Ci, can be replaced by a module Mb whose nodes A and B are connected by H equal to two serial cells Ci, and whose node D is connected to the midpoint of these two serial cells Ci.

[0051] Furthermore, the number H of cells Ci connecting nodes A and B of module Mb is strictly less than N, so module Mb does not see all N battery cells between its nodes A and B

[0052] Figure 2 illustrates another embodiment of a system 200 comprising a battery 201 with N cells elementary in series, and a charge balancing circuit connected to battery 201.

[0053] More specifically, Figure 2 illustrates an example of an embodiment in which: - the number Z of modules, each having the same number K of cells between its second and third nodes, is equal to N-1, - N is odd, and - a connection of half of the Z modules to elementary cells in series from a first terminal of battery 101 and a connection of the other half of the Z modules to elementary cells in series from a second terminal of battery 101, are symmetrical with respect to a central elementary cell.

[0054] In the example in Figure 2, K equals 3 and N equals 7 (so Z equals 6). In other examples not shown, the number N is different from 7, for example smaller than, or, conversely, greater than, 7, and / or the number K is different from 3, for example smaller than, or, conversely, greater than, 3.

[0055] Battery 201 comprises N elementary cells Ci, where i is an integer from 1 to N, connected in series, in ascending order of index, between the nodes or terminals V+ and V- of battery 201. In this example, the positive terminal of cell C1 and the negative terminal of cell C7 are connected to the V+ and V- terminals of the battery, respectively, and each of the intermediate cells C2 to C6 of the battery has its positive terminal connected to the negative terminal of the neighboring cell with a lower index, and its negative terminal connected to the positive terminal of the neighboring cell with a higher index. In this example, the central cell in the series arrangement of the N cells Ci is cell C4.

[0056] The load balancing circuit comprises Z load balancing modules Mj, with j an integer index from 1 to Z, or, put another way, from 1 to Nl.

[0057] A first half of the Z modules Mj is connected to ( (Nl) / 2)+K elementary cells Ci in series from the V+ end of the series association of the N cells of Ci of battery 201. A second half of the Z modules is connected to ( (Nl) / 2)+K elementary cells Ci in series from the V- end of the series association of the N cells of Ci of battery 201.

[0058] More specifically, modules Mj with index j ranging from 1 to Z / 2 (M1, M2, M3 in the example in Figure 2) are connected to cells Ci with index i ranging from 1 to ((N-l) / 2)+K (Cl, C2, C3, C4, C5 in the example in Figure 2), and modules Mj with index j ranging from (Z / 2)+1 to Nl (M4, M5 and M6 in the example in Figure 2) are connected to cells Ci with index i ranging from ((N+l) / 2)-K+l to N (C2, C3, C4, C5, C6 and C7 in the example in Figure 2).

[0059] For the first half of the Z modules Mj, each module Mj has its nodes A and D connected by the cell Ci with index i equal to j, and, for the second half of the Z modules Mj, each module Mj has its nodes A and D connected by the cell Ci with index i equal to j+1. For example, the module Ml has its nodes A and D connected by the cell Cl, and the module M5 has its nodes A and D connected by the cell C6.

[0060] In addition, for the first half of the Z modules Mj, each module Mj has its node A connected to the terminal of the cell Ci with index i equal to j which is on the side of the terminal of battery 201 connected to cell Cl, and, for the second half of the Z modules Mj, each module Mj has its node A connected to the terminal of the cell Ci with index i equal to j+1 which is on the side of the terminal of the battery connected to cell CN (or C7 in the example in Figure 2).

[0061] None of the modules Mj share its D node with the D node of any other module Mj. Furthermore, none of the modules Mj share its A and B nodes with the A and B nodes of each of the other modules Mj, respectively. For example, each module Mj has its A node not shared with the A node of every other module Mj, but may have its B node shared with the B node of another module Mj.

[0062] Since N is greater than or equal to K+2, none of the modules Mj sees all N battery cells between its nodes A and B.

[0063] The 200 system comprises Nl energy transfer modules in total.

[0064] Figure 3 illustrates another embodiment of a system 300 comprising a battery 301 comprising N elementary cells in series, and a charge balancing circuit connected to the battery 301.

