Method for controlling a battery charge of a polyphase electrical system for generating a DC voltage by switching the current lines

Abstract

The present invention relates to a method for controlling a polyphase electrical system comprising a battery with a distributed multilevel inverter, the method comprising at least one charging configuration of the battery (BAT) comprising the following simultaneously controlled steps of generating a first DC voltage at the output of a diode module (RD) from one current line (LT1) among the three lines (LT1, LT2, LT3) during which the elementary modules (MCLk) of the line (LT1) are controlled as a function of a first reference setpoint, and charging with AC voltage the cells (CLk) of the elementary modules (MCLk) of the two other current lines (LT2, LT3) among the three lines (LT1, LT2, LT3) during which the elementary modules (MCLk) of the two other lines (LT2, LT3) are controlled as a function of a second reference setpoint synchronised with an AC voltage of an extended power supply network (RES). The invention applies to electrified vehicles and to stationary storage systems.

Description

DESCRIPTION TITLE: METHOD FOR CONTROLLING A BATTERY CHARGE OF A POLYPHASE ELECTRICAL SYSTEM FOR THE GENERATION OF A DIRECT VOLTAGE BY SWITCHING THE CURRENT LINES

[0001] The present invention claims priority from French application No. 2305326 filed on 05 / 30 / 2023, the content of which (text, drawings and claims) is incorporated herein by reference.

[0002] The field of the invention relates to a method for controlling a polyphase electrical system for generating a DC electrical network when recharging a battery with single-phase current.

[0003] Electrified vehicles have a high-power traction battery, typically 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 current into compatible direct current from the battery, and a DC / DC converter transforms this direct voltage into a lower voltage suitable for the on-board network, typically around 12 volts. It is therefore possible to generate the on-board network voltage while the vehicle is charging.

[0004] 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 an electrochemical cell battery 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 W0-A1 -2017 / 153366 and W0-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.

[0005] The generation of DC voltage from the on-board network during AC vehicle charging is problematic for this architecture because it is necessary to activate the generation of a direct voltage by controlling the multi-level inverter distributed in the battery, then to produce the direct current of the on-board network via a DC / DC converter. To solve this problem of generating direct voltage during charging of the vehicle on an alternating current 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.

[0006] However, this solution is not suitable for single-phase charging. Since the battery's three current lines are connected in series, it is not possible to generate the common-mode voltage.

[0007] 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.

[0008] More specifically, the invention relates to a method for controlling a polyphase electrical system for recharging a power battery with electrochemical cells of said system, the battery comprising three current lines in which each line comprises 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 each current line.

[0009] According to the invention, the method comprises at least one battery charging configuration comprising the following steps controlled simultaneously:

[0010] - the generation of a first direct voltage at the output of a diode module from a current line among said three lines during which the elementary modules of said line are controlled according to a first reference setpoint,

[0011] - the alternating voltage charging of the cells of the elementary modules of the other two current lines among the three lines during which the elementary modules of said other two lines are controlled according to a second reference setpoint synchronized with an alternating voltage of an extended power supply network.

[0012] The method according to the invention may include the following additional characteristics, alone or in combination:

[0013] - The successively loop control of first, second and third battery charging configurations, the first charging configuration during which the first direct voltage is generated from a first current line and the charging of the cells with alternating voltage is carried out for second and third current lines, the second configuration during which the first direct voltage is generated from the second current line and the charging of the cells with alternating voltage is carried out for the first and third current lines, the third configuration during which the first direct voltage is generated from the third current line and the charging of the cells is carried out for the first and second current lines.

[0014] - The following steps prior to the control of one of said first, second and third charging configurations: a step of monitoring an electrical parameter representative of the maximum controllable value of the voltage wave of at least one of said current lines consisting of detecting whether the parameter is lower than a threshold, and in the event of detection that said parameter is lower than said threshold, the control of a fourth charging configuration comprising the charging with alternating voltage of the cells of the elementary modules of the first, second and third current lines simultaneously.

[0015] - The fourth charging configuration further comprises the series connection of the first, second and third current lines to a single phase branch of the electrical system for AC voltage charging.

[0016] - The voltage threshold is equal to the maximum value of the voltage wave of the extended power supply network.

