METHOD FOR CONTROLLING A BATTERY CHARGING OF A SINGLE-PHASE ELECTRICAL SYSTEM TO GENERATE A DIRECT VOLTAGE IN A SEQUENTIAL MODE

Abstract

The present invention relates to a method for controlling an electrical system comprising a first phase involving the control of elementary modules (MCLk) of at least one current line (LT1) of a battery according to a first reference setpoint synchronized with a single-phase alternating current from a power supply network (RES), and the connection of at least said current line (LT1) to a phase branch (BP1) of the electrical system connected to the power supply network (RES), and a second phase involving the disconnection of at least said current line from the power supply network, the control of elementary modules (MCLk) of at least said current line (LT1) according to a second reference setpoint in the form of a DC voltage waveform, and the connection of at least said current line (LT1) to at least one branch connected to a diode module. The invention is applicable to electric vehicles and stationary energy storage systems.Figure 1.

Description

Title of the invention: METHOD FOR CONTROLLING A BATTERY CHARGE OF A SINGLE-PHASE ELECTRICAL SYSTEM FOR THE GENERATION OF A DC VOLTAGE IN SEQUENTIAL MODE

[0001] The field of the invention relates to a method for controlling a polyphase electrical system for generating a DC electrical network during single-phase current recharging of a battery.

[0002] Electrified vehicles have a high-power traction battery, generally operating in a voltage range of 260 volts to 450 volts. When charging a vehicle with single-phase current, an AC / DC converter converts the alternating electric current into compatible direct current from the battery and a DC / DC converter transforms this direct voltage into another lower voltage suitable for the on-board network, generally around 12 volts. It is therefore possible to generate the voltage of the on-board network during the charging of the vehicle.

[0003] The applicant has developed a disruptive architecture known as a distributed multilevel inverter which makes it possible to dispense with the voltage converters usually integrated between a battery with electrochemical cells and the power supply network operating at 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 further describe innovative control methods for this architecture allowing the balancing of the cells in charge state and the generation of polyphase or direct electric current.

[0004] The generation of the DC voltage of the on-board network during a vehicle recharge using AC current is problematic for this architecture because it is necessary to activate the generation of a DC voltage by controlling the multi-level inverter distributed in the battery, then to produce the DC current of the on-board network via a DC / DC converter. To solve this problem of generating the DC voltage during a vehicle recharge on an AC electrical network, the applicant has provided a solution consisting of injecting a common mode voltage on all three current lines. This solution is described in patent document FR-A1-3121797.

[0005] However, this solution is not suitable for single-phase current charging. Indeed, since the three current lines of the battery are connected in series, it is not possible to generate the common mode voltage.

[0006] There is therefore a need to overcome the aforementioned problems. One objective of the invention is to propose a single-phase alternating current charging protocol, for a vehicle equipped with a distributed multi-level inverter battery architecture, making it possible to maintain the voltage of the vehicle's on-board network during charging.

[0007] More specifically, the invention relates to a method for controlling an electrical system for recharging a power battery with electrochemical cells of said system, the battery comprising at least one current line, said line comprising a plurality of elementary modules connected in series, each provided with a cell or a cluster of cells and a switching module comprising an H-bridge, forming a multi-level inverter distributed in the battery capable of generating a voltage waveform chosen at the terminals of said current line.

[0008] According to the invention, the method alternately comprises the following phases during a battery charging operation:

[0009] - a first phase comprising the control of elementary modules of at least said current line (according to a first reference setpoint synchronized with a single-phase alternating current of a supply network and the connection of at least said current line to a phase branch of the electrical system connected to the supply network for charging the battery,

[0010] - a second phase comprising the disconnection of at least said current line with the power supply network, the control of elementary modules of at least said current line according to a second reference setpoint of the shape of a direct voltage wave and the connection of at least said current line to at least one branch connected to a diode module so as to generate a first direct voltage at the output of the diode module.

