Battery system comprising means for synchronizing voltage and regulating current with electrical power supply network

Abstract

The invention relates to a battery system comprising a distributed multi-level inverter in a basic cell module of a battery, the distributed multi-level inverter allowing generation of alternating voltage waves on the current line of the battery and bidirectional operation on the electrical power supply network. According to the invention, the control unit of the battery comprises: determination means (20) for determining an electrical characteristic of an alternating voltage wave of the power supply network (RES); a synchronization means (21) for synchronizing the electrical characteristics of the alternating voltage waves of the current lines (LT1, LT2, LT3) of the battery system (BAT) with the waves of the power supply network (RES); electrical connection means (Kres) for electrically connecting the current lines (LT1, LT2, LT3) to the power supply network (RES), said electrical connection means being controlled as a function of a synchronization state (STE) of voltage waves of the battery system (BAT) and of the network; and a current regulating means (22) for regulating the current of the battery system (BAT) by actuating a reference voltage setpoint (Vref) of a current line of the battery system (BAT).

Description

Technical Field

[0001] The present invention claims priority from French application No. 2300095, filed on January 5, 2023, the content (text, drawings and claims) of which is incorporated herein by reference.

[0002] The field of the invention relates to a battery system with electrochemical cells comprising basic cell modules which form a distributed multilevel inverter in the battery. Background Art

[0003] In the field of stationary applications, electrochemical cells are used in high-voltage electrical networks to regulate them and, in particular, to store energy generated by photovoltaic and wind power plants. In the automotive sector, rechargeable electric vehicles include batteries and power electronics equipped with a voltage converter that adapts the voltage and current delivered by the battery to the various onboard electronic components. For these vehicles, the power electronics typically include a charger capable of converting AC voltage into DC voltage in order to recharge the battery from an extended electrical supply network operating on AC voltage.

[0004] A bidirectional charger allows for charging the battery using the power supply network and, in the case of so-called V2X (Vehicle to Everything) applications, discharging the battery to an electrical system external to the vehicle. For example, known documents WO 2022 / 200144 A1 and WO 2021004639 A1 describe a vehicle electrical power supply system including a bidirectional charger capable of charging the battery using energy from the power supply network and supplying power to an external load connected to another socket provided for this purpose on the vehicle.

[0005] These battery discharge solutions are only designed to electrically power loads connected to the vehicle's sockets and do not guarantee discharge to the power supply network. Furthermore, these bidirectional chargers require a stage of AC / DC and DC / AC converters, which typically experience energy losses of approximately 10% to 20% of the transmitted power during conversion.

[0006] The present applicant seeks to improve the energy efficiency of battery-powered systems. The present applicant has developed a so-called interrupt architecture with a distributed multilevel inverter, which makes it possible to dispense with the voltage converter typically integrated between a battery comprising electrochemical cells and a power supply network operating at AC voltage. This architecture has been the subject of several patent applications by the present applicant. Examples include documents WO 2017 / 153366 A1, WO 2021 / 048477 A1, and FR 3121797 A1. These documents describe a cell architecture comprising: a current path formed by basic modules, each of which comprises an electrochemical cell or a cluster of electrochemical cells, and switching modules for forming an H-bridge. These documents also describe an innovative control method for controlling this architecture, which allows for balancing the charge states of the cells and generating multiphase or DC current.

[0007] More precisely, it is possible to generate an AC voltage and an AC current at the output of the battery, which can be directly injected into an electric power machine or a power supply network. This architecture is particularly efficient because electrical efficiencies greater than 96% have been measured for recharging and discharging, and because it can eliminate the need for a voltage conversion level, particularly in electric vehicle applications. In stationary applications, especially for renewable energy facilities (where the battery system can store energy or regulate the network through controlled discharge), it is possible to connect the battery system directly to the power supply network without integrating a power conversion system (PCS). This therefore brings significant economic benefits. Summary of the Invention

[0008] The present invention seeks to propose an electrical energy storage system that overcomes the aforementioned problems and improves the connection phase of such a system to the network. The present invention aims to provide a battery system for electric vehicle and stationary applications, based on this architecture in the form of an integrated multi-level inverter, which allows bidirectional operation of the battery system with power supply networks operating with (single-phase and multi-phase) AC voltage. The present invention also aims to propose a solution for optimizing the regulation of charging and discharging currents on the power supply network.

[0009] More precisely, the present invention relates to a battery system with electrochemical cells for recharging / discharging on an extended electrical power supply network operating at an alternating voltage, the system comprising at least one current line comprising a plurality of basic modules forming a distributed multilevel inverter, each of the plurality of basic modules being equipped with a cell or a cluster of cells, and comprising a control unit for controlling the basic modules, the control unit being capable of generating a selected alternating voltage waveform at the terminals of the current line as a function of a reference voltage setpoint.

