METHOD FOR CONTROLLING A BATTERY CHARGING IN A MULTIPHASE ELECTRICAL SYSTEM FOR GENERATING A DIRECT VOLTAGE BY SWITCHING 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 battery charging configuration (BAT) comprising the following steps controlled simultaneously: generating a first DC voltage at the output of a diode module (RD) from a current line (LT1) 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, 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 said two other lines (LT2, LT3) are controlled according to a second reference setpoint synchronized with an AC voltage from an extended power supply network (RES).The invention applies to electrified vehicles and stationary storage systems. Figure 1.

Description

Title of the invention: METHOD FOR CONTROLLING A BATTERY CHARGING IN A MULTIPHASE ELECTRICAL SYSTEM FOR GENERATING A DIRECT VOLTAGE BY SWITCHING CURRENT LINES

[0001] The field of the invention relates to a method of controlling a polyphase electrical system for the generation of a DC electrical network during the single-phase current charging 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 current from the battery to a compatible direct current, and a DC / DC converter transforms this direct current into a lower voltage suitable for the vehicle's electrical system, typically around 12 volts. It is therefore possible to generate the electrical system voltage while the vehicle is charging.

[0003] The applicant has developed a disruptive architecture known as a distributed multilevel inverter that eliminates the need for the voltage converters typically integrated between an electrochemical cell battery and the AC power grid. 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. These documents describe a cell architecture comprising current lines formed by elementary modules, each containing 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, enabling the balancing of the cells under load and the generation of polyphase or direct current.

[0004] Generating the DC voltage for the vehicle's electrical system during AC charging is problematic for this architecture because it requires activating DC voltage generation by controlling the multilevel inverter distributed throughout the battery, and then producing the DC voltage for the electrical system via a DC / DC converter. To solve this problem of generating DC voltage during vehicle charging on an AC power grid, the applicant has proposed a solution consisting of injecting a common-mode voltage across 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 battery current lines are connected in series, it is not possible to generate the common mode voltage.

[0006] There is therefore a need to address 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 multilevel inverter battery architecture, allowing the vehicle's on-board network voltage to be maintained during charging.

[0007] More specifically, the invention relates to a method of 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 equipped 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 chosen voltage waveform across the terminals of each current line.

[0008] According to the invention, the method comprises at least one battery charging configuration including the following steps driven simultaneously:

[0009] - the generation of a first DC voltage at the output of a diode module starting from one of the three current lines during which the elementary modules of said line are controlled according to a first reference setpoint,

[0010] - the alternating voltage charge of the cells of the elementary modules of the two other current lines among the three lines during which the elementary modules of the said two other lines are controlled according to a second reference setpoint synchronized with an alternating voltage from an extended power supply network.

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

[0012] - The command successively loops first, second and third confi battery charging configurations, the first charging configuration during which the first DC voltage is generated from a first current line and the AC voltage charging of the cells is operated for the second and third current lines, the second configuration during which the first DC voltage is generated from the second current line and the AC voltage charging of the cells is operated for the first and third current lines, the third configuration during which the first DC voltage is generated from the third current line and the charging of the cells is operated for the first and second current lines.

[0013] - The following steps prior to ordering one of said first, Second and third load configurations: a monitoring step of an electrical parameter representative of the maximum controllable value of the voltage waveform of at least one of said current lines consisting of detecting whether the parameter is less than a threshold, and in the event of detection that said parameter is less than said threshold, the control of a fourth load configuration comprising the alternating voltage load of the cells of the elementary modules of the first, second and third current lines simultaneously.

[0014] - The fourth load configuration further includes the series connection of the first, second and third single-phase power lines of the electrical system for AC voltage load.

[0015] - The voltage threshold is equal to the maximum value of the network voltage waveform extended power supply.

[0016] - During the charging of the cells for the first, second and third confi Load figures, the load current lines are connected in parallel to a single-phase AC power interface.

[0017] - During the generation of the first DC voltage, the conversion of the first direct current voltage into a second direct current voltage in order to recharge a service battery of a direct current electrical network.

[0018] A polyphase electrical system is further provided comprising a power battery with electrochemical cells, three phase branches provided for charging the battery from an extended power supply network operating at alternating voltage, and a diode module electrically connected to said phase branches by three branches, the battery having three current lines, each line having a plurality of elementary modules connected in series, each equipped 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 selected voltage waveform across each current line, and comprising a control unit configured to implement any one of the embodiments of the control method according to the invention.