[0017] - During cell charging for the first, second and third charging configurations, the charging current lines are connected in parallel to a single-phase AC power interface.

[0018] - During the generation of the first direct voltage, the conversion of the first direct voltage into a second direct voltage so as to recharge a service battery of a direct voltage electrical network.

[0019] There is further provided a polyphase electrical system comprising a power battery with electrochemical cells, three phase branches provided for recharging the battery from an extended electrical supply network operating at alternating voltage, and a diode module electrically connected to said phase branches by three derivations, the battery comprising three current lines, each 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 each current line, and comprising a control unit configured to implement any one of the embodiments of the control method according to the invention.

[0020] According to one variant, the system comprises a power supply interface provided for a single-phase alternating voltage electrical load and a coupling device capable of electrically connecting the three phase branches in parallel to the power supply interface.

[0021] Furthermore, an electrified motor vehicle comprising such an electrical system is provided.

[0022] Furthermore, a stationary storage system comprising such an electrical system is provided.

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

[0024] The invention has the advantage that the method can be implemented by a fully software solution for controlling the polyphase electrical system. The invention allows the generation of a direct voltage for an electrical network simultaneously with charging the cells with single-phase current.

[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 a diode module for generating a direct voltage bus for a direct voltage electrical network powered by the battery.

[0028] [Fig.3] represents a charging configuration of the electrical system allowing the generation of a direct voltage and the charging of the other two current lines of the battery from a single-phase alternating current.

[0029] [Fig.4] represents an embodiment of the control method according to the invention.

[0030] [Fig.5] represents a single-phase voltage waveform used for the reference setpoint of the load lines during the method according to the invention.

[0031] [Fig.6] schematically represents an embodiment of the electrical system for an electrified vehicle.

[0032] 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 at direct voltage and also at alternating voltage without the intermediary of an inverter. The battery system can be connected directly to an extensive electrical supply network and to an electrical motive machine. The aim of the invention is to provide a control method for maintaining the voltage of a direct DC network supplied by the power battery during a charging with single-phase alternating current. In particular, the method aims to maintain the voltage of an electrified vehicle's on-board network while the vehicle is charging.

[0033] 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 figure 1.

[0034] With reference to Figure 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 BP1, 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 BP1, 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.

[0035] 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 LT1, LT2, LT3 line 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), particularly for automotive applications, or at a maximum voltage of 1500 volts DC or even higher, particularly for stationary storage systems.

[0036] In a first set of derivations of the phase branches BP1, BP2 and BP3, the BAT battery system comprises high-voltage switches Kres, also called high-voltage contactors, intended to electrically connect the BAT battery 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 at 50Hz or 60Hz AC voltage and comprises a three-phase line with three voltage lines P1, P2 and P3. The BAT battery system 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.

[0037] It should be noted that, thanks to this distributed multi-level inverter architecture 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.

[0038] 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.

[0039] 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.

[0040] Furthermore, another set of branches is provided for connecting the battery to a DC voltage bus. This part will be described in more detail in the following figures to describe the control method for maintaining the voltage of a DC voltage network during single-phase AC charging of the battery.

[0041] The BAT battery system also includes a BMS control unit, one of whose functions is to control the voltage waveform of each LT1 line, 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 to said connection terminals of the module MCLk.

[0042] 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:.

[0043] [Math 1]

[0045] 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.

[0046] It is recalled that an electrochemical cell is an electrical energy accumulator having two terminals, a positive electrode and a negative electrode, and presenting 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 lithium ions between the two porous electrodes.

[0047] In Figure 2, the BAT battery system is schematically illustrated in the polyphase electrical system. For the sake of clarity, the shunt assembly of the prime mover is no longer shown.

[0048] The polyphase electrical system comprises a third set of branch connections of the phase branches PB1, 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 BP1, BP2 and BP3. Branch connections D1, D2 and D3 are connected to a diode module RD comprising three diodes d1, d2 and d3 connected respectively to the branches 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.