[0010] According to the present invention, the system further comprises:

[0011] - determination means for determining the electrical characteristics of the alternating voltage wave of the power supply network,

[0012] - synchronization means for synchronizing the electrical characteristics of the alternating voltage wave of the current line of the battery system with the alternating voltage wave of the power supply network,

[0013] an electrical connection element for electrically connecting the current line to the power supply network, the electrical connection element being controlled according to the synchronization state of the voltage waves of the battery system and of the network,

[0014] A current regulating component for regulating the current of the battery system by manipulating a reference voltage setpoint of a current line of the battery system.

[0015] The system according to the invention may include the following additional features which may be taken individually or in combination:

[0016] The battery system comprises three current lines, wherein the synchronization means comprises: a conversion means for converting the measured voltages of the lines of the battery system and of the network into first vector commands; a determination means for determining a first voltage setpoint in the form of a vector command by a first regulator, the first regulator taking the first vector command as input; and a first modulation means for modulating the first voltage setpoint into a reference voltage setpoint of the battery system.

[0017] -The battery system includes three current lines, wherein the current regulation component includes: a conversion component, the conversion component is used to convert the measured current and the reference current setting value of the line of the battery system into a second vector command for the current; a determination component, the determination component is used to determine a second voltage setting value in the form of a vector command by a second regulator, and the second regulator takes the second vector command as input; and a second modulation component, the second modulation component is used to modulate the second voltage setting value into the reference voltage setting value of the battery system.

[0018] The battery system further comprises an estimator for estimating the phase of the power supply network, wherein the conversion means of the first vector command and / or the second vector command also depend on the estimation of the phase.

[0019] The battery system further comprises an estimator for estimating a voltage amplitude deviation between voltage waves of the power supply network and of the battery system, wherein the synchronization state depends on a ratio of the deviation relative to a predetermined error threshold.

[0020] The present invention also relates to an electrified motor vehicle comprising a rechargeable battery system and an electrical interface for connecting the battery system to an extended electrical power supply network for recharging and discharging on the power supply network, wherein the battery system is a battery system according to any one of the above-described embodiments.

[0021] The present invention also relates to a stationary battery system comprising a rechargeable battery system and an electrical interface for connecting the battery system to an extended electrical power supply network, wherein the battery system is a battery system according to any one of the above-mentioned embodiments.

[0022] A control method for controlling a battery system having electrochemical cells for discharging / recharging on an extended electrical supply network is also envisaged, the control method comprising the following steps in succession:

[0023] - determining the electrical characteristics of the alternating voltage waves of said power supply network,

[0024] - synchronizing the electrical characteristics of the alternating voltage wave of at least one current line of the battery system with the alternating voltage wave of the power supply network,

[0025] - electrically connecting the current line to the power supply network upon detecting that the synchronization state of the voltage waves of the battery system and of the network is less than a predetermined error threshold,

[0026] The current of the circuits of the battery system is then regulated by actuating a reference voltage setpoint value adapted to the actuation of the current circuits of the battery system.

[0027] According to a variant, said synchronization comprises the following steps:

[0028] - transforming the measured voltages of the lines of the battery system and of the network into first vector commands,

[0029] - determining a first voltage setpoint in the form of a vector command by a first regulator, said first regulator taking said first vector command as input,

[0030] - Modulating a first voltage setpoint in the form of a vector command in order to generate a reference voltage setpoint adapted to the control of the battery system in order to generate a voltage wave to be synchronized.

[0031] According to a variant, the current regulation of the battery system comprises the following steps:

[0032] - transforming the measured currents of the lines of the battery system and the reference current setpoint into a second vector command for the current,

[0033] - determining a second voltage setpoint in the form of a vector command by a second regulator which takes the second vector command as input,

[0034] - a second voltage set point in the form of a modulation vector command to generate a reference voltage set point adapted to the control of the battery system in order to regulate the charge / discharge current of the battery system.

[0035] The present invention also provides a control unit for a battery system according to the present invention, comprising a component with an integrated circuit specifically configured to implement a control method for recharging and discharging on the power supply network. The present invention also provides a computer program comprising instructions which, when executed by the control unit of the battery system, cause the control unit to implement any of the above-described embodiments of the control method for recharging and discharging on the power supply network.

[0036] The present invention has the following advantages:

[0037] The synchronization process and the current regulation process carried out by the control unit increase the safety of the recharging or discharging process and simultaneously avoid overcurrents when the high-voltage contactor is closed.

[0038] The energy efficiency during recharging is significantly greater than that of known solutions in the prior art, with an efficiency of approximately 98.5% observed in experiments. In electric vehicle applications, the vehicle recharging costs and therefore the vehicle usage costs are significantly reduced.

