Method for controlling battery charging in a single-phase current electrical system for generating a DC voltage in a parallel mode

Abstract

The present invention relates to a polyphase electrical system comprising a battery with a multilevel inverter distributed in the battery and comprising three current lines (LT1, LT2, LT3) and a diode module, wherein, during an operation for charging the battery with single-phase alternating current, the diode module powers a DC bus from two lines only from among the three lines (LT1, LT2, LT3), and wherein the voltages of each of the three lines (LT1, LT2, LT3) are controlled so as to generate a first DC voltage from the composition of the voltages of the two lines (LT2, LT3; LT2, LT1) and simultaneously generate a single-phase AC voltage (Vac) from the three lines (LT1, LT2, LT3) on the phase branch (BP1) in order to charge the battery (BAT). The invention further relates to a method for controlling the electrical system. The invention is applicable to electrified motor vehicles and to stationary storage systems.

Description

DESCRIPTION TITLE: METHOD FOR CONTROLLING A BATTERY CHARGE OF A SINGLE-PHASE ELECTRICAL SYSTEM FOR THE GENERATION OF A DIRECT VOLTAGE IN PARALLEL MODE

[0001] The present invention claims priority from French application No. 2305330 filed on 05 / 30 / 2023, the content of which (text, drawings and claims) is incorporated herein by reference.

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

[0003] Electrified vehicles have a high-power traction battery, typically operating in a voltage range of 260 volts to 450 volts. When charging a vehicle with single-phase current, an AC / DC converter converts the alternating current into compatible direct current from the battery, and a DC / DC converter transforms this direct voltage into a lower voltage suitable for the on-board network, typically around 12 volts. It is therefore possible to generate the on-board network voltage while the vehicle is charging.

[0004] The applicant has developed a disruptive architecture known as a distributed multilevel inverter which makes it possible to dispense with the voltage converters usually integrated between an electrochemical cell battery and the power supply network operating at alternating voltage. This architecture has been the subject of several patent applications by the applicant. Examples include documents W0-A1 -2017 / 153366 and W0-A1 -2021 / 048477. They describe a cell architecture which comprises current lines formed by elementary modules each comprising an electrochemical cell, or a cluster of cells, and a switching module forming an H-bridge. These documents also describe innovative control methods for this architecture allowing the balancing of the cells in the state of charge and the generation of polyphase or direct electric current.

[0005] The generation of DC voltage from the on-board network during AC vehicle charging is problematic for this architecture because it is necessary to activate the generation of a direct voltage by controlling the multi-level inverter distributed in the battery, then to produce the direct current of the on-board network via a DC / DC converter. To solve this problem of generating direct voltage during charging of the vehicle on an alternating current network, the applicant has provided a solution consisting of injecting a common mode voltage on all three current lines. This solution is described in patent document FR-A1-3121797.

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

[0007] There is therefore a need to overcome the aforementioned problems. One objective of the invention is to propose a single-phase alternating current charging protocol for a vehicle equipped with a distributed multi-level inverter battery architecture, making it possible to maintain the voltage of the vehicle's on-board network during charging.

[0008] More specifically, the invention relates to a polyphase electrical system comprising a power battery with electrochemical cells, a diode module, switches and three phase branches connected to an extended electrical power supply network, the battery comprising three current lines, each line comprising a plurality of elementary modules connected in series, each provided with a cell or a cluster of cells and a switching module comprising an H-bridge, forming a multilevel inverter distributed in the battery capable of generating a voltage waveform chosen at the terminals of each current line, switches being arranged so as to connect the three lines in series to a phase branch when charging the battery from a single-phase alternating charging current, the diode module supplying a direct voltage bus from voltages generated by said three current lines.

[0009] According to the invention, when charging the battery with single-phase alternating current, the diode module supplies the voltage bus from only two lines among said three lines, and the voltages of each of the three lines are controlled so as to generate a first direct voltage from the composition of the voltages of said two lines and to simultaneously generate a single-phase alternating voltage from the three lines on the phase branch for charging the battery.

[0010] The system according to the invention may include the following additional characteristics, alone or in combination:

[0011] - The diode module comprises at least four diodes: a first diode and a second diode being connected to the current lines in the on state during a negative alternation of the load current so as to connect in series a first current line and a second current line to the diode module, third diode and a fourth diode being connected to the current lines in the on state during a positive alternation of the load current so as to connect in series the second current line and the third current line to the diode module.

[0012] - The diode module has a fifth, sixth and seventh diodes each connected to a specific current line during a three-phase alternating current battery charge.