[0019] According to one variant, the system includes a power supply interface intended 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.

[0020] An electrified motor vehicle comprising such an electrical system is also planned.

[0021] A stationary storage system comprising such an electrical system is also planned.

[0022] The invention further provides a computer program comprising instructions which, when the program is executed by a control unit of a battery in a polyphase electrical system, cause the latter to implement any embodiments of the control method according to the invention.

[0023] The invention has the advantage that the method can be implemented by a fully software-based solution for controlling the polyphase electrical system. The invention enables the generation of a direct current voltage for an electrical network simultaneously with a single-phase current load on the cells.

[0024] Other features and advantages of the present invention will become more apparent upon reading the following detailed description, which includes embodiments of the invention given by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0025] [Fig-1] represents an embodiment of a polyphase system comprising a battery equipped with a multilevel inverter and intended to implement the control method according to the invention.

[0026] [Fig.2] represents an embodiment of the system according to the invention comprising a diode module for generating a DC voltage bus for a battery-powered DC voltage electrical network.

[0027] [Fig.3] represents an electrical system charging configuration allowing the generation of a direct current voltage and the charging of the two other current lines of the battery from a single-phase alternating current.

[0028] [Fig.4] represents an embodiment of the control method according to the invention.

[0029] [Fig.5] represents a single-phase voltage waveform used for the reference setpoint of the load lines during the process according to the invention.

[0030] [Fig.6] schematically represents an embodiment of the electrical system for an electrified vehicle.

[0031] The invention relates to a polyphase electrical system for energy storage in 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 with interconnected elementary cell modules forming a distributed multilevel inverter structure within the battery, allowing the battery to be connected to an electrical system operating at both direct current and alternating current without the need for an inverter. The battery system can be connected directly to an extended power grid and to an electric drive machine. The invention aims to provide a control method for maintaining the voltage of a DC network supplied by the power battery during single-phase alternating current charging.In particular, the process aims to maintain the voltage of an on-board network of an electrified vehicle during vehicle charging.

[0032] In this description, the term distributed multilevel inverter means that the Each current line, or each current line of the battery, in the case of a polyphase architecture, particularly 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 includes a means of 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 described in more detail in [Fig. 1].

[0033] With reference to [Fig. 1], the power battery BAT comprises a plurality n of elementary modules MCLk forming the multilevel inverter structure distributed within the battery and includes three current lines LT1, LT2, and LT3 connected to phase branches BPI, BP2, and BP3, 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 allow the battery to be connected to various systems designed to use alternating or direct current voltage. In this three-phase configuration, each current line comprises n / 3 elementary modules.

[0034] The BAT battery system has a voltage of several hundred volts across 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 a maximum voltage of 1500 volts DC or even higher, particularly for stationary storage systems.

[0035] In a first set of branch connections for phase branches BPI, BP2, and BP3, the battery system BAT includes high-voltage switches Kres, also called high-voltage contactors, for electrically connecting the battery BAT to an extended power supply network RES. Each current line LT1, LT2, and LT3 is connected, via these branch connections, 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 power supply network RES operates at 50 Hz or 60 Hz alternating voltage and comprises a three-phase line with three voltage lines PI, P2, and P3. The battery system BAT is adapted to generate three three-phase voltage waves offset by 2π / 3. The control of each current line is similar, differing only by a 2π / 3 offset between them.

[0036] It should be noted that, thanks to this multilevel inverter architecture distributed in the battery, the electrical system does not include an AC / voltage converter DC between the LT1, LT2 and LT3 power lines and the BPI, BP2 and BP3 phase branches operating in alternating current.

[0037] Furthermore, in an embodiment for an electrified vehicle, the battery system BAT is the vehicle's traction battery and also includes high-voltage switches Kmel for electrically connecting the battery BAT to a drive electric machine MEL. Each current line LT1, LT2, and LT3 is connected, via a second set of phase branch connections BPI, BP2, and BP3, on one 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 drive electric machine can be an asynchronous or synchronous machine, possibly a DC machine, since the battery system is capable of generating any form of voltage waveform, alternating or direct.

[0038] Alternatively, for an embodiment of a renewable energy installation, the second phase branch branch assembly can be connected to a photovoltaic system or a wind turbine installation. Alternatively, the battery is connected to the power supply network for grid regulation purposes.