[0039] Furthermore, this recharging concept uses the same components for three-phase recharging at 11kW, 22kW, and even higher power levels, and these same components are also used to ensure traction for the vehicle. Conventional architectures typically require a separate conversion element for high-power recharging (over 300kW) and for traction. This reduces power electronics costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other characteristics and advantages of the invention will become more apparent on reading the detailed description below of an embodiment of the invention given as a non-limiting example and the accompanying drawings, in which:

[0041] Figure 1 Schematically shows an embodiment of the electrical architecture of a battery system according to the present invention;

[0042] Figure 2 The synchronization function and current regulation function of the battery system according to the present invention are shown;

[0043] Figure 3 is a line diagram showing a synchronization phase for synchronizing the current paths of a battery system in terms of voltage and phase according to a control method according to the invention;

[0044] Figure 4 is a line diagram showing a current regulation phase for regulating the current of a current line of a battery system according to a control method according to the present invention;

[0045] Figure 5 A control method for controlling a battery system according to the invention is shown, which allows the battery system to be recharged and discharged on a power supply network and to regulate the current;

[0046] Figure 6 An embodiment of a battery system for an electrified vehicle is schematically shown. DETAILED DESCRIPTION

[0047] The present invention relates to an energy storage system for use in electric motor vehicles and for stationary storage systems in electrical installations, such as renewable energy installations or grid regulation installations. The system comprises an electrochemical battery comprising basic cell modules that are interconnected to form a distributed multilevel inverter structure within the battery. This distributed multilevel inverter structure enables the battery to be connected to electrical systems operating with both direct and alternating voltages without the need for inverters. The battery system can be directly connected to an extended electrical power supply network and to electric powered machines. More specifically, the invention relates to components and methods for synchronizing the battery system and for regulating the charging and discharging currents on the power supply network.

[0048] In this specification, the term "distributed multilevel inverter" means that, in the case of a multi-phase architecture (especially a three-phase architecture), the current path of the battery or each current path is formed by multiple basic modules, and each basic module includes a battery cell or a battery cell cluster, and a switching module for forming an H-bridge, and the control unit includes a control component for controlling the basic modules of the current path according to a reference set value, and is capable of generating a selected AC voltage waveform on each current path. Figure 1 The architecture is described in more detail in .

[0049] refer to Figure 1 The battery system BAT includes a basic module MCLk for forming a distributed multilevel inverter structure in the battery, and includes three current paths LT1, LT2, and LT3, with the basic module MCLk configured within the three current paths. In various variations, the battery system BAT may include a single current path LT1, only two current paths, or four or more current paths. In general, the battery system can be single-phase or multi-phase. The battery system BAT includes a high-voltage switch Kres (also called a high-voltage contactor) for electrically coupling the battery BAT to the power supply network RES. Each current path LT1, LT2, and LT3 is connected to a network connection switch KR1, KR2, and KR3, respectively, on one side, and to the neutral terminal N of the battery on the other side. The extended power supply network RES operates, for example, with a 50Hz or 60Hz AC voltage. The battery system BAT can generate three-phase voltages with a phase difference of 2π / 3. The operation of each current path is similar, differing only in the 2π / 3 phase difference between the current paths.

[0050] In the case of electric vehicle applications, the battery system BAT also includes a high-voltage switch Kmel for electrically coupling the battery BAT to the electric power machine MEL. Each current line LT1, LT2, and LT3 is connected on one side to a connection switch KM1, KM2, and KM3, respectively, of the electric machine, and on the other side to the neutral terminal N of the battery. The electric machine can be an asynchronous or synchronous machine, and optionally a DC machine, since the battery system is capable of generating any voltage waveform (AC or DC).

[0051] In addition, you can set the switch ( Figure 1 (not shown in FIG) electrically connects the three lines LT1, LT2, LT3 in series to allow the battery BAT to be connected to a single-phase network. In a variant, the battery system BAT may optionally include a single current line LT1.

[0052] The battery system BAT has a voltage of several hundred volts (e.g., 350 volts or 1000 volts) at its terminals. In the case of 350 volts, each line LT1, LT2, LT3 is equipped with, for example, 24 basic cell modules or clusters of basic cell modules connected in series. However, depending on electrical requirements, the battery system BAT may have a nominal voltage of only a few dozen volts (e.g., 24 V, 36 V, 48 V) (especially in motor vehicle applications) or a maximum voltage of up to 1500 V or even higher (especially in stationary storage systems).