[0013] - The voltages of the two lines supplying the diode module are controlled according to at least one voltage distribution parameter according to the following relationships: Vrefl = Vdc-Vac, Vref2 = Vac / 3 + D1 and Vref3 = Vdc - (Vac / 3) - D1, in positive alternation of the load current of the supply network, Vrefl = Vdc - Vac / 3 - D2, Vref2 = Vac / 3 + D2 and Vref3 = Vdc-Vac, in negative alternation of the load current of the supply network, where Vrefl, Vref2 and Vref3 are the voltages of the first, second and third current lines respectively, Vdc being the first direct voltage, Vac being the single-phase alternating voltage, D1 and D2 being first and second distribution parameters expressed in volts.

[0014] The invention also provides a motor vehicle comprising an electrical system according to any one of the preceding embodiments and a direct voltage bus supplied by the first direct voltage at the output of the diode module of said system during charging of the battery in single-phase alternating current.

[0015] According to a variant, the vehicle further comprises a converter, a direct voltage network and a service battery of said network electrically connected to the direct voltage bus and arranged so that the converter converts the first direct voltage into a second direct voltage to supply the direct voltage network while the battery is charging.

[0016] Further provided according to the invention is a stationary storage system comprising an electrical system according to any one of the embodiments. previous and a direct voltage bus powered by the first direct voltage at the output of the diode module of said system during a single-phase alternating current battery charge.

[0017] The invention further provides a method for controlling such a polyphase electrical system comprising the following steps during charging of the battery in single-phase alternating current:

[0018] - connecting the three lines in series to a phase branch during battery charging,

[0019] - connection of only two lines out of the three lines to the DC voltage bus via the diode module,

[0020] - controlling the voltages of each of the three lines so as to generate a first direct voltage from the composition of the voltages of said two lines and to simultaneously generate a single-phase alternating voltage from the three lines on the phase branch to charge the battery.

[0021] According to a variant of the method, the voltages of the two lines supplying the diode module are controlled according to at least one voltage distribution parameter according to the following relationships: Vrefl = Vdc-Vac, Vref2 = Vac / 3 + D1 and Vref3 = Vdc - Vac / 3 - D1, in positive alternation of the load current of the supply network, Vrefl = Vdc - Vac / 3 - D2, Vref2 = Vac / 3 + D2 and Vref3 = Vdc-Vac, in negative alternation of the load current of the supply network, where Vrefl, Vref2 and Vref3 are the voltages of the first, second and third current lines respectively, Vdc being the first direct voltage, Vac being the single-phase alternating voltage, D1 and D2 being first and second distribution parameters expressed in volts.

[0022] The invention provides a control unit of a polyphase electrical system configured to implement the control method according to any of its embodiments.

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

[0024] The electrical system of the invention allows generating a DC voltage bus simultaneously with single-phase current charging of a battery with an integrated multi-level inverter. The solution is also advantageous for its low cost and the battery voltage wave control solution which is entirely software-based.

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

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

[0027] [Fig.2] represents a first embodiment of the electrical system according to the invention comprising a diode module provided for the generation of a direct voltage simultaneously with a single-phase current recharge of the battery.

[0028] [Fig.3] represents the configuration of the switches of the electrical system according to the invention for this first embodiment during the generation of the direct voltage simultaneously with a single-phase current recharge of the battery.

[0029] [Fig.4] represents the alternating voltage generated by the three current lines of the battery during recharging with single-phase current supplied by the supply network.

[0030] [Fig.5] represents a simplified electrical diagram of the electrical system according to the invention during recharging during a positive alternation and a negative alternation of the charging current.

[0031] [Fig.6] includes graphs illustrating the voltages generated by the cells of the current lines LT1, LT2 and LT3 to generate the direct voltage Vdc during single-phase current charging in accordance with a first mode of configuration of the voltage distribution parameters.

[0032] [Fig.7] represents a graph illustrating the power absorbed by the cells of each current line LT1, LT2 and LT3 during single-phase AC charging according to the first configuration mode. On average, the simulation shows that the power absorbed is 763W per branch, or 2.3kW on the supply network side.

[0033] [Fig.8] represents a second embodiment of the electrical system according to the invention comprising a diode module provided for the generation of a direct voltage simultaneously with a recharge of the battery in single-phase current or in three-phase current.

[0034] [Fig.9] represents an embodiment of the electrical system for an electrified vehicle.