[0011] The method according to the invention may include the following additional characteristics, alone or in combination:

[0012] - The method further comprises, during the second phase, the conversion of the first direct voltage by a converter into a second direct voltage so as to recharge a service battery from a direct voltage electrical network.

[0013] - The second phase is commanded when a parameter representative of the state of charge of the service battery is below a threshold below which the supply power of the service battery is lower than the needs of the direct voltage electricity network.

[0014] - The first phase involves the series connection of three current lines, the control of the elementary modules of the three current lines and the series connection of the three current lines to the phase branch of the electrical system.

[0015] - The second phase involves the series connection of the three current lines to a derivation of the diode module and during which the first direct voltage is generated by controlling the same voltage wave on the three current lines simultaneously.

[0016] - The second phase involves connecting the three current lines to three dice specific rivations respectively of the diode module, and during which the first direct voltage is generated by the control of three voltage waves formed alternately on three current lines.

[0017] - The second phase involves connecting the three current lines to three dice specific rivations of the diode module, and during which the first direct voltage is generated by the control of three voltage waves formed simultaneously on three current lines.

[0018] - During the first and second phases, the elementary modules of each line of current participating in the generation of the voltage wave are alternated among the plurality of elementary modules of the battery to maintain the charge balance of the cells.

[0019] It is further envisaged an electrical system comprising a power battery with electrochemical cells, at least one phase branch provided for charging the battery from an extended electrical supply network operating at alternating voltage, and a diode module electrically connected at least to said phase branch by at least one branch, the battery comprising at least one current line, said line comprising a plurality of elementary modules connected in series, each provided with a cell or a cluster of cells and a switching module comprising an H-bridge, forming a multilevel inverter distributed in the battery capable of generating a voltage waveform chosen at the terminals of at least said current line, and comprising a control unit configured to implement the control method according to any one of the preceding embodiments.

[0020] The invention also provides a motor vehicle comprising such an electrical system further comprising a converter, a DC voltage network and a service battery of said network electrically connected at the output of the diode module and arranged so that, on the one hand, the service battery supplies said network during the first phase and, on the other hand, the converter converts the first DC voltage into a second DC voltage to supply the DC voltage network and charge the service battery during the second phase.

[0021] Further provided is a stationary storage system comprising the electrical system according to the invention.

[0022] A control unit is provided comprising means specifically configured to implement any of the embodiments of the control method.

[0023] There is further provided a computer program comprising instructions which, when the program is executed by a control unit of an electrical system, cause the latter to implement any one of the embodiments of the control method according to the invention.

[0024] The method is for generating DC bus power during a single-phase AC charging operation for a distributed multi-level inverter battery system within the battery.

[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:

[0026] [Fig-1] represents an embodiment of a polyphase system comprising a battery equipped with a multi-level inverter and intended to implement the control method according to the invention.

[0027] [Fig.2] represents an embodiment of the system according to the invention comprising the diode module for generating a direct voltage for a direct voltage electrical network.

[0028] [Fig.3] represents an embodiment of the algorithm of the control method according to the invention.

[0029] [Fig.4] represents a first configuration of the electrical system controlled during a first phase of the process for recharging the power battery.

[0030] [Fig.5] represents a second configuration of the electrical system controlled during a second phase of the process for recharging the service battery.

[0031] [Fig.6] represents an example of generation of the direct voltage at the output of the diode module for the second phase of the process where the voltage wave is generated alternately on the three derivation branches.

[0032] [Fig.7] represents a third configuration of the electrical system controlled during the second phase of the process for recharging the service battery.

[0033] [Fig.8] schematically represents an embodiment of the electrical system for an electrified vehicle.

