Battery comprising electrochemical cells distributed across a plurality of distinct cluster voltages

Abstract

The present invention relates to a power battery comprising a plurality of elementary energy storage modules connected in series in at least one current line so as to form a multilevel inverter distributed within the battery, wherein the plurality of elementary modules comprises at least one first elementary module in which the electrochemical cells (21) of the cluster (CL1) are interconnected according to a first interconnection configuration that determines a first cluster voltage level (VCL1), and a second elementary module in which the electrochemical cells (24) of the cluster (CL4) are interconnected according to a second interconnection configuration that determines a second cluster voltage level (VCL4), wherein the second cluster voltage level (VCL4) is the maximum cluster voltage of the battery and the first cluster voltage level (VCL1) is strictly lower than the second cluster voltage level (VCL4).

Description

[0001] DESCRIPTION

[0002] TITLE: BATTERY COMPRISING ELECTROCHEMICAL CELLS DISTRIBUTED INTO SEVERAL DISTINCT CLUSTER VOLTAGES

[0003]

[0001] The present invention claims priority from French application No. 2403859 filed on 04 / 15 / 2024, the content of which (text, drawings and claims) is incorporated herein by reference.

[0004]

[0002] The field of the invention relates to a power battery, in particular for electrified vehicles and stationary energy storage systems.

[0005]

[0003] Electrified vehicles are equipped with a traction battery with electrochemical cells, generally of the Lithium-ion type. To date, the costs, electrical efficiencies and energy densities of these systems still limit large-scale adoption for these vehicles. Car manufacturers are continually seeking new solutions to meet these technological challenges.

[0006]

[0004] The applicant has developed a distributed multilevel inverter architecture which makes it possible to avoid the use of voltage converters usually integrated between a battery and the power supply network operating on alternating voltage. This architecture has been the subject of several patent applications by the applicant. Examples include documents WO-A1-2017 / 153366 and WO-A1-2021 / 048477. They describe a cell architecture which comprises current lines formed by elementary modules each comprising an electrochemical cell, or a cluster of cells, and a switching module forming an H-bridge. These documents also describe innovative control methods for this architecture allowing the balancing of the cells in the state of charge and the generation of polyphase or direct electric current.

[0007]

[0005] More precisely, in this architecture the power functions are provided by electronic cards performing the DC / AC conversion function located near the cells and are based on very low voltage switching electronics. At each instant, the cell clusters are indifferently solicited by current pulses. The voltage wave produced on each current line is a function of the number of activated clusters. Furthermore, in the case of a stationary application, the distributed multilevel inverter architecture makes it possible to generate a three-phase network directly at the battery output, which makes it possible to eliminate the conventional bidirectional inverter.

[0008]

[0006] There is a need to overcome the aforementioned problems. In particular, one objective of the invention is to propose an improved architecture of a battery with a distributed multi-level inverter. One objective is to propose a control solution making it possible to increase the quality of the power waves for exchanges with an electrical network. Furthermore, one objective is to propose a battery having a lower cost.

[0009]

[0007] More specifically, the invention relates to a power battery comprising a plurality of elementary energy storage modules connected in series in at least one current line, each elementary module comprising a cluster of electrochemical cells and a switching module comprising an H-bridge, the electrochemical cells of each cluster being electrically interconnected according to an interconnection configuration within each cluster determining a cluster voltage level and the elementary modules being interconnected in series via the switching modules so as to form a distributed multilevel inverter in the battery capable of generating a voltage waveform chosen at the terminals of the current line by the series connection of a controlled selection of elementary modules from among the plurality.

[0010]

[0008] According to the invention, the plurality of elementary modules comprises at least a first elementary module in which the electrochemical cells of the cluster are interconnected according to a first interconnection configuration determining a first cluster voltage level and a second elementary module in which the electrochemical cells of the cluster are interconnected according to a second interconnection configuration determining a second cluster voltage level and the first and second interconnection configurations are arranged so that the second cluster voltage level is the maximum cluster voltage of the battery and in which the first cluster voltage level is strictly lower than the second cluster voltage level. The first and second cluster voltage levels are multiple values ​​of the individual voltage of the electrochemical cells, these values ​​being distinct from one another.

[0009] According to a variant, the first cluster voltage level is equal to a value between one quarter and three quarters of the second cluster voltage level, or is equal to half of the second cluster voltage level, or is equal to one third of the second cluster voltage level.