[0035] The invention relates to a polyphase electrical system for energy storage for electrified motor vehicles and stationary storage systems in electrical installations, for example for renewable energy or grid regulation installations. The polyphase system comprises an electrochemical battery comprising elementary cell modules interconnected so as to form a distributed multi-level inverter structure in the battery allowing the battery to be connected to an electrical system operating with direct voltage and also with alternating voltage without the intermediary of an inverter. The battery system can be connected directly to an extensive electrical supply network and to an electrical motive machine. The aim of the invention is to provide a control method for maintaining the voltage of a direct DC network supplied by the power battery during charging with single-phase alternating current.In particular, the method aims to maintain the voltage of an electrified vehicle's on-board network while the vehicle is charging.

[0036] In the present description, the term distributed multilevel inverter means that the current line or each current line of the battery, in the case of a polyphase architecture, in particular three-phase, is formed by a plurality of elementary modules connected in series and each elementary module comprises a cell or a cluster of cells, as well as a switching module forming an H-bridge, the control unit comprises a means for controlling the elementary modules of the current line according to a reference setpoint and is capable of generating a chosen voltage waveform, alternating and direct, on each current line. This architecture is the subject of a more detailed description in figure 1.

[0037] With reference to Figure 1, the power battery BAT comprises a plurality n of elementary modules MCLk forming the multi-level inverter structure distributed in the battery and comprises three current lines LT1, LT2 and LT3 connected to phase branches BP1, BP2 and BP3 and in which the modules are arranged MCLk elementary modules. The MCLk elementary modules are connected in series in each current line. The phase branches BP1, BP2 and BP3 allow the battery to be connected to different systems intended to use alternating or direct voltage. In this three-phase configuration, each current line has n / 3 elementary modules.

[0038] The BAT battery system has a voltage of several hundred volts at its terminals, for example 350 volts or 1000 volts. At 350 volts, each LT1, LT2, LT3 line is equipped, for example, with 24 elementary cell modules or cell clusters connected in series. However, depending on the electrical requirements, the BAT battery system has a nominal voltage of only several tens of volts (24V, 36V, 48V for example), particularly for automotive applications, or at a maximum voltage of 1500 volts DC or even higher, particularly for stationary storage systems.

[0039] In a first set of branch connections of the phase branches BP1, BP2 and BP3, the BAT battery system comprises high-voltage switches Kres, also called high-voltage contactors, intended to electrically connect the BAT battery to an extended electrical supply network RES. Each current line LT1, LT2 and LT3 is connected, via these 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 RES supply network operates at 50Hz or 60Hz alternating voltage and comprises a three-phase line equipped with three voltage lines P1, P2 and P3. The BAT battery system is adapted to generate three three-phase voltage waves offset by 2TT / 3. The control of each current line is similar, differing only by a 2TT / 3 offset between them.

[0040] It should be noted that, thanks to this distributed multi-level inverter architecture in the battery, the electrical system does not include an AC / DC voltage converter between the current lines LT1, LT2 and LT3 and the phase branches BP1, BP2 and BP3 operating in alternating current.

[0041] Furthermore, in the case of an embodiment for an electrified vehicle, the battery system BAT is the traction battery of the vehicle and further comprises high voltage switches Kmel intended to electrically connect the battery BAT to an electric motor machine MEL. Each current line LT1, LT2 and LT3 is connected, via a second set of derivations of the phase branches BP1, BP2 and BP3, on 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 driving electric machine can be an asynchronous or synchronous machine, possibly a direct current machine because the battery system is capable of generating any voltage waveform, alternating or direct.

[0042] Alternatively, for an embodiment of a renewable energy installation, the second phase branch branch assembly may be connected to a photovoltaic installation or a wind turbine installation. Alternatively, the battery is connected to the power supply network for network regulation purposes.

[0043] Furthermore, another set of branches is provided for connecting the battery to a DC voltage bus. This part will be described in more detail in the following figures to describe the control method for maintaining the voltage of a DC voltage network during single-phase AC charging of the battery.

[0044] The BAT battery system further comprises a BMS control unit, one of the functions of which is to control the voltage waveform of each line LT1, LT2, LT3 as a function of a reference setpoint Vref from the elementary modules MCLk. Each elementary module MCLk may comprise a single cell CLk, or a cluster of cells CLk which may be two, three, four, five, six or more cells, forming the elementary voltage Vclk. The elementary module MCLk further comprises a switching module COMk capable of configuring the elementary module MCLk in three different states to deliver the voltage Vmclk which is respectively said elementary voltage Vclk, a zero voltage and the inverted voltage Vclk to said connection terminals of the module MCLk.