[0049] The RD diode module has the function of generating a first direct voltage Vdc adjustable in shape and amplitude by controlling the generated voltage waveform Vlt1, Vlt2 and Vlt3 on the current lines LT1, LT2 and LT3 respectively. first direct voltage Vdc equal to the maximum voltage amplitude driven 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 LT 1 only, and the lines LT2, and LT3 are disconnected. Vdc can be generated from the line LT2 only, and the lines LT1, and LT3 are disconnected. Vdc can be generated from the line LT3 only, and the lines LT1, and LT2 are disconnected.

[0050] The RD diode module is made of common components that are easy to obtain and install. In addition, the diodes have the advantage of being reliable, robust and inexpensive.

[0051] Furthermore, in this example, a CONV DC / DC voltage converter is provided, connected to the output of the RD diode module and designed to convert the Vdc voltage into a second, lower level Vrdb voltage, for example 12 volts. Other values ​​are possible depending on the intended application, which may be between 12 volts and 450 volts. This CONV converter supplies a direct voltage network RDB when the converter is supplied by the Vdc voltage. 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 when charging the power battery from a single-phase current.

[0052] In addition, the polyphase system comprises switches K4 and K5 arranged to selectively connect in series and in parallel the current lines LT 1 , 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 LT 1 , LT2 and LT3 are connected in series to the phase branch BP1 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 BP1 , BP2 and BP3 connected to the extended power supply network RES.

[0053] Furthermore, the polyphase system includes a PR power supply interface suitable for electrically connecting the phase branches BP1, BP2 and BP3 to a single-phase power line. Typically, the power interface PR may be a connection socket, connection cable or any power interface means comprising a coupling device arranged to connect the three phase branches BP1, BP2 and BP3 in parallel to the single-phase power line operating at alternating voltage.

[0054] It should also be noted that the Vdc voltage is adjustable in amplitude depending on the operating configuration of the power battery BAT. In three-phase alternating current charging mode, the Vdc voltage 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] Figure 3 shows a charging configuration of the polyphase system allowing the BAT battery to be recharged from a single-phase alternating current simultaneously with the generation of a direct voltage Vdc at the output of the RD diode module. In this configuration, the two phase branches BP1, BP2 are connected in parallel to a single-phase power supply line of the power supply network. The switches KR1 and KR2 are closed. The BP3 phase branch is disconnected from the alternating power supply network, KR3 is open. Furthermore, the switches K6 and K7 are open. The LT3 line only is used to generate the direct voltage bus BDC at the output of the RD diode module. K8 is closed.

[0056] Furthermore, a method for controlling the battery BAT comprises the control of several charging configurations, comprising at least one charging configuration, during which the method comprises the generation of the direct voltage Vdc by a direct voltage formed by the cells of one of the current lines, the voltage Vlt3 of the line LT3 as illustrated in figure 3. For this purpose, the cells of the line LT3 are controlled according to a reference setpoint Vref3 of continuous form and of value between 100 volts and 450 volts. The cells of the other two current lines, LT1 and LT2 in figure 3, are each controlled according to a reference setpoint synchronized with the alternating voltage of the single-phase power supply network. Thus, the control method allows electrical recharging in single-phase current simultaneously with the generation of the direct voltage bus Vdc.

[0057] For this configuration of the battery with three current lines, the control method can therefore control three charging configurations CR1, CR2 and CR3. In the first charging configuration, the first direct voltage Vdc is generated from the first current line LT1 and the alternating voltage charging of the cells is carried out from the second LT2 and third LT3 current lines, in the second configuration CR2 the first direct voltage Vdc is generated from the second current line LT2 and the charging of the cells is carried out from the first LT1 and third LT3 current lines and in the third configuration CR3 the first direct voltage is generated from the third current line LT3 and the alternating voltage charging of the cells is carried out from the first LT1 and second LT2 current lines.

[0058] Furthermore, to maintain the charge balance of the cells between the lines LT1, LT2 and LT3, the control method comprises the control of these three charging configurations CR1, CR2 and CR3, controlled successively and in a loop during the charging of the battery BAT. These charging configurations are switched according to a chosen period of a duration between a few minutes and several tens of minutes. The period is of a constant duration for the three configurations.