[0065] More specifically, Figure 3 illustrates an example of an embodiment in which the number Z of modules, each having the same number K of cells between its second and third nodes, is equal to Nl. In the example in Figure 3, K is equal to 3 and N is equal to 8 (so Z is equal to 7). In other examples not shown, the number N is different from 8, for example, smaller than 8, or, conversely, greater than 8, and / or the number K is different from 3, for example, smaller than 3, or, conversely, greater than 3.

[0066] Battery 301 comprises N elementary cells Ci, where i is an integer index from 1 to N, connected in series, in ascending order of index, between the nodes or terminals V+ and V- of battery 201. In this example, the positive terminal of cell C1 and the negative terminal of cell C8 are respectively connected to the V+ and V- terminals of the battery, and each of the intermediate cells C2 to C7 of the battery has its positive terminal connected to the negative terminal of the neighboring cell with a lower index, and its negative terminal connected to the positive terminal of the neighboring cell with a higher index. In another example not shown, the negative terminal of cell C1 and the positive terminal of cell C8 are respectively connected to the V- and V+ terminals of the battery, and each of the intermediate cells C2 to C7 of the battery has its negative terminal connected to the positive terminal of the neighboring cell with a lower index, and its positive terminal connected to the negative terminal of the neighboring cell with a higher index.

[0067] The load balancing circuit comprises Z load balancing modules Mj, with j an integer index from 1 to Z, or, put another way, from 1 to Nl.

[0068] The Mj modules are connected such that none of the Mj modules shares its D node with the D node of any other Mj module, and, furthermore, none of the Mj modules shares its A and B nodes with the A and B nodes of each of the other Mj modules, respectively. For example, each Mj module has its A node not shared with the A node of every other Mj module, but may have its B node shared with the B node of another Mj module.

[0069] Since N is greater than or equal to K+2, none of the modules Mj sees all N battery cells between its nodes A and B.

[0070] More specifically, the modules Mj are separated into two groups, G1 and G2, each group G1, G2 comprising at most NK modules Mj. Group G1 comprises Y modules Mj, with Y an integer having a value between K1 and NK, group G2 then comprising N1Y modules Mj. In other words, group G1 comprises the modules Mj with index j ranging from 1 to Y, and group G2 comprises the modules Mj with index j ranging from Y+1 to N1. In the example in Figure 3, Y is equal to 4, hence it It follows that group G1 includes modules M1, M2, M3, M4 and that group G2 includes modules M5, M6 and M7.

[0071] The modules Mj of group G1 (index j ranging from 1 to Y) are connected to Y+K cells Ci with index i ranging from 1 to Y+K. The modules Mj of group G2 (index j ranging from Y+1 to N-1) are connected to cells Ci with index i ranging from Y+2-K to N.

[0072] Each module Mj of group G1 has its nodes A and D connected by the cell Ci with index i equal to j, and each module Mj of group G2 has its nodes A and D connected by the cell Ci with index i equal to j+1.

[0073] In addition, the modules Mj of group G1 each have their node A connected to the terminal of cell Ci with index i equal to j which is on the side of the terminal of battery 301 connected to cell Cl. The modules Mj of group G2 each have their node A connected to the terminal of cell Ci with index i equal to j+1 which is on the side of the terminal of battery 301 connected to cell CN (or C8 in figure 3).

[0074] The 300 system comprises Nl energy transfer modules in total.

[0075] Figure 4 illustrates another embodiment of a system 400 comprising a battery 401 comprising N elementary cells in series, and a charge balancing circuit connected to the battery 401.

[0076] More specifically, Figure 4 illustrates an example of an embodiment in which the number Z of modules, each having the same number K of cells between its second and third nodes, is equal to NK. In this embodiment, the 400 system further comprises Kl Mbu modules, with u an integer index ranging from N-K+1 to Nl. Each Mbu module has its first node A and its second node B connected by P cells in series, with P an integer between 2 and Kl. different for each of the Mbu modules. Each Mbu module also has its first node A and its third node D connected by exactly one of the P cells in series between the nodes A and B of that module.