[0039] 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 illustrate the control method for maintaining the voltage of a DC voltage network during single-phase AC charging of the battery.

[0040] 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 according to a reference setpoint Vref from the elementary modules MCLk. Each elementary module MCLk may comprise a single cell CLk, or a cluster of CLk cells of 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 module MCLk.

[0041] The COMk switching module is, for example, comprised of two switching parts forming an H-bridge that can be controlled in three different states by a control signal from the battery management unit (BMS) BAT, specifically addressing the MCLk module. The states are represented by a control variable uik that can take, for example, the values ​​1, 0, -1, representing the three different states respectively controlling the elementary voltage Vclk, a zero voltage, and the inverted voltage -Vclk at the connection terminals of the addressed elementary module k. by the control signal uik. Each COMk switching module comprises electronic components, such as power transistors, possibly of the MOSFET or HEMT (High Electron Mobility Transistor) type, driven by the control signals of the BMS control unit. Thus, the voltage Vmclk across each elementary module MCLk within a set n of modules can be controlled according to a control signal uik as shown in the following relation:

[0042] [Math.l] if V ref _M >n k -V dk if V refi (t) < -n^Vca otherwise

[0043] Thus, the BMS control unit can control, on each voltage line LT1, LT2, and LT3, any voltage waveform formed in amplitude steps equal to the elementary voltage Vclk, according to a reference voltage setpoint Vref, by connecting the cells in series via the COMk switching modules. The reference voltage setpoint Vref can be a sinusoidal waveform with a frequency of 50 Hz, any alternating waveform, for example a square wave, or can be a constant voltage, for example.

[0044] It is recalled that an electrochemical cell is an electrical energy storage device having two terminals, a positive electrode and a negative electrode, and exhibiting a voltage of a few volts, most often between approximately 2.3V and 4.2V. Cells can be of the Lithium-ion type (lithiumized Nickel Manganese Cobalt oxide (NMC) or lithium iron phosphate (LFP) can be cited as examples of active materials for the positive electrode), Nickel Cadmium (Ni-Cd), or Nickel Metal Hydride (Ni-MH), for example. More precisely, a Lithium-ion cell is composed primarily 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.

[0045] In [Fig.2], the BAT battery system is schematically illustrated in the system Polyphase electric. For clarity, the shunt assembly of the electric motor machine is no longer shown.

[0046] The polyphase electrical system includes a third set of branch connections for the phase branches PB1, PB2, and PB3 for connecting the battery BAT to a DC voltage bus BDC. This set of connections includes three branches D1, D2, and D3 connected respectively to the phase branches B1, BP2, and BP3. Branches D1, D2, and D3 are connected to a diode module RD comprising three diodes d1, d2, and d3 are connected respectively to branches D1, D2, and D3. In addition, switches K6, K7, and K8 are provided, arranged to selectively connect and disconnect diodes d1, d2, and d3 to their respective branches D1, D2, and D3. At the output of the diode module RD, the three diodes d1, d2, and d3 are connected together to a DC voltage bus (DCB). The DC voltage bus is suitable for powering at least one DC-operating system. It provides electrical power to one or more devices from a set of devices that may include one or more DC / DC voltage converters, an electric compressor, and an electric heater, for example, in an electrified vehicle application. Other electrical systems are possible depending on the application.

[0047] The diode module RD functions to generate a first DC voltage Vdc, adjustable in shape and amplitude by controlling the voltage waveforms generated Vlt1, Vlt2, and Vlt3 on the current lines LT1, LT2, and LT3, respectively. The first DC voltage Vdc is equal to the maximum voltage amplitude controlled among the three connected current lines LT1, LT2, and LT3. All three lines LT1, LT2, and LT3 can be connected to the diode module to generate the voltage Vdc, or only one line. For example, Vdc can be generated from line LT1 only, with lines LT2 and LT3 disconnected. Vdc can be generated from the LT3 line only, and the LT1 and LT2 lines are disconnected.

[0048] The RD diode module is made up of common components that are easy to obtain and assemble. In addition, diodes have the advantage of being reliable, robust and low cost.

[0049] Furthermore, this example includes a DC / DC voltage converter (CONV) connected to the output of the diode module (RD) and designed to convert the DC voltage (Vdc) into a second, lower voltage (Vrdb), for example, 12 volts. Other values ​​are possible depending on the intended application, ranging from 12 volts to 450 volts. This converter (CONV) supplies a DC voltage network (RDB) when the converter is powered by the DC voltage (Vdc). The DC voltage network (RDB) is further designed to include a service battery (BAT2) to stabilize the RDB network voltage and ensure the network's power requirements are met when the converter (CONV) is not supplying power, particularly when the power battery is being charged from a single-phase current.