[0011]

[0010] According to a variant, the first interconnection configuration comprises the electrochemical cells electrically connected in series and in parallel within the cluster, or the first interconnection configuration comprises all the electrochemical cells electrically connected in parallel within the cluster.

[0012]

[0011] According to a variant, the second interconnection configuration comprises all the electrochemical cells electrically connected in series within the cluster, or the second interconnection configuration comprises the electrochemical cells electrically connected in series and in parallel within the cluster.

[0013]

[0012] According to a variant, the plurality of elementary modules further comprises a third elementary module in which the electrochemical cells are interconnected according to a third interconnection configuration determining a third cluster voltage level and in which the third interconnection configuration comprises the electrochemical cells electrically connected in series and in parallel within the cluster so that the third cluster voltage level has an intermediate value between the first voltage level and the second voltage level.

[0014]

[0013] According to a variant, the elementary modules of the plurality all have the same even number of electrochemical cells within the cluster and in which the second and third interconnection configurations are arranged so that the second and third voltage levels are values ​​equal to a power of two multiplied by the value of the first voltage level.

[0015]

[0014] According to a variant, the first elementary module comprises the H-bridge switching module consisting of switches having an internal drain-source resistance lower than the internal drain-source resistance of the switches of the H-bridge switching module of the second elementary module.

[0016]

[0015] The invention further provides an electrical system comprising at least one phase branch and a power battery according to any one of the preceding embodiments, in which the battery comprises at least one current line electrically connected to the phase branch, the current line comprising at least the first and second elementary modules of the plurality of elementary modules, the system comprising a control unit configured to connect in series in the current line a controlled selection of elementary modules to generate a chosen voltage wave at the terminals of the current line and in which the controlled selection comprises at least the first and second elementary modules.

[0017]

[0016] The invention further provides a stationary energy storage system comprising such an electrical system.

[0018]

[0017] The invention further provides an electrified vehicle comprising such an electrical system, for example an electrified motor vehicle with an at least partially electrified powertrain comprising such an electrical system.

[0019]

[0018] The invention further provides a method for controlling a power battery comprising a plurality of elementary energy storage modules connected in series in at least one current line, each elementary module comprising a cluster of electrochemical cells and a switching module comprising an H-bridge, the electrochemical cells of each cluster being electrically interconnected according to an interconnection configuration within each cluster determining a cluster voltage level and the elementary modules being interconnected in series via the switching modules so as to form a distributed multilevel inverter in the battery capable of generating a voltage waveform chosen at the terminals of the current line by the series connection of a controlled selection of elementary modules from among the plurality,the method being implemented by a battery control unit and comprising the following steps:,

[0020]

[0019] - determining a voltage setpoint to be generated at the terminals of the current line,

[0021]

[0020] - the series connection among the plurality of elementary modules of at least one first elementary module delivering a first cluster voltage level and at least one second elementary module delivering a second cluster voltage level to generate a voltage wave according to the setpoint, the second cluster voltage level being the maximum cluster voltage of the battery and in which the first cluster voltage level is strictly lower than the second cluster voltage level.

[0022]

[0021] The invention provides a computer program comprising instructions which, when the program is executed by a control unit of a power battery, cause the latter to implement such a control method.

[0023]

[0022] The invention provides a control unit for a power battery comprising means specifically configured to implement the control method according to the invention.

[0024]

[0023] The invention provides a computer-readable recording medium comprising instructions which, when executed by a computer, cause the latter to implement the control method according to the invention.

[0025]

[0024] The invention makes it possible to stagger the voltage jumps, for a battery architecture with a multi-level inverter distributed in the battery, according to different levels when generating a voltage wave in order to improve the voltage regulation and the quality of the generated wave. The invention also makes it possible to reduce the number of H-bridge switching components and consequently the cost and energy efficiency of the battery.

[0026]

[0025] Other characteristics and advantages of the present invention will appear more clearly on reading the detailed description which follows, comprising embodiments of the invention given as non-limiting examples and illustrated by the appended drawings, in which:

[0027]

[0026] [Fig.1] schematically represents an embodiment of an electrical system comprising a power battery according to the invention.

[0028]

[0027] [Fig.2] schematically represents configurations for interconnecting electrochemical cells for clusters integrating a battery according to the invention.

[0029]

[0028] [Fig.3] schematically represents an example of an electrical architecture for an electrified vehicle according to the invention.

[0030]

[0029] [Fig.4] schematically represents an example of an electrical architecture for a stationary energy storage system according to the invention.