[0034] The invention relates to a polyphase electrical system for energy storage for electrified motor vehicles and stationary storage systems in electrical installations, for example for renewable energy or grid regulation installations. The polyphase system comprises an electrochemical battery comprising elementary cell modules interconnected so as to form a distributed multi-level inverter structure in the battery allowing the battery to be connected to an electrical system operating in direct voltage and also in alternating voltage without the intermediary of an inverter. The battery system can be connected directly to an extended electrical supply network and to an electrical motive machine. The invention aims to provide a control method for maintaining the voltage of a direct DC network supplied by the power battery during charging with single-phase alternating current. In particular, the method aims to maintain the voltage of an on-board network of an electrified vehicle during charging of the vehicle.

[0035] In the present description, the term distributed multilevel inverter means that the current line or each current line of the battery, in the case of a polyphase architecture, in particular three-phase, is formed by a plurality of elementary modules connected in series and each elementary module comprises a cell or a cluster of cells, as well as a switching module forming an H-bridge, the control unit comprises a means for controlling the elementary modules of the current line according to a reference setpoint and is capable of generating a chosen voltage waveform, alternating and direct, on each current line. This architecture is the subject of a more detailed description in [Fig. 1].

[0036] With reference to [Fig. 1], the power battery BAT comprises a plurality n of elementary modules MCLk forming the multi-level inverter structure distributed in the battery and comprises three current lines LT1, LT2 and LT3 connected to phase branches BPI, BP2 and BP3 and in which the elementary modules MCLk are arranged. The elementary modules MCLk are connected in series in each current line. The phase branches BPI, BP2 and BP3 make it possible to connect the battery to different systems intended to use an alternating or direct voltage. In this three-phase configuration, each current line comprises n / 3 elementary modules.

[0037] The BAT battery system has a voltage of several hundred volts at its terminals, for example 350 volts or 1000 volts. At 350 volts, each line LT1, LT2, LT3 is equipped, for example, with 24 elementary cell modules or cell clusters connected in series. However, depending on the electrical requirements, the BAT battery system has a nominal voltage of only several tens of volts (24V, 36V, 48V for example), in particular for motor vehicle applications, or at a maximum voltage of 1500 volts DC or even higher, in particular for stationary storage systems.

[0038] In a first set of derivations of the phase branches BPI, BP2 and BP3, the battery system BAT comprises high voltage switches Kres, also called high voltage contactors, 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 RES power supply network operates with an alternating voltage of 50Hz or 60Hz and comprises a three-phase line equipped with three voltage lines PI, P2 and P3. The BAT battery system is adapted to generate three three-phase voltage waves offset by 2ir / 3. The control of each current line is similar, differing only by a 2ir / 3 offset between them.

[0039] 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 BPI, BP2 and BP3 operating in alternating current.

[0040] 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 BPI, 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.

[0041] 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.

[0042] Furthermore, another set of branches is provided for connecting the battery to a DC voltage bus. This part will be the subject of a more detailed description in the following figures to describe the control method aimed at allowing the voltage of a DC voltage network to be maintained during single-phase AC current recharging of the battery.

[0043] The battery system BAT further comprises a BMS control unit, one of whose functions 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. Each elementary module MCLk may comprise a single cell CLk, or a cluster of cells CLk which may be two, three, four, five, six or more cells, forming the elementary voltage Vclk. The elementary module MCLk further comprises a switching module COMk capable of configuring the elementary module MCLk in three different states to deliver the voltage Vmclk which is respectively said elementary voltage Vclk, a zero voltage and the inverted voltage Vclk at said connection terminals of the MCLk module.

[0044] 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 said elementary voltage Vclk, a zero voltage and said inverted voltage - Vclk at said connection terminals of the elementary module k addressed by the control signal uik. Each switching module COMk comprises electronic components, such as power transistors, possibly of the MOSFET or HEMT type ("High Electron Mobility Transistor" in English), controlled by the control signals from the BMS control unit.Thus, the voltage Vmclk at the terminals of each elementary module MCLk among the set of a totality n of modules can be controlled according to a control signal uik according to the following relation: .

[0045] [Math.l] 1 « VrefAt) >nk'Vdk 1 if v ref jj ) < -n k - V clk ■ 0 otherwise

[0046] Thus, the BMS control unit can control on each voltage line LT1, LT2 and LT3, any voltage waveform formed by steps of amplitude equal to the elementary voltage Vclk 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.

