WO2023148227A1

WO2023148227A1 - Balancing the charge of an electric battery

Info

Publication number: WO2023148227A1
Application number: PCT/EP2023/052459
Authority: WO
Inventors: Alexandre Chureau
Original assignee: Enerstone
Priority date: 2022-02-07
Filing date: 2023-02-01
Publication date: 2023-08-10
Also published as: FR3132595A1; FR3132595B1

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 the priority of, the French patent application FR2201038 filed on February 7, 2022 and entitled "Charge balancing in an electric battery", which is considered to be an integral part of the this description within the limits provided for by law.

Technical area

The present description generally relates to electronic circuits, and, more particularly, to a system comprising an electric battery and energy transfer modules for balancing the charge levels of elementary cells of the battery.

Prior technique

[0003] An electric battery usually comprises a group of several elementary cells (accumulators, etc.) connected in series between two nodes or terminals for supplying a DC voltage. To maximize the performance of the battery and increase its lifetime, it is possible to connect to the intermediate nodes of the association in series of the cells of the battery, energy transfer modules in order to balance the levels of charge of the cells. Energy transfer modules then belong to a battery balancing circuit. Various configurations of circuits for balancing a battery and for connecting these balancing circuits to the cells of the battery have been proposed. However, these configurations have their own drawbacks.

Summary of the invention

[0004] There is a need for a system which overcomes all or part of the drawbacks of known systems comprising a battery and energy transfer modules connected to the elementary cells of the battery.

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

One embodiment provides a system comprising: an electric battery comprising an association of N elementary cells in series; And

Z first energy transfer modules, each first module having a first node and a second node connected by a corresponding set of K+1 elementary cells in series, and a third node connected to the first node by only one of the K+1 cells elements of said corresponding set. Each first module has its third node not common with the third node of each other first module. K is an integer greater than or equal to 2 identical for all the 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 another of the first modules.

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

According to 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 said midpoint of the association of the N elementary cells in series, a midpoint of said corresponding set of H elementary cells being the midpoint of the association of the N elementary cells in series. The second module has its third node not 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+1.

According to one embodiment, Z is equal to N-1 and N is odd. Further, a connection of a first half of the first N-1 modules to ((N-1)/2)+K elementary cells in series from a first end of the association of the N elementary cells in series and a connection of a second half of the first N-1 modules with ( (N-1) /2)+K elementary cells in series from a second end of the association of the N elementary cells in series are symmetrical to each other with respect to a central elementary cell of the association of the N elementary cells in series.

[0011] According to one embodiment, Z is less than or equal to N-1.

[0012] According to one embodiment, Z is equal to N-1.

According to one embodiment, Z is equal to NK and the system further comprises Kl second energy transfer modules. Every second module has a first node and a second node connected by a corresponding set of P elementary cells in series, and a third node 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 which is not common with the third node of each first module and of each other second module.

According to one embodiment, the system comprises exactly N-1 energy transfer modules in all.

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

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

These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments made on a non-limiting basis 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] FIG. 2 illustrates an example of another embodiment of a system comprising an electric battery and a balancing circuit; [0020] FIG. 3 illustrates an example of yet another embodiment of a system comprising an electric battery and a balancing circuit; And

[0021] FIG. 4 illustrates an example of yet another embodiment of a system comprising an electric battery and a balancing circuit.

Description of embodiments

The same elements have been designated by the same references in the various figures. In particular, the structural and/or functional elements common to the various embodiments may have the same references and may have identical structural, dimensional and material properties.

[0023] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "rear", "up", "down", "left", "right", etc., or relative, such as the terms "above", "below", "upper", "lower", etc., or to qualifiers of orientation, such as the terms "horizontal", "vertical", etc. ., unless otherwise specified, reference is made to the orientation of the figures.

[0024] Unless otherwise specified, the expressions “about”, “approximately”, “substantially”, and “of the order of” mean to within 10%, preferably within 5%.

[0025] Unless otherwise specified, when reference is made to two elements connected together, this means directly connected without intermediate elements other than conductors, and when reference is made to two connected elements (in English "coupled") between them, this means that these two elements can be connected or be linked via one or more other elements. [0026] For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been represented and are detailed. In particular, the known battery balancing algorithms, from which energy transfer modules can be controlled to balance the battery cell charge levels, have not been detailed, the embodiments described being compatible with these known algorithms. Moreover, the known implementations of energy transfer modules and their control circuits have not been detailed, the embodiments described being compatible with these known implementations.