[0045] The switching module COMk is for example made up of two switching parts forming an H-bridge controllable in the three different states by a control signal from the BMS control unit of the battery BAT specifically addressing the module MCLk. The states are represented by a control variable uik which can take for example the values ​​1, 0, -1 representing the three different states respectively controlling said elementary voltage Vclk, a zero voltage and said inverted voltage -Vclk at said connection terminals of the elementary module k addressed by the control signal uik. Each switching module COMk comprises electronic components, such as power transistors, possibly of the MOSFET or HEMT (High Electron Mobility Transistor) type, controlled by the control signals of the BMS control unit. Thus, the voltage Vmclk at the terminals of each elementary module MCLk among the set of a totality n of modules can be controlled according to a control signal uik according to the following relationship:

[0046] [Math 1]

[0048] Thus, the BMS control unit can control on each voltage line LT1, LT2 and LT3, any voltage waveform formed by steps of amplitude equal to the elementary voltage Vclk as a function of a reference voltage setpoint Vref by connecting the cells in series via the switching modules COMk. The reference voltage setpoint Vref can be of sinusoidal form with a frequency of 50 Hz, any alternating form, for example square, or can be of constant voltage for example.

[0049] It is recalled that an electrochemical cell is an electrical energy accumulator having two terminals, a positive electrode and a negative electrode, and presenting a voltage of a few volts, most often between 2.3V and 4.2V, approximately. The cells can be of the Lithium-ion type (a lithium Nickel Manganese Cobalt oxide NMC or a lithium iron phosphate LFP can be cited as examples of positive electrode active materials), Nickel Cadmium (Ni-cd), Nickel-Metal-Hydride (Ni-MH) for example. More precisely, a Lithium-ion cell is composed mainly of a porous positive electrode, a porous negative electrode, a separator and an electrolyte (which can be liquid, polymeric or solid). The operating principle of a Lithium-ion cell is based on the reversible exchange of lithium ions between the two porous electrodes.

[0050] In Figure 2, the BAT battery system is shown in a more simplified way in the polyphase electrical system. For the sake of clarity, the branch assembly of the prime mover is no longer shown. The electrical system comprises a first embodiment of an RD diode module allowing the generation of a direct voltage Vdc during single-phase current charging.

[0051] The polyphase electrical system comprises a third set of branch connections of the phase branches PB1, PB2 and PB3 for connecting the battery BAT to a direct voltage bus BDC. This set of branch connections comprises four branch connections DV1, DV2, DV3 and DV4 connected to the current lines of the battery. The branch connections DV1, DV2, DV3 and DV4 are connected to the diode module RD comprising four diodes d1, d2, d3 and d4, each branch comprising one diode respectively. The diode module RD has the function of generating a first direct voltage Vdc adjustable in shape and amplitude and is supplied at a given moment from only two lines among said three current lines of the battery BAT during a single-phase alternating current charge of the battery.When charging with single-phase current, it is intended to control a charging protocol during which the voltages of each of the three lines LT 1 , LT2 and LT3 are controlled according to voltage distribution parameters so as to generate the first direct voltage Vdc at the terminals of two lines, simultaneously with the generation of the single-phase alternating voltage on the phase branch BP1 . The first voltage Vdc is generated from a composition of the voltages of the lines LT 1 and LT2 or of the lines LT2 and LT3. In addition, the diodes d1 , d2, d3 and d4 and the respective derivations DV1 , DV2, DV3 and DV4 are arranged in such a way that the polarity of the charging current voltage determines which lines are used for the generation of the first voltage Vdc.

[0052] Concerning the electrical architecture of the RD diode module, the DV1 branch and the d1 diode connect point A to point E in the blocked direction of the d1 diode. Point A is positioned at the input of the LT1 current line, between the RES power supply network and the BAT battery. Point E is connected to a negative pole of the Vdc direct voltage bus. The DV2 branch and the d2 diode connect point B to the positive pole of the BDC direct voltage bus in the forward direction of the d2 diode. Point B is positioned between the LT1 line and the LT2 line. The DV3 branch and the d3 diode connect point C to the positive pole of the BDC direct voltage bus in the forward direction of the d3 diode. Point C is positioned between the LT2 current line and the LT3 line. The DV4 branch and the d4 diode connect point D to point E in the blocked direction of the d4 diode. Point D is positioned on the terminal of line LT3 connected to the neutral line.In addition, switches K6, K7, K8 and K9 are provided, arranged for connecting and disconnecting. selectively the diodes d1, d2, d3 and d4 to their respective derivation DV1, DV2, DV3 and DV4. The diodes d2 and d3 are connected together to the voltage bus BDC.