[0050] Furthermore, the polyphase system includes switches K4 and K5 arranged to selectively connect the LT1, LT2, and LT3 current lines in series and parallel, thus enabling single-phase and three-phase operation of the battery. More specifically, in single-phase configuration, switches KR2, KR3, and K5 are open, and switches KR1 and K4 are closed. Thus the lines Current lines LT1, LT2, and LT3 are connected in series to phase branch BPI, which is connected to the extended power supply network RES. In a three-phase configuration, switch K4 is open, and switches KR1, KR2, KR3, and K5 are closed. Therefore, current lines LT1, LT2, and LT3 are connected to phase branches BPI, BP2, and BP3, respectively, which are connected to the extended power supply network RES.

[0051] Furthermore, the polyphase system includes a power supply interface PR adapted to electrically connect the phase branches BPI, BP2, and BP3 to a single-phase power supply line. Typically, the power supply interface PR can be a branch plug, branch cable, or any power supply interface means comprising a coupling device arranged to connect the three phase branches BPI, BP2, and BP3 in parallel to the single-phase power supply line operating at alternating voltage.

[0052] It should also be noted that the voltage Vdc is adjustable in amplitude according to the operating configuration of the power battery BAT. In three-phase AC 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 is the subject of French patent application FR-A1-3121797 filed by the applicant.

[0053] In [Fig. 3], a charging configuration of the polyphase system is shown, enabling the battery BAT to be recharged from a single-phase alternating current simultaneously with the generation of a direct current voltage Vdc at the output of the diode module RD. In this configuration, the two phase branches BP1 and BP2 are connected in parallel to a single-phase power supply line. Switches KR1 and KR2 are closed. Phase branch BP3 is disconnected from the AC power supply; KR3 is open. Furthermore, switches K6 and K7 are open. Only line LT3 is used to generate the direct current voltage bus BDC at the output of the diode module RD. K8 is closed.

[0054] Furthermore, a method for controlling the BAT battery includes controlling several charging configurations, comprising at least one charging configuration, during which the method includes generating the DC voltage Vdc from a DC voltage formed by the cells of one of the current lines, the voltage Vlt3 of the LT3 line as illustrated in [Fig. 3]. To this end, the cells of the LT3 line are controlled according to a reference setpoint Vref3, which is continuous and has a value between 100 volts and 450 volts. The cells of the two other current lines, LT1 and LT2 in [Fig. 3], are each controlled according to a reference setpoint synchronized with the AC voltage of the single-phase power supply. Thus, the control method allows simultaneous single-phase current charging. due to the generation of the DC voltage bus Vdc.

[0055] For this three-current-line battery configuration, the control method can therefore drive three charging configurations CRI, CR2 and CR3. In the first charging configuration, the first DC voltage Vdc is generated from the first current line LT1 and the AC voltage charging of the cells is carried out from the second LT2 and third LT3 current lines; in the second configuration CR2 the first DC 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 DC voltage is generated from the third current line LT3 and the AC voltage charging of the cells is carried out from the first LT1 and second LT2 current lines.

[0056] Furthermore, to maintain the charge balance of the cells between lines LT1, LT2, and LT3, the control method includes controlling these three charging configurations CRI, CR2, and CR3, which are operated successively and in a loop during the charging of battery BAT. These charging configurations are switched according to a chosen period ranging from a few minutes to several tens of minutes. The period is of constant duration for all three configurations.

[0057] A monitoring function is also provided to verify 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. Indeed, in the event of significant battery discharge, 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.

[0058] To resolve this issue, the monitoring function is configured during battery charge initiation to detect whether the maximum controllable base voltage of at least one of the current lines LT1, LT2, and LT3 is below a voltage threshold. The voltage threshold depends on the mains voltage and can be between 150 volts and 350 volts, depending on the mains standard (120 volts or 230 volts).