[0030] The invention applies to electrified vehicles comprising an electric powertrain driven, at least partially, by an electric machine, i.e. with a fully electric or hybrid motor, preferably motor vehicles, but not only such as aircraft, trucks, tractors, bicycles, ships. The invention also finds application for stationary storage systems, for example renewable energy or network regulation installations.The power battery comprises elementary modules of electrochemical cells interconnected so as to form a multi-level inverter structure distributed in the battery allowing the latter to be connected to an electrical system operating at direct voltage or alternating voltage without the intermediary of an inverter. The battery system can be connected directly to an extended electrical power supply network and to an electrical motive machine.

[0031]

[0031] With reference to Figure 1, a polyphase electrical system is schematically represented and comprises a power battery BAT comprising a plurality n of elementary modules MCLk forming a multi-level inverter structure distributed in the battery. The battery BAT comprises three current lines LT1, LT2 and LT3 connected to phase branches BP1, BP2 and BP3 of the electrical system. Each current line LT1, LT2 and LT3 comprises a plurality of elementary modules MCLk interconnected in series. Each elementary module MCLk comprises a cluster of cells CLk and a switching module COMk forming an H-bridge.The elementary modules are interconnected in series via the switching modules COMk so as to form the distributed multi-level inverter in the battery BAT, which inverter is capable of generating a voltage waveform chosen at the terminals of each current line by the series connection of a controlled selection of elementary modules from among the plurality.

[0032]

[0032] According to the invention, each line LT1, LT2, LT3 comprises a plurality of elementary modules comprising clusters CLk of electrochemical cells, which can be interconnected separately within each cluster CLk to deliver a cluster voltage specific to each CLk. A cluster of cells CLk can comprise two, three, four, five, six, eight or more cells, forming the cluster voltage Vclk. This makes it possible to stagger the voltage jumps according to different levels when generating a voltage wave in order to improve the voltage regulation and therefore the quality of the wave generated. The voltage level of a cluster depends on the arrangement of the electrical connections between electrochemical cells. The interconnection connections within a cluster CLk can be in series, in parallel, or in series and parallel.The cluster voltage level corresponds to the amplitude of the voltage when the COMk switching module of said cluster connects the cell voltage to its connection terminals.

[0033]

[0033] A minimum value of the voltage level is equivalent to the voltage of an individual electrochemical cell, i.e. approximately 4.2 volts for a Lithium-ion type cell. The value 4.2 volts is indicated as an illustrative example. Other values ​​are possible depending on the chemistry chosen for the electrochemical cell. The minimum possible voltage jump in a current line is thus dependent on the cell chemistry used for an elementary module.

[0034]

[0034] A maximum value depends on the interconnection configuration within a cluster in number of electrochemical cells connected in series, for example 33.6 volts for eight cells connected in series. The interconnection configurations are configurable according to the desired electrical specifications in capacity and operating voltage. Examples will be provided in more detail in the remainder of the description.

[0035]

[0035] Furthermore, it is recalled that an electrochemical cell is an electrochemical energy storage element having two electrical connection terminals and having a voltage of a few volts, most often between 2.3V and 4.2V, approximately. The cells can be of the Lithium-ion type (a lithium Nickel Manganese Cobalt oxide NMC or a lithium iron phosphate LFP can be cited as examples of positive electrode active materials), Nickel Cadmium (Ni-cd), Nickel-Metal-Hydride (Ni-MH), Sodium-ion, for example. More precisely, a Lithium-ion cell is composed mainly of a porous positive electrode, a porous negative electrode, a separator and an electrolyte (which can be liquid, polymeric or solid). The operating principle of a Lithium-ion cell is based on the reversible exchange of Lithium ions between the two porous electrodes.

[0036]

[0036] Returning to the general description of the architecture of the BAT battery, the phase branches BP1, BP2 and BP3 make it possible to connect the battery to different systems designed to use an alternating or direct voltage. The BAT battery system delivers to its terminals a voltage of several hundred volts, for example with a maximum amplitude of 350, 400, 450, 500 or 1000 volts. However, other voltages are possible at lower values ​​24 volts, 36 volts, 48 ​​volts for example, or at higher values ​​of 1500 volts or more, in particular for stationary systems.