[0053] The RD diode module is made of common components that are easy to obtain and install. In addition, the diodes have the advantage of being reliable, robust and inexpensive.

[0054] Furthermore, in this example, a CONV DC / DC voltage converter is provided, connected to the output of the RD diode module and designed to convert the first voltage Vdc into a second voltage Vrdb of lower level, for example 12 volts. Other values ​​are possible depending on the intended application, which may be between 12 volts and 600 volts. This CONV converter supplies a direct voltage network RDB when the converter is supplied by the Vdc voltage. It is further provided that the direct voltage network RDB includes a service battery BAT2 to stabilize the voltage of the RDB network and to ensure the electrical needs of the RDB network when the CONV converter is not supplying it.

[0055] The DC voltage bus (DCB) is suitable for powering at least one system operating in DC voltage. It electrically powers one or more devices from a set of devices including one or more DC / DC voltage converters, an electric compressor, an electric heater, for example in the case of an electrified vehicle application. Other electrical systems are possible depending on the application.

[0056] In addition, the polyphase system comprises switches K4 and K5 arranged to selectively connect in series and in parallel the current lines LT 1 , LT2 and LT3 thus allowing single-phase operation and three-phase operation of the battery. More precisely, in single-phase configuration, switches KR2 and KR3 and K5 are open, and switches KR1 and K4 are closed. Thus the current lines LT 1 , LT2 and LT3 are connected in series to the phase branch BP1 connected to the extended power supply network RES. In three-phase configuration, switch K4 is open and switches KR1 , KR2, KR3 and K5 are closed. Thus the current lines LT1 , LT2 and LT3 are connected respectively to the phase branches BP1 , BP2 and BP3 connected to the extended power supply network RES.

[0057] Figure 3 represents the configuration of the electrical system for which the switches are driven in the positions allowing the battery to be charged in single-phase alternating current simultaneously with the generation of the first direct voltage Vdc at the output of the RD diode module.

[0058] The diode module RD is configured so that only two lines among the three lines generate the first direct voltage Vdc. The specific control of the voltages generated by each of the three lines controls the value of the voltage Vdc as well as the distribution of the voltages between the two lines. The invention therefore further provides a method for controlling the polyphase electrical system for connecting the diode module on the one hand, and on the other hand for controlling the voltage distribution between the two current lines used to generate the desired voltage Vdc. Several modes of voltage distribution configuration are possible and will be the subject of a more detailed description in the rest of the text for two distinct modes.

[0059] The control method is executed by a control unit of the polyphase electrical system. The control unit may be, for example, the battery control unit BAT or a supervisory control unit of a vehicle equipped with the polyphase electrical system. The control unit is provided with an integrated circuit computer and electronic memories, the computer and the memories being configured to execute the control method according to the invention. But this is not obligatory. Indeed, the computer could be external to the battery control unit or the supervisor, while being coupled to the latter. The control unit, according to the invention, may be implemented in the form of software modules (or computer modules (or "software")), or electronic circuits (or "hardware"), or a combination of electronic circuits and software modules.

[0060] According to the control method, to control a single-phase AC load from the supply network, switches KR1, K4, K6, K7, K8 and K9 are driven in the closed position. Switches KR2, KR3 and k5 are driven in the open position. The diode module RD is connected to the battery via branches DV1, DV2, DV3 and DV4. Current lines LT1, LT2 and LT3 are connected in series.

[0061] When recharging the battery cells, the voltage Vac generated between points A and D, composed of the sum of the voltages of lines LT1, LT2 and LT3, is in the form of a sinusoidal alternating voltage, for example a sinusoidal wave with a frequency of 50 Hz. More precisely, the battery control unit controls the elementary modules MCLk of the current lines LT1, LT2 and LT3 according to reference setpoints Vrefl , Vref2 and Vref3 synchronized with the single-phase alternating current of the RES supply network. A part k of the cells among the n cells of the three lines LT1 , LT2 and LT3 are connected in series so as to generate a synchronized alternating voltage wave. Once the synchronization is effective, with respect to a synchronization criterion, the control unit (supervision or battery) commands the connection of the three current lines to the phase branch BP1 connected to the network. The alternating current delivered by the RES network passes through the k electric cells of the battery which are selected to form the voltage wave.