[0059] The monitoring function further includes a control of a fourth load configuration CR4, dependent on the result of this detection, and comprising the simultaneous AC voltage loading of the cells of the current lines LT1, LT2, and LT3, during which the lines are connected in series. For the implementation of this fourth load configuration CR4, with reference to [Fig. 2], network switch KR1 is closed and switches KR2 and KR3 are open. Switch K4 is closed and switch K5 is open. Switches K6, K7, and K8 are opened to disconnect the RD diode module. The RDB network's DC voltage electrical needs are temporarily met by the BAT2 auxiliary battery, which supplies the Vrdb voltage until the voltage of each line rises above the voltage threshold.

[0060] In [Fig.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 driven by the control unit in accordance with the invention.

[0061] The method includes an initialization step E0 prior to the battery charging sequence from a line of a single-phase AC power supply. The storage system is not yet connected to the grid. The initialization step E0 includes starting the battery and the control unit.

[0062] Furthermore, the initialization step E0 may provide for a pre-charge of a capacitance of the voltage bus BDC in order to avoid a current peak phenomenon when closing one of the switches K6, K7 and K8.

[0063] Furthermore, before each closure of switches KR1, KR2, and K3, the control method includes a step to synchronize the voltage waves generated by the battery current lines with the AC power grid. More specifically, the synchronization involves phasing and controlling a voltage difference between a battery current line and the grid that is below a threshold (expressed in voltage), for example, a few volts. Synchronization of a line is performed at each load configuration change.

[0064] First, the control method includes a monitoring step El of an electrical parameter representative of the maximum controllable value of the voltage waveform Vltx of at least one of the current lines LT1, LT2, and LT3, or of each current line. The monitoring El consists of detecting whether this parameter is below a voltage threshold SI, for example, 310 volts. The maximum controllable value corresponds to the sum of the voltages of all the cells in a series-connected current line. This value is measurable at any given time by the battery control unit by means of voltage sensors on 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 SI is a value representative of the state of charge. SI can then be expressed in percentage points (%) of state of charge capacity or in ampere-hours.

[0065] If it is detected that one of the current lines has a maximum controllable voltage value that is lower than said SI threshold, the method commands the fourth load configuration CR4 comprising an AC voltage charging step ECH4 of the cells of the MCLk elementary modules of the first, second and third Current lines LT1, LT2, LT3 simultaneously. During ECH4 charging, the three current lines LT1, LT2 and LT3 are connected in series.

[0066] Figure 5 illustrates the single-phase alternating voltage generated on the phase branch of the battery system during charging ECH4 from the series-connected cells of the three series-configured current lines LT1, LT2, and LT3. The lower curve represents the voltage Vac generated at the battery terminals, expressed in volts, and the upper curve represents the lake current of the power supply network, expressed in amperes. This configuration has the advantage of being able to generate a peak voltage using all the elementary modules of the three current lines. This configuration allows the cells to be recharged when the battery's state of charge is low, for example, when the state of charge is less than 10% of the total charge.

[0067] If it is detected that each of the current lines has a controllable maximum voltage value that exceeds said threshold SI, the process controls one of the load configurations, for example the first load configuration CRI. Alternatively, the process can trigger the second load configuration CR2 or the third load configuration CR3.

[0068] The first CRI load configuration comprises the following steps, driven simultaneously: the generation EGN1 of the first DC voltage Vdc at the output of the diode module from the current line LT1, during which the element modules of said first line are driven according to a first reference setpoint Vrefl; and the AC voltage load ECH1 of the cells of the element modules of the two other current lines LT2 and LT3, during which the element modules of said two other lines are driven according to a second reference setpoint Vref2 synchronized with an AC voltage from the extended power supply network. Referring to [Fig. 5], the voltages Vlt2 and Vlt3 for lines LT2 and LT3, respectively, are generated identically to the Vac curve.

[0069] More specifically, the first setpoint Vrefl is a DC voltage signal with a value between 100 volts and 450 volts. The setpoint Vref2 is a signal measured from the single-phase AC power supply interface. The same Vref2 signal is used to synchronize the two current lines LT2 and LT3 to be loaded.

[0070] The first CRI load configuration is commanded during a period P.

[0071] Once this period P has elapsed, the control method includes a permutation of the load configuration. The permutation includes commanding the cessation of charging of the cells of line LT3, then the generation of a DC voltage by line LT3 in accordance with the first setpoint Vrefl, then the cessation of the generation of the DC voltage by line LT1, then the synchronization of the voltage Vltl with the alternating voltage of the network and finally the connection of the current line LT1 to the alternating power supply network.