In the remainder of the description, energy transfer modules are considered each having first, second and third nodes, and each being adapted to transfer electrical energy from the cell or cells connecting the first and third nodes of the module to the cell(s) connecting the third and second nodes of the module.

By way of example, such modules each comprise:

- a switch, for example a MOS (Metal Oxide Semiconductor) transistor, one conduction terminal of which is connected, for example connected, to the first node of the module and another conduction terminal of which is connected, for example connected, to an internal node of the module,

- a switch, for example an MOS transistor, one conduction terminal of which is connected, for example connected, to the second node of the module and of which another conduction terminal is connected, for example connected, to the internal node of the module, and

- an inductive element, one terminal of which is connected, for example connected, to the internal node of the module, and of which another terminal is connected, 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 of patent US 9847655, the content of these two patents being incorporated into the present application within the limits provided by the law, and the embodiments described being compatible with these example modules.

[0029] By way of example, each module of the type described above may also comprise a circuit for controlling its switches. The control of the module switches by its control circuit can be active or passive. An example of a module control circuit is described in relation to FIG. 4 of the two aforementioned patents.

[0030] Systems are known in which each module has its first node connected to a first terminal of the battery, its second node connected to a second terminal of the battery, and its third node connected to an intermediate node of the association of elementary cells in series of the battery. However, each module then sees all the DC voltage available between the battery terminals, which is not desirable. An example of such a system is for example described in relation to FIG. 2 of the two aforementioned patents.

There are also known systems in which each module has its first and second nodes connected by exactly two elementary cells of the battery, and its third node connected to the midpoint of these two elementary cells. These systems are very efficient for transferring energy between two neighboring cells, but are no longer efficient enough when energy has to be transferred between two distant cells, in particular because of the energy losses in the modules used for the transfer. An example of such a system is for example described in relation to FIG. 1 of the two aforementioned patents.

[0032] Systems are also known in which, with the exception of certain energy transfer modules connected to the terminals of the battery, each module has its first and second nodes connected by an even and strictly greater than two number of cells. elementary, 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, with X integer greater than or equal to 2, its third and second nodes connected by X cells, and its first and second nodes connected by 2*X cells. Examples of such systems are, for example, described in connection with 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 avoiding that one of the modules sees all the DC voltage of the battery. However, to balance any load imbalance between the battery cells of such a system, the minimum current that each module must be able to supply on its third node increases quadratically with the number N of battery cells, which is not desirable. For example, this minimum current is proportional to (N*N)/A, with A equal to 8 when X is equal to 2, and with A equal to 18 when X is equal to 3.

[0033] Systems are proposed here comprising a battery comprising N cells in series and N1 balancing modules. Among the Nl modules, there are N-2 modules (called "modules 1 to Q") for each of which the first and second nodes of the module are connected by Q+l cells, with Q integer greater than or equal to 2, and the first and 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 which is not common 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 which is n is not common with the first node of the other N-2 1 to Q modules and/or its second node which is not common with the second node of the other N-2 1 to Q modules. ' has its first and second nodes connected to the first and second battery terminals respectively, so that none of the Nl modules sees the full battery voltage. Among the N-2 modules 1 to Q, there are Z modules, with Z integer greater than or equal to 2, for which Q has the same value K. For two consecutive cells of the battery, 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 node of another of the Z modules. N is at least equal to 2+K.

In other words, a system is proposed here comprising an electric battery comprising 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+1 cells in series, and the third node of the module is connected to the first node of the module by only one of these K+1 cells. Each of the Z modules has its third node which is not common with the third node of the other modules. In addition, one of the N cells is connected between the first and third nodes of a 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. It is understood that Z is therefore at least equal to 2, and that N is at least equal to K+2.

Such a configuration of the connection of the modules to the cells of the battery allows the current that each module must be able to provide on its third node to allow the balancing of the battery to increase linearly with the number N of cells of the battery.

FIG. 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.

More particularly, Figure 1 illustrates an exemplary 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.

In the example of Figure 1, K is equal to 3 and N is equal to 8 (therefore Z is equal to 6). In other examples not illustrated, the number N is different from 8, for example smaller, or, on the contrary, greater than 8, and/or the number K is different from 3, for example smaller, or, on the contrary, contrary, greater than 3.