[0059] A monitoring function is also provided to check that each current line LT1, LT2 and LT3 of the battery BAT is capable of generating a sufficient voltage amplitude for connection to the AC power supply network. Indeed, in the event of significant discharge of the battery, due to the decrease in cell voltage resulting from a low charge level, it is possible that the maximum voltage of one of the lines may not reach the peak voltage of the network, thus preventing synchronization with the network.

[0060] To solve this problem, it is planned that the monitoring function is configured when initializing a battery charge to detect if the maximum controllable value of the voltage wave of at least one of the current lines LT1, LT2 and LT3 is lower than a voltage threshold. The voltage threshold depends on the voltage of the supply network and can be between 150 volts and 350 volts depending on the network standard (120 volts or 230 volts).

[0061] The monitoring function further includes a control of a fourth CR4 load configuration depending on the result of this detection and comprising the AC voltage charging of the cells of the current lines LT1, LT2, LT3 simultaneously during which the lines are connected in series. For the implementation of this fourth charging configuration CR4, with reference to Figure 2, the network switch KR1 is closed and the switches KR2 and KR3 are open. The switch K4 is closed and the switch K5 is open. The switches K6, K7 and K8 are open so as to disconnect the diode module RD. The electrical needs of the DC voltage RDB network are temporarily provided by the service battery BAT2 which delivers the voltage Vrdb until the voltage of each line becomes higher than the voltage threshold.

[0062] In Figure 4, the control method according to the invention is described in the form of a block diagram and illustrates the sequence of permutation of the load configurations controlled by the control unit in accordance with the invention.

[0063] The method comprises an initialization step E0 prior to the sequence of charging the battery from a line of a power supply network operating in single-phase alternating current. The storage system is not yet connected to the network. The initialization step E0 comprises the start-up of the battery and the control unit.

[0064] Furthermore, the initialization step E0 can provide for a precharge of a capacitance of the voltage bus BDC so as to avoid a current peak phenomenon when closing one of the switches K6, K7 and K8.

[0065] Furthermore, before each closure of switches KR1, KR2 and K3, the control method provides a step of synchronizing the voltage waves generated by the current lines of the battery with the AC power supply network. More precisely, the synchronization provides the phasing control and the piloting of a voltage amplitude difference between a current line of the battery and the network which is lower than a threshold (expressed in voltage), for example a few volts. The synchronization of a line is provided for each permutation of the load configuration.

[0066] First of all, the control method comprises a step E1 of monitoring an electrical parameter representative of the maximum controllable value of the voltage wave Vltx of at least one of the current lines LT1, LT2 and LT3, or each current line. Monitoring E1 consists of detecting whether said parameter is lower than a threshold voltage S1, for example 310 volts. The maximum controllable value corresponds to the sum of the voltages of all the cells in a current line connected in series. This value can be measured at any time by the battery control unit using voltage sensors for each cell or each cluster of cells. Alternatively, the electrical parameter is an estimate of the state of charge of the cells in each line and the threshold S1 is a value representative of the state of charge. S1 can then be expressed in points (%) of state of charge capacity or in ampere-hours.

[0067] In case of detection that one of the current lines has a maximum controllable voltage value which is lower than said threshold S1, the method controls the fourth charging configuration CR4 comprising a step of charging ECH4 in alternating voltage of the cells of the elementary modules MCLk of the first, second and third current lines LT1, LT2, LT3 simultaneously. During the charging ECH4 the three current lines LT1, LT2 and LT3 are connected in series.

[0068] Figure 5 illustrates the single-phase alternating voltage that is generated on the phase branch of the battery system during charging ECH4 from the series-connected cells of the three current lines LT1, LT2 and LT3 configured in series. The lower curve represents the voltage Vac generated at the battery terminals, expressed in volts, and the upper curve represents the current lac of the supply network expressed in amperes. This configuration has the advantage of being able to generate a peak voltage by using all the elementary modules of the three current lines. This configuration allows the cells to be recharged when the battery state of charge is low, for states of charge less than 10% of the total charge for example.

[0069] If it is detected that each of the current lines has a maximum controllable voltage value which is greater than said threshold S1, the method controls one of the load configurations, for example the first load configuration CR1. Alternatively, the method can trigger the second load configuration CR2 or the third load configuration CR3.