[0047] It is recalled that an electrochemical cell is an electrical energy accumulator having two terminals, a positive electrode and a negative electrode, 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) 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 ions lithium between the two porous electrodes.

[0048] In [Fig.2], the BAT battery system is schematically illustrated in the polyphase electrical system. For the sake of clarity, the branch assembly of the driving electric machine is no longer shown.

[0049] The polyphase electrical system comprises a third set of branch connections of the phase branches PB 1, PB2 and PB3 for connecting the battery BAT to a direct voltage bus BDC. This set of branch connections comprises three branch connections D1, D2 and D3 connected respectively to the phase branches BPI, BP2 and BP3. The branch connections D1, D2 and D3 are connected to a diode module RD comprising three diodes d1, d2 and d3 connected respectively to the branch connections D1, D2 and D3. In addition, switches K6, K7 and K8 are provided, arranged to selectively connect and disconnect the diodes d1, d2 and d3 to their respective branch connections D1, D2 and D3. At the output of the diode module RD, the three diodes d1, d2 and d3 are connected together to a direct voltage bus BDC. The direct voltage bus BDC is suitable for supplying at least one system operating with direct voltage.It supplies one or more electrical devices from a set of devices including one or more DC / DC voltage converters, an electric compressor, an electric heater, for example in the case of an electrified vehicle application. Other electrical systems are possible depending on the application.

[0050] The diode module RD has the function of generating a first direct voltage Vdc adjustable in shape and amplitude by controlling the generated voltage waveform Vltl, Vlt2 and Vlt3 on the current lines LT1, LT2 and LT3 respectively. The first direct voltage Vdc equals the maximum voltage amplitude controlled among the three current lines LT1, LT2 and LT3 which are connected. The three lines LT1, LT2 and LT3 can be connected to the diode module to generate the voltage Vdc or one line only. For example, Vdc can be generated from the line LT1 only, and the lines LT2 and LT3 are disconnected.

[0051] The RD diode module is made up of common components that are easy to obtain and assemble. In addition, the diodes have the advantage of being reliable, robust and low cost.

[0052] Furthermore, in this example, a CONV DC / DC voltage converter is provided, connected to the output of the diode module RD and designed to convert the voltage Vdc into a second voltage Vrdb of lower level, for example 12 volts. Other values ​​are possible depending on the intended application, which may be between 12 volts and 600 volts. This CONV converter supplies a direct voltage network RDB when the converter is supplied by the voltage Vdc. It is further provided that the direct voltage network RDB includes a service battery BAT2 making it possible to stabilize the voltage of the RDB network and to ensure the electrical needs of the RDB network when the CONV converter is not supplying it, in particular during the charging the power battery from single-phase current.

[0053] Furthermore, the polyphase system comprises switches K4 and K5 arranged to selectively connect in series and in parallel the current lines LT1, LT2 and LT3, thus allowing single-phase operation and three-phase operation of the battery. More precisely, in single-phase configuration, switches KR2 and KR3 and K5 are open, and switches KR1 and K4 are closed. Thus the current lines LT1, LT2 and LT3 are connected in series to the phase branch BPI connected to the extended power supply network RES. In three-phase configuration, switch K4 is open and switches KR1, KR2, KR3 and K5 are closed. Thus the current lines LT1, LT2 and LT3 are connected respectively to the phase branches BPI, BP2 and BP3 connected to the extended power supply network RES.

[0054] The voltage Vdc is adjustable in amplitude according to the operating configuration of the power battery BAT. In three-phase alternating current charging mode, the voltage Vdc can be generated simultaneously with charging by injecting a common mode voltage into the three current lines LT1, LT2 and LT3. This operating mode was the subject of French patent application FR-A1-3121797 by the applicant.