[0037]

[0037] In a first set of branch connections of the phase branches BP1, BP2 and BP3, the battery system BAT comprises high-voltage switches Kres, also called high-voltage contactors or relays, intended to electrically connect the battery BAT to an extended electrical supply network RES. Each current line LT1, LT2 and LT3 is connected, via these branches, on one side to a network connection switch, KR1, KR2 and KR3 respectively, and on the other side to a neutral terminal N of the battery. The extended supply network RES operates at an alternating voltage of 50 Hz or 60 Hz and comprises a three-phase line provided with three voltage lines P1, P2 and P3. The battery system BAT is adapted to generate three three-phase voltage waves offset by 2TT / 3. The control of each current line is similar, differing only by a 2TT / 3 offset between them.

[0038]

[0038] It should be noted that, thanks to this architecture of multi-level inverter distributed in the battery, the electrical system does not include an AC / DC voltage converter between the current lines LT1, LT2 and LT3 and the phase branches BP1, BP2 and BP3 operating in alternating current.

[0039]

[0039] Furthermore, in the case of an embodiment for an electrified vehicle, the battery system BAT is the traction battery of the vehicle and further comprises high voltage switches Kmel intended to electrically connect the battery BAT to an electric motor machine MEL. Each current line LT1, LT2 and LT3 is connected, via a second set of derivations of the phase branches BP1, BP2 and BP3, on a first side to a connection switch of the electric machine, KM1, KM2 and KM3 respectively, and on the other side to a neutral terminal N of the battery. The electric motor machine can be an asynchronous or synchronous machine, possibly a direct current machine because the battery system is capable of generating any voltage waveform, alternating or direct.

[0040]

[0040] Alternatively, for an embodiment of a renewable energy installation, the second phase branch branch assembly may be connected to a photovoltaic installation or a wind turbine installation. Alternatively, the battery is connected to the power supply network for network regulation purposes.

[0041]

[0041] Furthermore, another set of branches is provided for connecting the battery to a direct voltage bus, also called a high voltage bus, for the needs of an electrified vehicle, in particular. This latter set of branches comprises, for example, high voltage systems and a DC / DC voltage converter for the needs of an on-board network operating at 12 volts.

[0042]

[0042] The battery system BAT further comprises a control unit BMS, one of the functions of which is to control the voltage waveform of each line LT1, LT2, LT3 as a function of a reference setpoint Vref from the elementary modules MCLk. The switching module COMk is capable of configuring the elementary module MCLk in three different states to deliver the voltage Vmclk which is respectively said cluster voltage Vclk, a zero voltage and the inverted cluster voltage Vclk to said connection terminals of the module MCLk.

[0043]

[0043] The switching module COMk is for example made up of two switching parts forming an H-bridge controllable in the three different states by a control signal from the BMS control unit of the battery BAT specifically addressing the module MCLk. The states are represented by a control variable uik which can take for example the values ​​1, 0, -1 representing the three different states respectively controlling the cluster voltage Vclk, a zero voltage and the inverted voltage -Vclk at said connection terminals of the elementary module MCLk addressed by the control signal uik. Each switching module COMk comprises electronic components, such as power transistors, possibly of the MOSFET (“Metal Oxide Semiconductor Field Effect Transistor”) or HEMT (“High Electron Mobility Transistor” type), controlled by the control signals from the BMS control unit.

[0044]

[0044] Thus, an example of a mode of controlling the voltage Vmclk at the terminals of each elementary module MCLk among the set of a totality n of modules can be carried out as a function of a control signal uik according to the following relation:

[0046] Thus, the BMS control unit can control on each voltage line LT1, LT2 and LT3, any voltage waveform formed by amplitude steps composed of the cluster voltages Vclk of each activated cluster as a function of a reference voltage setpoint Vref by connecting the cells in series via the switching modules COMk. The reference voltage setpoint Vref can be of sinusoidal form with a frequency of 50 Hz, any alternating form, for example square, or can be of constant voltage for example.

[0045]

[0047] Other control variants are conceivable taking into account other criteria, such as for example the state of charge of the electrochemical cells of a cluster, their temperature, their state of aging, or even a possibly defective state of the switching module.

[0046]

[0048] Furthermore, preferably, line switches are also provided for connecting the three current lines LT1, LT2, LT3 in series. Alternatively, alternative embodiments of the battery BAT are envisaged, comprising a single current line LT1 comprising all the elementary modules MCLk connected in series.