[0053] The battery system BAT also includes a control unit BMS, one of the functions of which is to control the voltage waveform of line LT1 or each of lines LT1, LT2, and LT3 based on a reference set value Vref from a basic module MCLk. Each basic module MCLk may include a single cell CLk or a cell cluster CLk, where a cell cluster may be composed of two, three, four, five, six, or more cells, and forms a basic voltage Vclk. The basic module MCLk also includes a switch module COMk, which is capable of configuring the basic module MCLk into three different states to transmit voltages Vmclk (basic voltage Vclk, zero voltage, and reverse voltage Vclk, respectively) to the connection terminals of the basic module MCLk.

[0054] The switching module COMk is composed, for example, of two switching parts for forming a controllable H-bridge, which can be manipulated into three different states by a control signal from the control unit BMS of the battery BAT, the control signal being specifically sent to the module MCLk. The states are represented by a control variable uik, which can take the values 1, 0, and -1, for example, to represent three different states, which respectively control the basic voltage Vclk, zero voltage, and reverse voltage -Vclk at the connection terminals of the basic module k to which the control signal uik is sent. Each switching module COMk includes an electronic component, such as a power transistor of the MOSFET or HEMT (High Electron Mobility Transistor) type, which is manipulated by the control signal of the control unit BMS. Thus, in a set of all n modules, the voltage Vmclk at the terminals of each basic module MCLk can be manipulated according to the control signal uik according to the following relationship:

[0055] [Formula 1]

[0056]

[0057] The control unit BMS can control any voltage waveform formed by a level having an amplitude equal to the basic voltage Vclk on each of the voltage lines LT1, LT2, and LT3 according to the reference voltage setting value Vref. The reference voltage setting value Vref can have a sinusoidal form with a frequency of 50 Hz, any AC form (for example, a square form), or can be, for example, a constant voltage form.

[0058] Within the scope of the present invention, the control unit includes means for synchronizing a reference voltage setpoint Vref with the voltage of the network and for regulating the charging and discharging currents based on the reference voltage setpoint Vref. The control unit BMS is capable of determining at each moment the number q of basic modules required from the plurality n of basic modules in order to implement a voltage waveform for each voltage phase required by the setpoint Vref, with all basic cells having the same basic voltage Vclk.

[0059] It is noted that an electrochemical cell is an electric energy accumulator having two terminals (a positive electrode and a negative electrode) with a voltage of a few volts (most commonly, between about 2.3 V and 4.2 V). The cell may be of the lithium-ion type, the nickel-cadmium type or the nickel-metal hydride type. More precisely, a lithium-ion cell consists essentially of a porous positive electrode, a porous negative electrode, a separator and an electrolyte. The operating principle of a lithium-ion cell is based on the reversible exchange of lithium ions between two porous electrodes. The cell may, for example, be of the lithium iron phosphate type, the polymer lithium type or the solid electrolyte type.

[0060] refer to Figure 2 , describes components of a control unit BMS that implement synchronization and regulation functions for synchronizing the voltage waves generated by a battery system and regulating the charging and discharging currents when the battery system is electrically connected to a power supply network. This embodiment relates to the case of three-phase voltage synchronization. The synchronization function intervenes before the battery system is electrically connected to the power supply network, in other words, before switches KR1, KR2, and KR3 are closed, in order to avoid overcurrent conditions during connection. Figure 2 The embodiment described in is not limiting and, in particular, variants of voltage synchronization and current regulation of battery systems are envisaged, which may be single-phase or multi-phase (that is to say two-phase, three-phase or more).

[0061] The BMS control unit is equipped with a computer with integrated circuits and electronic memory, which are configured for the functions involved in synchronization and current regulation. The control unit can be implemented in the form of a software module (or computer program module, or "software"), or in the form of an electronic circuit (or "hardware"), or in the form of a combination of electronic circuits and software modules, such as an ASIC (Application Specific Integrated Circuit) or a DSP (Digital Signal Processor) type circuit.

[0062] The control unit BMS includes estimation or measurement means for estimating or measuring the instantaneous electrical characteristics of the voltage wave Vres of each current line of the power supply network. The measurements are possible when the battery system is not yet electrically connected to the network, in other words, when the switches KR1, KR2 and KR3 are open. Furthermore, the control unit includes estimation or measurement means for estimating or measuring the instantaneous electrical characteristics of the voltage Vbat and the current Ibat of each current line of the battery system. Figure 2 , these components are represented by the inputs Vres, Vbat and Ibat of the control unit BMS, respectively. These components make it possible to estimate the value of the voltage Vres of the power supply network.

[0063] Estimation means 20 for estimating the phase of each current line of the power supply network are also provided. Said estimation means are capable of simultaneously estimating the voltage frequency (approximately 50 Hz or 60 Hz) and the phase difference 201 of the network.

[0064] The control unit BMS comprises a voltage regulation module 21 whose function is to synchronize the power supply network and the battery system in terms of voltage and phase, and a current regulation module 22 which intervenes to control the charging and discharging currents when the battery system is synchronized with the network.