[0055] In single-phase current battery charging mode, provision is made to control a charging protocol comprising two sequential phases running alternately during the charging of the power battery BAT until the target state of charge of the charging operation is reached. The charging protocol according to the invention makes it possible to charge the service battery from the power battery in the event of detection that the state of charge of the service battery is not sufficient to guarantee a desired power level.

[0056] In [Fig.3], a mode of execution of the control method is represented in the form of functional blocks and will be described in connection with Figures 4 and [Fig.5] illustrating the two configurations of the system for its execution. The method is executed by a control unit of the polyphase electrical system. The control unit may be, for example, the battery control unit or a supervisory control unit of a vehicle equipped with the polyphase electrical system. 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 according to the invention. But this is not obligatory. Indeed, the computer could be external to the battery control unit or the supervisor, while being coupled to the latter.The control unit, according to the invention, can be produced in the form of software modules (or computer modules (or even "software")), or electronic circuits (or "hardware"), or even a combination of electronic circuits. and software modules.

[0057] In an initial step E0, the control unit initiates a battery recharging operation. The battery is connected to an external energy source providing an alternating electric current. In the case of an electrified vehicle, the battery can be connected to a charging terminal via an electric cable suitable for recharging with single-phase or three-phase current. The recharging operation is designed to charge the battery until it reaches a target state of charge. The recharging is carried out in a charging configuration where the battery is traversed by an alternating single-phase charging current with a frequency between 50 Hz and 60 Hz, at a voltage of 110 volts or 230 volts. The method according to the invention aims to maintain the power supply of a direct voltage network, for example the on-board network of the vehicle operating at 12 volts, supplied by the power battery during the execution of the recharging operation.

[0058] For this purpose, the method provides two sequential phases executed alternately depending on the state of charge of a service battery. A first phase, corresponding to step E1, has the function of charging the cells of the battery by a single-phase alternating current during which the current lines of the battery generate an alternating current voltage wave synchronized with the network. During this first phase, the electrical power supply of the direct voltage network is provided by the service battery. A second phase corresponding to step E2 has the function of punctually recharging the service battery from the direct voltage network when the latter is not able to deliver sufficient power for the direct voltage network during the recharging of the power battery.

[0059] In step E1, the control unit (supervision or battery) controls the charging of the power battery BAT. During this phase, the battery control unit first connects the three current lines LT1, LT2 and LT3 in series. More precisely, as illustrated in [Fig.4], the switch K4 is closed and the switch K5 is open. This first configuration of the system allows the recharging of all the electric cells of the battery from a single-phase current delivered by the phase branch BPI of the electrical system.

[0060] Then, according to the method, the battery control unit controls the elementary modules MCLk of the current lines LT1, LT2 and LT3 according to reference setpoints Vrefl, Vref2 and Vref3 synchronized with the single-phase alternating current of the power supply network RES. A part k of the cells among the n cells of the three lines LT1, LT2 and LT3 are connected in series so as to generate a synchronized alternating voltage wave. Once the synchronization is effective, for example the voltage and threshold difference is in accordance with a synchronization criterion nization, the control unit (supervision or battery) controls the connection of the three current lines to the phase branch BPI connected to the network. For this purpose, the switch KR1 is closed. The alternating current delivered by the network RES passes through the k electric cells of the battery which are selected to form the voltage wave.

[0061] Furthermore, during step E1, the diode module RD is disconnected from the phase branches. The switches K6, K7 and K8 are open. During this phase, the direct voltage network RDB is electrically powered by the service battery BAT2. For example, the vehicle's electrical systems connected to the on-board network, the computers are powered by the service battery BAT2. The state of charge of the service battery is greater than a threshold SL. Below SI, the service battery would not be able to meet the electrical needs of the consumer systems and the control unit is configured to control its recharging in such a case.

[0062] Preferably, the k cells among the n cells are alternated during the charging of the battery in order to maintain the balancing in charge state of the n cells of the three voltage lines LT1, LT2 and LT3. A function is provided which permutes the k cells selected among the n of the battery to form the voltage wave according to their charge state. Although preferred, the permutation function is not mandatory. Alternatively, other cell balancing means known to those skilled in the art may be provided.