[0062] During a positive alternation of the battery charging current, the voltage P1 of the supply network RES is higher than the neutral voltage N, the diodes d2 and d4 are conducting. The diodes d1 and d3 are blocked. Only the set of cell modules forming part of the LT2 line and the LT3 line can generate the first direct voltage Vdc, while the LT 1 line generates the alternating voltage Vdc - Vac.

[0063] During a negative alternation of the battery charging current, the voltage P1 of the supply network RES is lower than the neutral voltage N, the diodes d1 and d3 are conducting. The diodes d2 and d4 are blocked. Only the set of cell modules forming the line LT1 and the line LT2 can generate the first direct voltage Vdc, while the line LT3 generates the alternating voltage Vdc - Vac.

[0064] The control method therefore provides a step of controlling the voltages of each of the lines according to voltage distribution parameters so as to generate the first direct voltage Vdc at the terminals of the two lines LT2 and LT3 or LT1 and LT2 according to the sign alternation.

[0065] Figure 4 illustrates the single-phase alternating voltage that is generated on the phase branch of the battery system from the series-connected cells of the three current lines LT1, LT2 and LT3 configured in series. The lower curve represents the voltage Vac generated at the battery terminals, expressed in volts, and the upper curve represents the current lac of the supply network expressed in amperes.

[0066] Figure 5 illustrates the simplified electrical diagram of the electrical system in positive alternation and negative alternation for a first mode of configuration of the voltage distribution parameters aimed at distributing a balanced power between the current lines LT1, LT2 and LT3 under load.

[0067] More precisely, according to the distribution law controlled by the control unit, a first parameter D1 applies in positive alternation and a second parameter D2 applies in negative alternation. The parameters D1 and D2 are expressed as voltage values ​​in volts and are used to determine the power distribution between the lines. Vac is the reference single-phase alternating voltage of the supply network. D1 is the power distribution between the current lines LT1 and LT2 in positive alternation.

[0068] The voltages Vrefl , Vref2 and Vref3 for lines LT1 , LT2 and LT3 respectively are controlled according to the following relationship in positive alternation: Vrefl = Vdc-Vac, Vref2 = Vac / 3 + D1 and Vref3 = Vdc - Vac / 3 - D1 .

[0069] The voltages Vrefl, Vref2 and Vref3 for lines LT1, LT2 and LT3 respectively are controlled according to the following relationship in negative alternation Vrefl = Vdc - Vac / 3 - D2, Vref2 = Vac / 3 + D2 and Vref3 = Vdc-Vac.

[0070] In this non-limiting example of distribution of the first configuration mode, the power per current line is approximately equal to the value of lac*Vac / 3, D1 is then equal to 0 volts, and D2 is equal to 0 volts. Therefore in positive alternation: Vrefl = Vdc - Vac, Vref2 = Vac / 3 and Vref3 = Vdc-Vac / 3.

[0071] Figure 6 illustrates, in a first graph in the upper part, the voltages Vrefl, Vref2 and Vref3 generated by the cells of the current lines LT1, LT2 and LT3 respectively of the battery to generate the direct voltage Vdc during recharging in single-phase current for this first mode of configuration of the power balance distribution. The direct voltage Vdc is equal to 450 volts.

[0072] The second graph in the lower part illustrates the Vdc voltage obtained from the voltages generated by the battery module from only two current lines, LT2 and LT3 in positive alternation and LT1 and LT2 in negative alternation. The composition of the two voltages, Vref 2 and Vref 3 in positive alternation and Vref 1 and Vref 2 in negative alternation, forms a plateau voltage signal which allows the diode module to generate at its output the direct voltage Vdc, here 450 volts.

[0073] Figure 7 illustrates the power absorbed by the cells of each current line LT1, LT2 and LT3 during a single-phase AC battery charge according to the first configuration mode of the voltage distribution parameters. On average, the electrical system absorbs a power of 763W per current line, which is the equivalent of 2.3kW (10 Arms x 230 Vrms) on the grid side.

[0074] In Figure 8, another embodiment of the electrical architecture of the system is shown in which the diode module comprises diodes d1, d2, d3 and d4 allowing the generation of the first direct voltage Vdc in single-phase charging, in accordance with the embodiment described previously in Figure 2. The system further comprises diodes d3, d5 and d6 which allow the generation of the first direct voltage Vdc in three-phase charging. This diode module can be produced in the form of a single module where diode d3 is used in common for single-phase charging and three-phase charging. In a variant of this embodiment, the diode module can comprise four diodes for single-phase charging connected similarly to diodes d1, d2, d3 and d4, and three other diodes connected similarly to diodes d3, d5 and d6 for three-phase charging.In addition, switches K6, K7, K8, K9, K10 and K11 are selectively driven to connect each branch according to single-phase or three-phase charging mode.