The battery 101 comprises N elementary cells Ci, with i an integer index ranging from 1 to N, connected in series, in ascending order of index, between the nodes or terminals V+ and V- of battery 101. In this example, the positive terminal of cell C1 and the negative terminal of cell C8 are respectively connected to terminals V+ and V- 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 of lower index, and its negative terminal connected to the positive terminal of the neighboring cell of higher index.

The load balancing circuit includes Z load balancing modules Mj, with j an integer index ranging from 1 to Z, or, in other words, from 1 to N-2.

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

V+ of the battery 101, and, for each module Mj belonging to the second half of the modules Mj , the K+1 cells which connect the nodes A and B of the module are cells belonging to ((N-2)/2)+ K cells which are in series from the V- terminal of the battery 101.

More particularly, the modules Mj of index j ranging from 1 to Z/2 (M1, M2, M3 in the example of FIG. 1) are connected to the cells Ci of index i ranging from 1 to ( ( N- 2) /2)+K (Cl, C2, C3, C4, C5 and C6 in the example of FIG. 1), and the modules Mj of index j ranging from (Z/2)+1 to N- 2 (M4, M5 and M6 in the example of FIG. 1) are connected to cells Ci of index i ranging from ( (N+2 ) /2 ) -K+1 to N (C3, C4, C5, C6, C7 and C8 in the example of figure 1).

For the first half of the Z modules Mj, each module Mj has its first node A and its third node D interconnected by the cell Ci of index i equal to j, and, for the second half of the Z modules M , each module Mj has its nodes A and D interconnected by the cell Ci of index i equal to j+2. For example, module M1 has its nodes A and D connected by cell C1, and module M5 has its nodes A and D connected by cell C7.

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

None of the modules Mj has its common node D with the node D of one of the other modules Mj. Furthermore, none of the modules Mj has its nodes A and B common with the nodes A and B respectively of each of the other modules Mj. For example, each module Mj has its node A not common with the node A of each other module Mj, but can have its node B common with the node B of another module Mj.

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

The system 100 comprises N1 energy transfer modules in all and, as illustrated in FIG. 1, the balancing circuit then comprises an energy transfer module Mb in addition to the N-2 modules Mj.

In order to maintain a symmetrical system 100, the module Mb has its first node A and its second node B connected by an even number H of cells Ci in series. This module Mb also has its third node D connected to the midpoint 104 of the N cells Ci in series, that is to say to the point 104 of connection of the cell Ci of index i equal to N/2 to the cell Ci with index i equal to (N/2)+1. Point 104 also corresponds to the midpoint of the H cells Ci in series connecting nodes A and B of module Mb. The module Mb has its node D not common with the node D of each of the modules Mj.

Preferably, when K is odd as is the case in the example of Figure 1, the number H of cells Ci in series connecting between them the nodes A and B of the module Mb is equal to K+1 . Thus, each of the modules Mj and Mb sees the same number K+1 of cells Ci between its nodes A and B.

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

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

FIG. 2 illustrates another embodiment of a system 200 comprising a battery 201 comprising N cells elements in series, and a charge balancing circuit connected to the battery 201.

More particularly, FIG. 2 illustrates an exemplary 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 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 with respect to a central elementary cell.

In the example of Figure 2, K is equal to 3 and N is equal to 7 (therefore Z is equal to 6). In other examples not illustrated, the number N is different from 7, for example smaller, or, on the contrary, greater than 7, and/or the number K is different from 3, for example smaller, or, on the contrary, contrary, greater than 3.

The battery 201 comprises N elementary cells Ci, with i an integer index ranging from 1 to N, connected in series, in order of increasing index, between the nodes or terminals V+ and V- of the battery 201. In this example, the positive terminal of cell C1 and the negative terminal of cell C7 are respectively connected to the V+ and V- terminals of the battery, 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 of lower index, and its negative terminal connected to the positive terminal of the neighboring cell of higher index. In this example, the central cell of the series association of the N cells Ci is the cell C4. The load balancing circuit includes Z load balancing modules Mj, with j an integer index ranging from 1 to Z, or, in other words, from 1 to Nl.

A first half of the Z modules Mj is connected to ((N-1)/2)+K elementary cells Ci in series from the end V+ of the series association of the N cells of Ci of the battery 201. A second half of the Z modules is connected to ((N-1)/2)+K elementary cells Ci in series from the V- end of the series association of the N cells of Ci of the battery 201.