[0072] Once the configuration switchover is complete, the process controls the third load configuration CR3 during the period P. During this period, the process controls the generation EGN3 of the first DC voltage Vdc at the output of the diode module from the current line LT3 during which the elementary modules of the LT3 line are driven according to the DC voltage setpoint, and the AC voltage charge ECH3 of the cells of the elementary modules of the two other current lines LT1, LT2 during which the elementary modules are driven according to the reference setpoint Vref2 synchronized with the AC voltage of the extended power supply network.

[0073] Once this period P has elapsed, the control method includes a new load configuration switch to control the CR2 configuration. The switch involves first controlling the load on the cells of line LT2, then generating a DC voltage by line LT2 according to the first setpoint Vrefl, then stopping the generation of the DC voltage by line LT3, then synchronizing the voltage Vlt3 with the AC voltage of the grid, and finally connecting the LT3 power line to the AC power grid. Once the configuration switch is complete, the method controls the second CR2 configuration for the duration of period P, and then controls a new load configuration switch to control the first CR1 configuration.

[0074] It should be noted that the three load configurations cycle through to ensure cell balancing. At the end of each loop, the method includes a monitoring step E2 for an end-of-charge condition, such as detecting whether the value of an electrical parameter, such as the voltage of a cell or a group of cells, or the state of charge, reaches an end-of-charge threshold S2. The end-of-charge condition may be the detection of an end-of-charge request.

[0075] In the event of detection of an end of charge, the process switches to the E3 state of output of the charge.

[0076] It should be noted that the permutations of the CRI, CR2, and CR3 charging configurations do not necessarily involve the opening and closing of switches K6, K7, and K8 due to the presence of the pre-charge capability. Preferably, the switches remain closed throughout the entire control process.

[0077] In [Fig. 5] an embodiment of the electrical system is shown for an electrified vehicle with a fully electric or hybrid powertrain. The vehicle includes an electric drive machine 64 capable of transmitting torque to the drive wheels 62 of the vehicle through a transmission 61. The electric drive machine 64 The system can be three-phase. The vehicle includes an electrical system comprising the battery 60, arranged in a multilevel inverter architecture distributed throughout the battery as described in [Fig. 1]. The battery has three current lines capable of generating three-phase and single-phase voltage waves. The vehicle also includes a battery charging interface 68 for charging from an AC power supply. The charging interface 68 is a charging unit that electrically connects the terminals of the battery 60 to the charging station for AC charging in single-phase or three-phase current. The charging interface 68 is also capable of fast DC charging. The battery system 60 is advantageous in that its control unit 65 adapts the voltage waveform to AC or DC without the need for a voltage converter.The vehicle also includes a supervisory 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 drive machine 64, thus improving its energy efficiency in traction.

[0078] The battery can also be connected to a high-voltage DC bus, for example, operating at a nominal voltage 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 includes power electronics 69 comprising a diode module electrically connected to the battery's current lines. The diode module consists of at least three diodes as shown in [Fig. 2]. The output of the diode module supplies the 450-volt voltage bus, for example. In addition, the power electronics 69 includes 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 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.

[0079] In another embodiment, a stationary storage system comprising the electrical system according to the invention is envisaged.

[0080] The invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different variant embodiments of the invention by combining, for example, the different features 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 battery charging configuration (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 (LT1) 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 charging (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 successively loop control of first, second and third charging configurations (CRI, CR2, CR3) of the battery (BAT): - the first charging configuration (CRI) 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 (El) an electrical parameter representative of the maximum controllable value of the voltage wave (Vltl) of at least one of said current lines (LT1) consisting of detecting whether the parameter is lower than a threshold (SI), - and in the event of detection that said parameter is lower than said threshold (SI), 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. The method of claim 3 wherein the fourth load configuration (CR4) further comprises connecting in series the first, second and third current lines (LT1, LT2, LT3) to a single phase branch (BPI) of the electrical system for AC voltage charging.

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

6. A method according to any one of claims 2 to 5 wherein, during 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 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) so as to recharge a service battery (BAT2) of a direct voltage electrical network (RDB).

8. Polyphase electrical system comprising a power battery (BAT) with electrochemical cells, three phase branches (BPI, 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 (Dl, D2, D3), the battery (BAT)

9.

10.

11. 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 multi-level 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. 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). Electrified motor vehicle comprising an electrical system according to claim 8 or 9. Stationary storage system comprising an electrical system according to claim 8 or 9.

Images