[0063] Step El is controlled as long as the state of charge SOCBAT of the power battery BAT is lower than a threshold S2. The threshold S2 corresponds to the target state of charge, for example a value between 80% and 100% of the available capacity, preferably it is the maximum authorized state of charge. In addition, step El is controlled as long as the state of charge SOCbat2 of the service battery BAT2 is higher than the threshold SI corresponds to the lower power limit necessary to meet the electrical needs of the on-board network RDB.

[0064] In the event of detection that an electrical parameter representative of the state of charge SOCbat2 (the measurement of the voltage of the service battery BAT2 or its state of charge estimation) becomes lower than the threshold SI, the control unit (supervision or battery) controls the second phase E2 of the control method, a configuration of which is illustrated in [Fig.5]. During this step E2, several steps are provided.

[0065] The control method comprises disconnecting the current lines LT1, LT2 and LT3 from the power supply network RES. For this purpose, the switches KR1, KR2 and KR3 are controlled in the open position. Furthermore, in a second configuration of the system for step E2, the three current lines are configured in parallel. The switch K4 is open and the switch K5 is closed. This second configuration of the electrical system temporarily suspends the recharging of the BAT power battery.

[0066] The method further comprises, in this second phase E2, the control of the elementary modules MCLk of the current lines LT1, LT2 and LT3 according to second reference setpoints configured to generate DC voltage waves Vltl, Vlt2 and Vlt3 respectively so as to generate a first DC voltage Vdc at the output of the diode module RD. The DC voltage shape on each line LT1, LT2 and LT3 is for example a square signal of amplitude Vdc. On each current line LT1, LT2 and LT3, j cells are selected from the n / 3 total cells of each line and are connected in series via the H-bridges of the battery. The amplitude of the voltage Vdc is equal to the following relationship, Vdc = j* Vclk, where Vclk is the elementary voltage of the cells of the battery BAT.

[0067] Two wave generation variants are conceivable in this second configuration. In a first variant, the first DC voltage Vdc is generated by controlling three voltage waves Vlt1, Vlt2 and Vlt3 formed alternately on the three current lines LT1, LT2 and LT3 of the power battery BAT as illustrated in [Fig.6] where the graph shows the voltages in volts generated by the power battery BAT as a function of a time axis. The method further comprises, at this step E2, the connection of each current line LT1, LT2 and LT3 to their respective branch D1, D2 and D3 of the diode module RD. The switches K6, K7 and K8 are closed during step E2. The voltage Vdc is generated and is converted by the converter CONV into a second voltage Vrdb, of the 12 volt type for example, so as to charge the service battery BAT2.

[0068] In a second variant, the first direct voltage Vdc is generated by controlling the three voltage waves Vltl, Vlt2, Vlt3 formed simultaneously on three current lines LT1, LT2, LT3 of the power battery BAT. Identical to the first variant, the three current lines LT1, LT2 and LT3 are connected to the three specific derivations Dl, D2 and D3 respectively of the diode module RD. The switches K6, K7 and K8 are closed. The voltage Vdc is generated and is converted by the converter CONV into a second voltage Vrdb, of the 12 volt type for example.

[0069] Furthermore, in a third mode of configuration of the system for step E2, illustrated in [Fig.7], instead of generating the voltage wave Vdc on the three derivations, the current lines LT1, LT2 and LT3 are connected in series to the derivation D1 and the voltage Vdc is formed by a number] of cells connected in series, via the H-bridges, among the n cells of the battery. This configuration leaves the possibility of controlling a higher voltage compared to the previous variants. In this variant, the switches K5, K7 and K8 are in the open position. Switches K4 and K6 are in the closed position. For example, the voltage generated on current lines LT1, LT2 and LT3 in series is a direct voltage whose amplitude is adjustable, for example between 24 volts and 450 volts.