[0047]

[0049] In Figure 2, a non-limiting embodiment of clusters CL1, CL2, CL3 and CL4 of electrochemical cells forming the battery according to the invention is schematically described. Each cluster comprises eight electrochemical cells, in this example of the lithium-ion type, and each cell has an individual voltage of approximately 4.2 volts. According to the principle of the invention, the plurality of elementary modules of the battery comprises at least a first elementary module in which the electrochemical cells 21 of the cluster CL1 are interconnected according to a first interconnection configuration determining a first cluster voltage level VCL1 of value 4.2 volts and a second elementary module in which the electrochemical cells 24 of the cluster CL4 are interconnected according to a second interconnection configuration determining a second cluster voltage level VCL4 of value 33.6 volts.

[0048]

[0050] The first and second voltage levels have distinct and non-equal values. More specifically, the first and second interconnect configurations are arranged such that the second cluster voltage level is the maximum cluster voltage of the battery and the first cluster voltage level is strictly less than the second cluster voltage level. The first and second voltage levels are multiple values ​​of the individual voltage of the electrochemical cells.

[0049]

[0051] In this example, cluster CL2 determines a third cluster voltage level VCL2 of intermediate value of 8.4 volts and cluster CL3 determines a fourth cluster voltage level VCL3 of intermediate value of 16.8 volts. For cluster CL1, the electrochemical cells are interconnected in parallel. For cluster CL4, the electrochemical cells are interconnected in series. For cluster CL2, the electrochemical cells 22 are interconnected in series and parallel according to a configuration where two blocks of cells are interconnected in series and each comprise four cells in parallel. For cluster CL3, the electrochemical cells 23 are interconnected in series and parallel according to a configuration where four blocks of cells are interconnected in series and each comprise two cells in parallel.Other interconnection configuration variations are conceivable by those skilled in the art to provide a desired cluster voltage level depending on the number of electrochemical cells available.

[0050]

[0052] The electrical interconnections between cells in the same block are fixed. Each cluster is electrically connected to an individual H-bridge switching module.

[0051]

[0053] Furthermore, in this embodiment of the battery, each cluster comprises eight electrochemical cells so that the maximum voltage per cluster does not exceed 40 volts. Thus, the resistance value of the MOSFET switches of each switching module can reach Drain Source Resistance (RDSon) values ​​when the transistor is on of 0.2 milliohms. Furthermore, for lower voltage clusters, the MOSFET technology can be adapted so that the RDSon resistance values ​​have lower values, which has the advantage of reducing losses and improving the energy efficiency of the battery.

[0052]

[0054] Compared to an architecture of this type of battery described in the prior art, the number of H-bridge switching modules is reduced for a battery of the same capacity and voltage order of magnitude. In addition, the minimum voltage jumps may be reduced to the voltage of a single lithium-ion cell. However, this is not mandatory. The battery may comprise a combination of clusters of different voltage levels between the voltage of an individual cell and a desired maximum cluster voltage permitted by the number of cells in each cluster. The battery comprises at least one cluster having a voltage level between one-quarter of the maximum voltage and three-quarters of the maximum voltage.Preferably, the battery comprises at least one cluster having a voltage level equal to half the maximum cluster voltage, or at least one cluster having a voltage level equal to one third of the maximum cluster voltage.

[0053]

[0055] The invention has the following technical advantages. In automotive applications, the control command function is improved, particularly in the starting phases of a vehicle, due to the possibility of more finely controlling the power supply of the electrical machine, ranging from a voltage amplitude of a few volts to around ten volts. The quality of the current and voltage wave is also improved due to the reduction in harmonics and consequently the reduction in the number of filtering components.

[0054]

[0056] Furthermore, for an application of a stationary energy storage system, the current regulation is improved due to the reduction of current oscillations around a given setpoint. Furthermore, the architecture makes it possible to reduce the recirculation current between lines connected to each other in the case of an installation with several batteries connected to each other.

[0055]

[0057] A first method of distributing the clusters of electrochemical cells of a power battery according to the invention is now described by way of non-limiting example, comprising eleven clusters of electrochemical cells determining several distinct cluster voltage levels. A voltage level corresponds to the voltage of an individual electrochemical cell. In this example, each current line comprises eleven elementary modules, i.e. eleven clusters of cells that can be connected in series. Voltage jumps are controllable for values ​​ranging from 4.2 volts to 33.6 volts. Each cluster comprises eight cells whose interconnection configurations are arranged so that the cells are all electrically connected in parallel (CL1), in series and parallel (CL2, CL3) or all in series (CL4, CL5, CL6, CL7, CL8, CL9, CL10, CL11).