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

For the first half of the Z modules Mj, each module Mj has its nodes A and D connected by the cell Ci of 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 of index i equal to j+1. For example, module M1 has its nodes A and D connected by cell C1, and module M5 has its nodes A and D connected by cell C6.

Furthermore, for the first half of the Z modules Mj, each module Mj has its node A connected to the terminal of the cell Ci of index i equal to j which is on the side of the terminal of the battery 201 connected to the 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 of index i equal to j+1 which is on the side of the terminal of the connected battery to the cell CN (or C7 in the example of FIG. 2). None of the modules Mj has its common node D with the node D of one of the other modules Mj. Furthermore, none of the modules Mj has its nodes A and B common with the nodes A and B respectively of each of the other modules Mj. For example, each module Mj has its node A not common with the node A of each other module Mj, but can have its node B common with the node B of another module Mj.

[0063] System 200 includes N-1 power transfer modules in all.

FIG. 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.

More particularly, FIG. 3 illustrates an exemplary 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. In the example of FIG. 3, K is equal to 3 and N is equal to 8 (therefore Z is equal to 7). In other examples not illustrated, the number N is different from 8, for example smaller, or, on the contrary, greater than 8, and/or the number K is different from 3, for example smaller, or, on the contrary, contrary, greater than 3.

The battery 301 comprises N elementary cells Ci, with i an integer index ranging from 1 to N, connected in series, in order of increasing index, between the nodes or terminals V+ and V- of the battery 201. In this example, the positive terminal of cell C1 and the negative terminal of cell C8 are respectively connected to terminals V+ and V- 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 of lower index, and its negative terminal connected to the positive terminal of the neighboring cell of higher index. In another example not shown, the negative terminal of cell C1 and the positive terminal of cell C8 are respectively connected to terminals V- and V+ 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 of lower index, and its positive terminal connected to the negative terminal of the neighboring cell of higher index.

The load balancing circuit includes Z load balancing modules Mj, with j an integer index ranging from 1 to Z, or, in other words, from 1 to N-1.

The Mj modules are connected in such a way that none of the Mj modules has its common D node with the D node of one of the other Mj modules, and, moreover, none of the Mj modules has its A nodes and B common with the nodes A and B respectively of each of the other modules Mj. For example, each module Mj has its node A not common with the node A of each other module Mj, but can have its node B common with the node B of another module Mj.

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

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

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

Furthermore, the modules Mj of the group G1 each have their node A connected to the terminal of the cell Ci of index i equal to j which is on the side of the terminal of the battery 301 connected to the cell Cl. modules Mj of group G2 each have their node A connected to the terminal of cell Ci of index i equal to j+1 which is on the side of the terminal of battery 301 connected to cell CN (or C8 in FIG. 3) .

[0074] System 300 includes N-1 power transfer modules in all.

FIG. 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.

More particularly, FIG. 4 illustrates an exemplary 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 system 400 further comprises Kl modules Mbu, with u an integer index ranging from N-K+l 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 module Mbu also has its first node A and its third node D connected by exactly one of the P cells in series between nodes A and B of this module.

In the example of Figure 4, K is equal to 5 and N is equal to 8 (therefore Z is equal to 3). In other examples not illustrated, the number N is different from 8, for example smaller, or, on the contrary, greater than 8, and/or the number K is different from 5, for example smaller, or, on the contrary, contrary, greater than 5.

The battery 401 comprises N elementary cells Ci, with i an integer index ranging from 1 to N, connected in series, in order of increasing index, between the nodes or terminals V+ and V- of the battery 201. In the 4 example, the positive terminal of cell C1 and the negative terminal of cell C8 are respectively connected to terminals V+ and V- 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 of lower index, and its negative terminal connected to the positive terminal of the neighboring cell of higher index. In another example not shown, the negative terminal of cell C1 and the positive terminal of cell C8 are respectively connected to terminals V- and V+ 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 of lower index, and its positive terminal connected to the negative terminal of the neighboring cell of higher index.

The load balancing circuit comprises Z load balancing modules Mj, with j an integer index ranging from 1 to Z, or, in other words, from 1 to N-K.

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

The K-l modules Mbu are connected to the K cells Ci of index i ranging from N-K+1 to N. Each module Mbu has its nodes A and D connected by the cell Ci of index i equal to u. Each module Mbu has its nodes A and B connected by P cells Ci in series, with P decreasing when the index u of the module Mbu increases.