[0075] It should be noted that whatever the charging mode, the Vdc voltage is adjustable in amplitude from the control of the voltage waves of each voltage line. In three-phase alternating current charging mode, the Vdc voltage can be generated simultaneously with charging by injecting a common mode voltage into the three current lines LT1, LT2 and LT3. This operating mode was the subject of French patent application FR-A1-3121797 by the applicant and is described in more detail in this document.

[0076] In Figure 9 an embodiment of the electrical system is shown for an electrified vehicle with a fully electric motor or hybrid motor. The vehicle comprises an electric motor 64 capable of transmitting torque to the drive wheels 62 of the vehicle through a transmission 61. The electric machine 64 can be three-phase. The vehicle comprises an electrical system comprising the battery 60 according to the architecture with a multi-level inverter distributed in the battery in accordance with the description given in Figure 1. The battery comprises three current lines capable of generating three-phase and single-phase voltage waves. The vehicle further comprises an interface for recharging the battery 68 from a power supply network operating at alternating voltage. The recharging interface 68 is a recharging box electrically connecting the terminals of the battery 60 to the terminal for recharging at alternating voltage in single-phase or three-phase current.The charging interface 68 is also capable of rapid charging with direct voltage. The battery system 60 is. advantageous in that its control unit 65 adapts the voltage wave into alternating form or continuous wave form without using a voltage converter. The vehicle further comprises a supervision system 66 cooperating with the control unit 65 of the battery system 60. The battery system 60 can be directly electrically connected to the electric motor 64, thus improving its energy efficiency in traction.

[0077] The battery can further be connected to a high voltage DC bus, for example operating at a nominal voltage of between 100 and 800 volts, for example 450 volts, and to a low voltage on-board network 67 operating at a nominal voltage of type 12 volts. For this purpose, the electrical system comprises power electronics 69 comprising a diode module electrically connected to the current lines of the battery. The diode module is formed by at least four diodes according to the embodiments described in FIG. 2 or FIG. 6. The output of the diode module supplies the 450 volt voltage bus. In addition, the power electronics 69 comprises a DC / DC converter connecting the voltage bus to the on-board network 67 (450 volts / 12 volts) comprising a service battery.The electrical system is controlled so that the service battery supplies the said DC network during the first phase of the process and the converter converts the DC bus voltage (450 volts) to low voltage (12 volts) to supply the on-board network and charge the service battery during the second phase of the process.

[0078] In another embodiment, a stationary storage system is contemplated comprising the electrical system according to the invention.

[0079] The invention is described in the above by way of example. It is understood that the person skilled in the art is able to produce different variant embodiments of the invention by associating, for example, the different characteristics above taken alone or in combination, without departing from the scope of the invention.

Claims

CLAIMS 1. Polyphase electrical system comprising a power battery (BAT) with electrochemical cells, a diode module (RD), switches and three phase branches (BP1, BP2, BP3) connected to an extended electrical power supply network (RES), the battery (BAT) comprising three current lines (LT1, LT2, LT3), each line comprising a plurality of elementary modules (MCLk) connected in series, each provided with a cell (CLk) or a cluster of cells and a switching module (COMk) comprising an H-bridge, forming a multilevel inverter distributed in the battery (BAT) capable of generating a voltage waveform chosen at the terminals of each current line (LT1), switches (K4, K5) being arranged so as to connect the three lines (LT1, LT2, LT3) in series to a phase branch (BP1) when charging the battery from a charging current (lake) single-phase alternating current,the diode module (RD) supplying a direct voltage bus (BDC) from voltages (Vrefl, Vref2, Vref3) generated by said three current lines (LT1, LT2, LT3), characterized in that, when charging the battery with single-phase alternating current, the diode module (RD) supplies the voltage bus (BDC) from two lines (LT2, LT3; LT2, LT1) only among said three lines (LT1, LT2, LT3), and in that the voltages (Vrefl, Vref2, Vref3) of each of the three lines (LT1, LT2, LT3) are controlled so as to generate a first direct voltage (Vdc) from the composition of the voltages of said two lines (LT2, LT3; LT2, LT1) and to simultaneously generate a single-phase alternating voltage (Vac) from the three lines (LT 1 , LT2, LT3) on the phase branch (BP1 ) for charging the battery (BAT)., 2. Electrical system according to claim 1 in which the diode module comprises at least four diodes (d1, d2, d3, d4): a first diode (d1) and a second diode (d3) being connected to the current lines in the on state during a negative alternation of the load current (lac) so as to connect in series a first current line (LT1) and a second current line (LT2) to the diode module (RD), a third diode (d2) and a fourth diode (d4) being connected to the current lines in the on state during a positive alternation of the load current (lac) so as to connect in series the second current line (LT2) and the third current line (LT3) to the diode module (RD).