[0056]

[0058]

[0057] 059] In the preferred variant of this first distribution method, each cluster comprises the same number N of electrochemical cells, where N is an even number, in this example N is equal to eight. Other quantities of cells per cluster are conceivable, for example four, six, ten, twelve or more. Among one of these variants, the interconnection configuration for the maximum voltage clusters is arranged so that the cells are connected in series and parallel, for example the voltage of 33.6 volts is produced from two blocks of eight cells in series connected in parallel, the number N then being equal to 16. The other cluster voltage levels are formed by adding additional blocks in parallel. This variant doubles the electrical capacity of the battery.

[0058]

[0060] Furthermore, the interconnection configuration of the electrochemical cells of the clusters follows the architectural relationship in which, with respect to a cluster voltage delivered by a reference cluster, for example the one with the maximum value, another cluster which delivers the reference voltage divided by two then comprises blocks of cells placed in parallel whose capacity is doubled. This distribution mode corresponds to the example illustrated in Figure 2. In other words, the voltage levels above the lowest level, corresponding to an individual cell voltage, are values ​​equal to a power of two multiplied by the individual cell voltage.

[0059]

[0061] Furthermore, for purposes of optimizing the performance of the battery, the battery preferably comprises a greater number of clusters having a high voltage level (for example, 33.6 volts) than clusters having a low voltage level (for example, 4.2 volts or 8.4 volts). For an alternative configuration, the battery comprises a plurality of clusters delivering a desired maximum cluster voltage level and at least one cluster having a lower voltage level, equal to half the maximum voltage level, or equal to one third of the maximum voltage level.

[0060]

[0062] In another variant of this first distribution mode, it is envisaged that the number of electrochemical cells per cluster is not identical for all the clusters.

[0061]

[0063] A second mode of distribution of the clusters of electrochemical cells of a power battery according to the invention comprising eight clusters of electrochemical cells is now described by way of non-limiting example. From this distribution, the battery can generate any voltage level between 0 volts and 415.8 volts for a configuration comprising 99 cells, i.e. a quantity of cells close to the first distribution mode. This second distribution mode makes it possible to reduce the number of elementary modules and therefore the number of H-bridge switching modules. Consequently, the cost of the architecture is reduced.

[0062] 064] A third method of distributing the clusters of electrochemical cells of a power battery according to the invention comprising seven clusters of electrochemical cells is now described by way of non-limiting example. Each cluster of cells delivers a specific voltage level distinct from the other clusters. The voltage levels evolve according to a geometric progression in powers of two, 2 k ' where k is a positive integer.

[0063]

[0065] In this example for seven clusters and following this geometric sequence the voltage of the current line can be between 0 volts and 533 volts for 95 cells, i.e. a quantity of cells close to the first distribution mode. This third distribution mode makes it possible to reduce the number of elementary modules and therefore the number of H-bridge switching modules.

[0064] [C66] Furthermore, in an architectural variant, the type of chemistry used for the different clusters can differ between clusters. Thus, it is possible to adapt the cluster voltage level by choosing the appropriate chemistry for the desired cluster voltage.

[0065]

[0067] Furthermore, in the event of a cluster failure, this architecture allows a failed cluster to be replaced by a cluster comprising cells of an updated version or of a different chemistry. Thus, cells of several types can coexist in the same battery.

[0066]

[0068] Figure 3 schematically illustrates an electrified vehicle. By the term electrified, it should be understood that the vehicle comprises a fully electric motor or hybrid motor comprising the power battery according to the invention. The vehicle comprises an electric motor 34 capable of transmitting torque to the drive wheels 32 of the vehicle through a transmission 31. The electric machine 34 can be three-phase. The vehicle comprises an electrical system comprising the battery 30 according to the architecture with a multi-level inverter distributed in the battery in accordance with the description given in Figure 1. The battery comprises three current lines capable of generating three-phase and single-phase voltage waves. The vehicle further comprises an interface for recharging the battery 38 from a power supply network operating at alternating voltage.The charging interface 38 is an on-board charger electrically connecting the battery 30 to the charging terminal for charging with AC voltage in single-phase or three-phase current. The charging interface 38 is also capable of rapid charging with DC voltage.

[0067]

[0069] Each current line of the battery 30 comprises separate elementary cluster voltage modules in accordance with the invention. The vehicle further comprises a supervision system 36 cooperating with a control unit 35 of the battery system 30. The battery system 30 can be directly electrically connected to the electric motor 34, thus improving its energy efficiency in traction.