[0070] Step E2 is maintained as long as the state of charge of the service battery BAT2 is lower than the threshold SL. When the state of charge SOCbat2 becomes higher than SI, the method returns to step EL.

[0071] Furthermore, it is envisaged that the j cells among the n cells are alternated during the charging phase E2 of the service battery BAT2 in order to maintain the balancing in charge state of the n cells of the three voltage lines LT1, LT2 and LT3. A function is therefore provided which permutes the j cells selected from the n of the battery to form the voltage wave according to their charge state. Although preferential, the permutation function is not obligatory. Alternatively, other cell balancing means known to those skilled in the art may be provided.

[0072] Finally, when the state of charge SOCBAT reaches the target state of charge S2, then the method commands in step E3 the stopping of the recharging operation of the power battery BAT.

[0073] In a variant of the system, it is envisaged that the battery BAT comprises a single current line, for example the line LT1. This will be connected without the need to configure current lines in series. The bypass assembly of the diode module also comprises a single bypass line and a single diode. The control method is applicable for a single-phase alternating current load only.

[0074] In [Fig.8] an embodiment of the electrical system is shown for an electrified vehicle with a fully electric motor or hybrid motor. The vehicle comprises an electric motor machine 64 capable of transmitting torque to the drive wheels 62 of the vehicle through a transmission 61. The electric machine 64 may be three-phase. The vehicle comprises an electrical system comprising the battery 60 according to the architecture with a multi-level inverter distributed in the battery in accordance with the description given in [Fig.l]. The battery comprises three current lines capable of generating three-phase or single-phase voltage waves. The vehicle further comprises an interface for recharging the battery 68 from a power supply network operating at alternating voltage.The charging interface 68 is a charging box electrically connecting the terminals of the battery 60 to the terminal for charging in alternating voltage in single-phase current in accordance with the control method according to the invention. The charging interface 68 is also suitable for rapid charging in direct voltage. The battery system 60 is advantageous in that its control unit 65 adapts the voltage wave into alternating form or direct wave form without using a voltage converter. The vehicle. further comprises a supervision system 66 cooperating with the control unit 65 of the battery system 60. The battery system 60 can be directly electrically connected to the electric motor 64, thus improving its energy efficiency in traction.

[0075] The battery can also be connected to a high voltage DC bus, for example operating at a nominal voltage of between 350 and 800 volts, for example 450 volts, and to a low voltage on-board network 67 operating at a nominal voltage of 12 volts. For this purpose, the electrical system comprises power electronics 69 comprising a diode module electrically connected to three phase branches of the battery by three branches. The diode module is formed by three diodes each connected to a branch branch. The output of the diode module supplies the 450 volt voltage bus. Furthermore, the power electronics 69 comprises a DC / DC converter connecting the voltage bus to the on-board network 67 (450 volts / 12 volts) comprising a service battery.The electrical system is controlled so that the service battery supplies the said DC network during the first phase of the process and the converter converts the DC bus voltage (350 volts) into low voltage (12 volts) to supply the on-board network and charge the service battery during the second phase of the process.

[0076] In another embodiment, a stationary storage system comprising the electrical system according to the invention is envisaged.