Each module Mj has its node A connected to the terminal of the cell Ci of index i equal to j which is on the side of the terminal of the battery 401 to which the 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 the cell Ci of index i equal to u which is on the side of the terminal of the battery 401 to which the cell Cl is connected.

In the example of Figure 4, the system 400 therefore comprises four modules Mbu, namely the modules Mb4, Mb5, Mb6 and Mb7. Module Mb4 has its nodes A and D connected by cell C5, module Mb5 has its nodes A and D connected by cell C6, module Mb6 has its nodes A and D connected by cell C7 and module Mb7 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, to 4 for the Mb5 module, to 3 for the Mb6 module and to 2 for the Mb7 module.

None of the modules Mj and Mbu has its common node D with the node D of one of the other modules Mj and Mbu. Furthermore, none of the modules Mj and Mbu has its nodes A and B common with the nodes A and B respectively of each of the other modules Mj and Mbu. For example, each module Mj has its node A not common with the node A of each other module Mj, but can have its node B common 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 only sees all of the N cells of the battery between its nodes A and B.

[0085] System 400 includes N-1 power transfer modules in all.

An advantage of the embodiment shown in Figure 4 is that it is easy to add one or more cells Ci and a corresponding number of modules M, for example by connecting the cell or cells Ci in series on the side to cell Cl, the indices i, j, u and the values N, Y, and K then being updated. In particular, the addition of one or more cells Ci on the side of the cell Cl does not require modifying the connection of the modules Mj and Mbu which were already connected to the cells Cl to CN of the battery 401.

In the embodiments described previously in relation to FIGS. 1 to 4, although this has not been illustrated, the balancing circuit may comprise a management circuit in addition to the modules and, for example, their control circuits. The management circuit is, for example, configured to receive information relating to the state of charge of the cells Ci, and to control the modules accordingly so as to transfer electrical energy from the most charged cells or groups of cells. towards the less loaded cells or groups of cells. By way of example, the state of charge of the cells Ci can be determined by voltage and/or current measurements, or by any other known means.

Various embodiments and variants have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art. [0089] Finally, the practical implementation of the embodiments and variants described is within the abilities of those skilled in the art 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+1 elementary cells in series, and a third node ( D) connected to the first node (A) by only one of the K+1 elementary cells of said corresponding set, in which each first module (M1, M2) has its third node (D) not common with the third node (D) of each another first module, in which K is an integer greater than or equal to 2 identical for all the first modules (M1, M2), in which Z is an integer greater than or equal to 2, in which N is an integer greater than or equal to K +2, and in which an 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 (M1, M2), the third node (D) of said one (M1) of the first modules (M1, M2) being connected at the first node (A) of said another (M2) of the first modules (M1, M2). A system (100) according to claim 1, wherein: Z equals N- 2;

N is even; and a connection of a first half (M1, M2, M3) of the N-2 first 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 N-2 first 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 symmetrical to each other with respect to a midpoint (104) of the association of the N elementary cells in series. A system (100) according to claim 2, wherein: the system (100) comprises a second power 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 common with the third node (D) of each first module; and H is strictly less than N. A system (100) according to claim 3, in which:

K is odd; and the number H is equal to K+1. A system (200) according to claim 1, wherein: Z equals N-1;

N is odd; and a connection of a first half (M1, M2, M3) of the N1 first 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 Nl first modules to ( (Nl) /2)+K cells elementary cells (C2, C3, C4, C5, C6, C7) in series from a second end (V-) of the association of the N elementary cells in series are symmetrical to each other with respect to a central elementary cell (C4) of the association of the N elementary cells in series. A system (200, 300) according to claim 1, wherein Z is less than or equal to N1. A system (400) according to claim 1, wherein:

Z is equal to N-K; the system further comprises K-1 second energy transfer modules (Mb4, Mb5, Mb6, Mb7), 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, Mb 6, Mb7); and each second module (Mb4, Mb5, Mb6, Mb7) has its third node (D) not common with the third node (D) of each first module and of each other second module. A system (100; 200; 300; 400) according to any one of claims 1 to 7, wherein the system (100) comprises exactly N1 energy transfer modules in all. System (100; 200; 300; 400) according to any one of claims 1 to 8, in which none of the first modules (M1, M8) has its first (A) and second (B) nodes common with the first (A) and second (B) respective nodes of each of the other first modules (M1, M8).

. System according to any one of Claims 1 to 9, in which 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.