[0068]

[0070] The battery can also be connected to a high voltage DC bus, for example operating at a nominal voltage of between 100 and 800 volts, for example 450 volts, and to a low voltage on-board network 37 operating at a nominal voltage of 12 volts. For this purpose, the electrical system comprises power electronics 39 comprising a DC / DC converter connecting the voltage bus to the on-board network 37 (450 volts / 12 volts) comprising a service battery.

[0069]

[0071] Figure 4 schematically illustrates a stationary energy storage system 40 comprising the power battery according to the invention. In this type of application, the current lines of the power battery 40 are connected directly to a transformer 41. The transformer 41 is connected to an electrical network 42.

[0070]

[0072] A method for controlling the power battery is further provided, implemented by its control unit. The control unit is provided with an integrated circuit computer and electronic memories, the computer and the memories being configured to execute the control method. But this is not obligatory. Indeed, the computer could be external to the control unit, while being coupled to the latter. In the latter case, it can itself be arranged in the form of a dedicated computer comprising a possible dedicated program, for example. Consequently, the control unit, according to the invention, can be produced in the form of software modules (or computer software), or electronic circuits (or hardware), or a combination of electronic circuits and software modules.

[0071]

[0073] The control unit is adapted to supervise the parameters specific to the battery in cooperation with current and voltage sensors, such as the state of charge SOC (“State of Charge”) which designates the level of state of charge of the battery expressed by a ratio between the quantity of energy stored at a given instant and the maximum quantity of energy storable at a given instant, the open circuit voltage OCV (“Open Circuit Voltage”) expressed in volts, the charging current expressed in Amperes, the state of health SOH (“State of Health”), which designates the aging level parameter of the battery expressing a ratio between the maximum quantity of electricity storable at a given instant and the maximum quantity of electricity storable in the new state of the battery.

[0072]

[0074] According to the invention, the battery control unit is configured to generate a voltage waveform chosen at the terminals of the or each current line by the series connection of a controlled selection of elementary modules from among the plurality. More precisely, the method comprises a step of determining a voltage setpoint to be generated at the terminals of the current line, and a step of connecting in series among the plurality of elementary modules at least one first elementary module delivering a first cluster voltage level and at least one second elementary module delivering a second cluster voltage level to generate a voltage wave according to the setpoint. The second cluster voltage level is the maximum cluster voltage of the battery and the first cluster voltage level is strictly lower than the second cluster voltage level.The module selection is configured by the control unit so that the combination of selected cluster voltages is regulated as closely as possible to the voltage setpoint. A voltage regulator is provided to perform this function. The voltage waveform generated by the control unit can be a sine wave, a peaked sine wave, a square wave, a triangular wave, a pulse signal, or a DC voltage signal, for example.

[0073]

[0075] For example, at least one first module outputs a cluster voltage of between 3 volts and 4.5 volts and at least one second module outputs a cluster voltage of between 30 volts and 35 volts. A voltage waveform may be generated from a combination comprising several 33.6 volt cluster voltage modules, one or two 16.8 volt cluster voltage modules, and a 4.2 volt voltage module.

[0074]

[0076] Furthermore, according to a preferred variant, the selection is configured to maintain the balancing in charge state of the cell clusters between clusters of a current line. For this purpose, the control unit comprises means for estimating the charge state of each cluster of electrochemical cells and means for selecting or prioritizing the clusters as a function, in addition, of their charge state.

[0075]

[0077] Further, the selection is configured to maintain thermal homogeneity across all electrochemical cell clusters.

[0076]

[0078] The invention is described in the above by way of example. It is understood that the person skilled in the art is able to produce different variant embodiments of the invention by associating, for example, the different characteristics above taken alone or in combination, without departing from the scope of the invention.