[0077] 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

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3. Claims Method for controlling an electrical system for recharging a power battery (BAT) with electrochemical cells of said system, the battery (BAT) comprising at least one current line (LT1), said line comprising a plurality of elementary modules (MCLk) connected in series, each provided with a cell (CLk) or a cluster of cells and a switching module (COMk) comprising an H-bridge, forming a multilevel inverter distributed in the battery (BAT) capable of generating a voltage waveform (Vltl) chosen at the terminals of said current line (LT1), the method being characterized in that it alternately comprises the following phases during a charging operation of the battery (BAT): - a first phase (El) comprising the control of elementary modules (MCLk) of at least said current line (LT1) according to a first reference setpoint synchronized with a single-phase alternating current of a supply network (RES) and the connection of at least said current line (LT1) to a phase branch (BPI) of the electrical system connected to the supply network (RES) for charging the battery (BAT), - a second phase (E2) comprising the disconnection of at least said current line with the supply network, the control of elementary modules (MCLk) of at least said current line (LT1) according to a second reference setpoint of the shape of a direct voltage wave and the connection of at least said current line (LT1) to at least one branch (Dl) connected to a diode module (RD) so as to generate a first direct voltage (Vdc) at the output of the diode module (RD). Control method according to claim 1, comprising, during the second phase (E2), the conversion of the first direct voltage (Vdc) by a converter (CONV) into a second direct voltage (Vrdb) so as to recharge a service battery (BAT2) of a direct voltage electrical network (RDB). Control method according to claim 2 in which the second phase (E2) is controlled when a parameter (SOCbat2) representative of the state of charge of the service battery (BAT2) is lower than a threshold (SI) below which the supply power of the service battery (BAT2) is lower than the needs of the electricity network. direct voltage (RDB).

4. Control method according to any one of claims 1 to 3 in which the first phase (El) comprises the series connection of three current lines (LT1, LT2, LT3), the control of the elementary modules (MCLk) of the three current lines (LT1, LT2, LT3) and the series connection of the three current lines to the phase branch (PB1) of the electrical system.

5. Control method according to claim 4, in which the second phase (E2) comprises the series connection of the three current lines (LT1, LT2, LT3) to a branch (Dl) of the diode module (RD) and during which the first direct voltage (Vdc) is generated by controlling the same voltage wave on the three current lines (LT1, LT2, LT3) simultaneously.

6. Control method according to claim 4, in which the second phase (E2) comprises the connection of the three current lines (LT1, LT2, LT3) to three specific derivations respectively of the diode module (RD), and during which the first direct voltage (Vdc) is generated by the control of three voltage waves (Vltl, Vlt2, Vlt3) formed alternately on three current lines (LT1, LT2, LT3).

7. Control method according to claim 4, in which the second phase (E2) comprises the connection of the three current lines (LT1, LT2, LT3) to three specific derivations of the diode module (RD), and during which the first direct voltage (Vdc) is generated by the control of three voltage waves (Vltl, Vlt2, Vlt3) formed simultaneously on three current lines (LT1, LT2, LT3).

8. Control method according to any one of claims 1 to 7, wherein, during the first (El) and the second phase (E2), the elementary modules (MCLk) of each current line (LT1, LT2, LT3) participating in the generation of the voltage wave are alternated among the plurality of elementary modules (MCLk) of the battery (BAT) to maintain the charge balance of the cells (CLk).

9. Electrical system comprising a power battery (BAT) with electrochemical cells (CLk), at least one phase branch (BPI) provided for charging the battery (BAT) from an extended electrical supply network (RES) operating at alternating voltage, and a diode module (RD) electrically connected at least to said phase branch (PB1) by at least one branch (Dl), the battery comprising at least one current line (LT1), said line (LT1) comprising a plurality of elementary modules (MCLk) connected in series, each provided with a cell (CLk) or a cluster of cells and a switching module (COMk) comprising an H-bridge, forming a multi-level inverter distributed in the battery capable of generating a voltage waveform chosen at the terminals of at least said current line (LT1), characterized in that it comprises a control unit (BMS) configured to implement the control method according to any one of claims 1 to 8.

10. Motor vehicle comprising an electrical system according to claim 9 further comprising a converter (CONV), a direct voltage network (RDB) and a service battery (BAT2) of said network electrically connected at the output of the diode module (RD) and arranged so that, on the one hand, the service battery (BAT2) supplies said network (RDB) during the first phase (El) and that, on the other hand, the converter (CONV) converts the first direct voltage (Vdc) into a second direct voltage (Vrdb) to supply the direct voltage network (RDB) and charge the service battery (BAT2) during the second phase (E2).

11. A stationary storage system comprising an electrical system according to claim 9.

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