3. Electrical system according to claim 2, in which the diode module (RD) comprises a fifth, sixth and seventh diodes (d3, d5, d6) each connected to a specific current line (LT1, LT2, LT3) during charging of the battery (BAT) in three-phase alternating current.

4. Electrical system according to any one of claims 1 to 3, in which the voltages of the two lines (Vref2, Vref3; Vrefl, Vref2) supplying the diode module (RD) are controlled as a function of at least one voltage distribution parameter (D1, D2) according to the following relationships: Vrefl = Vdc-Vac, Vref2 = Vac / 3 + D1 and Vref3 = Vdc - (Vac / 3) - D1, in positive alternation of the load current of the supply network (RES), Vrefl = Vdc - Vac / 3 - D2, Vref2 = Vac / 3 + D2 and Vref3 = Vdc-Vac, in negative alternation of the load current of the supply network (RES), where Vrefl, Vref2 and Vref3 are the voltages of the first, second and third current lines respectively (LT1, LT2, LT3), Vdc being the first direct voltage, Vac being the single-phase alternating voltage, D1 and D2 being first and second distribution parameters expressed in volts.

5. Motor vehicle comprising an electrical system according to any one of claims 1 to 4 and a direct voltage bus (BDC) supplied by the first direct voltage (Vdc) at the output of the diode module (RD) of said system during charging of the battery (BAT) in single-phase alternating current.

6. Vehicle according to claim 5 further comprising a converter (CONV), a direct voltage network (RDB) and a service battery (BAT2) of said network electrically connected to the direct voltage bus (BDC) and arranged so that the converter (CONV) converts the first direct voltage (Vdc) into a second direct voltage (Vrdb) to supply the direct voltage network (RDB) during charging of the battery (BAT).

7. Stationary storage system comprising an electrical system according to any one of claims 1 to 4 and a direct voltage bus (DCB) powered by the first direct voltage (Vdc) at the output of the diode module (RD) of said system during a single-phase alternating current battery (BAT) charge.

8. Method for controlling a polyphase electrical system according to any one of claims 1 to 4, characterized in that it comprises the following steps during charging of the battery (BAT) in single-phase alternating current: connecting the three lines (LT 1 , LT2, LT3) in series to a phase branch (BP1 ) during charging of the battery, connecting only two lines (LT2, LT3; LT2, LT1 ) among the three lines (LT1 , LT2, LT3) to the direct voltage bus (BDC) via the diode module (RD), controlling the voltages (Vrefl , Vref2, Vref3) of each of the three lines so as to generate a first direct voltage (Vdc) from the composition of the voltages of said two lines (Vref2, Vref3; Vrefl , Vref2) and simultaneously generating a single-phase alternating voltage (Vrefl , Vref2, Vref3) from the three lines (LT 1 , LT2, LT3) on the phase branch (BP1 ) to charge the battery (BAT).

9. Control method according to claim 8 in which the voltages of the two lines (Vref2, Vref3; Vrefl, Vref2) supplying the diode module (RD) are controlled as a function of at least one voltage distribution parameter (D1, D2) according to the following relationships: Vrefl = Vdc-Vac, Vref2 = Vac / 3 + D1 and Vref3 = Vdc - (Vac / 3) - D1, in positive alternation of the load current of the supply network (RES), Vrefl = Vdc - Vac / 3 - D2, Vref2 = Vac / 3 + D2 and Vref3 = Vdc-Vac, in negative alternation of the load current of the supply network (RES), where Vrefl, Vref2 and Vref3 are the voltages of the first, second and third current lines respectively (LT1, LT2, LT3), Vdc being the first direct voltage, Vac being the single-phase alternating voltage, D1 and D2 being first and second distribution parameters expressed in volts.

10. Control unit of an electrical system configured to implement the control method according to any one of claims 8 to 9.

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