Claims

CLAIMS 1. Power battery (BAT) comprising a plurality of elementary energy storage modules (MCLk) connected in series in at least one current line (LT1), each elementary module (MCLk) comprising a cluster of electrochemical cells (CLk) and a switching module (COMk) comprising an H-bridge, the electrochemical cells of each cluster (CLk) being electrically interconnected according to an interconnection configuration within each cluster determining a cluster voltage level (Vclk) and the elementary modules (MCLk) being interconnected in series via the switching modules (COMk) so as to form a distributed multilevel inverter in the battery (BAT) capable of generating a voltage waveform chosen at the terminals of the current line (LT1) by the series connection of a controlled selection of elementary modules (MCLk) from among the plurality,characterized in that the plurality of elementary modules (MCLk) comprises at least a first elementary module in which the electrochemical cells (21) of the cluster (CL1) are interconnected according to a first interconnection configuration determining a first cluster voltage level (VCL1) and a second elementary module in which the electrochemical cells (24) of the cluster (CL4) are interconnected according to a second interconnection configuration determining a second cluster voltage level (VCL4) and in that the first and second interconnection configurations are arranged so that the second cluster voltage level (VCL4) is the maximum cluster voltage of the battery and in which the first cluster voltage level (VCL1) is strictly lower than the second cluster voltage level (VCL4)., 2. Battery according to claim 1 wherein the first cluster voltage level (VCL1) is equal to a value between one quarter and three quarters of the second cluster voltage level (VCL4), or is equal to half of the second cluster voltage level (VCL4), or is equal to one third of the second cluster voltage level (VCL4).

3. Battery according to any one of claims 1 to 2 wherein the first interconnection configuration comprises the electrochemical cells (22) electrically connected in series and in parallel within the cluster (CL1), or comprises all the electrochemical cells (21) electrically connected in parallel within the cluster (CL1).

4. Battery according to any one of claims 1 to 3 wherein the second interconnection configuration comprises all the electrochemical cells (24) electrically connected in series within the cluster (CL4), or comprises the electrochemical cells (24) electrically connected in series and in parallel within the cluster (CL4).

5. Battery according to any one of claims 1 to 4 wherein the plurality of elementary modules further comprises a third elementary module in which the electrochemical cells (22) of the cluster (CL2) are interconnected according to a third interconnection configuration determining a third cluster voltage level (VCL2) and in which the third interconnection configuration comprises the electrochemical cells (22) electrically connected in series and in parallel within the cluster (CL2) so that the third cluster voltage level (VCL2) has an intermediate value between the first voltage level (VCL1) and the second voltage level (VCL4).

6. Battery according to claim 5, in which the elementary modules (MCLk) of the plurality all have the same even number of electrochemical cells within the cluster and in which the second and third interconnection configurations are arranged so that the second and third voltage levels (VCL4, VCL2) are values ​​equal to a power of two multiplied by the value of the first voltage level (VCL1).

7. Battery according to any one of claims 1 to 6 in which the first elementary module comprises the H-bridge switching module consisting of switches having an internal drain-source resistance lower than the internal drain-source resistance of the switches of the H-bridge switching module of the second elementary module.

8. Electrical system comprising at least one phase branch (BP1) and a power battery (BAT) according to any one of claims 1 to 7 wherein the battery (BAT) comprises at least one current line (LT1) electrically connected to the phase branch (BP1), the current line (LT1) comprising at least the first and second elementary modules of the plurality of elementary modules (MCLk), the system comprising a control unit (BMS) configured to connect in series in the current line (LT1) a controlled selection of elementary modules (MCLk) to generate a chosen voltage wave at the terminals of the current line and wherein the controlled selection comprises at least the first and second elementary modules.

9. Stationary energy storage system comprising an electrical system according to claim 8.

10. Electrified vehicle with at least partially electrified powertrain comprising an electrical system according to claim 8.

11. Method for controlling a power battery comprising a plurality of elementary energy storage modules (MCLk) connected in series in at least one current line (LT1), each elementary module (MCLk) comprising a cluster (CLk) of electrochemical cells and a switching module (COMk) comprising an H-bridge, the electrochemical cells of each cluster (CLk) being electrically interconnected according to an interconnection configuration within each cluster determining a cluster voltage level (Vclk) and the elementary modules being interconnected in series via the switching modules (COMk) so as to form a distributed multilevel inverter in the battery (BAT) capable of generating a voltage waveform chosen at the terminals of the current line (LT1) by the series connection of a controlled selection of elementary modules from among the plurality,the method being implemented by a battery control unit and being characterized in that it comprises the following steps:, - the determination of a voltage setpoint to be generated at the terminals of the current line (LT1), - the series connection among the plurality of elementary modules of at least one first elementary module delivering a first cluster voltage level (VCL1) and at least one second elementary module delivering a second cluster voltage level (VCL4) to generate a voltage wave according to the setpoint, the second cluster voltage level (VCL4) being the maximum cluster voltage of the battery and the first cluster voltage level (VCL1) being strictly lower than the second cluster voltage level (VCL4).

Images