[0065] The function of the regulation module 21 is to regulate the voltage of the battery system in terms of voltage, amplitude, and phase, using the voltage of the power supply network as a reference. Based on this regulator 21, the control unit determines a setpoint value Vref, which controls the control modules of the battery cell clusters to generate a voltage wave on each line during the synchronization phase.

[0066] The regulation module 21 can act directly on the sinusoidal quantities, or by controlling the estimated direct and quadrature components, or by means of a control technique involving mathematical transformations, for example. In single-phase or multi-phase (two, three or more phases), the regulation module 21 comprises a regulation loop that uses a corrector based on the estimated electrical characteristics of the battery system and the supply network to control the voltage setpoint Vref of the or each current path of the battery system.

[0067] In case of three-phase application, refer to Figure 2 Transformation components 210 and 211 are provided to transform the power grid voltage signal Vres and the battery system voltage signal Vbat into digital models of vector commands Vres1 and Vbat1, respectively, with 50 Hz rotating magnetic fields in the Park plane. The resulting vector commands Vres1 and Vbat1 are used by a corrector 212 in a regulation loop to determine a voltage setpoint for the battery system, which takes the form of a setpoint for the vector command Vsync. Furthermore, corrector 212 determines an instantaneous error estimate Verr for the voltage signals.

[0068] Transformation components 210 and 211 are mathematical and signal processing functions that implement the Park transform, which is known to those skilled in the art in the field of electrical engineering for controlling three-phase motors. The Park transform has the advantage of simplifying and improving the performance of current and voltage controllers. The possibility of implementing other control principles is not excluded. Corrector 212 is a servo function known to those skilled in the art suitable for manipulating voltage setpoints. Corrector 212 is, for example, of the proportional-integral type. Other types of correctors are contemplated. In a variant, transformation components 210 and 211 can be estimators for estimating the sinusoidal electrical characteristics of the measured signal or for estimating the DC and quadrature components.

[0069] The function of the control switch module 23 is to select the control mode, either voltage regulation performed during the synchronization phase or current regulation when synchronization is active. The module 23 uses a control switch block 231 that activates one or another control mode depending on the estimation of the error Verr between the voltages of the network and the battery system.

[0070] More precisely, block 230 compares the error signal Verr with a predetermined threshold. When signal Verr is greater than the threshold, voltage regulation remains active. The resulting voltage setpoint Vsync of regulation block 21 is used to control the battery and to generate waveforms on each of the current paths.

[0071] When the signal Verr becomes less than the threshold, block 230 detects that the synchronization of the voltages is consistent in terms of amplitude and phase difference, and the battery system can be electrically connected to the network. This situation activates the current regulation of the battery system. Since the voltages are synchronized, overcurrent effects in the battery system are avoided. Block 230 can control Figure 1 The high-voltage switch Kres shown in FIG. When synchronization is detected and the synchronization remains stable during the confirmation time period, the switch is closed.

[0072] Furthermore, the control unit BMS includes a modulation function 24 capable of delivering a voltage setpoint adapted to the operation of the battery system based on a voltage setpoint (either from the voltage regulation module 21 or from the current regulation module 22). To implement voltage synchronization, a block 240 modulates the setpoint Vsync into a voltage regulation at the output of the servo loop.

[0073] Like the conversion blocks 210 and 211 , the block 240 takes as input an estimate 201 of the phase difference of the voltage signal of the network in order to adapt the inverse conversion to an optional change in the phase of the network.

[0074] exist Figure 3 In the figure, a line graph shows a simulation of voltage synchronization operation for a battery system. The horizontal axis is the time axis. In the upper range, the line graph shows the voltage of the battery system on the current line and the RMS voltage of the power supply network on the corresponding line (configured to 400 volts in this example). The middle range shows the synchronization error Verr between the voltage of the network and the battery system in volts. The lower range shows the number of cell clusters Qcl activated during synchronization. In this example, the current line includes 24 cell clusters connected in series in the current line of the battery.

[0075] On this graph, we observe that starting at 0.2 seconds, the first battery cell cluster is activated, the error decreases, and then stabilizes at 0.6 seconds. In the upper range, we observe a gradual increase in the battery voltage Vbat as the cells are activated (22 of the 24 modules are used). Simultaneously, the synchronization error decreases, and after confirming the duration, the control unit closes the contactors of the current path, activating current regulation.

[0076] refer to Figure 2 The function of the regulation module 22 is to regulate the battery system in terms of current, taking as input parameters a reference current setpoint Iref and an estimated instantaneous current Ibat expressed as an Irms value across the battery system. Based on this regulator 22 , the control unit determines a setpoint Vref, which controls the control modules of the battery cell clusters to generate a voltage wave on each line during the synchronization phase.