[0070] The first charging configuration CR1 comprises the following steps, controlled simultaneously, of the generation EGN1 of the first direct voltage Vdc at the output of the diode module from the current line LT1 during which the elementary modules of said first line are controlled according to a first setpoint of reference Vrefl, and of the load ECH1 in alternating voltage of the cells of the elementary modules of the two other current lines LT2, LT3 during which the elementary modules of said two other lines are controlled according to a second reference setpoint Vref2 synchronized with an alternating voltage of the extended power supply network. With reference to figure 5, the voltages Vlt2 and Vlt3 for the lines LT2 and LT3 respectively are generated identically to the curve Vac.

[0071] More precisely, the first setpoint Vrefl is a DC voltage signal with a value between 100 volts and 450 volts. The Vref2 setpoint is a signal measured from the power interface operating in single-phase AC. The same Vref2 signal is used to synchronize the two current lines LT2 and LT3 to be charged.

[0072] The first load configuration CR1 is controlled during a period P.

[0073] Once this period P has elapsed, the control method comprises a permutation of the charging configuration. The permutation comprises the command to stop charging the cells of the LT3 line, then the generation of a direct voltage by the LT3 line in accordance with the first setpoint Vrefl , then the stopping of the generation of the direct voltage by the LT1 line, then the synchronization of the voltage Vlt1 with the alternating voltage of the network and finally the connection of the LT1 current line to the alternating supply network.

[0074] Once the configuration permutation is completed, the method controls the third load configuration CR3 for the duration of the period P. During this period, the method controls the generation EGN3 of the first direct voltage Vdc at the output of the diode module from the current line LT3 during which the elementary modules of the line LT3 are controlled according to the direct voltage setpoint, and the charging ECH3 in alternating voltage of the cells of the elementary modules of the other two current lines LT1, LT2 during which the elementary modules are controlled according to the reference setpoint Vref2 synchronized with the alternating voltage of the extended power supply network.

[0075] Once this period P has elapsed, the control method comprises a new permutation of the charging configuration to control the configuration CR2. The permutation comprises the command to stop the charging of the cells of the line LT2, then the generation of a direct voltage by the line LT2 in accordance with the first Vrefl setpoint, then stopping the generation of the direct voltage by the LT3 line, then synchronizing the Vlt3 voltage with the alternating voltage of the network and finally connecting the LT3 current line to the alternating supply network. Once the configuration permutation is completed, the method controls the second configuration CR2 for the duration of the period P, to then control a new permutation of the load configuration and control the first configuration CR1.

[0076] It should be noted that the three charging configurations follow one another in a loop to ensure the balancing of the cells. At the end of each loop, the method comprises a step E2 of monitoring an end-of-charge condition consisting, for example, of detecting whether the value of an electrical parameter, voltage of a cell or of a set of cells or state of charge for example, reaches an end-of-charge threshold S2. The end-of-charge condition may be the detection of an end-of-charge request.

[0077] If the end of charging is detected, the process goes to state E3 for charging exit.

[0078] It should be noted that the permutations of the recharge configurations CR1, CR2 and CR3 do not necessarily involve the opening and closing of the switches K6, K7 and K8 due to the presence of the precharge capacitance. Preferably, the switches remain closed throughout the duration of the control process.

[0079] In Figure 5 an embodiment of the electrical system is shown for an electrified vehicle with fully electric or hybrid motorization. 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 can 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 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 68 from a power supply network operating at alternating voltage. The recharging interface 68 is a recharging box electrically connecting the terminals of the battery 60 to the terminal for recharging at alternating voltage in single-phase or three-phase current.The charging interface 68 is also capable of rapid charging with direct voltage. The battery system 60 is. advantageous in that its control unit 65 adapts the voltage wave into alternating form or continuous 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.

[0080] The battery can further 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 67 operating at a nominal voltage of type 12 volts. For this purpose, the electrical system comprises power electronics 69 comprising a diode module electrically connected to the current lines of the battery. The diode module is formed by at least three diodes in accordance with FIG. 2. The output of the diode module supplies the voltage bus 450 volts for example. In addition, 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 (450 volts) to low voltage (12 volts) to supply the on-board network and charge the service battery during the second phase of the process.