[0077] In the example in Figure 4, K equals 5 and N equals 8 (so Z equals 3). In other examples not shown, the number N is different from 8, for example smaller than, or, conversely, greater than, 8, and / or the number K is different from 5, for example smaller than, or, conversely, greater than, 5.

[0078] Battery 401 comprises N elementary cells Ci, with i an integer index from 1 to N, connected in series, in order of increasing index, between the nodes or terminals V+ and V- of battery 201. In the example in Figure 4, the positive terminal of cell Cl and the negative terminal of cell C8 are respectively connected to the V+ and V- terminals of the battery, and each of the intermediate cells C2 to C7 of the battery has its positive terminal connected to the negative terminal of the neighboring cell with a lower index, and its negative terminal connected to the positive terminal of the neighboring cell with a higher index.In another example not shown, the negative terminal of cell Cl and the positive terminal of cell C8 are respectively connected to the V- and V+ terminals of the battery, and each of the intermediate cells C2 to C7 of the battery has its negative terminal connected to the positive terminal of the neighboring cell with a lower index, and its positive terminal connected to the negative terminal of the neighboring cell with a higher index.

[0079] The load balancing circuit comprises Z load balancing modules Mj, with j an integer index from 1 to Z, or, put another way, from 1 to NK.

[0080] The Z modules Mj are connected to the N elementary cells Ci. More specifically, each module Mj has its nodes A and D connected by the cell Ci with index i equal to j •

[0081] The Kl Mbu modules are connected to the K Ci cells of index i ranging from N-K+l to N. Each Mbu module has its nodes A and D connected by the Ci cell of index i equal to u. Each Mbu module has its nodes A and B connected by P Ci cells in series, with P decreasing as the index u of the Mbu module increases.

[0082] Each module Mj has its node A connected to the terminal of cell Ci with index i equal to j which is on the side of the terminal of battery 401 to which cell Cl is connected (the V+ terminal in the example of Figure 4), and each module Mbu has its node A connected to the terminal of cell Ci with index i equal to u which is on the side of the terminal of battery 401 to which cell Cl is connected.

[0083] In the example in Figure 4, the 400 system comprises four Mb modules: Mb4, Mb5, Mb6, and Mb7. The Mb4 module has its nodes A and D connected by cell C5, the Mb5 module has its nodes A and D connected by cell C6, the Mb6 module has its nodes A and D connected by cell C7, and the Mb7 module has its nodes A and D connected by cell C8. Furthermore, P is between 2 and 5, and is equal to 5 for the Mb4 module, 4 for the Mb5 module, 3 for the Mb6 module, and 2 for the Mb7 module.

[0084] None of the modules Mj and Mbu share its node D with the node D of any other module Mj and Mbu. Furthermore, none of the modules Mj and Mbu share its nodes A and B with the nodes A and B of each of the other modules Mj and Mbu, respectively. For example, each module Mj has its node A not shared with the node A of every other module Mj, but may have its node B shared with the node B of another module Mj. Since N is greater than or equal to K+2, none of the modules Mj and Mbu do not see the total of the N cells of the battery between its nodes A and B.

[0085] The 400 system comprises Nl energy transfer modules in total.

[0086] One advantage of the embodiment illustrated in Figure 4 is that it is easy to add one or more Ci cells and a corresponding number of M modules, for example, by connecting the Ci cell(s) in series on the side to the Cl cell, with the indices i, j, u and the values ​​N, Y, and K then being updated. In particular, adding one or more Ci cells on the side of the Cl cell does not require modifying the connection of the Mj and Mbu modules that were already connected to the CN-connected Cl cells of battery 401.

[0087] In the embodiments described above in relation to Figures 1 to 4, although not illustrated, the balancing circuit may include a management circuit in addition to the modules and, for example, their control circuits. The management circuit is, for example, configured to receive information about the state of charge of the cells Ci and to control the modules accordingly, transferring electrical energy from the most heavily charged cells or groups of cells to the least charged cells or groups of cells. As an example, the state of charge of the cells Ci may be determined by voltage and / or current measurements, or by any other known means.

[0088] Various embodiments and variations have been described. A person skilled in the art will understand that some features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0089] Finally, the practical implementation of the described methods and variants is within the reach of the person in the trade, based on the functional indications given above.