[0077] Current regulation is performed by manipulating the battery system's setpoint value, Vref. This current regulation is performed by a servo loop that maintains the measured battery current and the setpoint current. The resulting current flowing through the battery system depends on the ratio of the voltage amplitude deviation to the network voltage. By regulating the voltage to a value greater than the network voltage, the discharge current is controlled, while by regulating the voltage to a value less than the network voltage, the recharge current is controlled.

[0078] The regulation module 22 can act directly on the sinusoidal quantities, or by controlling the estimated direct and quadrature components, or by a control technique involving, for example, mathematical transformations. In single-phase or multi-phase (two, three or more phases), the regulation module 22 comprises a regulation loop that uses a corrector based on the estimated electrical characteristics of the battery system and the current setpoint to control the voltage setpoint Vref of the or each current link of the battery system.

[0079] In case of three-phase application, refer to Figure 2 , transformation components 220 and 221 are provided for transforming the RMS current setpoint value Iref in amperes and the measured current Ibat of the battery system into digital models of vector commands Iref1 and Ibat1, respectively, with a 50 Hz rotating magnetic field in the Park plane. The resulting vector commands Iref1 and Ibat1 are used by a corrector 222 in a regulation loop to determine the voltage setpoint value of the battery system, which takes the form of a setpoint value of a vector command Vregc.

[0080] Transformation components 220 and 221 are mathematical and signal processing functions that perform the Park transform, which is known to those skilled in the art in the field of electrical engineering for controlling three-phase motors. The Park transform has the advantage of simplifying and improving the performance of current and voltage controllers. The possibility of implementing other control principles is not excluded. Corrector 222 is a servo function known to those skilled in the art suitable for manipulating voltage setpoints. Corrector 222 is, for example, of the proportional-integral type. Other types of correctors are contemplated. In a variant, transformation components 220 and 221 can be estimators for estimating the electrical characteristics of the measured signal or for estimating the DC and quadrature components.

[0081] Each of these conversion functions 210 and 211 for implementing voltage regulation, as well as the blocks 220 and 221 for implementing current regulation, takes as input an estimate 201 of the phase difference of the network voltage signal, so as to adapt the vector commands used in the regulation loop to any possible variations in the phase of the network. In fact, the phase may vary in cases where charging is required or when increasing the network's energy production. This improves the accuracy of the synchronization and the current regulation.

[0082] The setpoint value Vregc, in the form of a vector command from the current regulation 22, ensures current servoing by regulating the voltage setpoint value Vref of the current line or each current line of the battery system. When synchronization is detected to transmit a reference voltage setpoint adapted to the operation of the battery system, the setpoint value Vregc is transmitted to the modulation block 240. The same modulation block 240 as the synchronization block 21 or another modulation block specific to current regulation is used.

[0083] exist Figure 4 In Figure 1, a line graph shows a simulation of a current regulation operation for a battery system. The horizontal axis is the time axis. In the upper range, the line graph shows the current setpoint Iref and the resulting current in the form of the RMS value of the current path. The middle range shows the current Ires of a line of the network and the current of the corresponding line of the battery system. The lower range shows the number of cell clusters Qcl activated during current regulation. In this example, the current path includes 24 cell clusters connected in series in the battery's current path.

[0084] This graph shows that starting at 1.15 seconds, the current setpoint Iref is controlled to an RMS value of 16A. The battery current value increases very quickly, reaching the setpoint Iref at 1.4 seconds. The current regulation dynamics during this transition phase are very fast because the impedance of the electrical circuit is very low. Current convergence occurs in less than 200 milliseconds. The current profile is observed to be stable, with the current Icl flowing through the cluster always positive. The AC current Ires corresponds to the current in the network.

[0085] exist Figure 5In the figure, a flow chart is shown, which describes a control method according to the present invention for controlling a battery system to implement synchronization and charging and discharging current regulation. The method is implemented by a computing component having an integrated circuit of a control unit of the battery system. A computer program can be provided by the control unit of the battery system, the computer program comprising instructions which, when executed, direct the control unit to implement a control method for implementing synchronization and current regulation of the battery system. The method is applicable to recharging and discharging on single-phase and multi-phase power supply networks. Synchronization and current regulation can be performed on the current line of the battery or on multiple current lines (for example, two current lines of a battery in a two-phase configuration connected to a two-phase network, three current lines of a battery in a three-phase configuration connected to a three-phase network, four or more current lines).

[0086] In a first step E1 , the method consists in determining the electrical characteristics of the voltage wave of the power supply network, in particular the voltage and the phase of each current line of said network.

[0087] The method then comprises controlling the synchronization E2 of the electrical characteristics of the voltage wave of the or each current line of the battery system with the corresponding wave of the power supply network. During synchronization, the contactor Kres is opened, with reference to Figure 1 The synchronization aims to adjust the voltage value and phase of the battery system by taking the voltage of the network as a reference.