[0081] In another embodiment, a stationary storage system is contemplated comprising the electrical system according to the invention.

[0082] 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. Method for controlling a polyphase electrical system for recharging a power battery (BAT) with electrochemical cells of said system, the battery comprising three current lines (LT1, LT2, LT3) in which each line comprises 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 chosen at the terminals of each current line (LT1, LT2, LT3), the method being characterized in that it comprises at least one charging configuration of the battery (BAT) comprising the following steps controlled simultaneously: the generation (EGN1) of a first direct voltage (Vdc) at the output of a diode module (RD) from a current line (LT 1) among said three lines (LT1, LT2,LT3) during which the elementary modules (MCLk) of said line (LT1) are controlled according to a first reference setpoint, the charge (ECH1) in alternating voltage of the cells (CLk) of the elementary modules (MCLk) of the two other current lines (LT2, LT3) among the three lines (LT1, LT2, LT3) during which the elementary modules (MCLk) of said two other lines (LT2, LT3) are controlled according to a second reference setpoint synchronized with an alternating voltage of an extended power supply network (RES)., 2. Method according to claim 1 comprising the successive control in loop of first, second and third charging configurations (CR1, CR2, CR3) of the battery (BAT): the first charging configuration (CR1) during which the first direct voltage (Vdc) is generated (EGN1) from a first current line (LT1) and the charging of the cells in alternating voltage is carried out for second (LT2) and third (LT3) current lines, the second configuration (CR2) during which the first direct voltage (Vdc) is generated from the second current line (LT2) and the charging of the cells in alternating voltage is carried out for the first (LT1) and third (LT3) current lines, the third configuration (CR3) during which the first direct voltage (Vdc) is generated from the third current line (LT3) and the charging of the cells is carried out for the first (LT1) and second (LT3) current lines.

3. Method according to claim 2 further comprising the following steps prior to the control of one of said first, second and third charging configurations (CR1, CR2, CR3): a step of monitoring (E1) an electrical parameter representative of the maximum controllable value of the voltage wave (Vlt1) of at least one of said current lines (LT1) consisting of detecting whether the parameter is lower than a threshold (S1), and in the event of detection that said parameter is lower than said threshold (S1), the control of a fourth charging configuration (CR4) comprising the charging with alternating voltage of the cells (CLk) of the elementary modules (MCLk) of the first, second and third current lines (LT1, LT2, LT3) simultaneously.

4. Method according to claim 3 wherein the fourth charging configuration (CR4) further comprises the series connection of the first, second and third current lines (LT1, LT2, LT3) to a single phase branch (BP1) of the electrical system for charging in alternating voltage.

5. Method according to claim 3 or 4, in which the voltage threshold (S1) is equal to the maximum value of the wave of the voltage of the extended power supply network (RES).

6. Method according to any one of claims 2 to 5 wherein, during the charging of the cells for the first, second and third charging configurations (CR1, CR2, CR3), the charging current lines (LT2, LT3; LT1, LT3; LT1, LT2) are connected in parallel to a single-phase alternating current power supply interface (PR).

7. Method according to any one of claims 1 to 6 further comprising during the generation of the first direct voltage (Vdc), the conversion of the first direct voltage (Vdc) into a second direct voltage (Vrdb) of to recharge a service battery (BAT2) from a direct voltage electrical network (RDB).

8. Polyphase electrical system comprising a power battery (BAT) with electrochemical cells, three phase branches (BP1, BP2, BP3) provided for recharging the battery from an extended electrical supply network (RES) operating at alternating voltage, and a diode module (RD) electrically connected to said phase branches by three derivations (D1, D2, D3), the battery (BAT) comprising three current lines (LT1, LT2, LT3), each 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 chosen at the terminals of each current line, characterized in that it comprises a control unit (BMS) configured to implement the control method according to any one of claims 1 to 7.

9. System according to claim 8 comprising a power supply interface (PR) provided for an electrical load in single-phase alternating voltage and a coupling device capable of electrically connecting the three phase branches in parallel to the power supply interface (PR).

10. Electrified motor vehicle comprising an electrical system according to claim 8 or 9.

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

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