Claims

CLAIMS System (100; 200; 300; 400) comprising: an electric battery (101; 201; 301; 401) comprising an association of N elementary cells (C1, C2, C3, C4) in series; and Z first energy transfer modules (M1, M2), each first module having a first node (A) and a second node (B) connected by a corresponding set of K+l elementary cells in series, and a third node (D) connected to the first node (A) by one of the K+l elementary cells of said corresponding set, wherein each first module (M1, M2) has its third node (D) not common to the third node (D) of every other first module, wherein K is an integer greater than or equal to 2 identical for all first modules (M1, M2), wherein Z is an integer greater than or equal to 2, wherein N is an integer greater than or equal to K+2, and wherein one elementary cell (C1) is connected between the first (A) and third (D) nodes of one (M1) of the first modules (M1, M2), and to another elementary cell (C2) connected between the first (A) and third (D) nodes of another (M2) of the first modules (Ml, M2) ,the third node (D) of said one (M1) of the first modules (M1, M2) being connected to the first node (A) of said another (M2) of the first modules (M1, M2). System (100) according to claim 1, in which: Z is equal to N-2; N is even; and a connection of a first half (M1, M2, M3) of the first N-2 modules to ((N-2) / 2)+K elementary cells (C1, C2, C3, C4, C5, C6) in series from a first end (V+) of the association of the N elementary cells in series and a connection of a second half (M4, M5, M6) of the first N-2 modules to ( (N-2) / 2)+K elementary cells (C3, C4, C5, C6, C7) in series from a second end (V-) of the association of the N elementary cells in series are symmetric to each other with respect to a midpoint (104) of the association of the N elementary cells in series.System (100) according to claim 2, wherein: the system (100) comprises a second energy transfer module (Mb) having a first node (A) and a second node (B) connected by a corresponding set of H elementary cells (C3, C4, C5, C6) in series, and a third node (D) connected to said midpoint (104) of the association of the N elementary cells in series, a midpoint of said corresponding set of H elementary cells being the midpoint (104) of the association of the N elementary cells in series; the second module (Mb) has its third node (D) not in common with the third node (D) of each first module; and H is strictly less than N. System (100) according to claim 3, wherein:. K is odd; and the number H is equal to K+l. System (200) according to claim 1, wherein: Z is equal to Nl; N is odd; and a connection of a first half (M1, M2, M3) of the first N1 modules to ((N1) / 2)+K elementary cells (C1, C2, C3, C4, C5, C6) in series from a first end (V+) of the association of the N elementary cells in series and a connection of a second half (M4, M5, M6) of the first N1 modules to ((N1) / 2)+K cells Elementary cells (C2, C3, C4, C5, C6, C7) in series from a second end (V-) of the association of N elementary cells in series are symmetrical to each other with respect to a central elementary cell (C4) of the association of N elementary cells in series. System (200, 300) according to claim 1, wherein Z is less than or equal to N1. System (400) according to claim 1, wherein: Z is equal to NK; the system further comprises Kl second modules (Mb4, Mb5, Mb6, Mb7) of energy transfer, each second module having a first node (A) and a second node (B) connected by a corresponding set of P elementary cells in series, and a third node (D) connected to the first node (A) by only one of the P elementary cells of said corresponding set; P is an integer less than or equal to K; P is greater than or equal to 2; P has a different value for each of the second modules (Mb4, Mb5, Mb6, Mb7); and each second module (Mb4, Mb5, Mb6, Mb7) has its third node (D) not in common with the third node (D) of each first module and each other second module. System (100; 200; 300; 400) according to any one of claims 1 to 7, wherein the system (100) comprises exactly Nl energy transfer modules in total. System (100; 200; 300; 400) according to any one of claims 1 to 8, wherein none of the first modules (Ml, M8) has its first (A) and second (B) nodes in common with the respective first (A) and second (B) nodes of each of the other first modules (Ml, M8). . System according to any one of claims 1 to 9, wherein each energy transfer module (M1, M8, Mb, Mb4, Mb7) is adapted to transfer electrical energy from the cell or cells connecting its first (A) and third (D) nodes to the cell or cells connecting its third (D) and second (B) nodes, and vice versa.

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