[0088] During synchronization, the method provides, in step E3 , for verifying the synchronization state, which is the ratio of the voltage error between the network wave and the battery voltage wave relative to a predetermined error threshold, to determine the closing moment of the high-voltage contactor.

[0089] When the error is greater than the threshold, voltage regulation remains active and the resulting voltage setpoint of the regulation controls the battery system. The contactor remains open.

[0090] When the error becomes smaller than the error threshold, the method controls, in step E4 , the electrical connection of the or each current line of the battery system to the power supply network.

[0091] The method then controls, in step E5, the current regulation of the or each circuit of the battery system by taking into account the current setpoint I in the RMS value formula and the estimated RMS current of the battery. The method provides for determining a voltage setpoint in order to manipulate the voltage waveforms of the circuits of the battery system. By generating a voltage amplitude deviation between the synchronized voltage waveforms, either a charging current or a discharging current is generated in the or each current circuit of the battery.

[0092] The voltage and current regulation loops used for synchronization E2 and current regulation E5 in the method comprise servo loops including a correction. In a non-limiting example, the servo loops are of the PL correction type.

[0093] In the case of a three-phase battery system and network, the voltage and current regulation loops for implementing synchronization (E2) and current regulation (E5) involve converting or estimating the battery system's setpoints and measured values into vector commands in the Park plane for a 50 Hz rotating magnetic field. The Park transformation has the advantage of simplifying and improving the performance of the current and voltage controllers. The possibility of implementing other control principles is not excluded.

[0094] Furthermore, the control method according to the invention is applicable to single-phase or multi-phase battery systems. In single-phase or multi-phase configurations, the voltage synchronization step E2 and the current regulation step E5 can act either directly on the sinusoidal quantities, or via the management of the estimated direct and quadrature components, or by a control technique involving, for example, mathematical transformations.

[0095] exist Figure 6 , an embodiment of the application of a battery system 60 according to the present invention in a motor vehicle having an all-electric powertrain or a hybrid powertrain is described. The vehicle includes an electric power machine 64 capable of transmitting torque to drive wheels 62 of the vehicle via a transmission component 61. The electric power machine 64 may be three-phase. The vehicle includes a battery system 60, according to Figure 1 As described in , the battery system has a distributed multilevel inverter in the battery according to the architecture. The battery includes three current lines that can generate a three-phase voltage wave. The vehicle also includes a recharging interface 68 for recharging the battery from a power supply network operating at an AC voltage. The recharging interface 68 is a recharging box that, according to the method according to the present invention, is used to electrically connect the terminals of the battery 60 to the terminals for implementing AC voltage recharging. The recharging interface 68 can also implement fast recharging with a DC voltage. The advantage of the battery system 60 is that the control unit 65 of the battery system adapts the voltage wave to an AC form or a DC wave form without the need for a voltage converter.

[0096] The vehicle also includes a monitoring system 66 that cooperates with a control unit 65 of the battery system 60. The battery system 60 can be directly electrically connected to the electric power machine 64, thereby improving the energy efficiency of the electric power machine in terms of traction. The battery can also be connected to the vehicle's high-voltage DC onboard electrical network 63 (which operates at a nominal voltage of, for example, 350 volts) and to a low-voltage onboard electrical network 67 (which operates at a nominal voltage of, for example, 12 volts) that includes the battery. The DC onboard electrical networks 63 and 67 can be powered by the battery 60, optionally via an AC / DC converter.

[0097] Likewise, thanks to the present invention, after the synchronization phase, battery 60 can be securely connected electrically to an external, external electrical power supply system via recharging terminals operating at AC voltage. The charging and discharging currents are controlled by battery control unit 65 by regulating the voltage of the circuits of battery system 60.

Claims

1. A battery system (BAT) with electrochemical cells, the battery system being intended for recharging / discharging on an extended electrical supply network (RES) operating at an AC voltage, the system (BAT) comprising at least one current line (LT1), the at least one current line comprising a plurality of basic modules (MCLk) forming a distributed multilevel inverter, each of the plurality of basic modules being equipped with a cell or a cell cluster, and comprising a control unit (BMS) for controlling the basic modules (MCLk), the control unit being capable of generating a selected AC voltage waveform at the terminals of the current line (LT1) according to a reference voltage setpoint (Vref), characterised in that The system (BAT) further comprises: - determination means (20) for determining the electrical characteristics of the alternating voltage wave of the power supply network (RES), - a synchronization means (21) for synchronizing the electrical characteristics of the alternating voltage wave of the current line (LT1) of the battery system (BAT) with the alternating voltage wave of the power supply network (RES), an electrical connection element (Kres) for electrically connecting the power line (LT1) to the power supply network (RES), the electrical connection element being controlled as a function of the synchronization state (STE) of the voltage waveforms of the battery system (BAT) and of the network (RES), - a current regulating component (22) for regulating the current of the battery system (BAT) by manipulating a reference voltage set value (Vref) of a current line of the battery system (BAT).

2. The system according to claim 1, comprising three current paths (LT1, LT2, LT3), wherein: The synchronization component (21) includes: a conversion component (210, 211), the conversion component is used to convert the measured voltages (Vbat, Vres) of the lines (LT1, LT2, LT3) of the battery system (BAT) and the network (RES) into a first vector command (Vres1, Vbat1); a determination component (212), the determination component is used to determine a first voltage setting value (Vsync) in the form of a vector command by a first regulator, the first regulator taking the first vector command (Vres1, Vbat1) as input; and a first modulation component (240), the first modulation component is used to modulate the first voltage setting value (Vsync) into a reference voltage setting value (Vref) of the battery system (BAT).

3. The system according to claim 1 or 2, comprising three current paths (LT1, LT2, LT3), wherein: The current regulating component (22) comprises: a conversion component (220, 221), the conversion component being used to convert the measured current (Ibat) of the lines (LT1, LT2, LT3) of the battery system (BAT) and the reference current setting value (Iref) into a second vector command (Iref1, Ibat1) of the current; a determination component (222), the determination component being used to determine a second voltage setting value (Vregc) in the form of a vector command by a second regulator, the second regulator taking the second vector command (Iref1, Ibat1) as input; and a second modulation component (240), the second modulation component being used to modulate the second voltage setting value (Vregc) into a reference voltage setting value (Vref) of the battery system.

4. The system according to claim 2 or 3, further comprising an estimator (202) for estimating the phase (201) of the power supply network (RES), wherein The transformation means (210, 211, 220, 221) of the first vector command (Vres1, Vbat1) and / or the second vector command (Iref1, Ibat1) also depend on the estimation of said phase (201).

5. The system according to any one of claims 1 to 4, further comprising an estimator (212) for estimating a voltage amplitude deviation (Verr) between the voltage waves of the power supply network (RES) and the battery system (BAT), wherein The synchronization state (STE) depends on the ratio of the deviation (Verr) to a predetermined error threshold.

6. An electric motor vehicle comprising a rechargeable battery system (60) and an electrical interface (68) for connecting the battery system (60) to an extended electrical power supply network for recharging and discharging on the power supply network, wherein The battery system (60) is a battery system according to any one of claims 1 to 5.

7. A stationary battery system comprising a rechargeable battery system and an electrical interface for connecting the battery system to an extended electrical power supply network, wherein: The battery system is the battery system according to any one of claims 1 to 5.

8. A control method for controlling a battery system (BAT) having electrochemical cells, the battery system being configured to discharge / recharge on an extended electrical supply network (RES), the control method comprising the following steps in succession: - determining (E1) electrical characteristics of the alternating voltage wave of said power supply network (RES), - synchronizing (E2) the electrical characteristics of the alternating voltage wave of at least one current line (LT1) of the battery system (BAT) with the alternating voltage wave of the power supply network (RES), - electrically connecting (E4) the current line to the power supply network when it is detected (E3) that the synchronization state of the voltage waves of the battery system (BAT) and the network (RES) is less than a predetermined error threshold, - The current of the line (LT1) of the battery system (BAT) is then regulated (E5) by manipulating a reference voltage setpoint (Vref) adapted to the manipulation of the current line (LT1) of the battery system (BAT).

9. The control method according to claim 8, wherein: The synchronization (E2) comprises the following steps: - transforming the measured voltages (Vbat, Vres) of the lines (LT1, LT2, LT3) of the battery system (BAT) and of the network (RES) into first vector commands (Vres1, Vbat1), - determining a first voltage setpoint (Vsync) in the form of a vector command by a first regulator (212) which takes as input the first vector command (Vres1, Vbat1), - Modulating a first voltage set value (Vsync) in the form of a vector command to generate a reference voltage set value (Vref) to generate the voltage wave to be synchronized.

10. The control method according to claim 8 or 9, wherein: The current regulation (E5) of the battery system (BAT) comprises the following steps: - transforming the measured current (Ibat) of the lines (LT1, LT2, LT3) of the battery system (BAT) and a reference current setpoint (Iref) into a second vector command (Iref1, Ibat1) for the current, - determining a second voltage setpoint (Vregc) in the form of a vector command by a second regulator (222) which takes as input the second vector command (Iref1, Ibat1), - modulating a second voltage set point (Vregc) in the form of a vector command to generate a reference voltage set point (Vref) for regulating the charge / discharge current of the battery system (BAT).

Images